fix(vue): eslint/tsconfig migration + resolve type errors

@robonen/vue (toolkit): migrate to eslint flat config + composite tsconfig;
fix composable + test type errors (writable computed returns, null guards,
overload-compatible signatures, typed test helpers) — all type-level.

vue/toolkit/README.md

@@ -1,6 +1,6 @@
 # @robonen/vue
 
-Collection of composables and utilities for Vue 3.
+Collection of composables and utilities for Vue 3 — 100+ tree-shakeable, SSR-safe composables.
 
 ## Install
 
@@ -11,18 +11,31 @@ pnpm install @robonen/vue
 ## Composables
 
 | Category       | Composables |
-| -------------- | ------------------------------------------------------------------ |
+| -------------- | ----------- |
-| **browser**    | `useEventListener`, `useFocusGuard`, `useSupported`                |
+| **browser**    | `onKeyStroke`, `useActiveElement`, `useBodyScrollLock`, `useClickOutside`, `useClipboard`, `useCloseWatcher`, `useColorMode`, `useDevicePixelRatio`, `useDocumentReadyState`, `useDocumentVisibility`, `useDropZone`, `useElementBounding`, `useElementHover`, `useElementSize`, `useElementVisibility`, `useEscapeKey`, `useEventListener`, `useEyeDropper`, `useFavicon`, `useFileDialog`, `useFocus`, `useFocusGuard`, `useFocusWithin`, `useFps`, `useFullscreen`, `useGeolocation`, `useIdle`, `useIntersectionObserver`, `useIntervalFn`, `useKeyModifier`, `useMagicKeys`, `useMediaQuery`, `useMouse`, `useMousePressed`, `useMutationObserver`, `useNetwork`, `useObjectUrl`, `useOnline`, `usePageLeave`, `usePermission`, `usePointer`, `usePreferredColorScheme`, `usePreferredDark`, `useRafFn`, `useResizeObserver`, `useScreenOrientation`, `useScroll`, `useScrollLock`, `useShare`, `useSupported`, `useSwipe`, `useTabLeader`, `useTextSelection`, `useTitle`, `useVibrate`, `useWindowFocus`, `useWindowScroll`, `useWindowSize` |
-| **component**  | `unrefElement`, `useRenderCount`, `useRenderInfo`                  |
+| **component**  | `unrefElement`, `useForwardExpose`, `useTemplateRefsList` |
+| **debug**      | `useRenderCount`, `useRenderInfo` |
 | **lifecycle**  | `tryOnBeforeMount`, `tryOnMounted`, `tryOnScopeDispose`, `useMounted` |
 | **math**       | `useClamp` |
-| **reactivity** | `broadcastedRef`, `useCached`, `useLastChanged`, `useSyncRefs`     |
+| **reactivity** | `broadcastedRef`, `refAutoReset`, `refDebounced`, `refThrottled`, `until`, `useArrayFilter`, `useArrayFind`, `useArrayMap`, `useCached`, `useCloned`, `useCycleList`, `useLastChanged`, `usePrevious`, `useSyncRefs`, `useToNumber`, `useToString`, `watchDebounced`, `watchIgnorable`, `watchOnce`, `watchPausable`, `watchThrottled`, `whenever` |
-| **state**      | `useAppSharedState`, `useAsyncState`, `useContextFactory`, `useCounter`, `useInjectionStore`, `useToggle` |
+| **state**      | `useAppSharedState`, `useAsyncState`, `useContextFactory`, `useCounter`, `useId`, `useInjectionStore`, `useStepper`, `useToggle` |
 | **storage**    | `useLocalStorage`, `useSessionStorage`, `useStorage`, `useStorageAsync` |
-| **utilities**  | `useOffsetPagination`                                              |
+| **utilities**  | `useDebounceFn`, `useInterval`, `useOffsetPagination`, `useThrottleFn`, `useTimeoutFn`, `useTimestamp` |
+
+The package also exports event-filter helpers (`debounceFilter`, `throttleFilter`, `pausableFilter`, `createFilterWrapper`) and shared types (`ConfigurableWindow`, `ConfigurableDocument`, `ConfigurableNavigator`, `MaybeComputedElementRef`, …).
 
 ## Usage
 
 ```ts
-import { useToggle, useEventListener } from '@robonen/vue';
+import { useEventListener, useMagicKeys, useToggle } from '@robonen/vue';
+
+const { value, toggle } = useToggle();
+
+useEventListener('scroll', () => {/* … */}, { passive: true });
+
+const keys = useMagicKeys();
+watchEffect(() => {
+  if (keys['ctrl+s'].value)
+    save();
+});
 ```

vue/toolkit/eslint.config.ts

@@ -0,0 +1,3 @@
+import { base, compose, imports, stylistic, typescript, vitest, vue } from '@robonen/eslint';
+
+export default compose(base, typescript, vue, vitest, imports, stylistic);

vue/toolkit/oxlint.config.ts

@@ -1,4 +0,0 @@
-import { defineConfig } from 'oxlint';
-import { compose, base, typescript, vue, vitest, imports, stylistic } from '@robonen/oxlint';
-
-export default defineConfig(compose(base, typescript, vue, vitest, imports, stylistic));

vue/toolkit/package.json

@@ -37,19 +37,18 @@
     }
   },
   "scripts": {
-    "lint:check": "oxlint -c oxlint.config.ts",
+    "lint:check": "eslint .",
-    "lint:fix": "oxlint -c oxlint.config.ts --fix",
+    "lint:fix": "eslint . --fix",
     "test": "vitest run",
     "dev": "vitest dev",
     "build": "tsdown"
   },
   "devDependencies": {
-    "@robonen/oxlint": "workspace:*",
+    "@robonen/eslint": "workspace:*",
     "@robonen/tsconfig": "workspace:*",
     "@robonen/tsdown": "workspace:*",
-    "@stylistic/eslint-plugin": "catalog:",
     "@vue/test-utils": "catalog:",
-    "oxlint": "catalog:",
+    "eslint": "catalog:",
     "tsdown": "catalog:"
   },
   "dependencies": {

vue/toolkit/src/composables/browser/index.ts

@@ -1,7 +1,58 @@
+export * from './onKeyStroke';
+export * from './useActiveElement';
+export * from './useBodyScrollLock';
+export * from './useClickOutside';
+export * from './useClipboard';
+export * from './useCloseWatcher';
+export * from './useColorMode';
+export * from './useDevicePixelRatio';
+export * from './useDocumentReadyState';
+export * from './useDocumentVisibility';
+export * from './useDropZone';
+export * from './useElementBounding';
+export * from './useElementHover';
+export * from './useElementSize';
+export * from './useElementVisibility';
+export * from './useEscapeKey';
 export * from './useEventListener';
+export * from './useEyeDropper';
+export * from './useFavicon';
+export * from './useFileDialog';
+export * from './useFocus';
 export * from './useFocusGuard';
+export * from './useFocusWithin';
 export * from './useFps';
+export * from './useFullscreen';
+export * from './useGeolocation';
+export * from './useIdle';
+export * from './useIntersectionObserver';
 export * from './useIntervalFn';
+export * from './useKeyModifier';
+export * from './useMagicKeys';
+export * from './useMediaQuery';
+export * from './useMouse';
+export * from './useMousePressed';
+export * from './useMutationObserver';
+export * from './useNetwork';
+export * from './useObjectUrl';
+export * from './useOnline';
+export * from './usePageLeave';
+export * from './usePermission';
+export * from './usePointer';
+export * from './usePreferredColorScheme';
+export * from './usePreferredDark';
 export * from './useRafFn';
+export * from './useResizeObserver';
+export * from './useScreenOrientation';
+export * from './useScroll';
+export * from './useScrollLock';
+export * from './useShare';
 export * from './useSupported';
+export * from './useSwipe';
 export * from './useTabLeader';
+export * from './useTextSelection';
+export * from './useTitle';
+export * from './useVibrate';
+export * from './useWindowFocus';
+export * from './useWindowScroll';
+export * from './useWindowSize';

vue/toolkit/src/composables/browser/onKeyStroke/index.test.ts

@@ -0,0 +1,237 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, ref } from 'vue';
+import { onKeyDown, onKeyPressed, onKeyStroke, onKeyUp } from '.';
+
+function keydown(key: string, init: KeyboardEventInit = {}, target: EventTarget = globalThis) {
+  target.dispatchEvent(new KeyboardEvent('keydown', { key, ...init }));
+}
+
+describe(onKeyStroke, () => {
+  let stops: Array<() => void> = [];
+
+  function track(stop: () => void) {
+    stops.push(stop);
+    return stop;
+  }
+
+  afterEach(() => {
+    stops.forEach(stop => stop());
+    stops = [];
+  });
+
+  it('fires the handler for a matching string key', () => {
+    const handler = vi.fn();
+    track(onKeyStroke('a', handler));
+
+    keydown('a');
+    expect(handler).toHaveBeenCalledTimes(1);
+    expect(handler.mock.calls[0]![0]).toBeInstanceOf(KeyboardEvent);
+  });
+
+  it('ignores non-matching keys', () => {
+    const handler = vi.fn();
+    track(onKeyStroke('a', handler));
+
+    keydown('b');
+    expect(handler).not.toHaveBeenCalled();
+  });
+
+  it('matches any key in an array filter', () => {
+    const handler = vi.fn();
+    track(onKeyStroke(['a', 'b', 'c'], handler));
+
+    keydown('a');
+    keydown('b');
+    keydown('z');
+    expect(handler).toHaveBeenCalledTimes(2);
+  });
+
+  it('uses a predicate filter', () => {
+    const handler = vi.fn();
+    track(onKeyStroke((e: KeyboardEvent) => e.metaKey && e.key === 's', handler));
+
+    keydown('s');
+    expect(handler).not.toHaveBeenCalled();
+
+    keydown('s', { metaKey: true });
+    expect(handler).toHaveBeenCalledTimes(1);
+  });
+
+  it('matches every key when filter is omitted', () => {
+    const handler = vi.fn();
+    track(onKeyStroke(handler));
+
+    keydown('a');
+    keydown('b');
+    expect(handler).toHaveBeenCalledTimes(2);
+  });
+
+  it('matches every key when filter is `true`', () => {
+    const handler = vi.fn();
+    track(onKeyStroke(true, handler));
+
+    keydown('x');
+    expect(handler).toHaveBeenCalledTimes(1);
+  });
+
+  it('supports the handler-plus-options overload', () => {
+    const handler = vi.fn();
+    const target = document.createElement('div');
+    track(onKeyStroke(handler, { target }));
+
+    keydown('a', {}, target);
+    expect(handler).toHaveBeenCalledTimes(1);
+
+    keydown('a');
+    expect(handler).toHaveBeenCalledTimes(1);
+  });
+
+  it('attaches to a custom target', () => {
+    const handler = vi.fn();
+    const target = document.createElement('div');
+    track(onKeyStroke('a', handler, { target }));
+
+    keydown('a', {}, target);
+    expect(handler).toHaveBeenCalledTimes(1);
+
+    keydown('a');
+    expect(handler).toHaveBeenCalledTimes(1);
+  });
+
+  it('listens on a custom eventName', () => {
+    const handler = vi.fn();
+    const target = document.createElement('div');
+    track(onKeyStroke('a', handler, { target, eventName: 'keyup' }));
+
+    keydown('a', {}, target);
+    expect(handler).not.toHaveBeenCalled();
+
+    target.dispatchEvent(new KeyboardEvent('keyup', { key: 'a' }));
+    expect(handler).toHaveBeenCalledTimes(1);
+  });
+
+  it('dedupe ignores auto-repeated events', () => {
+    const handler = vi.fn();
+    track(onKeyStroke('a', handler, { dedupe: true }));
+
+    keydown('a', { repeat: false });
+    keydown('a', { repeat: true });
+    keydown('a', { repeat: true });
+    expect(handler).toHaveBeenCalledTimes(1);
+  });
+
+  it('dedupe accepts a reactive ref', () => {
+    const handler = vi.fn();
+    const dedupe = ref(false);
+    track(onKeyStroke('a', handler, { dedupe }));
+
+    keydown('a', { repeat: true });
+    expect(handler).toHaveBeenCalledTimes(1);
+
+    dedupe.value = true;
+    keydown('a', { repeat: true });
+    expect(handler).toHaveBeenCalledTimes(1);
+  });
+
+  it('without dedupe still fires for repeated events', () => {
+    const handler = vi.fn();
+    track(onKeyStroke('a', handler));
+
+    keydown('a', { repeat: true });
+    keydown('a', { repeat: true });
+    expect(handler).toHaveBeenCalledTimes(2);
+  });
+
+  it('stop handle removes the listener', () => {
+    const handler = vi.fn();
+    const stop = onKeyStroke('a', handler);
+
+    stop();
+    keydown('a');
+    expect(handler).not.toHaveBeenCalled();
+  });
+
+  it('cleans up when the effect scope is disposed', () => {
+    const handler = vi.fn();
+    const scope = effectScope();
+
+    scope.run(() => {
+      onKeyStroke('a', handler);
+    });
+
+    scope.stop();
+    keydown('a');
+    expect(handler).not.toHaveBeenCalled();
+  });
+
+  it('returns a no-op when target is unavailable (SSR / unsupported)', () => {
+    const handler = vi.fn();
+    const stop = onKeyStroke('a', handler, { target: null });
+
+    expect(typeof stop).toBe('function');
+    keydown('a');
+    expect(handler).not.toHaveBeenCalled();
+    // stop should be safely callable
+    expect(() => stop()).not.toThrow();
+  });
+});
+
+describe(onKeyDown, () => {
+  let stop: (() => void) | undefined;
+
+  afterEach(() => {
+    stop?.();
+    stop = undefined;
+  });
+
+  it('listens for keydown', () => {
+    const handler = vi.fn();
+    const target = document.createElement('div');
+    stop = onKeyDown('a', handler, { target });
+
+    keydown('a', {}, target);
+    expect(handler).toHaveBeenCalledTimes(1);
+  });
+});
+
+describe(onKeyUp, () => {
+  let stop: (() => void) | undefined;
+
+  afterEach(() => {
+    stop?.();
+    stop = undefined;
+  });
+
+  it('listens for keyup', () => {
+    const handler = vi.fn();
+    const target = document.createElement('div');
+    stop = onKeyUp('a', handler, { target });
+
+    keydown('a', {}, target);
+    expect(handler).not.toHaveBeenCalled();
+
+    target.dispatchEvent(new KeyboardEvent('keyup', { key: 'a' }));
+    expect(handler).toHaveBeenCalledTimes(1);
+  });
+});
+
+describe(onKeyPressed, () => {
+  let stop: (() => void) | undefined;
+
+  afterEach(() => {
+    stop?.();
+    stop = undefined;
+  });
+
+  it('listens for keypress', () => {
+    const handler = vi.fn();
+    const target = document.createElement('div');
+    stop = onKeyPressed('a', handler, { target });
+
+    keydown('a', {}, target);
+    expect(handler).not.toHaveBeenCalled();
+
+    target.dispatchEvent(new KeyboardEvent('keypress', { key: 'a' }));
+    expect(handler).toHaveBeenCalledTimes(1);
+  });
+});

vue/toolkit/src/composables/browser/onKeyStroke/index.ts

@@ -0,0 +1,197 @@
+import type { VoidFunction } from '@robonen/stdlib';
+import { isArray, isFunction, isString, noop } from '@robonen/stdlib';
+import { toValue } from 'vue';
+import type { MaybeRefOrGetter } from 'vue';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { defaultWindow } from '@/types';
+
+export type KeyPredicate = (event: KeyboardEvent) => boolean;
+export type KeyFilter = true | string | string[] | KeyPredicate;
+export type KeyStrokeEventName = 'keydown' | 'keypress' | 'keyup';
+
+export interface OnKeyStrokeOptions {
+  /**
+   * The keyboard event to listen for.
+   *
+   * @default 'keydown'
+   */
+  eventName?: KeyStrokeEventName;
+
+  /**
+   * The element to attach the listener to.
+   *
+   * @default window
+   */
+  target?: MaybeRefOrGetter<EventTarget | null | undefined>;
+
+  /**
+   * Register the listener as passive (cannot call `preventDefault`).
+   *
+   * @default false
+   */
+  passive?: boolean;
+
+  /**
+   * Ignore auto-repeated keydown events while a key is held down.
+   *
+   * @default false
+   */
+  dedupe?: MaybeRefOrGetter<boolean>;
+}
+
+/**
+ * Build a predicate from a key filter.
+ *
+ * - `function` → used as-is.
+ * - `string`   → matches `event.key`.
+ * - `string[]` → matches any key in the list.
+ * - `true`/anything else → matches every event.
+ */
+function createKeyPredicate(keyFilter: KeyFilter): KeyPredicate {
+  if (isFunction(keyFilter))
+    return keyFilter;
+
+  if (isString(keyFilter))
+    return (event: KeyboardEvent) => event.key === keyFilter;
+
+  if (isArray(keyFilter))
+    return (event: KeyboardEvent) => keyFilter.includes(event.key);
+
+  return () => true;
+}
+
+/**
+ * @name onKeyStroke
+ * @category Browser
+ * @description Listen for keyboard strokes. Accepts a key, list of keys, or a predicate and
+ * fires the handler for matching events. Auto-cleans up on scope dispose.
+ *
+ * Overload 1: Explicit key filter
+ */
+export function onKeyStroke(key: KeyFilter, handler: (event: KeyboardEvent) => void, options?: OnKeyStrokeOptions): VoidFunction;
+
+/**
+ * @name onKeyStroke
+ * @category Browser
+ * @description Listen for every keyboard stroke (no key filter).
+ *
+ * Overload 2: Omitted key filter (matches all keys)
+ *
+ * @param {(event: KeyboardEvent) => void} handler Callback invoked on a matching key event
+ * @param {OnKeyStrokeOptions} [options] Listener configuration
+ * @returns {VoidFunction} Stop handle that removes the listener
+ *
+ * @example
+ * onKeyStroke('ArrowDown', (e) => { e.preventDefault(); });
+ * onKeyStroke(['a', 'b', 'c'], (e) => console.log(e.key));
+ * onKeyStroke((e) => e.metaKey && e.key === 's', save, { eventName: 'keydown' });
+ *
+ * @since 0.0.15
+ */
+export function onKeyStroke(handler: (event: KeyboardEvent) => void, options?: OnKeyStrokeOptions): VoidFunction;
+
+export function onKeyStroke(...args: any[]): VoidFunction {
+  let key: KeyFilter;
+  let handler: (event: KeyboardEvent) => void;
+  let options: OnKeyStrokeOptions = {};
+
+  if (args.length === 3) {
+    key = args[0];
+    handler = args[1];
+    options = args[2];
+  }
+  else if (args.length === 2) {
+    if (typeof args[1] === 'object') {
+      key = true;
+      handler = args[0];
+      options = args[1];
+    }
+    else {
+      key = args[0];
+      handler = args[1];
+    }
+  }
+  else {
+    key = true;
+    handler = args[0];
+  }
+
+  const {
+    target = defaultWindow,
+    eventName = 'keydown',
+    passive = false,
+    dedupe = false,
+  } = options;
+
+  if (!target)
+    return noop;
+
+  const predicate = createKeyPredicate(key);
+
+  const listener = (event: KeyboardEvent) => {
+    if (event.repeat && toValue(dedupe))
+      return;
+
+    if (predicate(event))
+      handler(event);
+  };
+
+  return useEventListener(target, eventName, listener, { passive });
+}
+
+/**
+ * @name onKeyDown
+ * @category Browser
+ * @description Listen for `keydown` strokes. Shorthand for `onKeyStroke` with `eventName: 'keydown'`.
+ *
+ * @param {KeyFilter} key Key, list of keys, or predicate to match
+ * @param {(event: KeyboardEvent) => void} handler Callback invoked on a matching key event
+ * @param {Omit<OnKeyStrokeOptions, 'eventName'>} [options] Listener configuration
+ * @returns {VoidFunction} Stop handle that removes the listener
+ *
+ * @example
+ * onKeyDown('Enter', submit);
+ *
+ * @since 0.0.15
+ */
+export function onKeyDown(key: KeyFilter, handler: (event: KeyboardEvent) => void, options: Omit<OnKeyStrokeOptions, 'eventName'> = {}): VoidFunction {
+  return onKeyStroke(key, handler, { ...options, eventName: 'keydown' });
+}
+
+/**
+ * @name onKeyUp
+ * @category Browser
+ * @description Listen for `keyup` strokes. Shorthand for `onKeyStroke` with `eventName: 'keyup'`.
+ *
+ * @param {KeyFilter} key Key, list of keys, or predicate to match
+ * @param {(event: KeyboardEvent) => void} handler Callback invoked on a matching key event
+ * @param {Omit<OnKeyStrokeOptions, 'eventName'>} [options] Listener configuration
+ * @returns {VoidFunction} Stop handle that removes the listener
+ *
+ * @example
+ * onKeyUp('Escape', close);
+ *
+ * @since 0.0.15
+ */
+export function onKeyUp(key: KeyFilter, handler: (event: KeyboardEvent) => void, options: Omit<OnKeyStrokeOptions, 'eventName'> = {}): VoidFunction {
+  return onKeyStroke(key, handler, { ...options, eventName: 'keyup' });
+}
+
+/**
+ * @name onKeyPressed
+ * @category Browser
+ * @description Listen for `keypress` strokes. Shorthand for `onKeyStroke` with `eventName: 'keypress'`.
+ *
+ * @param {KeyFilter} key Key, list of keys, or predicate to match
+ * @param {(event: KeyboardEvent) => void} handler Callback invoked on a matching key event
+ * @param {Omit<OnKeyStrokeOptions, 'eventName'>} [options] Listener configuration
+ * @returns {VoidFunction} Stop handle that removes the listener
+ *
+ * @example
+ * onKeyPressed('a', type);
+ *
+ * @since 0.0.15
+ */
+export function onKeyPressed(key: KeyFilter, handler: (event: KeyboardEvent) => void, options: Omit<OnKeyStrokeOptions, 'eventName'> = {}): VoidFunction {
+  return onKeyStroke(key, handler, { ...options, eventName: 'keypress' });
+}

vue/toolkit/src/composables/browser/useActiveElement/index.test.ts

@@ -0,0 +1,207 @@
+import { describe, expect, it } from 'vitest';
+import { effectScope, isReadonly, nextTick } from 'vue';
+import { useActiveElement } from '.';
+
+describe(useActiveElement, () => {
+  it('tracks the focused element', async () => {
+    const input = document.createElement('input');
+    document.body.appendChild(input);
+
+    const scope = effectScope();
+    let active: ReturnType<typeof useActiveElement>;
+    scope.run(() => {
+      active = useActiveElement();
+    });
+
+    input.focus();
+    input.dispatchEvent(new FocusEvent('focusin', { bubbles: true }));
+    await nextTick();
+
+    expect(active!.value).toBe(input);
+
+    scope.stop();
+    input.remove();
+  });
+
+  it('returns a shallow ref (not readonly)', () => {
+    const scope = effectScope();
+    let active: ReturnType<typeof useActiveElement>;
+    scope.run(() => {
+      active = useActiveElement();
+    });
+
+    // shallowRef is writable internally; ensure we did not return a readonly wrapper
+    expect(isReadonly(active!)).toBeFalsy();
+
+    scope.stop();
+  });
+
+  it('reflects the active element on creation', () => {
+    const input = document.createElement('input');
+    document.body.appendChild(input);
+    input.focus();
+
+    const scope = effectScope();
+    let active: ReturnType<typeof useActiveElement>;
+    scope.run(() => {
+      active = useActiveElement();
+    });
+
+    // initial trigger should capture the already-focused element synchronously
+    expect(active!.value).toBe(input);
+
+    scope.stop();
+    input.remove();
+  });
+
+  it('traverses open shadow roots when deep', async () => {
+    const host = document.createElement('div');
+    document.body.appendChild(host);
+    const shadow = host.attachShadow({ mode: 'open' });
+    const inner = document.createElement('input');
+    shadow.appendChild(inner);
+
+    const scope = effectScope();
+    let active: ReturnType<typeof useActiveElement>;
+    scope.run(() => {
+      active = useActiveElement();
+    });
+
+    inner.focus();
+    document.dispatchEvent(new FocusEvent('focusin', { bubbles: true }));
+    await nextTick();
+
+    expect(active!.value).toBe(inner);
+
+    scope.stop();
+    host.remove();
+  });
+
+  it('does not descend into shadow roots when deep is false', async () => {
+    const host = document.createElement('div');
+    document.body.appendChild(host);
+    const shadow = host.attachShadow({ mode: 'open' });
+    const inner = document.createElement('input');
+    shadow.appendChild(inner);
+
+    const scope = effectScope();
+    let active: ReturnType<typeof useActiveElement>;
+    scope.run(() => {
+      active = useActiveElement({ deep: false });
+    });
+
+    inner.focus();
+    document.dispatchEvent(new FocusEvent('focusin', { bubbles: true }));
+    await nextTick();
+
+    // with deep:false we stay at the shadow host instead of piercing it
+    expect(active!.value).toBe(host);
+
+    scope.stop();
+    host.remove();
+  });
+
+  it('resets when focus leaves the window (blur with no relatedTarget)', async () => {
+    const input = document.createElement('input');
+    document.body.appendChild(input);
+
+    const scope = effectScope();
+    let active: ReturnType<typeof useActiveElement>;
+    scope.run(() => {
+      active = useActiveElement();
+    });
+
+    input.focus();
+    globalThis.dispatchEvent(new FocusEvent('focus'));
+    await nextTick();
+    expect(active!.value).toBe(input);
+
+    // simulate focus leaving the document entirely
+    input.blur();
+    globalThis.dispatchEvent(new FocusEvent('blur', { relatedTarget: null }));
+    await nextTick();
+    expect(active!.value).toBe(document.body);
+
+    scope.stop();
+    input.remove();
+  });
+
+  it('ignores window blur when focus moves to another element (relatedTarget set)', async () => {
+    const input = document.createElement('input');
+    document.body.appendChild(input);
+
+    const scope = effectScope();
+    let active: ReturnType<typeof useActiveElement>;
+    scope.run(() => {
+      active = useActiveElement();
+    });
+
+    input.focus();
+    await nextTick();
+    expect(active!.value).toBe(input);
+
+    // blur carrying a relatedTarget means focus stayed within the page -> ignore
+    const other = document.createElement('button');
+    globalThis.dispatchEvent(new FocusEvent('blur', { relatedTarget: other }));
+    await nextTick();
+    expect(active!.value).toBe(input);
+
+    scope.stop();
+    input.remove();
+  });
+
+  it('accepts a custom document via options', () => {
+    const fakeEl = document.createElement('textarea');
+    const fakeDocument = { activeElement: fakeEl } as unknown as Document;
+
+    const scope = effectScope();
+    let active: ReturnType<typeof useActiveElement>;
+    scope.run(() => {
+      active = useActiveElement({ document: fakeDocument });
+    });
+
+    expect(active!.value).toBe(fakeEl);
+
+    scope.stop();
+  });
+
+  it('does not throw and stays undefined when document has no active element', () => {
+    // emulate an environment (e.g. SSR / detached document) with no focus
+    const emptyDocument = { activeElement: null } as unknown as Document;
+
+    const scope = effectScope();
+    let active: ReturnType<typeof useActiveElement>;
+    scope.run(() => {
+      // pass a real window so listeners attach without error, but a doc with no focus
+      active = useActiveElement({ document: emptyDocument });
+    });
+
+    expect(active!.value).toBeNull();
+
+    scope.stop();
+  });
+
+  it('re-evaluates when the active element is removed (triggerOnRemoval)', async () => {
+    const input = document.createElement('input');
+    document.body.appendChild(input);
+
+    const scope = effectScope();
+    let active: ReturnType<typeof useActiveElement>;
+    scope.run(() => {
+      active = useActiveElement({ triggerOnRemoval: true });
+    });
+
+    input.focus();
+    await nextTick();
+    expect(active!.value).toBe(input);
+
+    input.remove();
+    // MutationObserver delivery is async; wait a microtask-ish tick
+    await new Promise(resolve => setTimeout(resolve, 0));
+    await nextTick();
+
+    expect(active!.value).toBe(document.body);
+
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useActiveElement/index.ts

@@ -0,0 +1,111 @@
+import { shallowRef } from 'vue';
+import type { ShallowRef } from 'vue';
+import { defaultWindow } from '@/types';
+import type { ConfigurableDocument, ConfigurableWindow } from '@/types';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { useMutationObserver } from '@/composables/browser/useMutationObserver';
+
+export interface UseActiveElementOptions extends ConfigurableWindow, ConfigurableDocument {
+  /**
+   * Search for the active element inside open shadow roots
+   *
+   * @default true
+   */
+  deep?: boolean;
+  /**
+   * Re-evaluate the active element when it is removed from the DOM.
+   * Uses a `MutationObserver` under the hood, so it is only enabled on demand.
+   *
+   * @default false
+   */
+  triggerOnRemoval?: boolean;
+}
+
+export type UseActiveElementReturn<T extends HTMLElement = HTMLElement> = ShallowRef<T | null | undefined>;
+
+/**
+ * @name useActiveElement
+ * @category Browser
+ * @description Reactive `document.activeElement`, traversing open shadow roots.
+ *
+ * @param {UseActiveElementOptions} [options={}] Options
+ * @returns {UseActiveElementReturn<T>} The currently focused element
+ *
+ * @example
+ * const active = useActiveElement();
+ *
+ * @example
+ * // keep tracking even if the focused node is detached from the DOM
+ * const active = useActiveElement({ triggerOnRemoval: true });
+ *
+ * @since 0.0.15
+ */
+export function useActiveElement<T extends HTMLElement>(
+  options: UseActiveElementOptions = {},
+): UseActiveElementReturn<T> {
+  const {
+    window = defaultWindow,
+    deep = true,
+    triggerOnRemoval = false,
+  } = options;
+
+  const document = options.document ?? window?.document;
+
+  const getDeepActiveElement = (): Element | null | undefined => {
+    let element = document?.activeElement;
+
+    if (deep) {
+      while (element?.shadowRoot)
+        element = element.shadowRoot.activeElement;
+    }
+
+    return element;
+  };
+
+  const activeElement = shallowRef<T | null | undefined>();
+
+  const trigger = (): void => {
+    activeElement.value = getDeepActiveElement() as T | null | undefined;
+  };
+
+  if (window) {
+    const listenerOptions = { capture: true, passive: true } as const;
+
+    // `focus` (capture) catches focus moving onto any element, including those
+    // inside open shadow roots; `blur` with no `relatedTarget` resets the ref
+    // when focus leaves the document/window entirely.
+    useEventListener(
+      window,
+      'blur',
+      (event: FocusEvent) => {
+        if (event.relatedTarget !== null)
+          return;
+
+        trigger();
+      },
+      listenerOptions,
+    );
+    useEventListener(window, 'focus', trigger, listenerOptions);
+  }
+
+  if (triggerOnRemoval && document) {
+    useMutationObserver(
+      () => [document.body],
+      (mutations) => {
+        for (const mutation of mutations) {
+          for (const removed of mutation.removedNodes) {
+            if (removed === activeElement.value || removed.contains(activeElement.value as Node)) {
+              trigger();
+              return;
+            }
+          }
+        }
+      },
+      { window, childList: true, subtree: true },
+    );
+  }
+
+  trigger();
+
+  return activeElement;
+}

vue/toolkit/src/composables/browser/useBodyScrollLock/index.test.ts

@@ -0,0 +1,43 @@
+import { afterEach, describe, expect, it } from 'vitest';
+import { useBodyScrollLock } from '.';
+
+describe(useBodyScrollLock, () => {
+  afterEach(() => {
+    document.body.style.overflow = '';
+    document.body.style.paddingRight = '';
+    document.body.style.touchAction = '';
+  });
+
+  it('locks body overflow', () => {
+    const release = useBodyScrollLock();
+    expect(document.body.style.overflow).toBe('hidden');
+    release();
+  });
+
+  it('restores original overflow after release', () => {
+    document.body.style.overflow = 'auto';
+    const release = useBodyScrollLock();
+    expect(document.body.style.overflow).toBe('hidden');
+    release();
+    expect(document.body.style.overflow).toBe('auto');
+  });
+
+  it('reference-counts concurrent holders', () => {
+    const r1 = useBodyScrollLock();
+    const r2 = useBodyScrollLock();
+    expect(document.body.style.overflow).toBe('hidden');
+
+    r1();
+    expect(document.body.style.overflow).toBe('hidden');
+
+    r2();
+    expect(document.body.style.overflow).toBe('');
+  });
+
+  it('release is idempotent', () => {
+    const release = useBodyScrollLock();
+    release();
+    release();
+    expect(document.body.style.overflow).toBe('');
+  });
+});

vue/toolkit/src/composables/browser/useBodyScrollLock/index.ts

@@ -0,0 +1,73 @@
+import { tryOnScopeDispose } from '@/composables/lifecycle/tryOnScopeDispose';
+import { isClient } from '@robonen/platform/multi';
+import type { VoidFunction } from '@robonen/stdlib';
+import { noop } from '@robonen/stdlib';
+
+interface LockState {
+  refs: number;
+  originalOverflow: string;
+  originalPaddingRight: string;
+  originalTouchAction: string;
+}
+
+let state: LockState | null = null;
+
+function acquire(): VoidFunction {
+  if (!isClient) return noop;
+
+  if (!state) {
+    const { body, documentElement } = document;
+    const scrollbarWidth = globalThis.innerWidth - documentElement.clientWidth;
+
+    state = {
+      refs: 0,
+      originalOverflow: body.style.overflow,
+      originalPaddingRight: body.style.paddingRight,
+      originalTouchAction: body.style.touchAction,
+    };
+
+    body.style.overflow = 'hidden';
+    body.style.touchAction = 'none';
+
+    // Compensate scrollbar removal to prevent layout shift
+    if (scrollbarWidth > 0) {
+      const computedPr = Number.parseInt(globalThis.getComputedStyle(body).paddingRight, 10) || 0;
+      body.style.paddingRight = `${computedPr + scrollbarWidth}px`;
+    }
+  }
+
+  state.refs++;
+
+  let released = false;
+  const release = () => {
+    if (released || !state) return;
+    released = true;
+    state.refs--;
+
+    if (state.refs === 0) {
+      document.body.style.overflow = state.originalOverflow;
+      document.body.style.paddingRight = state.originalPaddingRight;
+      document.body.style.touchAction = state.originalTouchAction;
+      state = null;
+    }
+  };
+
+  tryOnScopeDispose(release);
+  return release;
+}
+
+/**
+ * @name useBodyScrollLock
+ * @category Browser
+ * @description Reference-counted body scroll lock. Safe to invoke from multiple
+ * concurrent modals — the lock releases only after all holders release. Preserves
+ * the original overflow/padding/touch-action values and compensates for scrollbar
+ * removal to prevent layout shift.
+ *
+ * @returns {VoidFunction} Release function. Idempotent — call once per acquire.
+ *
+ * @since 0.0.14
+ */
+export function useBodyScrollLock(): VoidFunction {
+  return acquire();
+}

vue/toolkit/src/composables/browser/useClickOutside/index.test.ts

@@ -0,0 +1,77 @@
+import { describe, expect, it, vi } from 'vitest';
+import { defineComponent, h, nextTick, ref } from 'vue';
+import { mount } from '@vue/test-utils';
+import { useClickOutside } from '.';
+
+function mountWithOutside(handler: (e: Event) => void) {
+  const Comp = defineComponent({
+    setup() {
+      const target = ref<HTMLElement | null>(null);
+
+      return () => h('div', {
+        ref: (el: any) => { target.value = el; },
+        'data-testid': 'target',
+      }, [
+        h('button', { 'data-testid': 'inside' }, 'inside'),
+      ]);
+    },
+    mounted() {
+      useClickOutside(() => this.$el, handler);
+    },
+  });
+
+  return mount(Comp, { attachTo: document.body });
+}
+
+describe(useClickOutside, () => {
+  it('invokes handler on outside pointerdown', async () => {
+    const handler = vi.fn();
+    const w = mountWithOutside(handler);
+
+    const outside = document.createElement('button');
+    document.body.appendChild(outside);
+
+    await nextTick();
+    outside.dispatchEvent(new PointerEvent('pointerdown', { bubbles: true, composed: true }));
+    expect(handler).toHaveBeenCalledTimes(1);
+
+    outside.remove();
+    w.unmount();
+  });
+
+  it('does not invoke handler on inside pointerdown', async () => {
+    const handler = vi.fn();
+    const w = mountWithOutside(handler);
+    await nextTick();
+
+    const inside = w.find('[data-testid=inside]').element as HTMLElement;
+    inside.dispatchEvent(new PointerEvent('pointerdown', { bubbles: true, composed: true }));
+
+    expect(handler).not.toHaveBeenCalled();
+    w.unmount();
+  });
+
+  it('respects the ignore list', async () => {
+    const handler = vi.fn();
+    const ignored = document.createElement('div');
+    document.body.appendChild(ignored);
+
+    const Comp = defineComponent({
+      setup() {
+        return () => h('div', { 'data-testid': 'target' }, 'target');
+      },
+      mounted() {
+        useClickOutside(() => this.$el, handler, { ignore: [ignored] });
+      },
+    });
+
+    const w = mount(Comp, { attachTo: document.body });
+    await nextTick();
+
+    ignored.dispatchEvent(new PointerEvent('pointerdown', { bubbles: true, composed: true }));
+    expect(handler).not.toHaveBeenCalled();
+
+    ignored.remove();
+    w.unmount();
+  });
+});

vue/toolkit/src/composables/browser/useClickOutside/index.ts

@@ -0,0 +1,68 @@
+import type { MaybeComputedElementRef } from '@/composables/component/unrefElement';
+import { unrefElement } from '@/composables/component/unrefElement';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { defaultWindow } from '@/types';
+import type { MaybeRefOrGetter } from 'vue';
+import { toValue } from 'vue';
+import type { VoidFunction } from '@robonen/stdlib';
+import { noop } from '@robonen/stdlib';
+
+export interface UseClickOutsideOptions {
+  /**
+   * Elements that are inside `target` semantically but physically rendered
+   * elsewhere (e.g. portaled menus). Events originating in these nodes
+   * are treated as *inside* clicks.
+   */
+  ignore?: MaybeRefOrGetter<Array<MaybeComputedElementRef | undefined>>;
+
+  /**
+   * Detect outside pointer-down instead of click. Useful for dismissable layers
+   * that want to react as soon as the user starts interacting outside.
+   * @default 'pointerdown'
+   */
+  event?: 'pointerdown' | 'mousedown' | 'click';
+}
+
+/**
+ * @name useClickOutside
+ * @category Browser
+ * @description Invokes `handler` when a pointer event occurs outside `target`.
+ * SSR-safe: no-op on the server. Handles portaled/ignored subtrees and
+ * guards against synthetic "outside" clicks on removed nodes.
+ *
+ * @param {MaybeComputedElementRef} target Element to watch. Events inside it are ignored.
+ * @param {(event: PointerEvent | MouseEvent) => void} handler Callback invoked with the outside event
+ * @param {UseClickOutsideOptions} [options] Options
+ * @returns {VoidFunction} Stop handle to remove the listeners
+ *
+ * @since 0.0.14
+ */
+export function useClickOutside(
+  target: MaybeComputedElementRef,
+  handler: (event: PointerEvent | MouseEvent) => void,
+  options: UseClickOutsideOptions = {},
+): VoidFunction {
+  if (!defaultWindow) return noop;
+
+  const { event = 'pointerdown', ignore } = options;
+
+  const listener = (e: Event) => {
+    const el = unrefElement(target) as HTMLElement | undefined;
+    const pe = e as PointerEvent;
+    const path = (e.composedPath?.() ?? []) as Node[];
+    const eventTarget = (path[0] ?? e.target) as Node | null;
+
+    if (!el || !eventTarget) return;
+    if (el === eventTarget || el.contains(eventTarget)) return;
+
+    const ignoreList = toValue(ignore) ?? [];
+    for (const ref of ignoreList) {
+      const node = unrefElement(ref) as HTMLElement | undefined;
+      if (node && (node === eventTarget || node.contains(eventTarget))) return;
+    }
+
+    handler(pe);
+  };
+
+  return useEventListener(defaultWindow, event, listener, { passive: true, capture: true });
+}

vue/toolkit/src/composables/browser/useClipboard/index.test.ts

@@ -0,0 +1,169 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick } from 'vue';
+import type { UseClipboardReturn } from '.';
+import { useClipboard } from '.';
+
+function stubClipboard() {
+  const writeText = vi.fn(async () => {});
+  const readText = vi.fn(async () => 'pasted');
+  const navigator = {
+    clipboard: { writeText, readText },
+  } as unknown as Navigator;
+  return { navigator, writeText, readText };
+}
+
+afterEach(() => {
+  vi.unstubAllGlobals();
+});
+
+describe(useClipboard, () => {
+  it('reports support when the clipboard API exists', () => {
+    const { navigator } = stubClipboard();
+    const scope = effectScope();
+    let clip: UseClipboardReturn<false>;
+    scope.run(() => {
+      clip = useClipboard({ navigator });
+    });
+    expect(clip!.isSupported.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('is not supported without the clipboard API', () => {
+    const navigator = {} as unknown as Navigator;
+    const scope = effectScope();
+    let clip: UseClipboardReturn<false>;
+    scope.run(() => {
+      clip = useClipboard({ navigator });
+    });
+    expect(clip!.isSupported.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('copies text and sets copied flag', async () => {
+    const { navigator, writeText } = stubClipboard();
+    const scope = effectScope();
+    let clip: UseClipboardReturn<false>;
+    scope.run(() => {
+      clip = useClipboard({ navigator });
+    });
+
+    await clip!.copy('hello');
+    expect(writeText).toHaveBeenCalledWith('hello');
+    expect(clip!.text.value).toBe('hello');
+    expect(clip!.copied.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('copies the configured source when called without args', async () => {
+    const { navigator, writeText } = stubClipboard();
+    const scope = effectScope();
+    let clip: any;
+    scope.run(() => {
+      clip = useClipboard({ navigator, source: 'from-source' });
+    });
+
+    await clip.copy();
+    expect(writeText).toHaveBeenCalledWith('from-source');
+    scope.stop();
+  });
+
+  it('copies a value resolved from an async getter', async () => {
+    const { navigator, writeText } = stubClipboard();
+    const scope = effectScope();
+    let clip: UseClipboardReturn<false>;
+    scope.run(() => {
+      clip = useClipboard({ navigator });
+    });
+
+    await clip!.copy(async () => 'lazy');
+    expect(writeText).toHaveBeenCalledWith('lazy');
+    expect(clip!.text.value).toBe('lazy');
+    scope.stop();
+  });
+
+  it('skips when an async getter resolves to null', async () => {
+    const { navigator, writeText } = stubClipboard();
+    const scope = effectScope();
+    let clip: UseClipboardReturn<false>;
+    scope.run(() => {
+      clip = useClipboard({ navigator });
+    });
+
+    await clip!.copy(async () => undefined);
+    expect(writeText).not.toHaveBeenCalled();
+    expect(clip!.copied.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('exposes copyPending around an in-flight async copy', async () => {
+    const { navigator } = stubClipboard();
+    const scope = effectScope();
+    let clip: UseClipboardReturn<false>;
+    scope.run(() => {
+      clip = useClipboard({ navigator });
+    });
+
+    let release: (v: string) => void = () => {};
+    const promise = clip!.copy(() => new Promise<string>((resolve) => {
+      release = resolve;
+    }));
+    expect(clip!.copyPending.value).toBeTruthy();
+    release('done');
+    await promise;
+    expect(clip!.copyPending.value).toBeFalsy();
+    expect(clip!.text.value).toBe('done');
+    scope.stop();
+  });
+
+  it('ignores a stale async copy superseded by a newer one', async () => {
+    const { navigator, writeText } = stubClipboard();
+    const scope = effectScope();
+    let clip: UseClipboardReturn<false>;
+    scope.run(() => {
+      clip = useClipboard({ navigator });
+    });
+
+    let releaseSlow: (v: string) => void = () => {};
+    const slow = clip!.copy(() => new Promise<string>((resolve) => {
+      releaseSlow = resolve;
+    }));
+    const fast = clip!.copy(async () => 'fast');
+    await fast;
+    releaseSlow('slow');
+    await slow;
+
+    expect(clip!.text.value).toBe('fast');
+    expect(writeText).toHaveBeenCalledTimes(1);
+    expect(writeText).toHaveBeenCalledWith('fast');
+    scope.stop();
+  });
+
+  it('does nothing when unsupported', async () => {
+    const navigator = {} as unknown as Navigator;
+    const scope = effectScope();
+    let clip: UseClipboardReturn<false>;
+    scope.run(() => {
+      clip = useClipboard({ navigator });
+    });
+
+    await clip!.copy('x');
+    expect(clip!.copied.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('syncs text on copy/cut events when read is enabled', async () => {
+    const { navigator, readText } = stubClipboard();
+    const scope = effectScope();
+    let clip: UseClipboardReturn<false>;
+    scope.run(() => {
+      clip = useClipboard({ navigator, read: true });
+    });
+
+    globalThis.dispatchEvent(new Event('copy'));
+    await nextTick();
+    await Promise.resolve();
+    expect(readText).toHaveBeenCalled();
+    expect(clip!.text.value).toBe('pasted');
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useClipboard/index.ts

@@ -0,0 +1,152 @@
+import { shallowReadonly, shallowRef, toValue } from 'vue';
+import type { MaybeRefOrGetter, Ref } from 'vue';
+import { isString } from '@robonen/stdlib';
+import { defaultNavigator } from '@/types';
+import type { ConfigurableNavigator } from '@/types';
+import { useSupported } from '@/composables/browser/useSupported';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { useTimeoutFn } from '@/composables/utilities/useTimeoutFn';
+
+/**
+ * A value to copy: either a string or an (optionally async) getter that resolves to one.
+ */
+export type ClipboardValue = string | (() => Promise<string | undefined> | string | undefined);
+
+export interface UseClipboardOptions<Source> extends ConfigurableNavigator {
+  /**
+   * Sync `text` with the system clipboard by listening to copy/cut events
+   *
+   * @default false
+   */
+  read?: boolean;
+
+  /**
+   * Default source value to copy when `copy()` is called without an argument
+   */
+  source?: Source;
+
+  /**
+   * Milliseconds the `copied` flag stays `true` after a copy
+   *
+   * @default 1500
+   */
+  copiedDuring?: number;
+}
+
+export interface UseClipboardReturn<Optional extends boolean> {
+  /**
+   * Whether the async Clipboard API is available
+   */
+  isSupported: Readonly<Ref<boolean>>;
+
+  /**
+   * The current clipboard text (kept in sync when `read` is enabled)
+   */
+  text: Readonly<Ref<string>>;
+
+  /**
+   * `true` for `copiedDuring` ms after a successful copy
+   */
+  copied: Readonly<Ref<boolean>>;
+
+  /**
+   * `true` while an async `copy()` is in flight
+   */
+  copyPending: Readonly<Ref<boolean>>;
+
+  /**
+   * Copy a value to the clipboard
+   */
+  copy: Optional extends true ? (text?: ClipboardValue) => Promise<void> : (text: ClipboardValue) => Promise<void>;
+}
+
+/**
+ * @name useClipboard
+ * @category Browser
+ * @description Reactive async Clipboard API.
+ *
+ * @param {UseClipboardOptions} [options={}] Options
+ * @returns {UseClipboardReturn} `isSupported`, `text`, `copied`, `copyPending`, and `copy`
+ *
+ * @example
+ * const { text, copy, copied, isSupported } = useClipboard();
+ * copy('hello');
+ *
+ * @example
+ * // Copy a lazily/asynchronously resolved value
+ * copy(async () => (await fetch('/token').then(r => r.text())));
+ *
+ * @since 0.0.15
+ */
+export function useClipboard(options?: UseClipboardOptions<undefined>): UseClipboardReturn<false>;
+export function useClipboard(options: UseClipboardOptions<MaybeRefOrGetter<string>>): UseClipboardReturn<true>;
+export function useClipboard(
+  options: UseClipboardOptions<MaybeRefOrGetter<string> | undefined> = {},
+): UseClipboardReturn<boolean> {
+  const {
+    navigator = defaultNavigator,
+    read = false,
+    source,
+    copiedDuring = 1500,
+  } = options;
+
+  const isSupported = useSupported(() => navigator && 'clipboard' in navigator);
+
+  const text = shallowRef('');
+  const copied = shallowRef(false);
+  const copyPending = shallowRef(false);
+
+  // Guards against a slow async copy clobbering the result of a newer one
+  let lastResolveId = 0;
+
+  const timeout = useTimeoutFn(() => {
+    copied.value = false;
+  }, copiedDuring, { immediate: false });
+
+  async function updateText(): Promise<void> {
+    text.value = await navigator!.clipboard.readText();
+  }
+
+  if (isSupported.value && read)
+    useEventListener(['copy', 'cut'], updateText, { passive: true });
+
+  async function copy(value: ClipboardValue | undefined = toValue(source)): Promise<void> {
+    if (!isSupported.value || value === null || value === undefined)
+      return;
+
+    copyPending.value = true;
+
+    try {
+      let resolved: string | undefined;
+
+      if (isString(value)) {
+        resolved = value;
+      }
+      else {
+        const currentId = ++lastResolveId;
+        resolved = await value();
+
+        // Drop a stale async resolution superseded by a newer copy
+        if (resolved === null || resolved === undefined || currentId !== lastResolveId)
+          return;
+      }
+
+      await navigator!.clipboard.writeText(resolved);
+
+      text.value = resolved;
+      copied.value = true;
+      timeout.start();
+    }
+    finally {
+      copyPending.value = false;
+    }
+  }
+
+  return {
+    isSupported,
+    text: shallowReadonly(text),
+    copied: shallowReadonly(copied),
+    copyPending: shallowReadonly(copyPending),
+    copy,
+  };
+}

vue/toolkit/src/composables/browser/useCloseWatcher/index.test.ts

@@ -0,0 +1,348 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { effectScope } from 'vue';
+import { useCloseWatcher } from '.';
+
+/**
+ * Minimal fake of the native `CloseWatcher`: tracks instances so tests can drive
+ * close/destroy and assert recreation behaviour.
+ */
+function createCloseWatcherStub() {
+  const instances: FakeCloseWatcher[] = [];
+
+  class FakeCloseWatcher {
+    listeners = new Map<string, Set<(event: Event) => void>>();
+    destroyed = false;
+    requestCloseCalls = 0;
+    closeCalls = 0;
+
+    constructor() {
+      instances.push(this);
+    }
+
+    addEventListener(type: string, listener: (event: Event) => void) {
+      if (!this.listeners.has(type))
+        this.listeners.set(type, new Set());
+      this.listeners.get(type)!.add(listener);
+    }
+
+    removeEventListener(type: string, listener: (event: Event) => void) {
+      this.listeners.get(type)?.delete(listener);
+    }
+
+    requestClose() {
+      this.requestCloseCalls++;
+      this.fireClose();
+    }
+
+    close() {
+      this.closeCalls++;
+      this.fireClose();
+    }
+
+    destroy() {
+      this.destroyed = true;
+    }
+
+    private fireClose() {
+      const event = new Event('close');
+      this.listeners.get('close')?.forEach(fn => fn(event));
+    }
+
+    oncancel: ((event: Event) => void) | null = null;
+    onclose: ((event: Event) => void) | null = null;
+  }
+
+  // A window-like object that exposes CloseWatcher and basic event listening
+  const eventTarget = new EventTarget();
+  const win = {
+    CloseWatcher: FakeCloseWatcher,
+    addEventListener: eventTarget.addEventListener.bind(eventTarget),
+    removeEventListener: eventTarget.removeEventListener.bind(eventTarget),
+    dispatchEvent: eventTarget.dispatchEvent.bind(eventTarget),
+  } as unknown as Window;
+
+  return { win, instances };
+}
+
+/** A window-like object WITHOUT CloseWatcher (fallback path). */
+function createFallbackWindow() {
+  const eventTarget = new EventTarget();
+  const win = {
+    addEventListener: eventTarget.addEventListener.bind(eventTarget),
+    removeEventListener: eventTarget.removeEventListener.bind(eventTarget),
+    dispatchEvent: eventTarget.dispatchEvent.bind(eventTarget),
+  } as unknown as Window;
+
+  const dispatchKey = (key: string) =>
+    win.dispatchEvent(new KeyboardEvent('keydown', { key }));
+
+  return { win, dispatchKey };
+}
+
+afterEach(() => {
+  vi.unstubAllGlobals();
+});
+
+describe(useCloseWatcher, () => {
+  it('reports support when CloseWatcher exists on window', () => {
+    const { win } = createCloseWatcherStub();
+    const scope = effectScope();
+    let cw: ReturnType<typeof useCloseWatcher>;
+    scope.run(() => {
+      cw = useCloseWatcher({ window: win });
+    });
+    expect(cw!.isSupported.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('reports unsupported when CloseWatcher is absent', () => {
+    const { win } = createFallbackWindow();
+    const scope = effectScope();
+    let cw: ReturnType<typeof useCloseWatcher>;
+    scope.run(() => {
+      cw = useCloseWatcher({ window: win });
+    });
+    expect(cw!.isSupported.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('is a safe no-op when there is no window (SSR)', () => {
+    // Force the SSR branch with an explicit falsy (non-undefined) window so the
+    // default-parameter fallback to `defaultWindow` does not kick in: only
+    // `undefined` triggers a parameter default, `null` survives the destructure.
+    const scope = effectScope();
+    let cw: ReturnType<typeof useCloseWatcher>;
+    scope.run(() => {
+      cw = useCloseWatcher({ window: null as unknown as Window });
+    });
+
+    expect(cw!.isSupported.value).toBeFalsy();
+
+    const handler = vi.fn();
+    const stop = cw!.onClose(handler);
+    expect(() => cw!.close()).not.toThrow();
+    expect(handler).not.toHaveBeenCalled();
+    expect(() => stop()).not.toThrow();
+    expect(() => cw!.destroy()).not.toThrow();
+    scope.stop();
+  });
+
+  describe('native CloseWatcher path', () => {
+    it('fires registered handler when close() is requested', () => {
+      const { win, instances } = createCloseWatcherStub();
+      const scope = effectScope();
+      let cw: ReturnType<typeof useCloseWatcher>;
+      scope.run(() => {
+        cw = useCloseWatcher({ window: win });
+      });
+
+      const handler = vi.fn();
+      cw!.onClose(handler);
+      expect(instances).toHaveLength(1);
+
+      cw!.close();
+      expect(instances[0]!.requestCloseCalls).toBe(1);
+      expect(handler).toHaveBeenCalledTimes(1);
+      expect(handler.mock.calls[0]![0]).toBeInstanceOf(Event);
+      scope.stop();
+    });
+
+    it('fires handler when the native close event occurs (Esc / back)', () => {
+      const { win, instances } = createCloseWatcherStub();
+      const scope = effectScope();
+      let cw: ReturnType<typeof useCloseWatcher>;
+      scope.run(() => {
+        cw = useCloseWatcher({ window: win });
+      });
+
+      const handler = vi.fn();
+      cw!.onClose(handler);
+
+      // Simulate the platform firing the close event (e.g. Esc / Android back)
+      instances[0]!.close();
+      expect(handler).toHaveBeenCalledTimes(1);
+      scope.stop();
+    });
+
+    it('recreates the watcher after a close so it keeps working', () => {
+      const { win, instances } = createCloseWatcherStub();
+      const scope = effectScope();
+      let cw: ReturnType<typeof useCloseWatcher>;
+      scope.run(() => {
+        cw = useCloseWatcher({ window: win });
+      });
+
+      const handler = vi.fn();
+      cw!.onClose(handler);
+      expect(instances).toHaveLength(1);
+
+      cw!.close();
+      // a fresh watcher is created after the close fired
+      expect(instances).toHaveLength(2);
+
+      cw!.close();
+      expect(handler).toHaveBeenCalledTimes(2);
+      scope.stop();
+    });
+
+    it('fires all registered handlers with a single watcher', () => {
+      const { win, instances } = createCloseWatcherStub();
+      const scope = effectScope();
+      let cw: ReturnType<typeof useCloseWatcher>;
+      scope.run(() => {
+        cw = useCloseWatcher({ window: win });
+      });
+
+      const a = vi.fn();
+      const b = vi.fn();
+      cw!.onClose(a);
+      cw!.onClose(b);
+      // both handlers share one native watcher
+      expect(instances).toHaveLength(1);
+
+      cw!.close();
+      expect(a).toHaveBeenCalledTimes(1);
+      expect(b).toHaveBeenCalledTimes(1);
+      scope.stop();
+    });
+
+    it('stop handle removes only its own handler', () => {
+      const { win } = createCloseWatcherStub();
+      const scope = effectScope();
+      let cw: ReturnType<typeof useCloseWatcher>;
+      scope.run(() => {
+        cw = useCloseWatcher({ window: win });
+      });
+
+      const a = vi.fn();
+      const b = vi.fn();
+      const stopA = cw!.onClose(a);
+      cw!.onClose(b);
+
+      stopA();
+      cw!.close();
+      expect(a).not.toHaveBeenCalled();
+      expect(b).toHaveBeenCalledTimes(1);
+      scope.stop();
+    });
+
+    it('destroy() tears down the watcher and clears handlers', () => {
+      const { win, instances } = createCloseWatcherStub();
+      const scope = effectScope();
+      let cw: ReturnType<typeof useCloseWatcher>;
+      scope.run(() => {
+        cw = useCloseWatcher({ window: win });
+      });
+
+      const handler = vi.fn();
+      cw!.onClose(handler);
+      cw!.destroy();
+
+      expect(instances[0]!.destroyed).toBeTruthy();
+      cw!.close();
+      expect(handler).not.toHaveBeenCalled();
+      scope.stop();
+    });
+
+    it('survives a handler calling destroy() during dispatch', () => {
+      const { win } = createCloseWatcherStub();
+      const scope = effectScope();
+      let cw: ReturnType<typeof useCloseWatcher>;
+      scope.run(() => {
+        cw = useCloseWatcher({ window: win });
+      });
+
+      const other = vi.fn();
+      cw!.onClose(() => cw!.destroy());
+      cw!.onClose(other);
+
+      // dispatch must not throw even though destroy() clears the set mid-loop
+      expect(() => cw!.close()).not.toThrow();
+      // the snapshot means the second handler still runs for this dispatch
+      expect(other).toHaveBeenCalledTimes(1);
+      scope.stop();
+    });
+  });
+
+  describe('fallback (keydown) path', () => {
+    it('fires handler on Escape keydown', () => {
+      const { win, dispatchKey } = createFallbackWindow();
+      const scope = effectScope();
+      let cw: ReturnType<typeof useCloseWatcher>;
+      scope.run(() => {
+        cw = useCloseWatcher({ window: win });
+      });
+
+      const handler = vi.fn();
+      cw!.onClose(handler);
+
+      dispatchKey('Escape');
+      expect(handler).toHaveBeenCalledTimes(1);
+      scope.stop();
+    });
+
+    it('ignores non-Escape keys', () => {
+      const { win, dispatchKey } = createFallbackWindow();
+      const scope = effectScope();
+      let cw: ReturnType<typeof useCloseWatcher>;
+      scope.run(() => {
+        cw = useCloseWatcher({ window: win });
+      });
+
+      const handler = vi.fn();
+      cw!.onClose(handler);
+
+      dispatchKey('Enter');
+      expect(handler).not.toHaveBeenCalled();
+      scope.stop();
+    });
+
+    it('close() synthesizes a close event in the fallback path', () => {
+      const { win } = createFallbackWindow();
+      const scope = effectScope();
+      let cw: ReturnType<typeof useCloseWatcher>;
+      scope.run(() => {
+        cw = useCloseWatcher({ window: win });
+      });
+
+      const handler = vi.fn();
+      cw!.onClose(handler);
+
+      cw!.close();
+      expect(handler).toHaveBeenCalledTimes(1);
+      scope.stop();
+    });
+
+    it('destroy() removes the keydown listener', () => {
+      const { win, dispatchKey } = createFallbackWindow();
+      const scope = effectScope();
+      let cw: ReturnType<typeof useCloseWatcher>;
+      scope.run(() => {
+        cw = useCloseWatcher({ window: win });
+      });
+
+      const handler = vi.fn();
+      cw!.onClose(handler);
+      cw!.destroy();
+
+      dispatchKey('Escape');
+      expect(handler).not.toHaveBeenCalled();
+      scope.stop();
+    });
+  });
+
+  it('disposes when the effect scope stops', () => {
+    const { win, instances } = createCloseWatcherStub();
+    const scope = effectScope();
+    let cw: ReturnType<typeof useCloseWatcher>;
+    scope.run(() => {
+      cw = useCloseWatcher({ window: win });
+    });
+
+    cw!.onClose(vi.fn());
+    expect(instances[0]!.destroyed).toBeFalsy();
+
+    scope.stop();
+    expect(instances[0]!.destroyed).toBeTruthy();
+  });
+});

vue/toolkit/src/composables/browser/useCloseWatcher/index.ts

@@ -0,0 +1,175 @@
+import type { VoidFunction } from '@robonen/stdlib';
+import { noop } from '@robonen/stdlib';
+import type { Ref } from 'vue';
+import { defaultWindow } from '@/types';
+import type { ConfigurableWindow } from '@/types';
+import { useSupported } from '@/composables/browser/useSupported';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { tryOnScopeDispose } from '@/composables/lifecycle/tryOnScopeDispose';
+
+/**
+ * Subset of the native `CloseWatcher` instance surface we rely on.
+ *
+ * @see https://developer.mozilla.org/en-US/docs/Web/API/CloseWatcher
+ */
+interface CloseWatcherInstance {
+  requestClose: () => void;
+  close: () => void;
+  destroy: () => void;
+  addEventListener: (type: string, listener: (event: Event) => void) => void;
+  removeEventListener: (type: string, listener: (event: Event) => void) => void;
+  oncancel: ((event: Event) => void) | null;
+  onclose: ((event: Event) => void) | null;
+}
+
+type CloseWatcherConstructor = new (options?: { signal?: AbortSignal }) => CloseWatcherInstance;
+
+/**
+ * Handler invoked when a close request is received.
+ *
+ * The argument is the native `close` event when the platform `CloseWatcher`
+ * is used, or the `Escape` `KeyboardEvent` when falling back to keydown.
+ */
+export type CloseWatcherHandler = (event: Event) => void;
+
+export interface UseCloseWatcherOptions extends ConfigurableWindow {}
+
+export interface UseCloseWatcherReturn {
+  /**
+   * Whether the native `CloseWatcher` API is available.
+   */
+  isSupported: Readonly<Ref<boolean>>;
+
+  /**
+   * Register a handler for close requests (Esc key / Android back / `close()`).
+   *
+   * @returns A stop handle that removes this handler.
+   */
+  onClose: (handler: CloseWatcherHandler) => VoidFunction;
+
+  /**
+   * Request a close, firing every registered handler.
+   */
+  close: VoidFunction;
+
+  /**
+   * Tear down the watcher and remove all registered handlers.
+   */
+  destroy: VoidFunction;
+}
+
+/**
+ * @name useCloseWatcher
+ * @category Browser
+ * @description Wrap the native `CloseWatcher` API to handle close requests
+ * (the `Esc` key or the Android back gesture). Falls back to listening for
+ * `Escape` keydown when `CloseWatcher` is unavailable. SSR-safe.
+ *
+ * @param {UseCloseWatcherOptions} [options={}] Configuration options
+ * @returns {UseCloseWatcherReturn} `isSupported`, `onClose`, `close`, and `destroy`
+ *
+ * @example
+ * const { onClose, close, isSupported } = useCloseWatcher();
+ * onClose(() => { dialogOpen.value = false; });
+ *
+ * @example
+ * // Programmatically request a close
+ * close();
+ *
+ * @since 0.0.15
+ */
+export function useCloseWatcher(options: UseCloseWatcherOptions = {}): UseCloseWatcherReturn {
+  const { window = defaultWindow } = options;
+
+  const isSupported = useSupported(() => !!window && 'CloseWatcher' in window);
+
+  const handlers = new Set<CloseWatcherHandler>();
+  let watcher: CloseWatcherInstance | undefined;
+  let stopFallback: VoidFunction = noop;
+
+  const dispatch = (event: Event): void => {
+    // Snapshot so a handler that calls destroy()/onClose() can't mutate mid-loop
+    // eslint-disable-next-line unicorn/no-useless-spread
+    for (const handler of [...handlers])
+      handler(event);
+  };
+
+  const teardownWatcher = (): void => {
+    watcher?.destroy();
+    watcher = undefined;
+    stopFallback();
+    stopFallback = noop;
+  };
+
+  const ensureWatcher = (): void => {
+    if (!window)
+      return;
+
+    if (isSupported.value) {
+      if (watcher)
+        return;
+
+      const CloseWatcherCtor = (window as unknown as { CloseWatcher: CloseWatcherConstructor }).CloseWatcher;
+      watcher = new CloseWatcherCtor();
+      // The native watcher deactivates after a single close; recreate it so the
+      // returned `close()`/Esc keep working across multiple close requests.
+      watcher.addEventListener('close', (event: Event) => {
+        watcher = undefined;
+        dispatch(event);
+        ensureWatcher();
+      });
+      return;
+    }
+
+    // Fallback: only one keydown listener regardless of handler count
+    if (stopFallback !== noop)
+      return;
+
+    stopFallback = useEventListener(
+      window,
+      'keydown',
+      (event: KeyboardEvent) => {
+        if (event.key === 'Escape')
+          dispatch(event);
+      },
+      { passive: true },
+    );
+  };
+
+  const onClose = (handler: CloseWatcherHandler): VoidFunction => {
+    handlers.add(handler);
+    ensureWatcher();
+
+    return () => {
+      handlers.delete(handler);
+    };
+  };
+
+  const close = (): void => {
+    if (!window)
+      return;
+
+    if (watcher) {
+      watcher.requestClose();
+      return;
+    }
+
+    // No active native watcher (unsupported, torn down, or none registered yet):
+    // synthesize a close event so handlers still fire.
+    dispatch(new Event('close'));
+  };
+
+  const destroy = (): void => {
+    handlers.clear();
+    teardownWatcher();
+  };
+
+  tryOnScopeDispose(destroy);
+
+  return {
+    isSupported,
+    onClose,
+    close,
+    destroy,
+  };
+}

vue/toolkit/src/composables/browser/useColorMode/index.test.ts

@@ -0,0 +1,372 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick, ref } from 'vue';
+import { useColorMode } from '.';
+
+type Listener = (event: { matches: boolean }) => void;
+
+interface StubMql {
+  readonly matches: boolean;
+  media: string;
+  addEventListener: (type: string, cb: Listener) => void;
+  removeEventListener: (type: string, cb: Listener) => void;
+  dispatch: (value: boolean) => void;
+}
+
+function makeMql(initialMatches: boolean, media = ''): StubMql {
+  const listeners = new Set<Listener>();
+  let matches = initialMatches;
+
+  return {
+    get matches() {
+      return matches;
+    },
+    media,
+    addEventListener: (_: string, cb: Listener) => listeners.add(cb),
+    removeEventListener: (_: string, cb: Listener) => listeners.delete(cb),
+    dispatch(value: boolean) {
+      matches = value;
+      for (const cb of listeners) cb({ matches: value });
+    },
+  };
+}
+
+/**
+ * Build a stub `window` that reuses the real jsdom `document` (so DOM updates
+ * applied to `<html>` are observable) but with a controllable `matchMedia` for
+ * `prefers-color-scheme: dark`, an isolated in-memory `localStorage`, and a
+ * `getComputedStyle` shim for the transition-disabling reflow.
+ */
+function makeWindow(prefersDark: StubMql) {
+  const map = new Map<string, string>();
+
+  const storage: Storage = {
+    getItem: (key: string) => (map.has(key) ? map.get(key)! : null),
+    setItem: (key: string, value: string) => { map.set(key, String(value)); },
+    removeItem: (key: string) => { map.delete(key); },
+    clear: () => map.clear(),
+    key: (index: number) => [...map.keys()][index] ?? null,
+    get length() {
+      return map.size;
+    },
+  };
+
+  const win = {
+    document: globalThis.document,
+    matchMedia: vi.fn((query: string) =>
+      query.includes('dark') ? prefersDark : makeMql(false, query)),
+    localStorage: storage,
+    getComputedStyle: () => ({ opacity: '1' }),
+    dispatchEvent: () => true,
+    addEventListener: () => {},
+    removeEventListener: () => {},
+  } as unknown as Window & typeof globalThis;
+
+  return { win, storage, map };
+}
+
+function reset() {
+  document.documentElement.className = '';
+  document.documentElement.removeAttribute('data-theme');
+}
+
+describe(useColorMode, () => {
+  beforeEach(() => {
+    reset();
+    // Ensure module-captured defaultWindow.matchMedia is undefined so the
+    // composable must use the injected window.
+    vi.stubGlobal('matchMedia', undefined);
+  });
+
+  afterEach(() => {
+    vi.unstubAllGlobals();
+    reset();
+  });
+
+  it('applies the system class when in auto mode (dark)', async () => {
+    const prefersDark = makeMql(true);
+    const { win } = makeWindow(prefersDark);
+    const scope = effectScope();
+    let mode: ReturnType<typeof useColorMode>;
+
+    scope.run(() => {
+      mode = useColorMode({ window: win });
+    });
+    await nextTick();
+
+    expect(mode!.value).toBe('dark');
+    expect(mode!.system.value).toBe('dark');
+    expect(mode!.state.value).toBe('dark');
+    expect(document.documentElement.classList.contains('dark')).toBeTruthy();
+    expect(document.documentElement.classList.contains('light')).toBeFalsy();
+
+    scope.stop();
+  });
+
+  it('applies the system class when in auto mode (light)', async () => {
+    const prefersDark = makeMql(false);
+    const { win } = makeWindow(prefersDark);
+    const scope = effectScope();
+    let mode: ReturnType<typeof useColorMode>;
+
+    scope.run(() => {
+      mode = useColorMode({ window: win });
+    });
+    await nextTick();
+
+    expect(mode!.system.value).toBe('light');
+    expect(mode!.state.value).toBe('light');
+    expect(document.documentElement.classList.contains('light')).toBeTruthy();
+    expect(document.documentElement.classList.contains('dark')).toBeFalsy();
+
+    scope.stop();
+  });
+
+  it('writing the ref switches the applied class and removes the previous one', async () => {
+    const prefersDark = makeMql(false);
+    const { win } = makeWindow(prefersDark);
+    const scope = effectScope();
+    let mode: ReturnType<typeof useColorMode>;
+
+    scope.run(() => {
+      mode = useColorMode({ window: win });
+    });
+    await nextTick();
+
+    expect(document.documentElement.classList.contains('light')).toBeTruthy();
+
+    mode!.value = 'dark';
+    await nextTick();
+
+    expect(document.documentElement.classList.contains('dark')).toBeTruthy();
+    expect(document.documentElement.classList.contains('light')).toBeFalsy();
+    expect(mode!.value).toBe('dark');
+    expect(mode!.store.value).toBe('dark');
+
+    scope.stop();
+  });
+
+  it('reacts to system preference changes while in auto mode', async () => {
+    const prefersDark = makeMql(false);
+    const { win } = makeWindow(prefersDark);
+    const scope = effectScope();
+    let mode: ReturnType<typeof useColorMode>;
+
+    scope.run(() => {
+      mode = useColorMode({ window: win });
+    });
+    await nextTick();
+
+    expect(mode!.state.value).toBe('light');
+
+    prefersDark.dispatch(true);
+    await nextTick();
+
+    expect(mode!.system.value).toBe('dark');
+    expect(mode!.state.value).toBe('dark');
+    expect(document.documentElement.classList.contains('dark')).toBeTruthy();
+
+    scope.stop();
+  });
+
+  it('persists the value to storage and reads it back', async () => {
+    const prefersDark = makeMql(false);
+    const { win, storage } = makeWindow(prefersDark);
+    const scope = effectScope();
+    let mode: ReturnType<typeof useColorMode>;
+
+    scope.run(() => {
+      mode = useColorMode({ window: win });
+    });
+    await nextTick();
+
+    mode!.value = 'dark';
+    await nextTick();
+
+    expect(storage.getItem('vuetools-color-scheme')).toBe('dark');
+
+    // A second instance backed by the same storage should hydrate from it.
+    let restored: ReturnType<typeof useColorMode>;
+    scope.run(() => {
+      restored = useColorMode({ window: win });
+    });
+    await nextTick();
+
+    expect(restored!.value).toBe('dark');
+
+    scope.stop();
+  });
+
+  it('honours a custom storageKey', async () => {
+    const prefersDark = makeMql(false);
+    const { win, storage } = makeWindow(prefersDark);
+    const scope = effectScope();
+    let mode: ReturnType<typeof useColorMode>;
+
+    scope.run(() => {
+      mode = useColorMode({ window: win, storageKey: 'my-theme' });
+    });
+    await nextTick();
+
+    mode!.value = 'dark';
+    await nextTick();
+
+    expect(storage.getItem('my-theme')).toBe('dark');
+    expect(storage.getItem('vuetools-color-scheme')).toBeNull();
+
+    scope.stop();
+  });
+
+  it('does not persist when storageKey is null', async () => {
+    const prefersDark = makeMql(false);
+    const { win, map } = makeWindow(prefersDark);
+    const scope = effectScope();
+    let mode: ReturnType<typeof useColorMode>;
+
+    scope.run(() => {
+      mode = useColorMode({ window: win, storageKey: null });
+    });
+    await nextTick();
+
+    mode!.value = 'dark';
+    await nextTick();
+
+    expect(map.size).toBe(0);
+    expect(mode!.value).toBe('dark');
+
+    scope.stop();
+  });
+
+  it('emitAuto keeps the ref value as "auto" while resolving state', async () => {
+    const prefersDark = makeMql(true);
+    const { win } = makeWindow(prefersDark);
+    const scope = effectScope();
+    let mode: ReturnType<typeof useColorMode>;
+
+    scope.run(() => {
+      mode = useColorMode({ window: win, emitAuto: true });
+    });
+    await nextTick();
+
+    expect(mode!.value).toBe('auto');
+    expect(mode!.state.value).toBe('dark');
+
+    scope.stop();
+  });
+
+  it('writes to a custom attribute instead of class', async () => {
+    const prefersDark = makeMql(true);
+    const { win } = makeWindow(prefersDark);
+    const scope = effectScope();
+    let mode: ReturnType<typeof useColorMode>;
+
+    scope.run(() => {
+      mode = useColorMode({ window: win, attribute: 'data-theme' });
+    });
+    await nextTick();
+
+    expect(document.documentElement.getAttribute('data-theme')).toBe('dark');
+
+    mode!.value = 'light';
+    await nextTick();
+
+    expect(document.documentElement.getAttribute('data-theme')).toBe('light');
+    // Classes should not be touched in attribute mode.
+    expect(document.documentElement.classList.contains('dark')).toBeFalsy();
+
+    scope.stop();
+  });
+
+  it('supports custom modes', async () => {
+    const prefersDark = makeMql(false);
+    const { win } = makeWindow(prefersDark);
+    const scope = effectScope();
+    let mode: ReturnType<typeof useColorMode<'cafe' | 'dim'>>;
+
+    scope.run(() => {
+      mode = useColorMode<'cafe' | 'dim'>({
+        window: win,
+        modes: { cafe: 'cafe', dim: 'dim' },
+        initialValue: 'cafe',
+      });
+    });
+    await nextTick();
+
+    expect(document.documentElement.classList.contains('cafe')).toBeTruthy();
+
+    mode!.value = 'dim';
+    await nextTick();
+
+    expect(document.documentElement.classList.contains('dim')).toBeTruthy();
+    expect(document.documentElement.classList.contains('cafe')).toBeFalsy();
+
+    scope.stop();
+  });
+
+  it('invokes a custom onChanged handler instead of the default', async () => {
+    const prefersDark = makeMql(true);
+    const { win } = makeWindow(prefersDark);
+    const onChanged = vi.fn();
+    const scope = effectScope();
+
+    scope.run(() => {
+      useColorMode({ window: win, onChanged });
+    });
+    await nextTick();
+
+    expect(onChanged).toHaveBeenCalled();
+    const [firstMode, firstHandler] = onChanged.mock.calls[0]!;
+    expect(firstMode).toBe('dark');
+    expect(typeof firstHandler).toBe('function');
+    // Default handler suppressed: no class applied.
+    expect(document.documentElement.classList.contains('dark')).toBeFalsy();
+
+    scope.stop();
+  });
+
+  it('uses a custom storageRef when provided', async () => {
+    const prefersDark = makeMql(false);
+    const { win, map } = makeWindow(prefersDark);
+    const storageRef = ref<'auto' | 'dark' | 'light'>('dark');
+    const scope = effectScope();
+    let mode: ReturnType<typeof useColorMode>;
+
+    scope.run(() => {
+      mode = useColorMode({ window: win, storageRef });
+    });
+    await nextTick();
+
+    expect(mode!.value).toBe('dark');
+    expect(document.documentElement.classList.contains('dark')).toBeTruthy();
+    // storageRef bypasses useStorage, so nothing is written to localStorage.
+    expect(map.size).toBe(0);
+
+    storageRef.value = 'light';
+    await nextTick();
+
+    expect(document.documentElement.classList.contains('light')).toBeTruthy();
+
+    scope.stop();
+  });
+
+  it('does not throw on the SSR/unsupported path (no window)', async () => {
+    const scope = effectScope();
+    let mode: ReturnType<typeof useColorMode>;
+
+    expect(() => {
+      scope.run(() => {
+        mode = useColorMode({ window: undefined });
+      });
+    }).not.toThrow();
+    await nextTick();
+
+    // System detection unavailable -> defaults to light; state resolves to it.
+    expect(mode!.system.value).toBe('light');
+    expect(mode!.state.value).toBe('light');
+    // In-memory store still writable.
+    mode!.value = 'dark';
+    await nextTick();
+    expect(mode!.store.value).toBe('dark');
+
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useColorMode/index.ts

@@ -0,0 +1,256 @@
+import { computed, toRef, watch } from 'vue';
+import type { ComputedRef, MaybeRefOrGetter, Ref, WritableComputedRef } from 'vue';
+import { isString } from '@robonen/stdlib';
+import { defaultWindow } from '@/types';
+import type { ConfigurableWindow } from '@/types';
+import { unrefElement } from '@/composables/component/unrefElement';
+import type { MaybeElementRef } from '@/composables/component/unrefElement';
+import { usePreferredDark } from '@/composables/browser/usePreferredDark';
+import { useStorage } from '@/composables/storage/useStorage';
+import type { UseStorageOptions } from '@/composables/storage/useStorage';
+import { tryOnMounted } from '@/composables/lifecycle/tryOnMounted';
+
+export type BasicColorMode = 'light' | 'dark';
+export type BasicColorSchema = BasicColorMode | 'auto';
+
+export interface UseColorModeOptions<T extends string = BasicColorMode> extends UseStorageOptions<T | BasicColorMode>, ConfigurableWindow {
+  /**
+   * CSS selector (or element ref) for the target element the mode is applied to.
+   *
+   * @default 'html'
+   */
+  selector?: string | MaybeElementRef;
+
+  /**
+   * HTML attribute applied to the target element. Use `'class'` to toggle
+   * classes, or any attribute name (e.g. `'data-theme'`) to set its value.
+   *
+   * @default 'class'
+   */
+  attribute?: string;
+
+  /**
+   * The initial color mode used when no value is stored.
+   *
+   * @default 'auto'
+   */
+  initialValue?: MaybeRefOrGetter<T | BasicColorSchema>;
+
+  /**
+   * Map of color mode to the value applied to the target element. Extend this
+   * to support custom modes beyond `light`/`dark`/`auto`.
+   *
+   * @default { auto: '', light: 'light', dark: 'dark' }
+   */
+  modes?: Partial<Record<T | BasicColorSchema, string>>;
+
+  /**
+   * Custom handler called whenever the resolved mode changes. Receives the
+   * resolved mode and the default handler, allowing you to opt out of (or
+   * extend) the default DOM update.
+   */
+  onChanged?: (mode: T | BasicColorMode, defaultHandler: (mode: T | BasicColorMode) => void) => void;
+
+  /**
+   * Use a custom ref as the storage backing instead of `useStorage`.
+   */
+  storageRef?: Ref<T | BasicColorSchema>;
+
+  /**
+   * The key persisted into storage. Pass `null` to disable persistence
+   * (the mode lives only in memory).
+   *
+   * @default 'vuetools-color-scheme'
+   */
+  storageKey?: string | null;
+
+  /**
+   * Custom storage backend. Defaults to `window.localStorage`.
+   */
+  storage?: Storage;
+
+  /**
+   * Emit `'auto'` as the writable ref value when in auto mode, instead of the
+   * resolved `'light'`/`'dark'`. Useful for binding a tri-state UI.
+   *
+   * @default false
+   */
+  emitAuto?: boolean;
+
+  /**
+   * Briefly disable CSS transitions while the mode is applied, preventing a
+   * flash of transitioning colors during the switch.
+   *
+   * @default true
+   */
+  disableTransition?: boolean;
+}
+
+export type UseColorModeReturn<T extends string = BasicColorMode>
+  = WritableComputedRef<T | BasicColorSchema> & {
+    store: Ref<T | BasicColorSchema>;
+    system: ComputedRef<BasicColorMode>;
+    state: ComputedRef<T | BasicColorMode>;
+  };
+
+const CSS_DISABLE_TRANS = '*,*::before,*::after{-webkit-transition:none!important;-moz-transition:none!important;-o-transition:none!important;-ms-transition:none!important;transition:none!important}';
+
+/**
+ * @name useColorMode
+ * @category Browser
+ * @description Reactive color mode (`light` / `dark` / `auto`) with system
+ * detection, storage persistence, and automatic application of a class or
+ * attribute to a target element.
+ *
+ * @param {UseColorModeOptions<T>} [options={}] Options
+ * @returns {UseColorModeReturn<T>} A writable ref of the mode, augmented with `{ store, system, state }`
+ *
+ * @example
+ * const mode = useColorMode();
+ * mode.value = 'dark';
+ *
+ * @example
+ * // Custom modes and a data attribute
+ * const mode = useColorMode({
+ *   attribute: 'data-theme',
+ *   modes: { dim: 'dim', cafe: 'cafe' },
+ * });
+ *
+ * @example
+ * // Read the resolved system + effective state
+ * const { system, state } = useColorMode();
+ *
+ * @since 0.0.15
+ */
+export function useColorMode<T extends string = BasicColorMode>(
+  options: UseColorModeOptions<T> = {},
+): UseColorModeReturn<T> {
+  const {
+    selector = 'html',
+    attribute = 'class',
+    initialValue = 'auto',
+    window = defaultWindow,
+    storage,
+    storageKey = 'vuetools-color-scheme',
+    listenToStorageChanges = true,
+    storageRef,
+    emitAuto = false,
+    disableTransition = true,
+  } = options;
+
+  const modes = {
+    auto: '',
+    light: 'light',
+    dark: 'dark',
+    ...options.modes,
+  } as Record<BasicColorSchema | T, string>;
+
+  const preferredDark = usePreferredDark({ window });
+  const system = computed<BasicColorMode>(() => preferredDark.value ? 'dark' : 'light');
+
+  const resolveStore = (): Ref<T | BasicColorSchema> => {
+    if (storageRef)
+      return storageRef;
+
+    if (storageKey === null || storageKey === undefined)
+      return toRef(initialValue) as Ref<T | BasicColorSchema>;
+
+    const backend = storage ?? window?.localStorage;
+
+    if (!backend)
+      return toRef(initialValue) as Ref<T | BasicColorSchema>;
+
+    return useStorage<T | BasicColorSchema>(storageKey, initialValue, backend, {
+      window,
+      listenToStorageChanges,
+    });
+  };
+
+  const store = resolveStore();
+
+  const state = computed<T | BasicColorMode>(() =>
+    store.value === 'auto'
+      ? system.value
+      : store.value as T | BasicColorMode);
+
+  const updateHTMLAttrs = (target: string | MaybeElementRef, attr: string, value: string): void => {
+    const element = isString(target)
+      ? window?.document?.querySelector(target)
+      : unrefElement(target);
+
+    if (!element)
+      return;
+
+    const classesToAdd = new Set<string>();
+    const classesToRemove = new Set<string>();
+    let attributeToChange: { key: string; value: string } | null = null;
+
+    if (attr === 'class') {
+      const next = value.split(/\s/g);
+
+      // Toggle only the classes this composable owns (derived from `modes`),
+      // so unrelated classes on the element are left untouched.
+      for (const owned of Object.values<string>(modes).flatMap(mode => (mode || '').split(/\s/g)).filter(Boolean)) {
+        if (next.includes(owned))
+          classesToAdd.add(owned);
+        else
+          classesToRemove.add(owned);
+      }
+    }
+    else {
+      attributeToChange = { key: attr, value };
+    }
+
+    if (classesToAdd.size === 0 && classesToRemove.size === 0 && attributeToChange === null)
+      return;
+
+    let style: HTMLStyleElement | undefined;
+
+    if (disableTransition && window?.document) {
+      style = window.document.createElement('style');
+      style.append(window.document.createTextNode(CSS_DISABLE_TRANS));
+      window.document.head.append(style);
+    }
+
+    for (const className of classesToAdd)
+      element.classList.add(className);
+
+    for (const className of classesToRemove)
+      element.classList.remove(className);
+
+    if (attributeToChange)
+      element.setAttribute(attributeToChange.key, attributeToChange.value);
+
+    if (style && window?.document) {
+      // Force a reflow so the no-transition style is flushed before removal.
+      void window.getComputedStyle(style).opacity;
+      style.remove();
+    }
+  };
+
+  const defaultOnChanged = (mode: T | BasicColorMode): void => {
+    updateHTMLAttrs(selector, attribute, modes[mode] ?? mode);
+  };
+
+  const onChanged = (mode: T | BasicColorMode): void => {
+    if (options.onChanged)
+      options.onChanged(mode, defaultOnChanged);
+    else
+      defaultOnChanged(mode);
+  };
+
+  watch(state, onChanged, { flush: 'post', immediate: true });
+
+  tryOnMounted(() => onChanged(state.value));
+
+  const mode = computed<T | BasicColorSchema>({
+    get() {
+      return emitAuto ? store.value : state.value;
+    },
+    set(value) {
+      store.value = value;
+    },
+  });
+
+  return Object.assign(mode, { store, system, state }) as UseColorModeReturn<T>;
+}

vue/toolkit/src/composables/browser/useDevicePixelRatio/index.test.ts

@@ -0,0 +1,164 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, isReadonly, nextTick } from 'vue';
+import { useDevicePixelRatio } from '.';
+
+type Listener = (event: { matches: boolean }) => void;
+
+interface StubMql {
+  readonly matches: boolean;
+  media: string;
+  addEventListener: (type: string, cb: Listener) => void;
+  removeEventListener: (type: string, cb: Listener) => void;
+  dispatch: (value: boolean) => void;
+}
+
+function makeMql(media = ''): StubMql {
+  const listeners = new Set<Listener>();
+  let matches = true;
+
+  return {
+    get matches() {
+      return matches;
+    },
+    media,
+    addEventListener: (_: string, cb: Listener) => listeners.add(cb),
+    removeEventListener: (_: string, cb: Listener) => listeners.delete(cb),
+    dispatch(value: boolean) {
+      matches = value;
+      for (const cb of listeners) cb({ matches: value });
+    },
+  };
+}
+
+/** Returns one MediaQueryList per query string so re-binding can be exercised. */
+function stubMatchMediaByQuery() {
+  const map = new Map<string, StubMql>();
+  const spy = vi.fn((query: string) => {
+    if (!map.has(query))
+      map.set(query, makeMql(query));
+    return map.get(query)!;
+  });
+  vi.stubGlobal('matchMedia', spy);
+  return { spy, map };
+}
+
+/** A minimal window stub whose `devicePixelRatio` can be mutated in tests. */
+function makeWindowStub(initialRatio: number): Window & { devicePixelRatio: number } {
+  return {
+    devicePixelRatio: initialRatio,
+    matchMedia: globalThis.matchMedia,
+  } as unknown as Window & { devicePixelRatio: number };
+}
+
+describe(useDevicePixelRatio, () => {
+  beforeEach(() => {
+    vi.stubGlobal('matchMedia', undefined);
+  });
+  afterEach(() => vi.unstubAllGlobals());
+
+  it('reflects the initial devicePixelRatio', async () => {
+    stubMatchMediaByQuery();
+    const window = makeWindowStub(2);
+    const scope = effectScope();
+    let result: ReturnType<typeof useDevicePixelRatio>;
+    scope.run(() => {
+      result = useDevicePixelRatio({ window });
+    });
+    await nextTick();
+    expect(result!.pixelRatio.value).toBe(2);
+    scope.stop();
+  });
+
+  it('returns a readonly ref', async () => {
+    stubMatchMediaByQuery();
+    const window = makeWindowStub(1);
+    const scope = effectScope();
+    let result: ReturnType<typeof useDevicePixelRatio>;
+    scope.run(() => {
+      result = useDevicePixelRatio({ window });
+    });
+    await nextTick();
+    expect(isReadonly(result!.pixelRatio)).toBeTruthy();
+    scope.stop();
+  });
+
+  it('updates when the resolution media query flips', async () => {
+    const { map } = stubMatchMediaByQuery();
+    const window = makeWindowStub(1);
+    const scope = effectScope();
+    let result: ReturnType<typeof useDevicePixelRatio>;
+    scope.run(() => {
+      result = useDevicePixelRatio({ window });
+    });
+    await nextTick();
+    expect(result!.pixelRatio.value).toBe(1);
+
+    // Simulate a zoom: the real ratio changes, then the current query flips.
+    window.devicePixelRatio = 2;
+    map.get('(resolution: 1dppx)')!.dispatch(false);
+    await nextTick();
+    expect(result!.pixelRatio.value).toBe(2);
+
+    scope.stop();
+  });
+
+  it('re-binds the listener after the ratio changes', async () => {
+    const { spy, map } = stubMatchMediaByQuery();
+    const window = makeWindowStub(1);
+    const scope = effectScope();
+    let result: ReturnType<typeof useDevicePixelRatio>;
+    scope.run(() => {
+      result = useDevicePixelRatio({ window });
+    });
+    await nextTick();
+
+    window.devicePixelRatio = 3;
+    map.get('(resolution: 1dppx)')!.dispatch(false);
+    await nextTick();
+    expect(result!.pixelRatio.value).toBe(3);
+
+    // The query string should now track 3dppx (new MediaQueryList created).
+    expect(spy).toHaveBeenCalledWith('(resolution: 3dppx)');
+
+    // Further changes are driven by the new MediaQueryList.
+    window.devicePixelRatio = 1.5;
+    map.get('(resolution: 3dppx)')!.dispatch(false);
+    await nextTick();
+    expect(result!.pixelRatio.value).toBe(1.5);
+
+    scope.stop();
+  });
+
+  it('stops tracking after stop()', async () => {
+    const { map } = stubMatchMediaByQuery();
+    const window = makeWindowStub(1);
+    const scope = effectScope();
+    let result: ReturnType<typeof useDevicePixelRatio>;
+    scope.run(() => {
+      result = useDevicePixelRatio({ window });
+    });
+    await nextTick();
+
+    result!.stop();
+
+    window.devicePixelRatio = 2;
+    map.get('(resolution: 1dppx)')!.dispatch(false);
+    await nextTick();
+    expect(result!.pixelRatio.value).toBe(1);
+
+    scope.stop();
+  });
+
+  it('defaults to 1 with a no-op stop when no window is available (SSR)', async () => {
+    const scope = effectScope();
+    let result: ReturnType<typeof useDevicePixelRatio>;
+    scope.run(() => {
+      result = useDevicePixelRatio({ window: undefined });
+    });
+    await nextTick();
+    expect(result!.pixelRatio.value).toBe(1);
+    // stop() must be safe to call even when nothing was bound.
+    expect(() => result!.stop()).not.toThrow();
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useDevicePixelRatio/index.ts

@@ -0,0 +1,63 @@
+import { noop } from '@robonen/stdlib';
+import { shallowReadonly, shallowRef, watch } from 'vue';
+import type { ShallowRef, WatchStopHandle } from 'vue';
+import { defaultWindow } from '@/types';
+import type { ConfigurableWindow } from '@/types';
+import { useMediaQuery } from '@/composables/browser/useMediaQuery';
+
+export interface UseDevicePixelRatioOptions extends ConfigurableWindow {}
+
+export interface UseDevicePixelRatioReturn {
+  /**
+   * Reactive, readonly `window.devicePixelRatio`. Defaults to `1` on the
+   * server / when no window is available.
+   */
+  pixelRatio: Readonly<ShallowRef<number>>;
+  /**
+   * Stop tracking the device pixel ratio. Idempotent and a no-op on SSR.
+   */
+  stop: WatchStopHandle;
+}
+
+/**
+ * @name useDevicePixelRatio
+ * @category Browser
+ * @description Reactively track `window.devicePixelRatio`, updated via a
+ * `matchMedia(resolution)` listener (fires on zoom and on monitor changes).
+ *
+ * @param {UseDevicePixelRatioOptions} [options={}] Options (custom `window`)
+ * @returns {UseDevicePixelRatioReturn} `{ pixelRatio, stop }`
+ *
+ * @example
+ * const { pixelRatio } = useDevicePixelRatio();
+ *
+ * @since 0.0.15
+ */
+export function useDevicePixelRatio(options: UseDevicePixelRatioOptions = {}): UseDevicePixelRatioReturn {
+  const { window = defaultWindow } = options;
+
+  const pixelRatio = shallowRef(1);
+
+  // `devicePixelRatio` has no `change` event; the canonical trick is to watch a
+  // `(resolution: Ndppx)` media query whose threshold tracks the current ratio.
+  // When the real ratio crosses that threshold the query flips, re-evaluating
+  // the reactive query string and re-binding to a fresh MediaQueryList.
+  const query = useMediaQuery(() => `(resolution: ${pixelRatio.value}dppx)`, options);
+
+  let stop: WatchStopHandle = noop;
+
+  if (window) {
+    stop = watch(
+      query,
+      () => {
+        pixelRatio.value = window.devicePixelRatio;
+      },
+      { immediate: true },
+    );
+  }
+
+  return {
+    pixelRatio: shallowReadonly(pixelRatio),
+    stop,
+  };
+}

vue/toolkit/src/composables/browser/useDocumentReadyState/index.test.ts

@@ -0,0 +1,143 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick } from 'vue';
+import { useDocumentReadyState } from '.';
+
+afterEach(() => {
+  vi.unstubAllGlobals();
+  Object.defineProperty(document, 'readyState', { value: 'complete', configurable: true });
+});
+
+function setReadyState(state: DocumentReadyState) {
+  Object.defineProperty(document, 'readyState', { value: state, configurable: true });
+  document.dispatchEvent(new Event('readystatechange'));
+}
+
+describe(useDocumentReadyState, () => {
+  it('reads the current ready state', () => {
+    const scope = effectScope();
+    let readyState: ReturnType<typeof useDocumentReadyState>;
+    scope.run(() => {
+      readyState = useDocumentReadyState();
+    });
+
+    expect(readyState!.value).toBe('complete');
+    scope.stop();
+  });
+
+  it('reflects a non-default initial state at setup time', () => {
+    Object.defineProperty(document, 'readyState', { value: 'loading', configurable: true });
+
+    const scope = effectScope();
+    let readyState: ReturnType<typeof useDocumentReadyState>;
+    scope.run(() => {
+      readyState = useDocumentReadyState();
+    });
+
+    expect(readyState!.value).toBe('loading');
+    scope.stop();
+  });
+
+  it('updates on readystatechange', async () => {
+    Object.defineProperty(document, 'readyState', { value: 'loading', configurable: true });
+
+    const scope = effectScope();
+    let readyState: ReturnType<typeof useDocumentReadyState>;
+    scope.run(() => {
+      readyState = useDocumentReadyState();
+    });
+
+    expect(readyState!.value).toBe('loading');
+
+    setReadyState('interactive');
+    await nextTick();
+    expect(readyState!.value).toBe('interactive');
+
+    setReadyState('complete');
+    await nextTick();
+    expect(readyState!.value).toBe('complete');
+
+    scope.stop();
+  });
+
+  it('invokes onChange with new state, previous state, and the event', async () => {
+    Object.defineProperty(document, 'readyState', { value: 'loading', configurable: true });
+
+    const onChange = vi.fn();
+    const scope = effectScope();
+    scope.run(() => {
+      useDocumentReadyState({ onChange });
+    });
+
+    setReadyState('interactive');
+    await nextTick();
+
+    expect(onChange).toHaveBeenCalledTimes(1);
+    const [state, previous, event] = onChange.mock.calls[0]!;
+    expect(state).toBe('interactive');
+    expect(previous).toBe('loading');
+    expect(event).toBeInstanceOf(Event);
+
+    setReadyState('complete');
+    await nextTick();
+
+    expect(onChange).toHaveBeenCalledTimes(2);
+    expect(onChange.mock.calls[1]!.slice(0, 2)).toEqual(['complete', 'interactive']);
+    scope.stop();
+  });
+
+  it('does not update or fire onChange when the state is unchanged', async () => {
+    const onChange = vi.fn();
+    const scope = effectScope();
+    let readyState: ReturnType<typeof useDocumentReadyState>;
+    scope.run(() => {
+      readyState = useDocumentReadyState({ onChange });
+    });
+
+    // readyState is already 'complete'; dispatching with no real change is a no-op
+    document.dispatchEvent(new Event('readystatechange'));
+    await nextTick();
+
+    expect(onChange).not.toHaveBeenCalled();
+    expect(readyState!.value).toBe('complete');
+    scope.stop();
+  });
+
+  it('is SSR-safe and returns "loading" without a document', () => {
+    // Passing `document: undefined` resolves to the default document, so to exercise the
+    // no-document branch we cast a falsy value that bypasses the default-parameter logic.
+    const scope = effectScope();
+    let readyState: ReturnType<typeof useDocumentReadyState>;
+    scope.run(() => {
+      readyState = useDocumentReadyState({ document: null as unknown as Document });
+    });
+
+    expect(readyState!.value).toBe('loading');
+    scope.stop();
+  });
+
+  it('accepts a custom document instance', async () => {
+    const onChange = vi.fn();
+    let listener: ((event: Event) => void) | undefined;
+    const customDoc = {
+      readyState: 'loading' as DocumentReadyState,
+      addEventListener: (_type: string, cb: (event: Event) => void) => { listener = cb; },
+      removeEventListener: vi.fn(),
+    } as unknown as Document;
+
+    const scope = effectScope();
+    let readyState: ReturnType<typeof useDocumentReadyState>;
+    scope.run(() => {
+      readyState = useDocumentReadyState({ document: customDoc, onChange });
+    });
+
+    expect(readyState!.value).toBe('loading');
+
+    (customDoc as { readyState: DocumentReadyState }).readyState = 'complete';
+    listener?.(new Event('readystatechange'));
+    await nextTick();
+
+    expect(readyState!.value).toBe('complete');
+    expect(onChange).toHaveBeenCalledWith('complete', 'loading', expect.any(Event));
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useDocumentReadyState/index.ts

@@ -0,0 +1,67 @@
+import { shallowRef } from 'vue';
+import type { ShallowRef } from 'vue';
+import { defaultDocument } from '@/types';
+import type { ConfigurableDocument } from '@/types';
+import { useEventListener } from '@/composables/browser/useEventListener';
+
+export interface UseDocumentReadyStateOptions extends ConfigurableDocument {
+  /**
+   * Called whenever `document.readyState` changes, receiving the new state,
+   * the previous state, and the originating `readystatechange` event.
+   *
+   * @default undefined
+   */
+  onChange?: (
+    state: DocumentReadyState,
+    previous: DocumentReadyState,
+    event: Event,
+  ) => void;
+}
+
+export type UseDocumentReadyStateReturn = ShallowRef<DocumentReadyState>;
+
+/**
+ * @name useDocumentReadyState
+ * @category Browser
+ * @description Reactive `document.readyState` (`loading` | `interactive` | `complete`), updated on `readystatechange`.
+ *
+ * @param {UseDocumentReadyStateOptions} [options={}] Options (custom `document`, `onChange` callback)
+ * @returns {UseDocumentReadyStateReturn} The current document ready state
+ *
+ * @example
+ * const readyState = useDocumentReadyState();
+ * watch(readyState, (state) => {
+ *   if (state === 'complete') runAfterLoad();
+ * });
+ *
+ * @example
+ * useDocumentReadyState({
+ *   onChange: (state) => {
+ *     if (state === 'interactive') hydrate();
+ *   },
+ * });
+ *
+ * @since 0.0.15
+ */
+export function useDocumentReadyState(
+  options: UseDocumentReadyStateOptions = {},
+): UseDocumentReadyStateReturn {
+  const { document = defaultDocument, onChange } = options;
+
+  const readyState = shallowRef<DocumentReadyState>(document?.readyState ?? 'loading');
+
+  if (document) {
+    useEventListener(document, 'readystatechange', (event) => {
+      const previous = readyState.value;
+      const state = document.readyState;
+
+      if (state === previous)
+        return;
+
+      readyState.value = state;
+      onChange?.(state, previous, event);
+    }, { passive: true });
+  }
+
+  return readyState;
+}

vue/toolkit/src/composables/browser/useDocumentVisibility/index.test.ts

@@ -0,0 +1,131 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick } from 'vue';
+import { useDocumentVisibility } from '.';
+
+afterEach(() => {
+  vi.unstubAllGlobals();
+  Object.defineProperty(document, 'visibilityState', { value: 'visible', configurable: true });
+});
+
+function setVisibility(state: DocumentVisibilityState) {
+  Object.defineProperty(document, 'visibilityState', { value: state, configurable: true });
+  document.dispatchEvent(new Event('visibilitychange'));
+}
+
+describe(useDocumentVisibility, () => {
+  it('reads the current visibility state', () => {
+    const scope = effectScope();
+    let visibility: ReturnType<typeof useDocumentVisibility>;
+    scope.run(() => {
+      visibility = useDocumentVisibility();
+    });
+
+    expect(visibility!.value).toBe('visible');
+    scope.stop();
+  });
+
+  it('updates on visibilitychange', async () => {
+    const scope = effectScope();
+    let visibility: ReturnType<typeof useDocumentVisibility>;
+    scope.run(() => {
+      visibility = useDocumentVisibility();
+    });
+
+    setVisibility('hidden');
+    await nextTick();
+
+    expect(visibility!.value).toBe('hidden');
+    scope.stop();
+  });
+
+  it('invokes onChange with new state, previous state, and the event', async () => {
+    const onChange = vi.fn();
+    const scope = effectScope();
+    scope.run(() => {
+      useDocumentVisibility({ onChange });
+    });
+
+    setVisibility('hidden');
+    await nextTick();
+
+    expect(onChange).toHaveBeenCalledTimes(1);
+    const [state, previous, event] = onChange.mock.calls[0]!;
+    expect(state).toBe('hidden');
+    expect(previous).toBe('visible');
+    expect(event).toBeInstanceOf(Event);
+
+    setVisibility('visible');
+    await nextTick();
+
+    expect(onChange).toHaveBeenCalledTimes(2);
+    expect(onChange.mock.calls[1]!.slice(0, 2)).toEqual(['visible', 'hidden']);
+    scope.stop();
+  });
+
+  it('does not update or fire onChange when the state is unchanged', async () => {
+    const onChange = vi.fn();
+    const scope = effectScope();
+    let visibility: ReturnType<typeof useDocumentVisibility>;
+    scope.run(() => {
+      visibility = useDocumentVisibility({ onChange });
+    });
+
+    // visibilityState is already 'visible'; dispatching with no real change is a no-op
+    document.dispatchEvent(new Event('visibilitychange'));
+    await nextTick();
+
+    expect(onChange).not.toHaveBeenCalled();
+    expect(visibility!.value).toBe('visible');
+    scope.stop();
+  });
+
+  it('reflects a non-default initial state at setup time', () => {
+    Object.defineProperty(document, 'visibilityState', { value: 'hidden', configurable: true });
+
+    const scope = effectScope();
+    let visibility: ReturnType<typeof useDocumentVisibility>;
+    scope.run(() => {
+      visibility = useDocumentVisibility();
+    });
+
+    expect(visibility!.value).toBe('hidden');
+    scope.stop();
+  });
+
+  it('is SSR-safe and returns "visible" without a document', () => {
+    const scope = effectScope();
+    let visibility: ReturnType<typeof useDocumentVisibility>;
+    scope.run(() => {
+      visibility = useDocumentVisibility({ document: undefined });
+    });
+
+    expect(visibility!.value).toBe('visible');
+    scope.stop();
+  });
+
+  it('accepts a custom document instance', async () => {
+    const onChange = vi.fn();
+    let listener: ((event: Event) => void) | undefined;
+    const customDoc = {
+      visibilityState: 'visible' as DocumentVisibilityState,
+      addEventListener: (_type: string, cb: (event: Event) => void) => { listener = cb; },
+      removeEventListener: vi.fn(),
+    } as unknown as Document;
+
+    const scope = effectScope();
+    let visibility: ReturnType<typeof useDocumentVisibility>;
+    scope.run(() => {
+      visibility = useDocumentVisibility({ document: customDoc, onChange });
+    });
+
+    expect(visibility!.value).toBe('visible');
+
+    (customDoc as { visibilityState: DocumentVisibilityState }).visibilityState = 'hidden';
+    listener?.(new Event('visibilitychange'));
+    await nextTick();
+
+    expect(visibility!.value).toBe('hidden');
+    expect(onChange).toHaveBeenCalledWith('hidden', 'visible', expect.any(Event));
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useDocumentVisibility/index.ts

@@ -0,0 +1,67 @@
+import { shallowRef } from 'vue';
+import type { ShallowRef } from 'vue';
+import { defaultDocument } from '@/types';
+import type { ConfigurableDocument } from '@/types';
+import { useEventListener } from '@/composables/browser/useEventListener';
+
+export interface UseDocumentVisibilityOptions extends ConfigurableDocument {
+  /**
+   * Called whenever `document.visibilityState` changes, receiving the new state,
+   * the previous state, and the originating `visibilitychange` event.
+   *
+   * @default undefined
+   */
+  onChange?: (
+    state: DocumentVisibilityState,
+    previous: DocumentVisibilityState,
+    event: Event,
+  ) => void;
+}
+
+export type UseDocumentVisibilityReturn = ShallowRef<DocumentVisibilityState>;
+
+/**
+ * @name useDocumentVisibility
+ * @category Browser
+ * @description Reactive `document.visibilityState`.
+ *
+ * @param {UseDocumentVisibilityOptions} [options={}] Options (custom `document`, `onChange` callback)
+ * @returns {UseDocumentVisibilityReturn} The current visibility state
+ *
+ * @example
+ * const visibility = useDocumentVisibility();
+ * watch(visibility, (state) => {
+ *   if (state === 'visible') refresh();
+ * });
+ *
+ * @example
+ * useDocumentVisibility({
+ *   onChange: (state) => {
+ *     if (state === 'hidden') pausePlayback();
+ *   },
+ * });
+ *
+ * @since 0.0.15
+ */
+export function useDocumentVisibility(
+  options: UseDocumentVisibilityOptions = {},
+): UseDocumentVisibilityReturn {
+  const { document = defaultDocument, onChange } = options;
+
+  const visibility = shallowRef<DocumentVisibilityState>(document?.visibilityState ?? 'visible');
+
+  if (document) {
+    useEventListener(document, 'visibilitychange', (event) => {
+      const previous = visibility.value;
+      const state = document.visibilityState;
+
+      if (state === previous)
+        return;
+
+      visibility.value = state;
+      onChange?.(state, previous, event);
+    }, { passive: true });
+  }
+
+  return visibility;
+}

vue/toolkit/src/composables/browser/useDropZone/index.test.ts

@@ -0,0 +1,288 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick, ref } from 'vue';
+import { useDropZone } from '.';
+
+interface FakeDataTransfer {
+  files: File[];
+  items: Array<{ type: string }>;
+  dropEffect: string;
+}
+
+function makeFile(name = 'a.png', type = 'image/png'): File {
+  return new File(['x'], name, { type });
+}
+
+// jsdom lacks DragEvent / DataTransfer, so we synthesize an Event with a dataTransfer payload.
+function dispatchDrag(
+  el: EventTarget,
+  type: 'dragenter' | 'dragover' | 'dragleave' | 'drop',
+  files: File[] = [],
+): { event: Event; dataTransfer: FakeDataTransfer } {
+  const dataTransfer: FakeDataTransfer = {
+    files,
+    items: files.map(f => ({ type: f.type })),
+    dropEffect: 'none',
+  };
+
+  const event = new Event(type, { bubbles: true, cancelable: true });
+  Object.defineProperty(event, 'dataTransfer', { value: dataTransfer, configurable: true });
+
+  el.dispatchEvent(event);
+  return { event, dataTransfer };
+}
+
+describe(useDropZone, () => {
+  let el: HTMLElement;
+
+  beforeEach(() => {
+    el = document.createElement('div');
+    document.body.appendChild(el);
+  });
+
+  afterEach(() => {
+    el.remove();
+    vi.unstubAllGlobals();
+  });
+
+  it('exposes reactive state', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const { isOverDropZone, files, isSupported } = useDropZone(el);
+      expect(isOverDropZone.value).toBeFalsy();
+      expect(files.value).toBeNull();
+      expect(isSupported).toBeDefined();
+    });
+    scope.stop();
+  });
+
+  it('sets isOverDropZone on dragenter and clears on matching dragleave', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const { isOverDropZone } = useDropZone(el);
+
+      dispatchDrag(el, 'dragenter', [makeFile()]);
+      expect(isOverDropZone.value).toBeTruthy();
+
+      dispatchDrag(el, 'dragleave', [makeFile()]);
+      expect(isOverDropZone.value).toBeFalsy();
+    });
+    scope.stop();
+  });
+
+  it('uses a counter so nested enter/leave keeps isOverDropZone true', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const { isOverDropZone } = useDropZone(el);
+
+      dispatchDrag(el, 'dragenter', [makeFile()]);
+      dispatchDrag(el, 'dragenter', [makeFile()]);
+      expect(isOverDropZone.value).toBeTruthy();
+
+      dispatchDrag(el, 'dragleave', [makeFile()]);
+      expect(isOverDropZone.value).toBeTruthy();
+
+      dispatchDrag(el, 'dragleave', [makeFile()]);
+      expect(isOverDropZone.value).toBeFalsy();
+    });
+    scope.stop();
+  });
+
+  it('collects dropped files and resets isOverDropZone', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const { files, isOverDropZone } = useDropZone(el);
+
+      dispatchDrag(el, 'dragenter', [makeFile()]);
+      const dropped = [makeFile('one.png'), makeFile('two.png')];
+      dispatchDrag(el, 'drop', dropped);
+
+      expect(files.value).toHaveLength(2);
+      expect(files.value?.[0]!.name).toBe('one.png');
+      expect(isOverDropZone.value).toBeFalsy();
+    });
+    scope.stop();
+  });
+
+  it('invokes lifecycle callbacks', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const onEnter = vi.fn();
+      const onOver = vi.fn();
+      const onLeave = vi.fn();
+      const onDrop = vi.fn();
+
+      useDropZone(el, { onEnter, onOver, onLeave, onDrop });
+
+      const f = [makeFile()];
+      dispatchDrag(el, 'dragenter', f);
+      dispatchDrag(el, 'dragover', f);
+      dispatchDrag(el, 'dragleave', f);
+      dispatchDrag(el, 'drop', f);
+
+      expect(onEnter).toHaveBeenCalledTimes(1);
+      expect(onOver).toHaveBeenCalledTimes(1);
+      expect(onLeave).toHaveBeenCalledTimes(1);
+      expect(onDrop).toHaveBeenCalledTimes(1);
+      expect(onEnter).toHaveBeenCalledWith(null, expect.any(Event));
+      expect(onDrop.mock.calls[0]![0]).toHaveLength(1);
+    });
+    scope.stop();
+  });
+
+  it('accepts a shorthand onDrop function as options', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const onDrop = vi.fn();
+      useDropZone(el, onDrop);
+
+      dispatchDrag(el, 'drop', [makeFile()]);
+      expect(onDrop).toHaveBeenCalledTimes(1);
+    });
+    scope.stop();
+  });
+
+  it('respects multiple: false by keeping only the first file', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const { files } = useDropZone(el, { multiple: false });
+
+      // Two files dragged: validation should reject, so drop is ignored
+      dispatchDrag(el, 'drop', [makeFile('a.png'), makeFile('b.png')]);
+      expect(files.value).toBeNull();
+
+      // Single file passes and only the first is kept
+      dispatchDrag(el, 'drop', [makeFile('solo.png')]);
+      expect(files.value).toHaveLength(1);
+      expect(files.value?.[0]!.name).toBe('solo.png');
+    });
+    scope.stop();
+  });
+
+  it('filters by dataTypes array', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const onDrop = vi.fn();
+      const { files } = useDropZone(el, { dataTypes: ['image/png'], onDrop });
+
+      // wrong type rejected
+      dispatchDrag(el, 'drop', [makeFile('doc.pdf', 'application/pdf')]);
+      expect(files.value).toBeNull();
+      expect(onDrop).not.toHaveBeenCalled();
+
+      // correct type accepted
+      dispatchDrag(el, 'drop', [makeFile('img.png', 'image/png')]);
+      expect(files.value).toHaveLength(1);
+      expect(onDrop).toHaveBeenCalledTimes(1);
+    });
+    scope.stop();
+  });
+
+  it('supports dataTypes as a predicate function', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const predicate = vi.fn((types: readonly string[]) => types.includes('image/png'));
+      const { files } = useDropZone(el, { dataTypes: predicate });
+
+      dispatchDrag(el, 'drop', [makeFile('img.png', 'image/png')]);
+      expect(predicate).toHaveBeenCalled();
+      expect(files.value).toHaveLength(1);
+    });
+    scope.stop();
+  });
+
+  it('reacts to a reactive dataTypes ref', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const allowed = ref<string[]>(['image/png']);
+      const { files } = useDropZone(el, { dataTypes: allowed });
+
+      dispatchDrag(el, 'drop', [makeFile('doc.pdf', 'application/pdf')]);
+      expect(files.value).toBeNull();
+
+      allowed.value = ['application/pdf'];
+      dispatchDrag(el, 'drop', [makeFile('doc.pdf', 'application/pdf')]);
+      expect(files.value).toHaveLength(1);
+    });
+    scope.stop();
+  });
+
+  it('sets dropEffect to none for invalid drags', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      useDropZone(el, { dataTypes: ['image/png'] });
+
+      const { dataTransfer } = dispatchDrag(el, 'dragenter', [makeFile('doc.pdf', 'application/pdf')]);
+      expect(dataTransfer.dropEffect).toBe('none');
+    });
+    scope.stop();
+  });
+
+  it('sets dropEffect to copy for valid drags', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      useDropZone(el, { dataTypes: ['image/png'] });
+
+      const { dataTransfer } = dispatchDrag(el, 'dragenter', [makeFile('img.png', 'image/png')]);
+      expect(dataTransfer.dropEffect).toBe('copy');
+    });
+    scope.stop();
+  });
+
+  it('preventDefaultForUnhandled calls preventDefault on invalid drags', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      useDropZone(el, { dataTypes: ['image/png'], preventDefaultForUnhandled: true });
+
+      const { event } = dispatchDrag(el, 'dragenter', [makeFile('doc.pdf', 'application/pdf')]);
+      expect(event.defaultPrevented).toBeTruthy();
+    });
+    scope.stop();
+  });
+
+  it('works with a reactive element ref target', async () => {
+    const scope = effectScope();
+    await scope.run(async () => {
+      const target = ref<HTMLElement | null>(null);
+      const { isOverDropZone } = useDropZone(target);
+
+      target.value = el;
+      await nextTick();
+
+      dispatchDrag(el, 'dragenter', [makeFile()]);
+      expect(isOverDropZone.value).toBeTruthy();
+    });
+    scope.stop();
+  });
+
+  it('works with document as the target', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const { isOverDropZone } = useDropZone(document);
+
+      dispatchDrag(document, 'dragenter', [makeFile()]);
+      expect(isOverDropZone.value).toBeTruthy();
+    });
+    scope.stop();
+  });
+
+  it('stops listening after the scope is disposed', () => {
+    const onDrop = vi.fn();
+    const scope = effectScope();
+    scope.run(() => {
+      useDropZone(el, { onDrop });
+    });
+    scope.stop();
+
+    dispatchDrag(el, 'drop', [makeFile()]);
+    expect(onDrop).not.toHaveBeenCalled();
+  });
+
+  it('reports isSupported via the configurable window option', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const { isSupported } = useDropZone(el, { window: undefined });
+      expect(isSupported.value).toBeFalsy();
+    });
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useDropZone/index.ts

@@ -0,0 +1,205 @@
+import type { ComputedRef, MaybeRef, MaybeRefOrGetter, ShallowRef } from 'vue';
+import { shallowRef, toValue, unref } from 'vue';
+import { isFunction } from '@robonen/stdlib';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { useSupported } from '@/composables/browser/useSupported';
+import { unrefElement } from '@/composables/component/unrefElement';
+import type { MaybeComputedElementRef } from '@/composables/component/unrefElement';
+import { defaultNavigator, defaultWindow } from '@/types';
+import type { ConfigurableNavigator, ConfigurableWindow } from '@/types';
+
+export type UseDropZoneDataTypes = MaybeRef<readonly string[]> | ((types: readonly string[]) => boolean);
+
+export interface UseDropZoneOptions extends ConfigurableWindow, ConfigurableNavigator {
+  /**
+   * Allowed data types. If not set, all data types are allowed.
+   * Can also be a predicate that receives the dragged item types and returns whether they are valid.
+   */
+  dataTypes?: UseDropZoneDataTypes;
+  /**
+   * Allow multiple files to be dropped.
+   *
+   * @default true
+   */
+  multiple?: boolean;
+  /**
+   * Call `preventDefault` even for drags that fail validation, suppressing the browser's default handling.
+   *
+   * @default false
+   */
+  preventDefaultForUnhandled?: boolean;
+  /**
+   * Fired when valid files are dropped on the target.
+   */
+  onDrop?: (files: File[] | null, event: DragEvent) => void;
+  /**
+   * Fired when a drag enters the target.
+   */
+  onEnter?: (files: File[] | null, event: DragEvent) => void;
+  /**
+   * Fired when a drag leaves the target.
+   */
+  onLeave?: (files: File[] | null, event: DragEvent) => void;
+  /**
+   * Fired repeatedly while a drag hovers over the target.
+   */
+  onOver?: (files: File[] | null, event: DragEvent) => void;
+}
+
+export interface UseDropZoneReturn {
+  /**
+   * Whether a valid drag is currently hovering over the target.
+   */
+  isOverDropZone: ShallowRef<boolean>;
+  /**
+   * The dropped files, or `null` when nothing has been dropped yet.
+   */
+  files: ShallowRef<File[] | null>;
+  /**
+   * Whether the Drag and Drop API is available in the current environment.
+   */
+  isSupported: ComputedRef<boolean>;
+}
+
+type DropZoneEventType = 'enter' | 'over' | 'leave' | 'drop';
+
+/**
+ * @name useDropZone
+ * @category Browser
+ * @description Create a drag-and-drop file drop zone on a target element or document.
+ *
+ * @param {MaybeComputedElementRef | MaybeRefOrGetter<Document | null | undefined>} target - The element (or document) acting as the drop zone.
+ * @param {UseDropZoneOptions | UseDropZoneOptions['onDrop']} [options] - Drop zone options, or a shorthand `onDrop` callback.
+ * @returns {UseDropZoneReturn} The reactive drop zone state.
+ *
+ * @example
+ * const dropZone = useTemplateRef<HTMLElement>('dropZone');
+ * const { isOverDropZone, files } = useDropZone(dropZone, {
+ *   dataTypes: ['image/png'],
+ *   onDrop: (files) => console.log(files),
+ * });
+ *
+ * @since 0.0.15
+ */
+export function useDropZone(
+  target: MaybeComputedElementRef | MaybeRefOrGetter<Document | null | undefined>,
+  options: UseDropZoneOptions | UseDropZoneOptions['onDrop'] = {},
+): UseDropZoneReturn {
+  const _options: UseDropZoneOptions = isFunction(options) ? { onDrop: options } : options;
+  const {
+    window = defaultWindow,
+    navigator = defaultNavigator,
+    multiple = true,
+    preventDefaultForUnhandled = false,
+  } = _options;
+
+  const isOverDropZone = shallowRef(false);
+  const files = shallowRef<File[] | null>(null);
+  const isSupported = useSupported(() => window && 'DataTransfer' in window);
+
+  let counter = 0;
+  let isValid = true;
+
+  const getFiles = (event: DragEvent): File[] | null => {
+    const list = Array.from(event.dataTransfer?.files ?? []);
+    if (list.length === 0)
+      return null;
+    return multiple ? list : [list[0]!];
+  };
+
+  const checkDataTypes = (types: readonly string[]): boolean => {
+    // `dataTypes` may be a predicate function, so unwrap with `unref` (not `toValue`,
+    // which would call a function as a getter).
+    const dataTypes = unref(_options.dataTypes);
+
+    if (isFunction(dataTypes))
+      return dataTypes(types);
+
+    if (!dataTypes?.length)
+      return true;
+
+    if (types.length === 0)
+      return false;
+
+    return types.every(type => dataTypes.some(allowed => type.includes(allowed)));
+  };
+
+  const checkValidity = (items: DataTransferItemList): boolean => {
+    const types = Array.from(items ?? []).map(item => item.type);
+    const dataTypesValid = checkDataTypes(types);
+    const multipleFilesValid = multiple || items.length <= 1;
+
+    return dataTypesValid && multipleFilesValid;
+  };
+
+  // Safari fires drag events without populating `dataTransfer.items`, so validation
+  // cannot be trusted there — always accept the drag and let `drop` resolve files.
+  const isSafari = (): boolean => {
+    if (!navigator || !window)
+      return false;
+    return /^(?:(?!chrome|android).)*safari/i.test(navigator.userAgent) && !('chrome' in window);
+  };
+
+  const handleDragEvent = (event: DragEvent, type: DropZoneEventType): void => {
+    const items = event.dataTransfer?.items;
+    isValid = (items && checkValidity(items)) ?? false;
+
+    if (preventDefaultForUnhandled)
+      event.preventDefault();
+
+    if (!isSafari() && !isValid) {
+      if (event.dataTransfer)
+        event.dataTransfer.dropEffect = 'none';
+      return;
+    }
+
+    event.preventDefault();
+    if (event.dataTransfer)
+      event.dataTransfer.dropEffect = 'copy';
+
+    const currentFiles = getFiles(event);
+
+    switch (type) {
+      case 'enter':
+        counter += 1;
+        isOverDropZone.value = true;
+        _options.onEnter?.(null, event);
+        break;
+      case 'over':
+        _options.onOver?.(null, event);
+        break;
+      case 'leave':
+        counter -= 1;
+        if (counter === 0)
+          isOverDropZone.value = false;
+        _options.onLeave?.(null, event);
+        break;
+      case 'drop':
+        counter = 0;
+        isOverDropZone.value = false;
+        if (isValid) {
+          files.value = currentFiles;
+          _options.onDrop?.(currentFiles, event);
+        }
+        break;
+    }
+  };
+
+  const resolveTarget = (): EventTarget | null | undefined => {
+    const value = toValue(target as MaybeRefOrGetter<unknown>);
+    if (value instanceof Document)
+      return value;
+    return unrefElement(target as MaybeComputedElementRef);
+  };
+
+  useEventListener<DragEvent>(resolveTarget, 'dragenter', event => handleDragEvent(event, 'enter'));
+  useEventListener<DragEvent>(resolveTarget, 'dragover', event => handleDragEvent(event, 'over'));
+  useEventListener<DragEvent>(resolveTarget, 'dragleave', event => handleDragEvent(event, 'leave'));
+  useEventListener<DragEvent>(resolveTarget, 'drop', event => handleDragEvent(event, 'drop'));
+
+  return {
+    isOverDropZone,
+    files,
+    isSupported,
+  };
+}

vue/toolkit/src/composables/browser/useElementBounding/index.test.ts

@@ -0,0 +1,153 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, ref } from 'vue';
+import { useElementBounding } from '.';
+
+class StubObserver {
+  observe = vi.fn();
+  disconnect = vi.fn();
+  unobserve = vi.fn();
+  takeRecords = vi.fn(() => []);
+}
+
+describe(useElementBounding, () => {
+  beforeEach(() => {
+    vi.stubGlobal('ResizeObserver', StubObserver);
+    vi.stubGlobal('MutationObserver', StubObserver);
+  });
+  afterEach(() => vi.unstubAllGlobals());
+
+  it('reads the bounding rect immediately', () => {
+    const el = document.createElement('div');
+    el.getBoundingClientRect = () => ({
+      width: 100, height: 50, top: 10, left: 20, right: 120, bottom: 60, x: 20, y: 10,
+    } as DOMRect);
+
+    const scope = effectScope();
+    let bounds: ReturnType<typeof useElementBounding>;
+    scope.run(() => {
+      bounds = useElementBounding(ref(el));
+    });
+
+    expect(bounds!.width.value).toBe(100);
+    expect(bounds!.height.value).toBe(50);
+    expect(bounds!.top.value).toBe(10);
+    expect(bounds!.left.value).toBe(20);
+    expect(bounds!.x.value).toBe(20);
+    expect(bounds!.y.value).toBe(10);
+    scope.stop();
+  });
+
+  it('update recomputes the rect', () => {
+    const el = document.createElement('div');
+    let w = 10;
+    el.getBoundingClientRect = () => ({ width: w, height: 0, top: 0, left: 0, right: 0, bottom: 0, x: 0, y: 0 } as DOMRect);
+
+    const scope = effectScope();
+    let bounds: ReturnType<typeof useElementBounding>;
+    scope.run(() => {
+      bounds = useElementBounding(ref(el));
+    });
+
+    expect(bounds!.width.value).toBe(10);
+    w = 200;
+    bounds!.update();
+    expect(bounds!.width.value).toBe(200);
+    scope.stop();
+  });
+
+  it('resets to zero when target is null', () => {
+    const scope = effectScope();
+    let bounds: ReturnType<typeof useElementBounding>;
+    scope.run(() => {
+      bounds = useElementBounding(ref(null));
+    });
+
+    expect(bounds!.width.value).toBe(0);
+    expect(bounds!.height.value).toBe(0);
+    scope.stop();
+  });
+
+  // NOTE: defaultWindow is captured at import time, so vi.stubGlobal does not
+  // reach requestAnimationFrame. We inject a fake window via the `window` option.
+  it('defers measurement to the next frame with updateTiming "next-frame"', () => {
+    const raf = vi.fn((cb: FrameRequestCallback) => {
+      cb(0);
+      return 1;
+    });
+    const fakeWindow = { requestAnimationFrame: raf, cancelAnimationFrame: vi.fn() } as unknown as Window;
+
+    const el = document.createElement('div');
+    let w = 10;
+    el.getBoundingClientRect = () => ({ width: w, height: 0, top: 0, left: 0, right: 0, bottom: 0, x: 0, y: 0 } as DOMRect);
+
+    const scope = effectScope();
+    let bounds: ReturnType<typeof useElementBounding>;
+    scope.run(() => {
+      bounds = useElementBounding(ref(el), { updateTiming: 'next-frame', window: fakeWindow });
+    });
+
+    // The immediate update went through requestAnimationFrame
+    expect(raf).toHaveBeenCalled();
+    expect(bounds!.width.value).toBe(10);
+
+    w = 200;
+    bounds!.update();
+    expect(bounds!.width.value).toBe(200);
+    scope.stop();
+  });
+
+  it('coalesces multiple "next-frame" updates into a single read per frame', () => {
+    let scheduled: FrameRequestCallback | undefined;
+    const raf = vi.fn((cb: FrameRequestCallback) => {
+      scheduled = cb;
+      return 1;
+    });
+    const fakeWindow = { requestAnimationFrame: raf, cancelAnimationFrame: vi.fn() } as unknown as Window;
+
+    const el = document.createElement('div');
+    const getRect = vi.fn(() => ({ width: 0, height: 0, top: 0, left: 0, right: 0, bottom: 0, x: 0, y: 0 } as DOMRect));
+    el.getBoundingClientRect = getRect;
+
+    const scope = effectScope();
+    let bounds: ReturnType<typeof useElementBounding>;
+    scope.run(() => {
+      bounds = useElementBounding(ref(el), { updateTiming: 'next-frame', immediate: false, window: fakeWindow });
+    });
+
+    bounds!.update();
+    bounds!.update();
+    bounds!.update();
+
+    // Only one frame was scheduled despite three update() calls
+    expect(raf).toHaveBeenCalledTimes(1);
+    expect(getRect).not.toHaveBeenCalled();
+
+    // Flushing the frame reads the rect exactly once
+    scheduled!(0);
+    expect(getRect).toHaveBeenCalledTimes(1);
+
+    // A new update after the frame flushed schedules a fresh frame
+    bounds!.update();
+    expect(raf).toHaveBeenCalledTimes(2);
+    scope.stop();
+  });
+
+  it('cancels a pending frame on scope dispose', () => {
+    const raf = vi.fn(() => 42);
+    const caf = vi.fn();
+    const fakeWindow = { requestAnimationFrame: raf, cancelAnimationFrame: caf } as unknown as Window;
+
+    const el = document.createElement('div');
+    el.getBoundingClientRect = () => ({ width: 0, height: 0, top: 0, left: 0, right: 0, bottom: 0, x: 0, y: 0 } as DOMRect);
+
+    const scope = effectScope();
+    scope.run(() => {
+      useElementBounding(ref(el), { updateTiming: 'next-frame', window: fakeWindow });
+    });
+
+    // The immediate update scheduled a frame that never ran (raf returns id without invoking)
+    expect(raf).toHaveBeenCalled();
+    scope.stop();
+    expect(caf).toHaveBeenCalledWith(42);
+  });
+});

vue/toolkit/src/composables/browser/useElementBounding/index.ts

@@ -0,0 +1,199 @@
+import { shallowRef, watch } from 'vue';
+import type { Ref } from 'vue';
+import { defaultWindow } from '@/types';
+import type { ConfigurableWindow } from '@/types';
+import type { MaybeComputedElementRef } from '@/composables/component/unrefElement';
+import { unrefElement } from '@/composables/component/unrefElement';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { useResizeObserver } from '@/composables/browser/useResizeObserver';
+import { useMutationObserver } from '@/composables/browser/useMutationObserver';
+import { tryOnScopeDispose } from '@/composables/lifecycle/tryOnScopeDispose';
+
+export interface UseElementBoundingOptions extends ConfigurableWindow {
+  /**
+   * Reset values to 0 when the element is unmounted
+   *
+   * @default true
+   */
+  reset?: boolean;
+
+  /**
+   * Recalculate on window resize
+   *
+   * @default true
+   */
+  windowResize?: boolean;
+
+  /**
+   * Recalculate on window scroll
+   *
+   * @default true
+   */
+  windowScroll?: boolean;
+
+  /**
+   * Calculate immediately on mount
+   *
+   * @default true
+   */
+  immediate?: boolean;
+
+  /**
+   * When to recalculate the bounding box.
+   *
+   * - `'sync'` measures synchronously, the moment a trigger fires.
+   * - `'next-frame'` defers measurement to the next animation frame. This
+   *   batches bursts of triggers (e.g. rapid scroll/resize) into a single
+   *   read per frame, avoiding repeated layout thrash from `getBoundingClientRect`.
+   *
+   * @default 'sync'
+   */
+  updateTiming?: 'sync' | 'next-frame';
+}
+
+export interface UseElementBoundingReturn {
+  height: Ref<number>;
+  width: Ref<number>;
+  top: Ref<number>;
+  right: Ref<number>;
+  bottom: Ref<number>;
+  left: Ref<number>;
+  x: Ref<number>;
+  y: Ref<number>;
+  /**
+   * Manually recalculate the bounding box, honouring `updateTiming`.
+   */
+  update: () => void;
+}
+
+/**
+ * @name useElementBounding
+ * @category Browser
+ * @description Reactive bounding box of an element (`getBoundingClientRect`),
+ * kept in sync via `ResizeObserver`, `MutationObserver`, and window scroll/resize.
+ * Supports deferring reads to the next animation frame to avoid layout thrash.
+ *
+ * @param {MaybeComputedElementRef} target Element to measure
+ * @param {UseElementBoundingOptions} [options={}] Options
+ * @returns {UseElementBoundingReturn} Reactive bounds and a manual `update`
+ *
+ * @example
+ * const { width, height, top, left } = useElementBounding(el);
+ *
+ * @example
+ * // Batch rapid scroll/resize reads into one measurement per frame
+ * const bounds = useElementBounding(el, { updateTiming: 'next-frame' });
+ *
+ * @since 0.0.15
+ */
+export function useElementBounding(
+  target: MaybeComputedElementRef,
+  options: UseElementBoundingOptions = {},
+): UseElementBoundingReturn {
+  const {
+    reset = true,
+    windowResize = true,
+    windowScroll = true,
+    immediate = true,
+    updateTiming = 'sync',
+    window = defaultWindow,
+  } = options;
+
+  const height = shallowRef(0);
+  const width = shallowRef(0);
+  const top = shallowRef(0);
+  const right = shallowRef(0);
+  const bottom = shallowRef(0);
+  const left = shallowRef(0);
+  const x = shallowRef(0);
+  const y = shallowRef(0);
+
+  function recalculate() {
+    const el = unrefElement(target);
+
+    if (!el) {
+      if (reset) {
+        height.value = 0;
+        width.value = 0;
+        top.value = 0;
+        right.value = 0;
+        bottom.value = 0;
+        left.value = 0;
+        x.value = 0;
+        y.value = 0;
+      }
+      return;
+    }
+
+    const rect = el.getBoundingClientRect();
+
+    height.value = rect.height;
+    width.value = rect.width;
+    top.value = rect.top;
+    right.value = rect.right;
+    bottom.value = rect.bottom;
+    left.value = rect.left;
+    x.value = rect.x;
+    y.value = rect.y;
+  }
+
+  // Pending animation frame id, so deferred reads coalesce and can be cancelled.
+  // `pending` is the source of truth for coalescing; `rafId` is only kept for
+  // cancellation. A separate flag avoids ordering bugs when the scheduler runs
+  // the callback synchronously (the assignment below would otherwise clobber the
+  // id the callback just cleared).
+  let pending = false;
+  let rafId: number | undefined;
+
+  function update() {
+    if (updateTiming === 'next-frame' && window) {
+      // Coalesce: only schedule one read per frame
+      if (pending)
+        return;
+
+      pending = true;
+      rafId = window.requestAnimationFrame(() => {
+        pending = false;
+        rafId = undefined;
+        recalculate();
+      });
+      return;
+    }
+
+    recalculate();
+  }
+
+  useResizeObserver(target, update);
+  watch(() => unrefElement(target), el => !el && update());
+  useMutationObserver(target, update, { attributeFilter: ['style', 'class'] });
+
+  if (windowScroll)
+    useEventListener('scroll', update, { capture: true, passive: true });
+
+  if (windowResize)
+    useEventListener('resize', update, { passive: true });
+
+  if (window && immediate)
+    update();
+
+  // Cancel any pending frame so we don't read a detached/disposed element
+  tryOnScopeDispose(() => {
+    if (pending && rafId !== undefined && window)
+      window.cancelAnimationFrame(rafId);
+
+    pending = false;
+    rafId = undefined;
+  });
+
+  return {
+    height,
+    width,
+    top,
+    right,
+    bottom,
+    left,
+    x,
+    y,
+    update,
+  };
+}

vue/toolkit/src/composables/browser/useElementHover/index.test.ts

@@ -0,0 +1,183 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, isReadonly, ref } from 'vue';
+import { useElementHover } from '.';
+
+function dispatch(el: HTMLElement, type: 'mouseenter' | 'mouseleave') {
+  el.dispatchEvent(new Event(type));
+}
+
+describe(useElementHover, () => {
+  beforeEach(() => vi.useFakeTimers());
+  afterEach(() => vi.useRealTimers());
+
+  it('is false initially', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isHovered: ReturnType<typeof useElementHover>;
+    scope.run(() => {
+      isHovered = useElementHover(ref(el));
+    });
+
+    expect(isHovered!.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('toggles on mouseenter / mouseleave', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isHovered: ReturnType<typeof useElementHover>;
+    scope.run(() => {
+      isHovered = useElementHover(ref(el));
+    });
+
+    dispatch(el, 'mouseenter');
+    expect(isHovered!.value).toBeTruthy();
+
+    dispatch(el, 'mouseleave');
+    expect(isHovered!.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('returns a writable shallow ref (not readonly)', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isHovered: ReturnType<typeof useElementHover>;
+    scope.run(() => {
+      isHovered = useElementHover(ref(el));
+    });
+
+    expect(isReadonly(isHovered!)).toBeFalsy();
+    scope.stop();
+  });
+
+  it('respects delayEnter', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isHovered: ReturnType<typeof useElementHover>;
+    scope.run(() => {
+      isHovered = useElementHover(ref(el), { delayEnter: 100 });
+    });
+
+    dispatch(el, 'mouseenter');
+    expect(isHovered!.value).toBeFalsy();
+
+    vi.advanceTimersByTime(99);
+    expect(isHovered!.value).toBeFalsy();
+
+    vi.advanceTimersByTime(1);
+    expect(isHovered!.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('respects delayLeave', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isHovered: ReturnType<typeof useElementHover>;
+    scope.run(() => {
+      isHovered = useElementHover(ref(el), { delayLeave: 200 });
+    });
+
+    dispatch(el, 'mouseenter');
+    expect(isHovered!.value).toBeTruthy();
+
+    dispatch(el, 'mouseleave');
+    expect(isHovered!.value).toBeTruthy();
+
+    vi.advanceTimersByTime(199);
+    expect(isHovered!.value).toBeTruthy();
+
+    vi.advanceTimersByTime(1);
+    expect(isHovered!.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('cancels a pending enter timer when leaving before the delay elapses', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isHovered: ReturnType<typeof useElementHover>;
+    scope.run(() => {
+      isHovered = useElementHover(ref(el), { delayEnter: 100 });
+    });
+
+    dispatch(el, 'mouseenter');
+    vi.advanceTimersByTime(50);
+    expect(isHovered!.value).toBeFalsy();
+
+    // Leaving cancels the pending enter; with no leave delay it settles to false.
+    dispatch(el, 'mouseleave');
+    vi.advanceTimersByTime(100);
+    expect(isHovered!.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('cancels a pending leave timer when re-entering before the delay elapses', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isHovered: ReturnType<typeof useElementHover>;
+    scope.run(() => {
+      isHovered = useElementHover(ref(el), { delayLeave: 200 });
+    });
+
+    dispatch(el, 'mouseenter');
+    expect(isHovered!.value).toBeTruthy();
+
+    dispatch(el, 'mouseleave');
+    vi.advanceTimersByTime(100);
+    // Re-enter before the leave delay finishes: stays hovered, no flip.
+    dispatch(el, 'mouseenter');
+    vi.advanceTimersByTime(200);
+    expect(isHovered!.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('stops listening once the scope is disposed', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isHovered: ReturnType<typeof useElementHover>;
+    scope.run(() => {
+      isHovered = useElementHover(ref(el));
+    });
+
+    scope.stop();
+
+    dispatch(el, 'mouseenter');
+    expect(isHovered!.value).toBeFalsy();
+  });
+
+  it('clears a pending timer on scope dispose (no late update)', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isHovered: ReturnType<typeof useElementHover>;
+    scope.run(() => {
+      isHovered = useElementHover(ref(el), { delayEnter: 100 });
+    });
+
+    dispatch(el, 'mouseenter');
+    scope.stop();
+
+    vi.advanceTimersByTime(200);
+    expect(isHovered!.value).toBeFalsy();
+  });
+
+  it('returns a static ref and registers no listeners when window is falsy (SSR)', () => {
+    // `defaultWindow` is captured at import time and cannot be stubbed via
+    // vi.stubGlobal, so we cast a falsy window through options to exercise the
+    // SSR early-return without touching the global. Note that passing literal
+    // `undefined` would resolve back to `defaultWindow` via the destructure
+    // default, hence the explicit null cast here.
+    const el = document.createElement('div');
+    const addSpy = vi.spyOn(el, 'addEventListener');
+    const scope = effectScope();
+    let isHovered: ReturnType<typeof useElementHover>;
+    scope.run(() => {
+      isHovered = useElementHover(ref(el), { window: null as unknown as Window });
+    });
+
+    expect(isHovered!.value).toBeFalsy();
+    expect(addSpy).not.toHaveBeenCalled();
+
+    dispatch(el, 'mouseenter');
+    expect(isHovered!.value).toBeFalsy();
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useElementHover/index.ts

@@ -0,0 +1,91 @@
+import { computed, shallowRef } from 'vue';
+import type { ShallowRef } from 'vue';
+import type { ConfigurableWindow } from '@/types';
+import { defaultWindow } from '@/types';
+import type { MaybeComputedElementRef } from '@/composables/component/unrefElement';
+import { unrefElement } from '@/composables/component/unrefElement';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { tryOnScopeDispose } from '@/composables/lifecycle/tryOnScopeDispose';
+
+export interface UseElementHoverOptions extends ConfigurableWindow {
+  /**
+   * Delay in milliseconds before flipping the state to hovered on `mouseenter`.
+   *
+   * @default 0
+   */
+  delayEnter?: number;
+
+  /**
+   * Delay in milliseconds before flipping the state to not-hovered on `mouseleave`.
+   *
+   * @default 0
+   */
+  delayLeave?: number;
+}
+
+export type UseElementHoverReturn = ShallowRef<boolean>;
+
+/**
+ * @name useElementHover
+ * @category Browser
+ * @description Reactive hover state of an element, driven by `mouseenter` /
+ * `mouseleave`. Supports independent enter/leave delays to debounce flicker.
+ *
+ * @param {MaybeComputedElementRef} target Element to track (ref, getter, or component instance)
+ * @param {UseElementHoverOptions} [options={}] Options (`delayEnter`, `delayLeave`, `window`)
+ * @returns {UseElementHoverReturn} Reactive hover state ref
+ *
+ * @example
+ * const el = useTemplateRef('el');
+ * const isHovered = useElementHover(el);
+ *
+ * @example
+ * const isHovered = useElementHover(el, { delayEnter: 100, delayLeave: 200 });
+ *
+ * @since 0.0.15
+ */
+export function useElementHover(
+  target: MaybeComputedElementRef,
+  options: UseElementHoverOptions = {},
+): UseElementHoverReturn {
+  const {
+    delayEnter = 0,
+    delayLeave = 0,
+    window = defaultWindow,
+  } = options;
+
+  const isHovered = shallowRef(false);
+
+  let timer: ReturnType<typeof setTimeout> | undefined;
+
+  const clear = (): void => {
+    if (timer !== undefined) {
+      clearTimeout(timer);
+      timer = undefined;
+    }
+  };
+
+  const toggle = (entering: boolean): void => {
+    const delay = entering ? delayEnter : delayLeave;
+
+    clear();
+
+    if (delay)
+      timer = setTimeout(() => { isHovered.value = entering; }, delay);
+    else
+      isHovered.value = entering;
+  };
+
+  // SSR / no DOM: return a static, never-updating ref.
+  if (!window)
+    return isHovered;
+
+  const targetElement = computed(() => unrefElement(target) as HTMLElement | undefined | null);
+
+  useEventListener(targetElement, 'mouseenter', () => toggle(true), { passive: true });
+  useEventListener(targetElement, 'mouseleave', () => toggle(false), { passive: true });
+
+  tryOnScopeDispose(clear);
+
+  return isHovered;
+}

vue/toolkit/src/composables/browser/useElementSize/index.test.ts

@@ -0,0 +1,229 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick, ref } from 'vue';
+import { useElementSize } from '.';
+
+interface StubInstance {
+  cb: ResizeObserverCallback;
+  observe: ReturnType<typeof vi.fn>;
+  disconnect: ReturnType<typeof vi.fn>;
+  unobserve: ReturnType<typeof vi.fn>;
+}
+
+let instances: StubInstance[] = [];
+
+class StubResizeObserver {
+  observe = vi.fn();
+  disconnect = vi.fn();
+  unobserve = vi.fn();
+  cb: ResizeObserverCallback;
+  constructor(cb: ResizeObserverCallback) {
+    this.cb = cb;
+    instances.push(this);
+  }
+}
+
+function fire(width: number, height: number, fields: Partial<ResizeObserverEntry> = {}) {
+  instances[0]!.cb([
+    {
+      contentBoxSize: [{ inlineSize: width, blockSize: height }],
+      contentRect: { width, height },
+      ...fields,
+    } as unknown as ResizeObserverEntry,
+  ], {} as ResizeObserver);
+}
+
+describe(useElementSize, () => {
+  beforeEach(() => {
+    instances = [];
+    vi.stubGlobal('ResizeObserver', StubResizeObserver);
+  });
+  afterEach(() => vi.unstubAllGlobals());
+
+  it('uses the initial size when the target resolves to no element', () => {
+    const scope = effectScope();
+    let size: ReturnType<typeof useElementSize>;
+    scope.run(() => {
+      size = useElementSize(ref(undefined), { width: 5, height: 7 });
+    });
+
+    expect(size!.width.value).toBe(5);
+    expect(size!.height.value).toBe(7);
+    scope.stop();
+  });
+
+  it('measures synchronously on mount via offset size', () => {
+    const el = document.createElement('div');
+    Object.defineProperty(el, 'offsetWidth', { value: 80, configurable: true });
+    Object.defineProperty(el, 'offsetHeight', { value: 60, configurable: true });
+    const scope = effectScope();
+    let size: ReturnType<typeof useElementSize>;
+    scope.run(() => {
+      size = useElementSize(ref(el), { width: 5, height: 7 });
+    });
+
+    // tryOnMounted runs synchronously outside a component, overwriting the initial size.
+    expect(size!.width.value).toBe(80);
+    expect(size!.height.value).toBe(60);
+    scope.stop();
+  });
+
+  it('reports size from contentBoxSize', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let size: ReturnType<typeof useElementSize>;
+    scope.run(() => {
+      size = useElementSize(ref(el));
+    });
+
+    instances[0]!.cb([
+      { contentBoxSize: [{ inlineSize: 100, blockSize: 50 }], contentRect: { width: 0, height: 0 } } as unknown as ResizeObserverEntry,
+    ], {} as ResizeObserver);
+
+    expect(size!.width.value).toBe(100);
+    expect(size!.height.value).toBe(50);
+    scope.stop();
+  });
+
+  it('falls back to contentRect when box sizes are missing', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let size: ReturnType<typeof useElementSize>;
+    scope.run(() => {
+      size = useElementSize(ref(el));
+    });
+
+    instances[0]!.cb([
+      { contentBoxSize: undefined, contentRect: { width: 30, height: 40 } } as unknown as ResizeObserverEntry,
+    ], {} as ResizeObserver);
+
+    expect(size!.width.value).toBe(30);
+    expect(size!.height.value).toBe(40);
+    scope.stop();
+  });
+
+  it('normalises a single (non-array) ResizeObserverSize object', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let size: ReturnType<typeof useElementSize>;
+    scope.run(() => {
+      size = useElementSize(ref(el));
+    });
+
+    // Older Firefox reports box sizes as a single object rather than an array.
+    instances[0]!.cb([
+      { contentBoxSize: { inlineSize: 12, blockSize: 34 }, contentRect: { width: 0, height: 0 } } as unknown as ResizeObserverEntry,
+    ], {} as ResizeObserver);
+
+    expect(size!.width.value).toBe(12);
+    expect(size!.height.value).toBe(34);
+    scope.stop();
+  });
+
+  it('sums multiple box fragments in a single pass', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let size: ReturnType<typeof useElementSize>;
+    scope.run(() => {
+      size = useElementSize(ref(el));
+    });
+
+    instances[0]!.cb([
+      {
+        contentBoxSize: [
+          { inlineSize: 10, blockSize: 5 },
+          { inlineSize: 20, blockSize: 7 },
+        ],
+        contentRect: { width: 0, height: 0 },
+      } as unknown as ResizeObserverEntry,
+    ], {} as ResizeObserver);
+
+    expect(size!.width.value).toBe(30);
+    expect(size!.height.value).toBe(12);
+    scope.stop();
+  });
+
+  it('reads borderBoxSize when box is "border-box"', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let size: ReturnType<typeof useElementSize>;
+    scope.run(() => {
+      size = useElementSize(ref(el), { width: 0, height: 0 }, { box: 'border-box' });
+    });
+
+    instances[0]!.cb([
+      {
+        borderBoxSize: [{ inlineSize: 200, blockSize: 120 }],
+        contentBoxSize: [{ inlineSize: 1, blockSize: 1 }],
+        contentRect: { width: 0, height: 0 },
+      } as unknown as ResizeObserverEntry,
+    ], {} as ResizeObserver);
+
+    expect(size!.width.value).toBe(200);
+    expect(size!.height.value).toBe(120);
+    scope.stop();
+  });
+
+  it('measures SVG elements via getBoundingClientRect', () => {
+    const el = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
+    el.getBoundingClientRect = () => ({ width: 64, height: 48 }) as DOMRect;
+    const scope = effectScope();
+    let size: ReturnType<typeof useElementSize>;
+    scope.run(() => {
+      size = useElementSize(ref(el), { width: 0, height: 0 }, { window: globalThis as unknown as Window });
+    });
+
+    // Even though the entry advertises a different box size, the SVG path wins.
+    instances[0]!.cb([
+      { contentBoxSize: [{ inlineSize: 999, blockSize: 999 }], contentRect: { width: 999, height: 999 } } as unknown as ResizeObserverEntry,
+    ], {} as ResizeObserver);
+
+    expect(size!.width.value).toBe(64);
+    expect(size!.height.value).toBe(48);
+    scope.stop();
+  });
+
+  it('resets to 0 when the element detaches', async () => {
+    const el = ref<HTMLElement | undefined>(document.createElement('div'));
+    const scope = effectScope();
+    let size: ReturnType<typeof useElementSize>;
+    scope.run(() => {
+      size = useElementSize(el, { width: 5, height: 7 });
+    });
+
+    fire(100, 50);
+    expect(size!.width.value).toBe(100);
+
+    el.value = undefined;
+    await nextTick();
+
+    expect(size!.width.value).toBe(0);
+    expect(size!.height.value).toBe(0);
+    scope.stop();
+  });
+
+  it('stop() disconnects the observer and the detach watcher', async () => {
+    const el = ref<HTMLElement | undefined>(document.createElement('div'));
+    const scope = effectScope();
+    let size: ReturnType<typeof useElementSize>;
+    scope.run(() => {
+      size = useElementSize(el, { width: 0, height: 0 });
+    });
+
+    await nextTick();
+    expect(instances[0]!.disconnect).not.toHaveBeenCalled();
+
+    fire(100, 50);
+    expect(size!.width.value).toBe(100);
+
+    size!.stop();
+    // The observer is torn down so it stops delivering callbacks in a real browser.
+    expect(instances[0]!.disconnect).toHaveBeenCalled();
+
+    // The detach watcher is also stopped: clearing the target no longer resets the size to 0.
+    el.value = undefined;
+    await nextTick();
+    expect(size!.width.value).toBe(100);
+    expect(size!.height.value).toBe(50);
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useElementSize/index.ts

@@ -0,0 +1,121 @@
+import { computed, shallowRef, watch } from 'vue';
+import type { ShallowRef } from 'vue';
+import { toArray } from '@robonen/stdlib';
+import type { ConfigurableWindow } from '@/types';
+import { defaultWindow } from '@/types';
+import type { MaybeComputedElementRef } from '@/composables/component/unrefElement';
+import { unrefElement } from '@/composables/component/unrefElement';
+import { useResizeObserver } from '@/composables/browser/useResizeObserver';
+import type { UseResizeObserverOptions } from '@/composables/browser/useResizeObserver';
+import { tryOnMounted } from '@/composables/lifecycle/tryOnMounted';
+
+export interface ElementSize {
+  width: number;
+  height: number;
+}
+
+export interface UseElementSizeOptions extends UseResizeObserverOptions, ConfigurableWindow {}
+
+export interface UseElementSizeReturn {
+  width: ShallowRef<number>;
+  height: ShallowRef<number>;
+  stop: () => void;
+}
+
+/**
+ * @name useElementSize
+ * @category Browser
+ * @description Reactive size of an element, backed by `ResizeObserver`.
+ * Measures synchronously on mount, handles SVG elements via `getBoundingClientRect`,
+ * and sums multiple box fragments (e.g. multi-column layouts).
+ *
+ * @param {MaybeComputedElementRef} target Element to measure (ref, getter, or component instance)
+ * @param {ElementSize} [initialSize={ width: 0, height: 0 }] Initial size, restored when the element detaches
+ * @param {UseElementSizeOptions} [options={}] Options forwarded to `ResizeObserver` (`box`, `window`)
+ * @returns {UseElementSizeReturn} Reactive `width`, `height`, and a `stop` handle
+ *
+ * @example
+ * const el = useTemplateRef('el');
+ * const { width, height } = useElementSize(el);
+ *
+ * @example
+ * const { width, height, stop } = useElementSize(el, { width: 100, height: 100 }, { box: 'border-box' });
+ *
+ * @since 0.0.15
+ */
+export function useElementSize(
+  target: MaybeComputedElementRef,
+  initialSize: ElementSize = { width: 0, height: 0 },
+  options: UseElementSizeOptions = {},
+): UseElementSizeReturn {
+  const { window = defaultWindow, box = 'content-box' } = options;
+
+  const width = shallowRef(initialSize.width);
+  const height = shallowRef(initialSize.height);
+
+  const isSVG = computed(() => unrefElement(target)?.namespaceURI?.includes('svg'));
+
+  const { stop: stopObserver } = useResizeObserver(target, ([entry]) => {
+    if (!entry)
+      return;
+
+    // SVG elements report unreliable box sizes in some browsers; measure the layout box instead.
+    if (window && isSVG.value) {
+      const el = unrefElement(target);
+      if (el) {
+        const rect = el.getBoundingClientRect();
+        width.value = rect.width;
+        height.value = rect.height;
+      }
+      return;
+    }
+
+    const boxSize = box === 'border-box'
+      ? entry.borderBoxSize
+      : box === 'content-box'
+        ? entry.contentBoxSize
+        : entry.devicePixelContentBoxSize;
+
+    if (boxSize) {
+      // Normalise the cross-browser `ResizeObserverSize | ReadonlyArray<ResizeObserverSize>` shape
+      // and sum fragments (e.g. multi-column layouts) in a single pass.
+      let nextWidth = 0;
+      let nextHeight = 0;
+      for (const size of toArray(boxSize as ResizeObserverSize | ResizeObserverSize[])) {
+        nextWidth += size.inlineSize;
+        nextHeight += size.blockSize;
+      }
+      width.value = nextWidth;
+      height.value = nextHeight;
+    }
+    else {
+      width.value = entry.contentRect.width;
+      height.value = entry.contentRect.height;
+    }
+  }, options);
+
+  // Provide a measurement immediately on mount, before the first observer callback fires.
+  tryOnMounted(() => {
+    const el = unrefElement(target);
+    if (el) {
+      width.value = 'offsetWidth' in el ? (el as HTMLElement).offsetWidth : initialSize.width;
+      height.value = 'offsetHeight' in el ? (el as HTMLElement).offsetHeight : initialSize.height;
+    }
+  });
+
+  // Reset to the initial size when the element is attached/detached.
+  const stopWatch = watch(
+    () => unrefElement(target),
+    (el) => {
+      width.value = el ? initialSize.width : 0;
+      height.value = el ? initialSize.height : 0;
+    },
+  );
+
+  const stop = (): void => {
+    stopObserver();
+    stopWatch();
+  };
+
+  return { width, height, stop };
+}

vue/toolkit/src/composables/browser/useElementVisibility/index.test.ts

@@ -0,0 +1,145 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, isReadonly, ref } from 'vue';
+import type { UseElementVisibilityReturn } from '.';
+import { useElementVisibility } from '.';
+
+let instances: StubIntersectionObserver[] = [];
+let lastInit: IntersectionObserverInit | undefined;
+
+class StubIntersectionObserver {
+  observe = vi.fn();
+  disconnect = vi.fn();
+  unobserve = vi.fn();
+  takeRecords = vi.fn();
+  cb: IntersectionObserverCallback;
+  init?: IntersectionObserverInit;
+  constructor(cb: IntersectionObserverCallback, init?: IntersectionObserverInit) {
+    this.cb = cb;
+    this.init = init;
+    lastInit = init;
+    instances.push(this);
+  }
+}
+
+describe(useElementVisibility, () => {
+  beforeEach(() => {
+    instances = [];
+    lastInit = undefined;
+    vi.stubGlobal('IntersectionObserver', StubIntersectionObserver);
+  });
+  afterEach(() => vi.unstubAllGlobals());
+
+  it('is false initially and updates on intersection', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isVisible: UseElementVisibilityReturn<false>;
+    scope.run(() => {
+      isVisible = useElementVisibility(ref(el));
+    });
+
+    expect(isVisible!.value).toBeFalsy();
+
+    instances[0]!.cb([{ isIntersecting: true, time: 1 } as IntersectionObserverEntry], {} as IntersectionObserver);
+    expect(isVisible!.value).toBeTruthy();
+
+    instances[0]!.cb([{ isIntersecting: false, time: 2 } as IntersectionObserverEntry], {} as IntersectionObserver);
+    expect(isVisible!.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('uses the most recent entry by time', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isVisible: UseElementVisibilityReturn<false>;
+    scope.run(() => {
+      isVisible = useElementVisibility(ref(el));
+    });
+
+    instances[0]!.cb([
+      { isIntersecting: false, time: 5 } as IntersectionObserverEntry,
+      { isIntersecting: true, time: 10 } as IntersectionObserverEntry,
+    ], {} as IntersectionObserver);
+    expect(isVisible!.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('respects initialValue', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isVisible: UseElementVisibilityReturn<false>;
+    scope.run(() => {
+      isVisible = useElementVisibility(ref(el), { initialValue: true });
+    });
+
+    expect(isVisible!.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('returns a writable shallow ref (not readonly) by default', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isVisible: UseElementVisibilityReturn<false>;
+    scope.run(() => {
+      isVisible = useElementVisibility(ref(el));
+    });
+
+    expect(isReadonly(isVisible!)).toBeFalsy();
+    scope.stop();
+  });
+
+  it('forwards rootMargin and threshold to the observer', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    scope.run(() => useElementVisibility(ref(el), { rootMargin: '10px', threshold: [0, 0.5, 1] }));
+
+    expect(lastInit?.rootMargin).toBe('10px');
+    expect(lastInit?.threshold).toEqual([0, 0.5, 1]);
+    scope.stop();
+  });
+
+  it('stops observing after first visibility when once is true', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isVisible: UseElementVisibilityReturn<false>;
+    scope.run(() => {
+      isVisible = useElementVisibility(ref(el), { once: true });
+    });
+
+    const observer = instances[0]!;
+
+    // Not visible yet: should not disconnect.
+    observer.cb([{ isIntersecting: false, time: 1 } as IntersectionObserverEntry], {} as IntersectionObserver);
+    expect(observer.disconnect).not.toHaveBeenCalled();
+    expect(isVisible!.value).toBeFalsy();
+
+    // Becomes visible: stop() should disconnect the observer.
+    observer.cb([{ isIntersecting: true, time: 2 } as IntersectionObserverEntry], {} as IntersectionObserver);
+    expect(isVisible!.value).toBeTruthy();
+    expect(observer.disconnect).toHaveBeenCalled();
+    scope.stop();
+  });
+
+  it('exposes observer controls when controls is true', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let result: UseElementVisibilityReturn<true>;
+    scope.run(() => {
+      result = useElementVisibility(ref(el), { controls: true });
+    });
+
+    expect(result!).toHaveProperty('isVisible');
+    expect(result!).toHaveProperty('stop');
+    expect(result!).toHaveProperty('pause');
+    expect(result!).toHaveProperty('resume');
+    expect(result!).toHaveProperty('isSupported');
+    expect(result!).toHaveProperty('isActive');
+
+    expect(result!.isVisible.value).toBeFalsy();
+    instances[0]!.cb([{ isIntersecting: true, time: 1 } as IntersectionObserverEntry], {} as IntersectionObserver);
+    expect(result!.isVisible.value).toBeTruthy();
+
+    result!.stop();
+    expect(instances[0]!.disconnect).toHaveBeenCalled();
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useElementVisibility/index.ts

@@ -0,0 +1,108 @@
+import { shallowRef } from 'vue';
+import type { ShallowRef } from 'vue';
+import type { MaybeComputedElementRef } from '@/composables/component/unrefElement';
+import { useIntersectionObserver } from '@/composables/browser/useIntersectionObserver';
+import type { UseIntersectionObserverOptions, UseIntersectionObserverReturn } from '@/composables/browser/useIntersectionObserver';
+
+export interface UseElementVisibilityOptions<Controls extends boolean = false> extends UseIntersectionObserverOptions {
+  /**
+   * The initial visibility state, used before the observer reports its first entry.
+   *
+   * @default false
+   */
+  initialValue?: boolean;
+
+  /**
+   * Stop observing as soon as the element becomes visible for the first time.
+   *
+   * @default false
+   */
+  once?: boolean;
+
+  /**
+   * Expose the underlying observer controls (`pause`, `resume`, `stop`, ...)
+   * alongside the visibility ref instead of returning the ref directly.
+   *
+   * @default false
+   */
+  controls?: Controls;
+}
+
+export interface UseElementVisibilityReturnWithControls extends UseIntersectionObserverReturn {
+  /**
+   * Whether the element is currently visible within the root/viewport.
+   */
+  isVisible: ShallowRef<boolean>;
+}
+
+export type UseElementVisibilityReturn<Controls extends boolean = false>
+  = Controls extends true
+    ? UseElementVisibilityReturnWithControls
+    : ShallowRef<boolean>;
+
+/**
+ * @name useElementVisibility
+ * @category Browser
+ * @description Track whether an element is visible within the viewport (or a
+ * custom scroll root), backed by `IntersectionObserver`.
+ *
+ * @param {MaybeComputedElementRef} target Element to track
+ * @param {UseElementVisibilityOptions} [options={}] Options
+ * @returns {UseElementVisibilityReturn} Visibility ref, or `{ isVisible, ...controls }` when `controls` is `true`
+ *
+ * @example
+ * const isVisible = useElementVisibility(el);
+ *
+ * @example
+ * const { isVisible, stop } = useElementVisibility(el, { controls: true, once: true });
+ *
+ * @since 0.0.15
+ */
+export function useElementVisibility(
+  target: MaybeComputedElementRef,
+  options?: UseElementVisibilityOptions<false>,
+): UseElementVisibilityReturn<false>;
+export function useElementVisibility(
+  target: MaybeComputedElementRef,
+  options: UseElementVisibilityOptions<true>,
+): UseElementVisibilityReturn<true>;
+export function useElementVisibility(
+  target: MaybeComputedElementRef,
+  options: UseElementVisibilityOptions<boolean> = {},
+): UseElementVisibilityReturn<boolean> {
+  const {
+    initialValue = false,
+    once = false,
+    controls = false,
+    ...observerOptions
+  } = options;
+
+  const isVisible = shallowRef(initialValue);
+
+  const observer = useIntersectionObserver(target, (entries) => {
+    // Use the most recent entry to reflect the latest state.
+    let latest = isVisible.value;
+    let latestTime = 0;
+
+    for (const entry of entries) {
+      if (entry.time >= latestTime) {
+        latestTime = entry.time;
+        latest = entry.isIntersecting;
+      }
+    }
+
+    isVisible.value = latest;
+
+    if (once && latest)
+      observer.stop();
+  }, observerOptions);
+
+  if (controls) {
+    return {
+      ...observer,
+      isVisible,
+    };
+  }
+
+  return isVisible;
+}

vue/toolkit/src/composables/browser/useEscapeKey/index.test.ts

@@ -0,0 +1,59 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { useEscapeKey } from '.';
+
+function dispatchEscape() {
+  globalThis.dispatchEvent(new KeyboardEvent('keydown', { key: 'Escape' }));
+}
+
+describe(useEscapeKey, () => {
+  afterEach(() => {
+    // Ensure no lingering subscribers between tests
+  });
+
+  it('fires handler on Escape', () => {
+    const h = vi.fn();
+    const stop = useEscapeKey(h);
+
+    dispatchEscape();
+    expect(h).toHaveBeenCalledTimes(1);
+
+    stop();
+  });
+
+  it('ignores non-Escape keys', () => {
+    const h = vi.fn();
+    const stop = useEscapeKey(h);
+
+    globalThis.dispatchEvent(new KeyboardEvent('keydown', { key: 'Enter' }));
+    expect(h).not.toHaveBeenCalled();
+
+    stop();
+  });
+
+  it('only topmost handler fires when multiple are stacked', () => {
+    const bottom = vi.fn();
+    const top = vi.fn();
+
+    const stopBottom = useEscapeKey(bottom);
+    const stopTop = useEscapeKey(top);
+
+    dispatchEscape();
+    expect(top).toHaveBeenCalledTimes(1);
+    expect(bottom).not.toHaveBeenCalled();
+
+    stopTop();
+    dispatchEscape();
+    expect(bottom).toHaveBeenCalledTimes(1);
+
+    stopBottom();
+  });
+
+  it('stop handle unsubscribes the listener', () => {
+    const h = vi.fn();
+    const stop = useEscapeKey(h);
+    stop();
+
+    dispatchEscape();
+    expect(h).not.toHaveBeenCalled();
+  });
+});

vue/toolkit/src/composables/browser/useEscapeKey/index.ts

@@ -0,0 +1,60 @@
+import type { VoidFunction } from '@robonen/stdlib';
+import { noop } from '@robonen/stdlib';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { tryOnScopeDispose } from '@/composables/lifecycle/tryOnScopeDispose';
+import { defaultWindow } from '@/types';
+
+type EscapeListener = (event: KeyboardEvent) => void;
+
+// Module-scoped stack: only the topmost non-paused layer handles Escape so that
+// nested dismissables behave correctly (top-most dialog closes first).
+const stack: EscapeListener[] = [];
+let installed = false;
+let cleanup: VoidFunction = noop;
+
+function install() {
+  if (installed || !defaultWindow) return;
+  installed = true;
+
+  cleanup = useEventListener(defaultWindow, 'keydown', (event: KeyboardEvent) => {
+    if (event.key !== 'Escape') return;
+
+    const top = stack.at(-1);
+    top?.(event);
+  }, { capture: true });
+}
+
+function uninstall() {
+  if (!installed || stack.length > 0) return;
+  installed = false;
+  cleanup();
+  cleanup = noop;
+}
+
+/**
+ * @name useEscapeKey
+ * @category Browser
+ * @description Register a callback for the topmost Escape keydown. Uses an internal
+ * stack so that nested layers (e.g. nested Dialogs) dismiss in the correct order —
+ * only the most recently-registered listener fires for a given keydown.
+ *
+ * @param {(event: KeyboardEvent) => void} handler Callback invoked on the topmost Escape
+ * @returns {VoidFunction} Stop handle that removes the subscription
+ *
+ * @since 0.0.14
+ */
+export function useEscapeKey(handler: EscapeListener): VoidFunction {
+  if (!defaultWindow) return noop;
+
+  install();
+  stack.push(handler);
+
+  const stop = () => {
+    const i = stack.lastIndexOf(handler);
+    if (i !== -1) stack.splice(i, 1);
+    uninstall();
+  };
+
+  tryOnScopeDispose(stop);
+  return stop;
+}

vue/toolkit/src/composables/browser/useEventListener/index.test.ts

@@ -1,4 +1,4 @@
-import { describe, it, expect, vi, afterEach } from 'vitest';
+import { afterEach, describe, expect, it, vi } from 'vitest';
 import { defineComponent, effectScope, nextTick, ref } from 'vue';
 import { mount } from '@vue/test-utils';
 import { useEventListener } from '.';

vue/toolkit/src/composables/browser/useEyeDropper/index.test.ts

@@ -0,0 +1,169 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick } from 'vue';
+import { useEyeDropper } from '.';
+
+/**
+ * Build a fake `window` carrying an `EyeDropper` constructor whose `open()`
+ * resolves with the supplied hex. Passed through options so it reaches the
+ * import-time-captured `defaultWindow` substitute (see test gotcha).
+ */
+function createWindowWithEyeDropper(hex = '#ff0000') {
+  const open = vi.fn(async (_options?: { signal?: AbortSignal }) => ({ sRGBHex: hex }));
+
+  class EyeDropper {
+    open = open;
+    get [Symbol.toStringTag]() {
+      return 'EyeDropper' as const;
+    }
+  }
+
+  const win = { EyeDropper } as unknown as Window & typeof globalThis;
+
+  return { window: win, open };
+}
+
+describe(useEyeDropper, () => {
+  afterEach(() => {
+    vi.unstubAllGlobals();
+    vi.restoreAllMocks();
+  });
+
+  it('reports supported when EyeDropper exists on window', () => {
+    const scope = effectScope();
+    const { window } = createWindowWithEyeDropper();
+
+    let result: ReturnType<typeof useEyeDropper>;
+    scope.run(() => {
+      result = useEyeDropper({ window });
+    });
+
+    expect(result!.isSupported.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('reports unsupported when EyeDropper is absent', () => {
+    const scope = effectScope();
+    const win = {} as unknown as Window & typeof globalThis;
+
+    let result: ReturnType<typeof useEyeDropper>;
+    scope.run(() => {
+      result = useEyeDropper({ window: win });
+    });
+
+    expect(result!.isSupported.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('is SSR safe when window is undefined', async () => {
+    const scope = effectScope();
+
+    let result: ReturnType<typeof useEyeDropper>;
+    scope.run(() => {
+      result = useEyeDropper({ window: undefined as unknown as Window });
+    });
+
+    expect(result!.isSupported.value).toBeFalsy();
+    await expect(result!.open()).resolves.toBeUndefined();
+    scope.stop();
+  });
+
+  it('defaults sRGBHex to an empty string', () => {
+    const scope = effectScope();
+    const { window } = createWindowWithEyeDropper();
+
+    let result: ReturnType<typeof useEyeDropper>;
+    scope.run(() => {
+      result = useEyeDropper({ window });
+    });
+
+    expect(result!.sRGBHex.value).toBe('');
+    scope.stop();
+  });
+
+  it('honors the initialValue option', () => {
+    const scope = effectScope();
+    const { window } = createWindowWithEyeDropper();
+
+    let result: ReturnType<typeof useEyeDropper>;
+    scope.run(() => {
+      result = useEyeDropper({ window, initialValue: '#123456' });
+    });
+
+    expect(result!.sRGBHex.value).toBe('#123456');
+    scope.stop();
+  });
+
+  it('updates sRGBHex and returns the result when open() succeeds', async () => {
+    const scope = effectScope();
+    const { window, open } = createWindowWithEyeDropper('#00ff00');
+
+    let result: ReturnType<typeof useEyeDropper>;
+    scope.run(() => {
+      result = useEyeDropper({ window });
+    });
+
+    const picked = await result!.open();
+
+    expect(open).toHaveBeenCalledTimes(1);
+    expect(picked).toEqual({ sRGBHex: '#00ff00' });
+
+    await nextTick();
+    expect(result!.sRGBHex.value).toBe('#00ff00');
+    scope.stop();
+  });
+
+  it('forwards open options (e.g. AbortSignal) to the native open()', async () => {
+    const scope = effectScope();
+    const { window, open } = createWindowWithEyeDropper();
+
+    let result: ReturnType<typeof useEyeDropper>;
+    scope.run(() => {
+      result = useEyeDropper({ window });
+    });
+
+    const controller = new AbortController();
+    await result!.open({ signal: controller.signal });
+
+    expect(open).toHaveBeenCalledWith({ signal: controller.signal });
+    scope.stop();
+  });
+
+  it('returns undefined and does not call the API when unsupported', async () => {
+    const scope = effectScope();
+    const win = {} as unknown as Window & typeof globalThis;
+
+    let result: ReturnType<typeof useEyeDropper>;
+    scope.run(() => {
+      result = useEyeDropper({ window: win });
+    });
+
+    await expect(result!.open()).resolves.toBeUndefined();
+    expect(result!.sRGBHex.value).toBe('');
+    scope.stop();
+  });
+
+  it('propagates rejection when the user cancels the picker', async () => {
+    const scope = effectScope();
+    const error = new DOMException('aborted', 'AbortError');
+
+    class EyeDropper {
+      open = vi.fn(async () => {
+        throw error;
+      });
+
+      get [Symbol.toStringTag]() {
+        return 'EyeDropper' as const;
+      }
+    }
+    const win = { EyeDropper } as unknown as Window & typeof globalThis;
+
+    let result: ReturnType<typeof useEyeDropper>;
+    scope.run(() => {
+      result = useEyeDropper({ window: win });
+    });
+
+    await expect(result!.open()).rejects.toThrow(error);
+    expect(result!.sRGBHex.value).toBe('');
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useEyeDropper/index.ts

@@ -0,0 +1,98 @@
+import { shallowRef } from 'vue';
+import type { ComputedRef, ShallowRef } from 'vue';
+import { defaultWindow } from '@/types';
+import type { ConfigurableWindow } from '@/types';
+import { useSupported } from '@/composables/browser/useSupported';
+
+export interface EyeDropperOpenOptions {
+  /**
+   * An `AbortSignal` that can be used to cancel the operation.
+   *
+   * @see https://developer.mozilla.org/en-US/docs/Web/API/AbortSignal
+   */
+  signal?: AbortSignal;
+}
+
+export interface EyeDropperResult {
+  /**
+   * The selected color, in sRGB hexadecimal format (e.g. `#a1b2c3`).
+   */
+  sRGBHex: string;
+}
+
+export interface EyeDropper {
+  open: (options?: EyeDropperOpenOptions) => Promise<EyeDropperResult>;
+  [Symbol.toStringTag]: 'EyeDropper';
+}
+
+export type EyeDropperConstructor = new () => EyeDropper;
+
+export interface UseEyeDropperOptions extends ConfigurableWindow {
+  /**
+   * Initial `sRGBHex` value before any color has been picked.
+   *
+   * @default ''
+   */
+  initialValue?: string;
+}
+
+export interface UseEyeDropperReturn {
+  /**
+   * Whether the [EyeDropper API](https://developer.mozilla.org/en-US/docs/Web/API/EyeDropper) is supported
+   */
+  isSupported: ComputedRef<boolean>;
+
+  /**
+   * The most recently picked color, in sRGB hexadecimal format
+   */
+  sRGBHex: ShallowRef<string>;
+
+  /**
+   * Open the eyedropper and let the user pick a color. Resolves with the
+   * result, or `undefined` when the API is unsupported.
+   */
+  open: (openOptions?: EyeDropperOpenOptions) => Promise<EyeDropperResult | undefined>;
+}
+
+/**
+ * @name useEyeDropper
+ * @category Browser
+ * @description Reactive wrapper around the [EyeDropper API](https://developer.mozilla.org/en-US/docs/Web/API/EyeDropper) for picking colors from the screen.
+ *
+ * @param {UseEyeDropperOptions} [options={}] Options
+ * @returns {UseEyeDropperReturn} `isSupported`, `sRGBHex`, and `open()`
+ *
+ * @example
+ * const { isSupported, sRGBHex, open } = useEyeDropper();
+ * if (isSupported.value)
+ *   await open();
+ *
+ * @since 0.0.15
+ */
+export function useEyeDropper(options: UseEyeDropperOptions = {}): UseEyeDropperReturn {
+  const {
+    window = defaultWindow,
+    initialValue = '',
+  } = options;
+
+  const isSupported = useSupported(() => !!window && 'EyeDropper' in window);
+  const sRGBHex = shallowRef(initialValue);
+
+  async function open(openOptions?: EyeDropperOpenOptions): Promise<EyeDropperResult | undefined> {
+    if (!isSupported.value || !window)
+      return;
+
+    const EyeDropperCtor = (window as unknown as { EyeDropper: EyeDropperConstructor }).EyeDropper;
+    const eyeDropper = new EyeDropperCtor();
+    const result = await eyeDropper.open(openOptions);
+    sRGBHex.value = result.sRGBHex;
+
+    return result;
+  }
+
+  return {
+    isSupported,
+    sRGBHex,
+    open,
+  };
+}

vue/toolkit/src/composables/browser/useFavicon/index.test.ts

@@ -0,0 +1,141 @@
+import { beforeEach, describe, expect, it } from 'vitest';
+import { effectScope, nextTick, ref } from 'vue';
+import { useFavicon } from '.';
+
+describe(useFavicon, () => {
+  beforeEach(() => {
+    document.head.querySelectorAll('link[rel*="icon"]').forEach(el => el.remove());
+  });
+
+  it('creates a link element with the icon href', () => {
+    const scope = effectScope();
+    scope.run(() => useFavicon('/icon.png'));
+
+    const link = document.head.querySelector<HTMLLinkElement>('link[rel*="icon"]');
+    expect(link).not.toBeNull();
+    expect(link!.href).toContain('/icon.png');
+    scope.stop();
+  });
+
+  it('updates the href when the ref changes', async () => {
+    const scope = effectScope();
+    let favicon: ReturnType<typeof useFavicon>;
+    scope.run(() => {
+      favicon = useFavicon('/a.png');
+    });
+
+    favicon!.value = '/b.png';
+    await nextTick();
+
+    const link = document.head.querySelector<HTMLLinkElement>('link[rel*="icon"]');
+    expect(link!.href).toContain('/b.png');
+    scope.stop();
+  });
+
+  it('prepends the baseUrl', () => {
+    const scope = effectScope();
+    scope.run(() => useFavicon('icon.png', { baseUrl: 'https://cdn.example.com/' }));
+
+    const link = document.head.querySelector<HTMLLinkElement>('link[rel*="icon"]');
+    expect(link!.href).toBe('https://cdn.example.com/icon.png');
+    scope.stop();
+  });
+
+  it('sets the MIME type from the file extension', () => {
+    const scope = effectScope();
+    scope.run(() => useFavicon('/icon.svg'));
+
+    const link = document.head.querySelector<HTMLLinkElement>('link[rel*="icon"]');
+    expect(link!.type).toBe('image/svg');
+    scope.stop();
+  });
+
+  it('does not set a bogus MIME type for query-string or data hrefs', () => {
+    const scope = effectScope();
+    scope.run(() => useFavicon('/icon.png?v=2'));
+
+    const link = document.head.querySelector<HTMLLinkElement>('link[rel*="icon"]');
+    expect(link!.href).toContain('/icon.png?v=2');
+    expect(link!.type).toBe('');
+    scope.stop();
+  });
+
+  it('does not set a bogus MIME type for extensionless hrefs', () => {
+    const scope = effectScope();
+    scope.run(() => useFavicon('/favicon'));
+
+    const link = document.head.querySelector<HTMLLinkElement>('link[rel*="icon"]');
+    expect(link!.type).toBe('');
+    scope.stop();
+  });
+
+  it('tracks a getter source reactively', async () => {
+    const scope = effectScope();
+    const dark = ref(false);
+    scope.run(() => useFavicon(() => (dark.value ? '/dark.png' : '/light.png')));
+
+    let link = document.head.querySelector<HTMLLinkElement>('link[rel*="icon"]');
+    expect(link!.href).toContain('/light.png');
+
+    dark.value = true;
+    await nextTick();
+
+    link = document.head.querySelector<HTMLLinkElement>('link[rel*="icon"]');
+    expect(link!.href).toContain('/dark.png');
+    scope.stop();
+  });
+
+  it('follows an external writable ref passed as source', async () => {
+    const scope = effectScope();
+    const source = ref('/one.png');
+    let favicon: ReturnType<typeof useFavicon>;
+    scope.run(() => {
+      favicon = useFavicon(source);
+    });
+
+    // returned ref reflects the source
+    expect(favicon!.value).toBe('/one.png');
+
+    source.value = '/two.png';
+    await nextTick();
+
+    const link = document.head.querySelector<HTMLLinkElement>('link[rel*="icon"]');
+    expect(link!.href).toContain('/two.png');
+    scope.stop();
+  });
+
+  it('respects a custom rel attribute', () => {
+    const scope = effectScope();
+    scope.run(() => useFavicon('/apple.png', { rel: 'apple-touch-icon' }));
+
+    const link = document.head.querySelector<HTMLLinkElement>('link[rel*="apple-touch-icon"]');
+    expect(link).not.toBeNull();
+    expect(link!.href).toContain('/apple.png');
+    link!.remove();
+    scope.stop();
+  });
+
+  it('reuses existing matching link elements instead of creating new ones', async () => {
+    const scope = effectScope();
+    let favicon: ReturnType<typeof useFavicon>;
+    scope.run(() => {
+      favicon = useFavicon('/first.png');
+    });
+
+    favicon!.value = '/second.png';
+    await nextTick();
+
+    const links = document.head.querySelectorAll('link[rel*="icon"]');
+    expect(links).toHaveLength(1);
+    expect((links[0] as HTMLLinkElement).href).toContain('/second.png');
+    scope.stop();
+  });
+
+  it('is SSR-safe when no document is available', () => {
+    const scope = effectScope();
+    expect(() => {
+      scope.run(() => useFavicon('/icon.png', { document: undefined }));
+    }).not.toThrow();
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useFavicon/index.ts

@@ -0,0 +1,109 @@
+import { toRef, watch } from 'vue';
+import type { ComputedRef, MaybeRef, MaybeRefOrGetter, Ref } from 'vue';
+import { isString } from '@robonen/stdlib';
+import { defaultDocument } from '@/types';
+import type { ConfigurableDocument } from '@/types';
+
+export interface UseFaviconOptions extends ConfigurableDocument {
+  /**
+   * Base URL prepended to the icon href
+   *
+   * @default ''
+   */
+  baseUrl?: string;
+
+  /**
+   * The `rel` attribute of the favicon link element
+   *
+   * @default 'icon'
+   */
+  rel?: string;
+}
+
+export type UseFaviconReturn = ComputedRef<string | null | undefined> | Ref<string | null | undefined>;
+
+// Matches a real file extension at the very end of the path portion of the href,
+// e.g. `/foo.png` -> `png`, but NOT `/foo.png?v=2`, `data:...`, or extensionless hrefs.
+const FILE_EXTENSION_RE = /\.([a-z0-9]+)$/i;
+
+/**
+ * @name useFavicon
+ * @category Browser
+ * @description Reactive favicon.
+ *
+ * @param {MaybeRefOrGetter<string | null | undefined>} [newIcon] Initial icon href. A getter or readonly ref yields a read-only `ComputedRef`; a writable ref or plain value yields a writable `Ref`.
+ * @param {UseFaviconOptions} [options={}] Options
+ * @returns {UseFaviconReturn} A ref bound to the favicon href
+ *
+ * @example
+ * const favicon = useFavicon();
+ * favicon.value = '/new-icon.png';
+ *
+ * @example
+ * // Track an existing reactive source (read-only result)
+ * const isDark = useDark();
+ * const favicon = useFavicon(() => isDark.value ? '/dark.png' : '/light.png');
+ *
+ * @since 0.0.15
+ */
+export function useFavicon(
+  newIcon: MaybeRefOrGetter<string | null | undefined>,
+  options?: UseFaviconOptions,
+): ComputedRef<string | null | undefined>;
+export function useFavicon(
+  newIcon?: MaybeRef<string | null | undefined>,
+  options?: UseFaviconOptions,
+): Ref<string | null | undefined>;
+export function useFavicon(
+  newIcon: MaybeRefOrGetter<string | null | undefined> = null,
+  options: UseFaviconOptions = {},
+): UseFaviconReturn {
+  const {
+    baseUrl = '',
+    rel = 'icon',
+    document = defaultDocument,
+  } = options;
+
+  const favicon = toRef(newIcon);
+  const selector = `link[rel*="${rel}"]`;
+
+  const applyIcon = (icon: string) => {
+    if (!document)
+      return;
+
+    const href = `${baseUrl}${icon}`;
+    const elements = document.head.querySelectorAll<HTMLLinkElement>(selector);
+
+    if (!elements.length) {
+      const link = document.createElement('link');
+
+      link.rel = rel;
+      link.href = href;
+
+      // Only set a MIME type when the icon actually ends in a file extension;
+      // otherwise we'd emit garbage like `image/png?v=2` or `image/` for
+      // query-string, extensionless, or data: hrefs.
+      const extension = FILE_EXTENSION_RE.exec(icon)?.[1];
+      if (extension)
+        link.type = `image/${extension}`;
+
+      document.head.append(link);
+
+      return;
+    }
+
+    for (const element of elements)
+      element.href = href;
+  };
+
+  watch(
+    favicon,
+    (icon, oldIcon) => {
+      if (isString(icon) && icon !== oldIcon)
+        applyIcon(icon);
+    },
+    { immediate: true },
+  );
+
+  return favicon;
+}

vue/toolkit/src/composables/browser/useFileDialog/index.test.ts

@@ -0,0 +1,211 @@
+import { describe, expect, it, vi } from 'vitest';
+import { effectScope, ref } from 'vue';
+import { useFileDialog } from '.';
+
+function makeFile(name = 'a.txt'): File {
+  return new File(['content'], name, { type: 'text/plain' });
+}
+
+function makeFileList(files: File[]): FileList {
+  const list = {
+    length: files.length,
+    item: (index: number) => files[index] ?? null,
+    [Symbol.iterator]: () => files[Symbol.iterator](),
+  } as unknown as FileList;
+  files.forEach((file, index) => {
+    (list as unknown as Record<number, File>)[index] = file;
+  });
+  return list;
+}
+
+function withScope<T>(fn: () => T): { result: T; stop: () => void } {
+  const scope = effectScope();
+  const result = scope.run(fn)!;
+  return { result, stop: () => scope.stop() };
+}
+
+describe(useFileDialog, () => {
+  it('exposes files, open, reset, onChange, onCancel', () => {
+    const { result, stop } = withScope(() => useFileDialog());
+    expect(result.files.value).toBeNull();
+    expect(typeof result.open).toBe('function');
+    expect(typeof result.reset).toBe('function');
+    expect(typeof result.onChange).toBe('function');
+    expect(typeof result.onCancel).toBe('function');
+    stop();
+  });
+
+  it('seeds files from initialFiles (array)', () => {
+    const file = makeFile();
+    const { result, stop } = withScope(() => useFileDialog({ initialFiles: [file] }));
+    expect(result.files.value).not.toBeNull();
+    expect(result.files.value!).toHaveLength(1);
+    expect(result.files.value![0]).toBe(file);
+    stop();
+  });
+
+  it('seeds files from initialFiles (FileList)', () => {
+    const list = makeFileList([makeFile('x.txt'), makeFile('y.txt')]);
+    const { result, stop } = withScope(() => useFileDialog({ initialFiles: list }));
+    expect(result.files.value!).toHaveLength(2);
+    stop();
+  });
+
+  it('clicks the input element when open() is called', () => {
+    const input = document.createElement('input');
+    const click = vi.spyOn(input, 'click').mockImplementation(() => {});
+    const { result, stop } = withScope(() => useFileDialog({ input }));
+
+    result.open();
+    expect(click).toHaveBeenCalledTimes(1);
+    stop();
+  });
+
+  it('applies options to the input element on open()', () => {
+    const input = document.createElement('input');
+    vi.spyOn(input, 'click').mockImplementation(() => {});
+    const { result, stop } = withScope(() => useFileDialog({
+      input,
+      accept: 'image/*',
+      multiple: false,
+      directory: true,
+    }));
+
+    result.open();
+    expect(input.accept).toBe('image/*');
+    expect(input.multiple).toBeFalsy();
+    expect(input.webkitdirectory).toBeTruthy();
+    stop();
+  });
+
+  it('merges local options on open(), overriding instance options for that call', () => {
+    const input = document.createElement('input');
+    vi.spyOn(input, 'click').mockImplementation(() => {});
+    const { result, stop } = withScope(() => useFileDialog({ input, accept: 'image/*' }));
+
+    result.open({ accept: '.pdf', multiple: false });
+    expect(input.accept).toBe('.pdf');
+    expect(input.multiple).toBeFalsy();
+    stop();
+  });
+
+  it('sets capture attribute only when provided', () => {
+    const input = document.createElement('input');
+    vi.spyOn(input, 'click').mockImplementation(() => {});
+    const { result, stop } = withScope(() => useFileDialog({ input, capture: 'user' }));
+
+    result.open();
+    expect(input.capture).toBe('user');
+    stop();
+  });
+
+  it('reads reactive options via getters/refs', () => {
+    const input = document.createElement('input');
+    vi.spyOn(input, 'click').mockImplementation(() => {});
+    const accept = ref('image/*');
+    const { result, stop } = withScope(() => useFileDialog({ input, accept }));
+
+    result.open();
+    expect(input.accept).toBe('image/*');
+
+    accept.value = 'video/*';
+    result.open();
+    expect(input.accept).toBe('video/*');
+    stop();
+  });
+
+  it('updates files and triggers onChange when the input changes', () => {
+    const input = document.createElement('input');
+    const { result, stop } = withScope(() => useFileDialog({ input }));
+
+    const onChange = vi.fn();
+    result.onChange(onChange);
+
+    const list = makeFileList([makeFile()]);
+    // jsdom does not let you assign input.files via real selection, so override the getter.
+    Object.defineProperty(input, 'files', { configurable: true, get: () => list });
+    input.dispatchEvent(new Event('change'));
+
+    expect(result.files.value).toBe(list);
+    expect(result.files.value!).toHaveLength(1);
+    expect(onChange).toHaveBeenCalledTimes(1);
+    expect(onChange).toHaveBeenCalledWith(list);
+    stop();
+  });
+
+  it('triggers onCancel when the dialog is dismissed', () => {
+    const input = document.createElement('input');
+    const { result, stop } = withScope(() => useFileDialog({ input }));
+
+    const onCancel = vi.fn();
+    result.onCancel(onCancel);
+
+    input.dispatchEvent(new Event('cancel'));
+    expect(onCancel).toHaveBeenCalledTimes(1);
+    stop();
+  });
+
+  it('reset() clears files and fires onChange(null) when the input had a value', () => {
+    const input = document.createElement('input');
+    // jsdom forbids assigning a non-empty value to a file input, so stub value with a settable getter/setter.
+    let internalValue = 'a.txt';
+    Object.defineProperty(input, 'value', {
+      configurable: true,
+      get: () => internalValue,
+      set: (v: string) => { internalValue = v; },
+    });
+    const { result, stop } = withScope(() => useFileDialog({ input }));
+
+    const onChange = vi.fn();
+    result.onChange(onChange);
+
+    const list = makeFileList([makeFile()]);
+    Object.defineProperty(input, 'files', { configurable: true, get: () => list });
+    input.dispatchEvent(new Event('change'));
+    onChange.mockClear();
+
+    result.reset();
+    expect(result.files.value).toBeNull();
+    expect(input.value).toBe('');
+    expect(onChange).toHaveBeenCalledWith(null);
+    stop();
+  });
+
+  it('open({ reset: true }) clears the previous selection before opening', () => {
+    const input = document.createElement('input');
+    vi.spyOn(input, 'click').mockImplementation(() => {});
+    const { result, stop } = withScope(() => useFileDialog({ input }));
+
+    const list = makeFileList([makeFile()]);
+    Object.defineProperty(input, 'files', { configurable: true, get: () => list });
+    input.dispatchEvent(new Event('change'));
+    expect(result.files.value).not.toBeNull();
+
+    result.open({ reset: true });
+    expect(result.files.value).toBeNull();
+    stop();
+  });
+
+  it('onChange returns an off() that unsubscribes', () => {
+    const input = document.createElement('input');
+    const { result, stop } = withScope(() => useFileDialog({ input }));
+
+    const onChange = vi.fn();
+    const { off } = result.onChange(onChange);
+    off();
+
+    Object.defineProperty(input, 'files', { configurable: true, value: makeFileList([makeFile()]) });
+    input.dispatchEvent(new Event('change'));
+    expect(onChange).not.toHaveBeenCalled();
+    stop();
+  });
+
+  it('files ref is readonly (no input element created in SSR)', () => {
+    // document undefined simulates SSR; no input is created so open() is a no-op.
+    const { result, stop } = withScope(() => useFileDialog({ document: undefined }));
+    expect(result.files.value).toBeNull();
+    expect(() => result.open()).not.toThrow();
+    expect(() => result.reset()).not.toThrow();
+    stop();
+  });
+});

vue/toolkit/src/composables/browser/useFileDialog/index.ts

@@ -0,0 +1,244 @@
+import { computed, shallowRef, toValue, watchEffect } from 'vue';
+import type { ComputedRef, MaybeRefOrGetter } from 'vue';
+import { defaultDocument } from '@/types';
+import type { ConfigurableDocument } from '@/types';
+import { unrefElement } from '@/composables/component/unrefElement';
+import type { MaybeComputedElementRef } from '@/composables/component/unrefElement';
+
+export interface UseFileDialogOptions extends ConfigurableDocument {
+  /**
+   * Allow selecting multiple files
+   *
+   * @default true
+   */
+  multiple?: MaybeRefOrGetter<boolean>;
+
+  /**
+   * Comma-separated list of accepted file types (the input's `accept` attribute)
+   *
+   * @default '*'
+   */
+  accept?: MaybeRefOrGetter<string>;
+
+  /**
+   * Hint for which camera/microphone to use on mobile capture (the input's `capture` attribute)
+   */
+  capture?: MaybeRefOrGetter<string>;
+
+  /**
+   * Reset the selected files each time `open()` is called
+   *
+   * @default false
+   */
+  reset?: MaybeRefOrGetter<boolean>;
+
+  /**
+   * Select directories instead of files (sets `webkitdirectory`)
+   *
+   * @default false
+   */
+  directory?: MaybeRefOrGetter<boolean>;
+
+  /**
+   * Initial files to seed `files` with before any dialog is opened
+   */
+  initialFiles?: File[] | FileList;
+
+  /**
+   * Use a custom `<input type="file">` element instead of an internally created one
+   */
+  input?: MaybeComputedElementRef<HTMLInputElement>;
+}
+
+/**
+ * Subscribe to an event; returns an unsubscribe function.
+ */
+export type FileDialogEventHookOn<T = void> = (callback: (param: T) => void) => { off: () => void };
+
+export interface UseFileDialogReturn {
+  /**
+   * The currently selected files, or `null` when none are selected
+   */
+  files: ComputedRef<FileList | null>;
+
+  /**
+   * Open the file dialog, optionally overriding options for this call only
+   */
+  open: (localOptions?: Partial<UseFileDialogOptions>) => void;
+
+  /**
+   * Clear the current selection
+   */
+  reset: () => void;
+
+  /**
+   * Register a callback fired when the selection changes
+   */
+  onChange: FileDialogEventHookOn<FileList | null>;
+
+  /**
+   * Register a callback fired when the dialog is dismissed without a selection
+   */
+  onCancel: FileDialogEventHookOn;
+}
+
+const DEFAULT_OPTIONS: UseFileDialogOptions = {
+  multiple: true,
+  accept: '*',
+  reset: false,
+  directory: false,
+};
+
+interface EventHook<T> {
+  on: FileDialogEventHookOn<T>;
+  trigger: (param: T) => void;
+}
+
+function createEventHook<T = void>(): EventHook<T> {
+  const callbacks = new Set<(param: T) => void>();
+
+  const on: FileDialogEventHookOn<T> = (callback) => {
+    callbacks.add(callback);
+    return {
+      off: () => {
+        callbacks.delete(callback);
+      },
+    };
+  };
+
+  const trigger = (param: T): void => {
+    callbacks.forEach(cb => cb(param));
+  };
+
+  return { on, trigger };
+}
+
+function toFileList(files: File[] | FileList | undefined): FileList | null {
+  if (!files)
+    return null;
+
+  if (typeof FileList !== 'undefined' && files instanceof FileList)
+    return files;
+
+  // Materialize a plain array into a FileList via DataTransfer when available.
+  if (typeof DataTransfer !== 'undefined') {
+    const dt = new DataTransfer();
+    for (const file of files)
+      dt.items.add(file);
+    return dt.files;
+  }
+
+  // Fallback: build a FileList-like object (environments without DataTransfer, e.g. jsdom).
+  const array = Array.from(files);
+  const list = {
+    length: array.length,
+    item: (index: number) => array[index] ?? null,
+    [Symbol.iterator]: () => array[Symbol.iterator](),
+  } as unknown as FileList;
+  array.forEach((file, index) => {
+    (list as unknown as Record<number, File>)[index] = file;
+  });
+  return list;
+}
+
+/**
+ * @name useFileDialog
+ * @category Browser
+ * @description Open a native file dialog programmatically and reactively track the selected files.
+ *
+ * @param {UseFileDialogOptions} [options={}] Options
+ * @returns {UseFileDialogReturn} `files`, `open`, `reset`, `onChange`, and `onCancel`
+ *
+ * @example
+ * const { files, open, onChange } = useFileDialog({ accept: 'image/*' });
+ * onChange((selected) => console.log(selected));
+ * open();
+ *
+ * @example
+ * // Override options for a single call
+ * const { open } = useFileDialog();
+ * open({ multiple: false, accept: '.pdf' });
+ *
+ * @since 0.0.15
+ */
+export function useFileDialog(options: UseFileDialogOptions = {}): UseFileDialogReturn {
+  const {
+    document = defaultDocument,
+  } = options;
+
+  const files = shallowRef<FileList | null>(toFileList(options.initialFiles));
+
+  const { on: onChange, trigger: changeTrigger } = createEventHook<FileList | null>();
+  const { on: onCancel, trigger: cancelTrigger } = createEventHook();
+
+  const inputRef = shallowRef<HTMLInputElement | undefined>();
+
+  // Eagerly resolve the input element (custom or internally created) and wire its
+  // handlers, re-running if a reactive `options.input` target changes.
+  watchEffect(() => {
+    const input = unrefElement(options.input)
+      ?? (document ? document.createElement('input') : undefined);
+
+    if (input) {
+      input.type = 'file';
+      input.onchange = (event: Event) => {
+        const result = event.target as HTMLInputElement;
+        files.value = result.files;
+        changeTrigger(files.value);
+      };
+      input.oncancel = () => {
+        cancelTrigger();
+      };
+    }
+
+    inputRef.value = input;
+  });
+
+  const reset = (): void => {
+    files.value = null;
+    const el = inputRef.value;
+    if (el && el.value) {
+      el.value = '';
+      changeTrigger(null);
+    }
+  };
+
+  const applyOptions = (opts: UseFileDialogOptions): void => {
+    const el = inputRef.value;
+    if (!el)
+      return;
+
+    el.multiple = toValue(opts.multiple)!;
+    el.accept = toValue(opts.accept)!;
+    el.webkitdirectory = toValue(opts.directory)!;
+    if ('capture' in opts)
+      el.capture = toValue(opts.capture)!;
+  };
+
+  const open = (localOptions?: Partial<UseFileDialogOptions>): void => {
+    const el = inputRef.value;
+    if (!el)
+      return;
+
+    const mergedOptions: UseFileDialogOptions = {
+      ...DEFAULT_OPTIONS,
+      ...options,
+      ...localOptions,
+    };
+
+    applyOptions(mergedOptions);
+
+    if (toValue(mergedOptions.reset))
+      reset();
+
+    el.click();
+  };
+
+  return {
+    files: computed(() => files.value),
+    open,
+    reset,
+    onChange,
+    onCancel,
+  };
+}

vue/toolkit/src/composables/browser/useFocus/index.test.ts

@@ -0,0 +1,173 @@
+import { describe, expect, it } from 'vitest';
+import { effectScope, nextTick, ref } from 'vue';
+import { useFocus } from '.';
+
+function host<T>(fn: () => T): { result: T; stop: () => void } {
+  const scope = effectScope();
+  let result!: T;
+  scope.run(() => {
+    result = fn();
+  });
+  return { result, stop: () => scope.stop() };
+}
+
+describe(useFocus, () => {
+  it('reflects focus and blur events on the target', async () => {
+    const input = document.createElement('input');
+    document.body.appendChild(input);
+
+    const { result, stop } = host(() => useFocus(input));
+    await nextTick();
+
+    expect(result.focused.value).toBeFalsy();
+
+    input.dispatchEvent(new FocusEvent('focus'));
+    expect(result.focused.value).toBeTruthy();
+
+    input.dispatchEvent(new FocusEvent('blur'));
+    expect(result.focused.value).toBeFalsy();
+
+    stop();
+    input.remove();
+  });
+
+  it('focuses the element when writing true', async () => {
+    const input = document.createElement('input');
+    document.body.appendChild(input);
+
+    const { result, stop } = host(() => useFocus(input));
+    await nextTick();
+
+    result.focused.value = true;
+    // jsdom dispatches the focus event synchronously from .focus()
+    expect(document.activeElement).toBe(input);
+    expect(result.focused.value).toBeTruthy();
+
+    stop();
+    input.remove();
+  });
+
+  it('blurs the element when writing false', async () => {
+    const input = document.createElement('input');
+    document.body.appendChild(input);
+
+    const { result, stop } = host(() => useFocus(input));
+    await nextTick();
+
+    result.focused.value = true;
+    expect(document.activeElement).toBe(input);
+
+    result.focused.value = false;
+    expect(document.activeElement).not.toBe(input);
+    expect(result.focused.value).toBeFalsy();
+
+    stop();
+    input.remove();
+  });
+
+  it('focuses on mount when initialValue is true', async () => {
+    const input = document.createElement('input');
+    document.body.appendChild(input);
+
+    const { result, stop } = host(() => useFocus(input, { initialValue: true }));
+    // the watch runs with flush: 'post'
+    await nextTick();
+
+    expect(document.activeElement).toBe(input);
+    expect(result.focused.value).toBeTruthy();
+
+    stop();
+    input.remove();
+  });
+
+  it('passes preventScroll to focus()', async () => {
+    const input = document.createElement('input');
+    document.body.appendChild(input);
+    let receivedOptions: FocusOptions | undefined;
+    const originalFocus = input.focus.bind(input);
+    input.focus = (opts?: FocusOptions) => {
+      receivedOptions = opts;
+      originalFocus(opts);
+    };
+
+    const { result, stop } = host(() => useFocus(input, { preventScroll: true }));
+    await nextTick();
+
+    result.focused.value = true;
+    expect(receivedOptions).toEqual({ preventScroll: true });
+
+    stop();
+    input.remove();
+  });
+
+  it('respects focusVisible by checking :focus-visible', async () => {
+    const input = document.createElement('input');
+    document.body.appendChild(input);
+    // emulate the element NOT matching :focus-visible (e.g. mouse focus)
+    input.matches = () => false;
+
+    const { result, stop } = host(() => useFocus(input, { focusVisible: true }));
+    await nextTick();
+
+    input.dispatchEvent(new FocusEvent('focus'));
+    // focus should be ignored because :focus-visible did not match
+    expect(result.focused.value).toBeFalsy();
+
+    // now emulate a keyboard focus that does match
+    input.matches = (selector: string) => selector === ':focus-visible';
+    input.dispatchEvent(new FocusEvent('focus'));
+    expect(result.focused.value).toBeTruthy();
+
+    stop();
+    input.remove();
+  });
+
+  it('tracks a reactive (changing) target', async () => {
+    const a = document.createElement('input');
+    const b = document.createElement('input');
+    document.body.append(a, b);
+
+    const target = ref<HTMLElement>(a);
+    const { result, stop } = host(() => useFocus(target));
+    await nextTick();
+
+    // start unfocused, then focus the first target
+    a.dispatchEvent(new FocusEvent('focus'));
+    expect(result.focused.value).toBeTruthy();
+    a.dispatchEvent(new FocusEvent('blur'));
+    expect(result.focused.value).toBeFalsy();
+
+    // swap the tracked target; listeners follow the reactive ref
+    target.value = b;
+    await nextTick();
+
+    // events on the new element are now tracked
+    b.dispatchEvent(new FocusEvent('focus'));
+    expect(result.focused.value).toBeTruthy();
+    b.dispatchEvent(new FocusEvent('blur'));
+    expect(result.focused.value).toBeFalsy();
+
+    // events on the old element no longer affect state
+    a.dispatchEvent(new FocusEvent('focus'));
+    expect(result.focused.value).toBeFalsy();
+
+    stop();
+    a.remove();
+    b.remove();
+  });
+
+  it('does not throw when the target is null', async () => {
+    const target = ref<HTMLElement | null>(null);
+    const { result, stop } = host(() => useFocus(target));
+    await nextTick();
+
+    expect(result.focused.value).toBeFalsy();
+    // writing to a null target must be a no-op, not a crash
+    expect(() => {
+      result.focused.value = true;
+    }).not.toThrow();
+    expect(result.focused.value).toBeFalsy();
+
+    stop();
+  });
+});

vue/toolkit/src/composables/browser/useFocus/index.ts

@@ -0,0 +1,113 @@
+import { computed, shallowRef, watch } from 'vue';
+import type { WritableComputedRef } from 'vue';
+import { unrefElement } from '@/composables/component/unrefElement';
+import type { MaybeComputedElementRef } from '@/composables/component/unrefElement';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import type { ConfigurableWindow } from '@/types';
+
+export interface UseFocusOptions extends ConfigurableWindow {
+  /**
+   * Initial focus state. When `true`, the element is focused on mount.
+   *
+   * @default false
+   */
+  initialValue?: boolean;
+  /**
+   * Only consider the element focused when it matches `:focus-visible`,
+   * mirroring the browser's keyboard-focus heuristics.
+   *
+   * @default false
+   */
+  focusVisible?: boolean;
+  /**
+   * Prevent the browser from scrolling the element into view when focusing it.
+   *
+   * @default false
+   */
+  preventScroll?: boolean;
+}
+
+export interface UseFocusReturn {
+  /**
+   * Reactive focus state. Read it to know whether the target is focused, or
+   * write to it to programmatically focus (`true`) or blur (`false`) the target.
+   */
+  focused: WritableComputedRef<boolean>;
+}
+
+/**
+ * @name useFocus
+ * @category Browser
+ * @description Reactive focus state of an element. The returned `focused` ref tracks
+ * focus/blur events and can be written to in order to focus or blur the target.
+ *
+ * @param {MaybeComputedElementRef} target - The element (or template ref) to track.
+ * @param {UseFocusOptions} [options={}] - Options
+ * @returns {UseFocusReturn} An object containing the writable `focused` ref.
+ *
+ * @example
+ * const el = useTemplateRef<HTMLInputElement>('el');
+ * const { focused } = useFocus(el);
+ * // focus the element imperatively
+ * focused.value = true;
+ *
+ * @example
+ * // only treat keyboard focus as focused
+ * const { focused } = useFocus(el, { focusVisible: true });
+ *
+ * @since 0.0.15
+ */
+export function useFocus(
+  target: MaybeComputedElementRef,
+  options: UseFocusOptions = {},
+): UseFocusReturn {
+  const {
+    initialValue = false,
+    focusVisible = false,
+    preventScroll = false,
+  } = options;
+
+  const innerFocused = shallowRef(false);
+  const targetElement = computed(() => unrefElement(target) as HTMLElement | undefined | null);
+
+  const listenerOptions = { passive: true } as const;
+
+  useEventListener(
+    targetElement,
+    'focus',
+    (event: FocusEvent) => {
+      if (!focusVisible || (event.target as HTMLElement).matches?.(':focus-visible'))
+        innerFocused.value = true;
+    },
+    listenerOptions,
+  );
+
+  useEventListener(
+    targetElement,
+    'blur',
+    () => {
+      innerFocused.value = false;
+    },
+    listenerOptions,
+  );
+
+  const focused = computed<boolean>({
+    get: () => innerFocused.value,
+    set(value: boolean) {
+      if (!value && innerFocused.value)
+        targetElement.value?.blur();
+      else if (value && !innerFocused.value)
+        targetElement.value?.focus({ preventScroll });
+    },
+  });
+
+  watch(
+    targetElement,
+    () => {
+      focused.value = initialValue;
+    },
+    { immediate: true, flush: 'post' },
+  );
+
+  return { focused };
+}

vue/toolkit/src/composables/browser/useFocusGuard/index.test.ts

@@ -1,4 +1,4 @@
-import { describe, it, beforeEach, afterEach, expect } from 'vitest';
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
 import { mount } from '@vue/test-utils';
 import { defineComponent, nextTick } from 'vue';
 import { useFocusGuard } from '.';

vue/toolkit/src/composables/browser/useFocusWithin/index.test.ts

@@ -0,0 +1,194 @@
+import { describe, expect, it } from 'vitest';
+import { effectScope, nextTick, shallowRef } from 'vue';
+import { useFocusWithin } from '.';
+
+function makeTree(): { container: HTMLDivElement; input: HTMLInputElement; outside: HTMLButtonElement } {
+  const container = document.createElement('div');
+  const input = document.createElement('input');
+  container.appendChild(input);
+
+  const outside = document.createElement('button');
+
+  document.body.appendChild(container);
+  document.body.appendChild(outside);
+
+  return { container, input, outside };
+}
+
+describe(useFocusWithin, () => {
+  it('is not focused initially when nothing inside has focus', () => {
+    const { container } = makeTree();
+
+    const scope = effectScope();
+    let result: ReturnType<typeof useFocusWithin>;
+    scope.run(() => {
+      result = useFocusWithin(container);
+    });
+
+    expect(result!.focused.value).toBeFalsy();
+
+    scope.stop();
+    document.body.replaceChildren();
+  });
+
+  it('becomes focused when a descendant receives focus', async () => {
+    const { container, input } = makeTree();
+
+    const scope = effectScope();
+    let result: ReturnType<typeof useFocusWithin>;
+    scope.run(() => {
+      result = useFocusWithin(container);
+    });
+
+    input.focus();
+    container.dispatchEvent(new FocusEvent('focusin', { bubbles: true }));
+    await nextTick();
+
+    expect(result!.focused.value).toBeTruthy();
+
+    scope.stop();
+    document.body.replaceChildren();
+  });
+
+  it('is focused when the target element itself receives focus', async () => {
+    const { container } = makeTree();
+    container.tabIndex = 0;
+
+    const scope = effectScope();
+    let result: ReturnType<typeof useFocusWithin>;
+    scope.run(() => {
+      result = useFocusWithin(container);
+    });
+
+    container.focus();
+    container.dispatchEvent(new FocusEvent('focusin', { bubbles: true }));
+    await nextTick();
+
+    expect(result!.focused.value).toBeTruthy();
+
+    scope.stop();
+    document.body.replaceChildren();
+  });
+
+  it('clears focus when focus leaves the element entirely', async () => {
+    const { container, input, outside } = makeTree();
+
+    const scope = effectScope();
+    let result: ReturnType<typeof useFocusWithin>;
+    scope.run(() => {
+      result = useFocusWithin(container);
+    });
+
+    input.focus();
+    container.dispatchEvent(new FocusEvent('focusin', { bubbles: true }));
+    await nextTick();
+    expect(result!.focused.value).toBeTruthy();
+
+    // Move focus to an element outside the container.
+    outside.focus();
+    container.dispatchEvent(new FocusEvent('focusout', { bubbles: true, relatedTarget: outside }));
+    await nextTick();
+
+    expect(result!.focused.value).toBeFalsy();
+
+    scope.stop();
+    document.body.replaceChildren();
+  });
+
+  it('stays focused when focus moves between descendants', async () => {
+    const { container, input } = makeTree();
+    const second = document.createElement('input');
+    container.appendChild(second);
+
+    const scope = effectScope();
+    let result: ReturnType<typeof useFocusWithin>;
+    scope.run(() => {
+      result = useFocusWithin(container);
+    });
+
+    input.focus();
+    container.dispatchEvent(new FocusEvent('focusin', { bubbles: true }));
+    await nextTick();
+    expect(result!.focused.value).toBeTruthy();
+
+    // focusout fires as focus shifts, but the second input is still inside
+    // the container, so `:focus-within` keeps the state true.
+    second.focus();
+    container.dispatchEvent(new FocusEvent('focusout', { bubbles: true, relatedTarget: second }));
+    await nextTick();
+
+    expect(result!.focused.value).toBeTruthy();
+
+    scope.stop();
+    document.body.replaceChildren();
+  });
+
+  it('reflects focus that already lives inside the target on creation', () => {
+    const { container, input } = makeTree();
+    input.focus();
+
+    const scope = effectScope();
+    let result: ReturnType<typeof useFocusWithin>;
+    scope.run(() => {
+      result = useFocusWithin(container);
+    });
+
+    expect(result!.focused.value).toBeTruthy();
+
+    scope.stop();
+    document.body.replaceChildren();
+  });
+
+  it('accepts a reactive ref target', async () => {
+    const { container, input } = makeTree();
+    const targetRef = shallowRef<HTMLElement | null>(container);
+
+    const scope = effectScope();
+    let result: ReturnType<typeof useFocusWithin>;
+    scope.run(() => {
+      result = useFocusWithin(targetRef);
+    });
+
+    input.focus();
+    container.dispatchEvent(new FocusEvent('focusin', { bubbles: true }));
+    await nextTick();
+
+    expect(result!.focused.value).toBeTruthy();
+
+    scope.stop();
+    document.body.replaceChildren();
+  });
+
+  it('exposes a read-only computed (write throws / has no setter)', () => {
+    const { container } = makeTree();
+
+    const scope = effectScope();
+    let result: ReturnType<typeof useFocusWithin>;
+    scope.run(() => {
+      result = useFocusWithin(container);
+    });
+
+    // computed without a setter ignores writes (does not mutate internal state)
+    // @ts-expect-error - intentionally writing to a read-only computed
+    result!.focused.value = true;
+    expect(result!.focused.value).toBeFalsy();
+
+    scope.stop();
+    document.body.replaceChildren();
+  });
+
+  it('does not throw and stays false when window is unavailable (SSR)', () => {
+    const { container } = makeTree();
+
+    const scope = effectScope();
+    let result: ReturnType<typeof useFocusWithin>;
+    scope.run(() => {
+      result = useFocusWithin(container, { window: undefined });
+    });
+
+    expect(result!.focused.value).toBeFalsy();
+
+    scope.stop();
+    document.body.replaceChildren();
+  });
+});

vue/toolkit/src/composables/browser/useFocusWithin/index.ts

@@ -0,0 +1,83 @@
+import { computed, shallowRef } from 'vue';
+import type { ComputedRef } from 'vue';
+import { defaultWindow } from '@/types';
+import type { ConfigurableWindow } from '@/types';
+import { unrefElement } from '@/composables/component/unrefElement';
+import type { MaybeComputedElementRef } from '@/composables/component/unrefElement';
+import { useEventListener } from '@/composables/browser/useEventListener';
+
+export interface UseFocusWithinOptions extends ConfigurableWindow {}
+
+export interface UseFocusWithinReturn {
+  /**
+   * Whether the element or any of its descendants currently hold focus.
+   */
+  focused: ComputedRef<boolean>;
+}
+
+/**
+ * @name useFocusWithin
+ * @category Browser
+ * @description Reactive tracking of whether an element or any of its
+ * descendants are focused, backed by the `focusin`/`focusout` events.
+ *
+ * @param {MaybeComputedElementRef} target Element to track
+ * @param {UseFocusWithinOptions} [options={}] Options
+ * @returns {UseFocusWithinReturn} `{ focused }` reactive focus-within state
+ *
+ * @example
+ * const el = useTemplateRef<HTMLElement>('el');
+ * const { focused } = useFocusWithin(el);
+ *
+ * @since 0.0.15
+ */
+export function useFocusWithin(
+  target: MaybeComputedElementRef,
+  options: UseFocusWithinOptions = {},
+): UseFocusWithinReturn {
+  const { window = defaultWindow } = options;
+
+  const _focused = shallowRef(false);
+  const focused = computed(() => _focused.value);
+
+  const activeElement = window?.document?.activeElement;
+
+  const targetElement = computed(() => unrefElement(target) as HTMLElement | undefined | null);
+
+  if (window) {
+    useEventListener(targetElement, 'focusin', () => {
+      _focused.value = true;
+    }, { passive: true });
+
+    useEventListener(targetElement, 'focusout', (event: FocusEvent) => {
+      // After focus leaves a descendant, confirm focus did not simply move to
+      // another descendant. `event.relatedTarget` carries the element about to
+      // receive focus; if it is still inside `target` we remain focused. We
+      // also consult the `:focus-within` pseudo-class as a fallback for cases
+      // where `relatedTarget` is unavailable.
+      const el = unrefElement(target);
+
+      if (!el) {
+        _focused.value = false;
+        return;
+      }
+
+      const next = event.relatedTarget as Node | null;
+      if (next && el.contains(next)) {
+        _focused.value = true;
+        return;
+      }
+
+      _focused.value = el.matches?.(':focus-within') ?? false;
+    }, { passive: true });
+  }
+
+  // Reflect focus that already lives inside the target on initialization.
+  const el = unrefElement(target);
+  if (el && activeElement && (el === activeElement || el.contains(activeElement)))
+    _focused.value = true;
+
+  return {
+    focused,
+  };
+}

vue/toolkit/src/composables/browser/useFps/index.test.ts

@@ -1,4 +1,4 @@
-import { describe, expect, it, vi, beforeEach, afterEach } from 'vitest';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 import { effectScope } from 'vue';
 import { useFps } from '.';
 

vue/toolkit/src/composables/browser/useFullscreen/index.test.ts

@@ -0,0 +1,311 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick, shallowRef } from 'vue';
+import { useFullscreen } from '.';
+
+type Listener = (ev: Event) => void;
+
+interface FakeEl {
+  requestFullscreen: ReturnType<typeof vi.fn>;
+  addEventListener: ReturnType<typeof vi.fn>;
+  removeEventListener: ReturnType<typeof vi.fn>;
+}
+
+interface FakeDoc {
+  documentElement: FakeEl;
+  exitFullscreen: ReturnType<typeof vi.fn>;
+  fullscreenElement: Element | null;
+  fullScreen: boolean;
+  addEventListener: (event: string, cb: Listener) => void;
+  removeEventListener: (event: string, cb: Listener) => void;
+  dispatch: (event: string) => void;
+}
+
+function createFakeElement(): FakeEl {
+  return {
+    requestFullscreen: vi.fn(async () => {}),
+    addEventListener: vi.fn(),
+    removeEventListener: vi.fn(),
+  };
+}
+
+function createFakeDocument(el?: FakeEl): FakeDoc {
+  const listeners = new Map<string, Set<Listener>>();
+  const documentElement = el ?? createFakeElement();
+
+  const doc: FakeDoc = {
+    documentElement,
+    exitFullscreen: vi.fn(async () => {}),
+    fullscreenElement: null,
+    fullScreen: false,
+    addEventListener(event, cb) {
+      if (!listeners.has(event))
+        listeners.set(event, new Set());
+      listeners.get(event)!.add(cb);
+    },
+    removeEventListener(event, cb) {
+      listeners.get(event)?.delete(cb);
+    },
+    dispatch(event) {
+      listeners.get(event)?.forEach(cb => cb(new Event(event)));
+    },
+  };
+
+  return doc;
+}
+
+afterEach(() => {
+  vi.unstubAllGlobals();
+});
+
+describe(useFullscreen, () => {
+  it('reports support when request/exit/flag methods exist', () => {
+    const document = createFakeDocument();
+    const scope = effectScope();
+    let fs: ReturnType<typeof useFullscreen>;
+    scope.run(() => {
+      fs = useFullscreen(undefined, { document: document as unknown as Document });
+    });
+    expect(fs!.isSupported.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('is not supported when the Fullscreen API is absent (SSR/unsupported)', () => {
+    const document = {
+      documentElement: { addEventListener: vi.fn(), removeEventListener: vi.fn() },
+      addEventListener: vi.fn(),
+      removeEventListener: vi.fn(),
+    } as unknown as Document;
+    const scope = effectScope();
+    let fs: ReturnType<typeof useFullscreen>;
+    scope.run(() => {
+      fs = useFullscreen(undefined, { document });
+    });
+    expect(fs!.isSupported.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('is not supported when no document is available (SSR)', () => {
+    const scope = effectScope();
+    let fs: ReturnType<typeof useFullscreen>;
+    // No document and no defaultDocument in jsdom-less branch — pass an explicit undefined.
+    scope.run(() => {
+      fs = useFullscreen(undefined, { document: undefined });
+    });
+    expect(fs!.isSupported.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('starts not fullscreen', () => {
+    const document = createFakeDocument();
+    const scope = effectScope();
+    let fs: ReturnType<typeof useFullscreen>;
+    scope.run(() => {
+      fs = useFullscreen(undefined, { document: document as unknown as Document });
+    });
+    expect(fs!.isFullscreen.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('enter() requests fullscreen on the target element and sets the flag', async () => {
+    const el = createFakeElement();
+    const document = createFakeDocument(el);
+    const scope = effectScope();
+    let fs: ReturnType<typeof useFullscreen>;
+    scope.run(() => {
+      fs = useFullscreen(undefined, { document: document as unknown as Document });
+    });
+
+    await fs!.enter();
+    expect(el.requestFullscreen).toHaveBeenCalledTimes(1);
+    expect(fs!.isFullscreen.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('enter() requests fullscreen on a provided target element', async () => {
+    const target = createFakeElement();
+    const document = createFakeDocument();
+    const scope = effectScope();
+    let fs: ReturnType<typeof useFullscreen>;
+    scope.run(() => {
+      fs = useFullscreen(target as unknown as HTMLElement, { document: document as unknown as Document });
+    });
+
+    await fs!.enter();
+    expect(target.requestFullscreen).toHaveBeenCalledTimes(1);
+    expect(document.documentElement.requestFullscreen).not.toHaveBeenCalled();
+    expect(fs!.isFullscreen.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('enter() is a no-op when already fullscreen', async () => {
+    const el = createFakeElement();
+    const document = createFakeDocument(el);
+    const scope = effectScope();
+    let fs: ReturnType<typeof useFullscreen>;
+    scope.run(() => {
+      fs = useFullscreen(undefined, { document: document as unknown as Document });
+    });
+
+    await fs!.enter();
+    el.requestFullscreen.mockClear();
+    await fs!.enter();
+    expect(el.requestFullscreen).not.toHaveBeenCalled();
+    scope.stop();
+  });
+
+  it('exit() calls exitFullscreen and clears the flag', async () => {
+    const el = createFakeElement();
+    const document = createFakeDocument(el);
+    const scope = effectScope();
+    let fs: ReturnType<typeof useFullscreen>;
+    scope.run(() => {
+      fs = useFullscreen(undefined, { document: document as unknown as Document });
+    });
+
+    await fs!.enter();
+    await fs!.exit();
+    expect(document.exitFullscreen).toHaveBeenCalledTimes(1);
+    expect(fs!.isFullscreen.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('exit() is a no-op when not fullscreen', async () => {
+    const document = createFakeDocument();
+    const scope = effectScope();
+    let fs: ReturnType<typeof useFullscreen>;
+    scope.run(() => {
+      fs = useFullscreen(undefined, { document: document as unknown as Document });
+    });
+
+    await fs!.exit();
+    expect(document.exitFullscreen).not.toHaveBeenCalled();
+    scope.stop();
+  });
+
+  it('toggle() flips between enter and exit', async () => {
+    const el = createFakeElement();
+    const document = createFakeDocument(el);
+    const scope = effectScope();
+    let fs: ReturnType<typeof useFullscreen>;
+    scope.run(() => {
+      fs = useFullscreen(undefined, { document: document as unknown as Document });
+    });
+
+    await fs!.toggle();
+    expect(fs!.isFullscreen.value).toBeTruthy();
+    expect(el.requestFullscreen).toHaveBeenCalledTimes(1);
+
+    await fs!.toggle();
+    expect(fs!.isFullscreen.value).toBeFalsy();
+    expect(document.exitFullscreen).toHaveBeenCalledTimes(1);
+    scope.stop();
+  });
+
+  it('does nothing when unsupported', async () => {
+    const document = {
+      documentElement: { addEventListener: vi.fn(), removeEventListener: vi.fn() },
+      addEventListener: vi.fn(),
+      removeEventListener: vi.fn(),
+    } as unknown as Document;
+    const scope = effectScope();
+    let fs: ReturnType<typeof useFullscreen>;
+    scope.run(() => {
+      fs = useFullscreen(undefined, { document });
+    });
+
+    await fs!.enter();
+    expect(fs!.isFullscreen.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('syncs isFullscreen to true on fullscreenchange when our element is the fullscreen element', async () => {
+    const document = createFakeDocument();
+    const scope = effectScope();
+    let fs: ReturnType<typeof useFullscreen>;
+    scope.run(() => {
+      fs = useFullscreen(undefined, { document: document as unknown as Document });
+    });
+
+    // Simulate the browser entering fullscreen for the document element.
+    document.fullScreen = true;
+    document.fullscreenElement = document.documentElement as unknown as Element;
+    document.dispatch('fullscreenchange');
+    await nextTick();
+
+    expect(fs!.isFullscreen.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('syncs isFullscreen to false on fullscreenchange when fullscreen ends', async () => {
+    const el = createFakeElement();
+    const document = createFakeDocument(el);
+    const scope = effectScope();
+    let fs: ReturnType<typeof useFullscreen>;
+    scope.run(() => {
+      fs = useFullscreen(undefined, { document: document as unknown as Document });
+    });
+
+    await fs!.enter();
+    expect(fs!.isFullscreen.value).toBeTruthy();
+
+    // Browser exits fullscreen (e.g. user pressed Escape).
+    document.fullScreen = false;
+    document.fullscreenElement = null;
+    document.dispatch('fullscreenchange');
+    await nextTick();
+
+    expect(fs!.isFullscreen.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('resolves the target from a getter ref', async () => {
+    const target = createFakeElement();
+    const elRef = shallowRef<FakeEl | null>(null);
+    const document = createFakeDocument();
+    const scope = effectScope();
+    let fs: ReturnType<typeof useFullscreen>;
+    scope.run(() => {
+      fs = useFullscreen(() => elRef.value as unknown as HTMLElement, { document: document as unknown as Document });
+    });
+
+    elRef.value = target;
+    await nextTick();
+
+    await fs!.enter();
+    expect(target.requestFullscreen).toHaveBeenCalledTimes(1);
+    scope.stop();
+  });
+
+  it('autoExit exits fullscreen when the scope is disposed', async () => {
+    const el = createFakeElement();
+    const document = createFakeDocument(el);
+    const scope = effectScope();
+    let fs: ReturnType<typeof useFullscreen>;
+    scope.run(() => {
+      fs = useFullscreen(undefined, { document: document as unknown as Document, autoExit: true });
+    });
+
+    await fs!.enter();
+    expect(fs!.isFullscreen.value).toBeTruthy();
+
+    scope.stop();
+    // onScopeDispose triggers exit() (fire-and-forget); allow the microtask to flush.
+    await Promise.resolve();
+    expect(document.exitFullscreen).toHaveBeenCalledTimes(1);
+  });
+
+  it('does not autoExit by default', async () => {
+    const el = createFakeElement();
+    const document = createFakeDocument(el);
+    const scope = effectScope();
+    let fs: ReturnType<typeof useFullscreen>;
+    scope.run(() => {
+      fs = useFullscreen(undefined, { document: document as unknown as Document });
+    });
+
+    await fs!.enter();
+    scope.stop();
+    await Promise.resolve();
+    expect(document.exitFullscreen).not.toHaveBeenCalled();
+  });
+});

vue/toolkit/src/composables/browser/useFullscreen/index.ts

@@ -0,0 +1,231 @@
+import { computed, shallowRef } from 'vue';
+import type { ComputedRef, ShallowRef } from 'vue';
+import { isFunction } from '@robonen/stdlib';
+import type { ConfigurableDocument } from '@/types';
+import { defaultDocument } from '@/types';
+import type { MaybeComputedElementRef } from '@/composables/component/unrefElement';
+import { unrefElement } from '@/composables/component/unrefElement';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { useSupported } from '@/composables/browser/useSupported';
+import { tryOnMounted } from '@/composables/lifecycle/tryOnMounted';
+import { tryOnScopeDispose } from '@/composables/lifecycle/tryOnScopeDispose';
+
+export interface UseFullscreenOptions extends ConfigurableDocument {
+  /**
+   * Automatically exit fullscreen when the component is unmounted
+   *
+   * @default false
+   */
+  autoExit?: boolean;
+}
+
+export interface UseFullscreenReturn {
+  /**
+   * Whether the Fullscreen API is supported for the target element
+   */
+  isSupported: ComputedRef<boolean>;
+  /**
+   * Whether the target element is currently in fullscreen mode
+   */
+  isFullscreen: ShallowRef<boolean>;
+  /**
+   * Request fullscreen mode for the target element
+   */
+  enter: () => Promise<void>;
+  /**
+   * Exit fullscreen mode
+   */
+  exit: () => Promise<void>;
+  /**
+   * Toggle fullscreen mode for the target element
+   */
+  toggle: () => Promise<void>;
+}
+
+// Vendor-prefixed `fullscreenchange` event names across engines.
+const eventHandlers = [
+  'fullscreenchange',
+  'webkitfullscreenchange',
+  'webkitendfullscreen',
+  'mozfullscreenchange',
+  'MSFullscreenChange',
+] as unknown as Array<'fullscreenchange'>;
+
+const requestMethods = [
+  'requestFullscreen',
+  'webkitRequestFullscreen',
+  'webkitEnterFullscreen',
+  'webkitEnterFullScreen',
+  'webkitRequestFullScreen',
+  'mozRequestFullScreen',
+  'msRequestFullscreen',
+] as const;
+
+const exitMethods = [
+  'exitFullscreen',
+  'webkitExitFullscreen',
+  'webkitExitFullScreen',
+  'webkitCancelFullScreen',
+  'mozCancelFullScreen',
+  'msExitFullscreen',
+] as const;
+
+const fullscreenFlags = [
+  'fullScreen',
+  'webkitIsFullScreen',
+  'webkitDisplayingFullscreen',
+  'mozFullScreen',
+  'msFullscreenElement',
+] as const;
+
+const fullscreenElements = [
+  'fullscreenElement',
+  'webkitFullscreenElement',
+  'mozFullScreenElement',
+  'msFullscreenElement',
+] as const;
+
+const listenerOptions = { capture: false, passive: true } as const;
+
+/**
+ * @name useFullscreen
+ * @category Browser
+ * @description Reactive Fullscreen API for an element (or the document element).
+ * Handles vendor-prefixed fallbacks for request/exit/state detection and syncs
+ * `isFullscreen` from `fullscreenchange` events. SSR-safe.
+ *
+ * @param {MaybeComputedElementRef} [target] Element to display fullscreen (ref, getter, or component instance). Defaults to `document.documentElement`
+ * @param {UseFullscreenOptions} [options={}] Options (`document`, `autoExit`)
+ * @returns {UseFullscreenReturn} `{ isSupported, isFullscreen, enter, exit, toggle }`
+ *
+ * @example
+ * const el = useTemplateRef('el');
+ * const { isFullscreen, enter, exit, toggle } = useFullscreen(el);
+ *
+ * @example
+ * // Fullscreen the whole page
+ * const { toggle } = useFullscreen();
+ *
+ * @since 0.0.15
+ */
+export function useFullscreen(
+  target?: MaybeComputedElementRef,
+  options: UseFullscreenOptions = {},
+): UseFullscreenReturn {
+  const {
+    document = defaultDocument,
+    autoExit = false,
+  } = options;
+
+  const targetRef = computed(() => unrefElement(target) ?? document?.documentElement);
+  const isFullscreen = shallowRef(false);
+
+  const has = (method: string): boolean =>
+    Boolean((document && method in document) || (targetRef.value && method in targetRef.value));
+
+  const requestMethod = computed<typeof requestMethods[number] | undefined>(
+    () => requestMethods.find(has),
+  );
+
+  const exitMethod = computed<typeof exitMethods[number] | undefined>(
+    () => exitMethods.find(has),
+  );
+
+  const fullscreenFlag = computed<typeof fullscreenFlags[number] | undefined>(
+    () => fullscreenFlags.find(has),
+  );
+
+  const fullscreenElementMethod = fullscreenElements.find(m => document && m in document);
+
+  const isSupported = useSupported(() =>
+    targetRef.value
+    && document
+    && requestMethod.value !== undefined
+    && exitMethod.value !== undefined
+    && fullscreenFlag.value !== undefined);
+
+  const isCurrentElementFullScreen = (): boolean => {
+    if (fullscreenElementMethod)
+      return (document as any)?.[fullscreenElementMethod] === targetRef.value;
+    return false;
+  };
+
+  const isElementFullScreen = (): boolean => {
+    const flag = fullscreenFlag.value;
+    if (!flag)
+      return false;
+
+    const docFlag = document && (document as any)[flag];
+    if (docFlag !== null && docFlag !== undefined)
+      return Boolean(docFlag);
+
+    // Fallback for WebKit / iOS Safari, where the flag lives on the element itself.
+    const elFlag = (targetRef.value as any)?.[flag];
+    if (elFlag !== null && elFlag !== undefined)
+      return Boolean(elFlag);
+
+    return false;
+  };
+
+  async function exit(): Promise<void> {
+    if (!isSupported.value || !isFullscreen.value)
+      return;
+
+    const method = exitMethod.value;
+    if (method) {
+      if (typeof (document as any)?.[method] === 'function')
+        await (document as any)[method]();
+      else {
+        // Fallback for Safari iOS, where exit lives on the element.
+        const el = targetRef.value as any;
+        if (isFunction(el?.[method]))
+          await el[method]();
+      }
+    }
+
+    isFullscreen.value = false;
+  }
+
+  async function enter(): Promise<void> {
+    if (!isSupported.value || isFullscreen.value)
+      return;
+
+    if (isElementFullScreen())
+      await exit();
+
+    const el = targetRef.value as any;
+    const method = requestMethod.value;
+    if (method && isFunction(el?.[method])) {
+      await el[method]();
+      isFullscreen.value = true;
+    }
+  }
+
+  async function toggle(): Promise<void> {
+    await (isFullscreen.value ? exit() : enter());
+  }
+
+  const handlerCallback = (): void => {
+    const elementFullScreen = isElementFullScreen();
+    // Only sync to `false`, or to `true` when *our* element is the fullscreen one,
+    // so multiple instances on the page don't clobber each other.
+    if (!elementFullScreen || (elementFullScreen && isCurrentElementFullScreen()))
+      isFullscreen.value = elementFullScreen;
+  };
+
+  useEventListener(document, eventHandlers, handlerCallback, listenerOptions);
+  useEventListener(() => targetRef.value, eventHandlers, handlerCallback, listenerOptions);
+
+  tryOnMounted(handlerCallback, { sync: false });
+
+  if (autoExit)
+    tryOnScopeDispose(exit);
+
+  return {
+    isSupported,
+    isFullscreen,
+    enter,
+    exit,
+    toggle,
+  };
+}

vue/toolkit/src/composables/browser/useGeolocation/index.test.ts

@@ -0,0 +1,266 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick, shallowRef } from 'vue';
+import { useGeolocation } from '.';
+
+afterEach(() => vi.unstubAllGlobals());
+
+function stubGeolocation() {
+  let successCb: PositionCallback | null = null;
+  let errorCb: PositionErrorCallback | null = null;
+  let lastOptions: PositionOptions | undefined;
+  const watchPosition = vi.fn((success: PositionCallback, err?: PositionErrorCallback | null, opts?: PositionOptions) => {
+    successCb = success;
+    errorCb = err ?? null;
+    lastOptions = opts;
+    return 1;
+  });
+  const clearWatch = vi.fn();
+  const getCurrentPosition = vi.fn((success: PositionCallback, err?: PositionErrorCallback | null, opts?: PositionOptions) => {
+    successCb = success;
+    errorCb = err ?? null;
+    lastOptions = opts;
+  });
+  const navigator = { geolocation: { watchPosition, clearWatch, getCurrentPosition } } as unknown as Navigator;
+  return {
+    navigator,
+    watchPosition,
+    clearWatch,
+    getCurrentPosition,
+    getOptions: () => lastOptions,
+    emit: (position: GeolocationPosition) => successCb?.(position),
+    emitError: (err: GeolocationPositionError) => errorCb?.(err),
+  };
+}
+
+function makePosition(latitude: number, longitude: number, timestamp = 123): GeolocationPosition {
+  return {
+    timestamp,
+    coords: {
+      latitude,
+      longitude,
+      accuracy: 5,
+      altitude: null,
+      altitudeAccuracy: null,
+      heading: null,
+      speed: null,
+    } as GeolocationCoordinates,
+  } as GeolocationPosition;
+}
+
+function makeError(code = 1, message = 'denied'): GeolocationPositionError {
+  return { code, message, PERMISSION_DENIED: 1, POSITION_UNAVAILABLE: 2, TIMEOUT: 3 } as GeolocationPositionError;
+}
+
+describe(useGeolocation, () => {
+  it('starts watching immediately by default', () => {
+    const { watchPosition, navigator } = stubGeolocation();
+    const scope = effectScope();
+    scope.run(() => useGeolocation({ navigator }));
+    expect(watchPosition).toHaveBeenCalled();
+    scope.stop();
+  });
+
+  it('does not start watching when immediate is false', () => {
+    const { watchPosition, navigator } = stubGeolocation();
+    const scope = effectScope();
+    let geo: ReturnType<typeof useGeolocation>;
+    scope.run(() => {
+      geo = useGeolocation({ navigator, immediate: false });
+    });
+    expect(watchPosition).not.toHaveBeenCalled();
+    expect(geo!.isActive.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('updates coords on position change', () => {
+    const { emit, navigator } = stubGeolocation();
+    const scope = effectScope();
+    let geo: ReturnType<typeof useGeolocation>;
+    scope.run(() => {
+      geo = useGeolocation({ navigator });
+    });
+
+    emit(makePosition(1, 2));
+
+    expect(geo!.coords.value.latitude).toBe(1);
+    expect(geo!.coords.value.longitude).toBe(2);
+    expect(geo!.locatedAt.value).toBe(123);
+    expect(geo!.ready.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('tracks active state across resume/pause', () => {
+    const { navigator } = stubGeolocation();
+    const scope = effectScope();
+    let geo: ReturnType<typeof useGeolocation>;
+    scope.run(() => {
+      geo = useGeolocation({ navigator });
+    });
+    expect(geo!.isActive.value).toBeTruthy();
+    geo!.pause();
+    expect(geo!.isActive.value).toBeFalsy();
+    geo!.resume();
+    expect(geo!.isActive.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('clears the watch on pause', () => {
+    const { clearWatch, navigator } = stubGeolocation();
+    const scope = effectScope();
+    let geo: ReturnType<typeof useGeolocation>;
+    scope.run(() => {
+      geo = useGeolocation({ navigator });
+    });
+    geo!.pause();
+    expect(clearWatch).toHaveBeenCalledWith(1);
+    scope.stop();
+  });
+
+  it('does not re-watch when already active', () => {
+    const { watchPosition, navigator } = stubGeolocation();
+    const scope = effectScope();
+    let geo: ReturnType<typeof useGeolocation>;
+    scope.run(() => {
+      geo = useGeolocation({ navigator });
+    });
+    geo!.resume();
+    geo!.resume();
+    expect(watchPosition).toHaveBeenCalledTimes(1);
+    scope.stop();
+  });
+
+  it('records errors and invokes onError', () => {
+    const { emitError, navigator } = stubGeolocation();
+    const onError = vi.fn();
+    const scope = effectScope();
+    let geo: ReturnType<typeof useGeolocation>;
+    scope.run(() => {
+      geo = useGeolocation({ navigator, onError });
+    });
+
+    const err = makeError();
+    emitError(err);
+
+    expect(geo!.error.value).toBe(err);
+    expect(onError).toHaveBeenCalledWith(err);
+    scope.stop();
+  });
+
+  it('clears the error after a successful fix', () => {
+    const { emit, emitError, navigator } = stubGeolocation();
+    const scope = effectScope();
+    let geo: ReturnType<typeof useGeolocation>;
+    scope.run(() => {
+      geo = useGeolocation({ navigator });
+    });
+
+    emitError(makeError());
+    expect(geo!.error.value).not.toBeNull();
+    emit(makePosition(1, 2));
+    expect(geo!.error.value).toBeNull();
+    scope.stop();
+  });
+
+  it('passes position options to watchPosition', () => {
+    const { getOptions, navigator } = stubGeolocation();
+    const scope = effectScope();
+    scope.run(() => useGeolocation({ navigator, enableHighAccuracy: false, maximumAge: 1000, timeout: 5000 }));
+    expect(getOptions()).toEqual({ enableHighAccuracy: false, maximumAge: 1000, timeout: 5000 });
+    scope.stop();
+  });
+
+  it('restarts the watcher when reactive options change while active', async () => {
+    const { watchPosition, clearWatch, getOptions, navigator } = stubGeolocation();
+    const highAccuracy = shallowRef(false);
+    const scope = effectScope();
+    scope.run(() => useGeolocation({ navigator, enableHighAccuracy: highAccuracy }));
+
+    expect(watchPosition).toHaveBeenCalledTimes(1);
+    expect(getOptions()?.enableHighAccuracy).toBeFalsy();
+
+    highAccuracy.value = true;
+    await nextTick();
+
+    expect(clearWatch).toHaveBeenCalledWith(1);
+    expect(watchPosition).toHaveBeenCalledTimes(2);
+    expect(getOptions()?.enableHighAccuracy).toBeTruthy();
+    scope.stop();
+  });
+
+  it('does not restart on option change when paused', async () => {
+    const { watchPosition, navigator } = stubGeolocation();
+    const timeout = shallowRef(1000);
+    const scope = effectScope();
+    let geo: ReturnType<typeof useGeolocation>;
+    scope.run(() => {
+      geo = useGeolocation({ navigator, timeout, immediate: false });
+    });
+
+    timeout.value = 2000;
+    await nextTick();
+
+    expect(watchPosition).not.toHaveBeenCalled();
+    expect(geo!.isActive.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('getCurrentPosition resolves and updates state without a watch', async () => {
+    const { watchPosition, getCurrentPosition, emit, navigator } = stubGeolocation();
+    const scope = effectScope();
+    let geo: ReturnType<typeof useGeolocation>;
+    scope.run(() => {
+      geo = useGeolocation({ navigator, immediate: false });
+    });
+
+    const promise = geo!.getCurrentPosition();
+    emit(makePosition(10, 20, 999));
+    const position = await promise;
+
+    expect(getCurrentPosition).toHaveBeenCalled();
+    expect(watchPosition).not.toHaveBeenCalled();
+    expect(position.coords.latitude).toBe(10);
+    expect(geo!.coords.value.latitude).toBe(10);
+    expect(geo!.locatedAt.value).toBe(999);
+    expect(geo!.ready.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('getCurrentPosition rejects on error', async () => {
+    const { emitError, navigator } = stubGeolocation();
+    const scope = effectScope();
+    let geo: ReturnType<typeof useGeolocation>;
+    scope.run(() => {
+      geo = useGeolocation({ navigator, immediate: false });
+    });
+
+    const promise = geo!.getCurrentPosition();
+    const err = makeError();
+    emitError(err);
+
+    await expect(promise).rejects.toBe(err);
+    expect(geo!.error.value).toBe(err);
+    scope.stop();
+  });
+
+  it('reports unsupported when geolocation is missing', () => {
+    const navigator = {} as Navigator;
+    const scope = effectScope();
+    let geo: ReturnType<typeof useGeolocation>;
+    scope.run(() => {
+      geo = useGeolocation({ navigator });
+    });
+    expect(geo!.isSupported.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('getCurrentPosition rejects when unsupported', async () => {
+    const navigator = {} as Navigator;
+    const scope = effectScope();
+    let geo: ReturnType<typeof useGeolocation>;
+    scope.run(() => {
+      geo = useGeolocation({ navigator, immediate: false });
+    });
+    await expect(geo!.getCurrentPosition()).rejects.toThrow('not supported');
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useGeolocation/index.ts

@@ -0,0 +1,236 @@
+import { shallowReadonly, shallowRef, toValue, watch } from 'vue';
+import type { MaybeRefOrGetter, Ref } from 'vue';
+import { noop } from '@robonen/stdlib';
+import { defaultNavigator } from '@/types';
+import type { ConfigurableNavigator } from '@/types';
+import { useSupported } from '@/composables/browser/useSupported';
+import { tryOnScopeDispose } from '@/composables/lifecycle/tryOnScopeDispose';
+
+export interface UseGeolocationOptions extends ConfigurableNavigator {
+  /**
+   * A boolean that indicates the application would like to receive the best
+   * possible results. Reactive — changing it while watching restarts the watcher.
+   *
+   * @default true
+   */
+  enableHighAccuracy?: MaybeRefOrGetter<boolean>;
+
+  /**
+   * The maximum age in milliseconds of a possible cached position that is
+   * acceptable to return. Reactive — changing it while watching restarts the watcher.
+   *
+   * @default 30000
+   */
+  maximumAge?: MaybeRefOrGetter<number>;
+
+  /**
+   * The maximum length of time in milliseconds the device is allowed to take in
+   * order to return a position. Reactive — changing it while watching restarts the watcher.
+   *
+   * @default 27000
+   */
+  timeout?: MaybeRefOrGetter<number>;
+
+  /**
+   * Start watching the position immediately
+   *
+   * @default true
+   */
+  immediate?: boolean;
+
+  /**
+   * Called whenever the Geolocation API reports an error. Receives the
+   * `GeolocationPositionError`. Useful for reacting to permission denials or
+   * timeouts without setting up a watcher on `error`.
+   *
+   * @default () => {}
+   */
+  onError?: (error: GeolocationPositionError) => void;
+}
+
+export interface UseGeolocationReturn {
+  /**
+   * Whether the Geolocation API is supported in the current environment.
+   */
+  isSupported: Readonly<Ref<boolean>>;
+
+  /**
+   * The most recent set of coordinates.
+   */
+  coords: Readonly<Ref<Omit<GeolocationPosition['coords'], 'toJSON'>>>;
+
+  /**
+   * The timestamp of the most recent position, or `null` before the first fix.
+   */
+  locatedAt: Readonly<Ref<number | null>>;
+
+  /**
+   * The most recent error, or `null` if none.
+   */
+  error: Readonly<Ref<GeolocationPositionError | null>>;
+
+  /**
+   * Whether at least one position fix has been received.
+   */
+  ready: Readonly<Ref<boolean>>;
+
+  /**
+   * Whether the position is currently being watched.
+   */
+  isActive: Readonly<Ref<boolean>>;
+
+  /**
+   * Start watching the position.
+   */
+  resume: () => void;
+
+  /**
+   * Stop watching the position.
+   */
+  pause: () => void;
+
+  /**
+   * Request the current position once, without starting a continuous watch.
+   * Resolves with the position (and updates `coords`/`locatedAt`) or rejects
+   * with a `GeolocationPositionError`.
+   */
+  getCurrentPosition: () => Promise<GeolocationPosition>;
+}
+
+const DEFAULT_COORDS: Omit<GeolocationPosition['coords'], 'toJSON'> = {
+  accuracy: 0,
+  latitude: Number.POSITIVE_INFINITY,
+  longitude: Number.POSITIVE_INFINITY,
+  altitude: null,
+  altitudeAccuracy: null,
+  heading: null,
+  speed: null,
+};
+
+/**
+ * @name useGeolocation
+ * @category Browser
+ * @description Reactive Geolocation API. Watches the device position, exposing
+ * reactive coordinates, error, and readiness state, plus pause/resume controls
+ * and a one-shot `getCurrentPosition`.
+ *
+ * @param {UseGeolocationOptions} [options={}] Options
+ * @returns {UseGeolocationReturn} Reactive position, error, readiness, and watch controls
+ *
+ * @example
+ * const { coords, locatedAt, error, ready } = useGeolocation();
+ *
+ * @example
+ * // One-shot fetch without a continuous watch
+ * const { getCurrentPosition } = useGeolocation({ immediate: false });
+ * const position = await getCurrentPosition();
+ *
+ * @since 0.0.15
+ */
+export function useGeolocation(options: UseGeolocationOptions = {}): UseGeolocationReturn {
+  const {
+    enableHighAccuracy = true,
+    maximumAge = 30000,
+    timeout = 27000,
+    navigator = defaultNavigator,
+    immediate = true,
+    onError = noop,
+  } = options;
+
+  const isSupported = useSupported(() => navigator && 'geolocation' in navigator);
+
+  const locatedAt = shallowRef<number | null>(null);
+  const error = shallowRef<GeolocationPositionError | null>(null);
+  const coords = shallowRef<Omit<GeolocationPosition['coords'], 'toJSON'>>(DEFAULT_COORDS);
+  const ready = shallowRef(false);
+  const isActive = shallowRef(false);
+
+  function resolveOptions(): PositionOptions {
+    return {
+      enableHighAccuracy: toValue(enableHighAccuracy),
+      maximumAge: toValue(maximumAge),
+      timeout: toValue(timeout),
+    };
+  }
+
+  function updatePosition(position: GeolocationPosition): void {
+    locatedAt.value = position.timestamp;
+    coords.value = position.coords;
+    error.value = null;
+    ready.value = true;
+  }
+
+  function handleError(err: GeolocationPositionError): void {
+    error.value = err;
+    onError(err);
+  }
+
+  let watcher: number | null = null;
+
+  function resume(): void {
+    if (!isSupported.value || !navigator || watcher !== null)
+      return;
+
+    watcher = navigator.geolocation.watchPosition(updatePosition, handleError, resolveOptions());
+    isActive.value = true;
+  }
+
+  function pause(): void {
+    if (watcher === null || !navigator)
+      return;
+
+    navigator.geolocation.clearWatch(watcher);
+    watcher = null;
+    isActive.value = false;
+  }
+
+  function getCurrentPosition(): Promise<GeolocationPosition> {
+    return new Promise((resolve, reject) => {
+      if (!isSupported.value || !navigator) {
+        reject(new Error('Geolocation is not supported'));
+        return;
+      }
+
+      navigator.geolocation.getCurrentPosition(
+        (position) => {
+          updatePosition(position);
+          resolve(position);
+        },
+        (err) => {
+          handleError(err);
+          reject(err);
+        },
+        resolveOptions(),
+      );
+    });
+  }
+
+  // Restart the watcher when reactive position options change while active.
+  watch(
+    () => resolveOptions(),
+    () => {
+      if (isActive.value) {
+        pause();
+        resume();
+      }
+    },
+    { deep: true },
+  );
+
+  if (immediate)
+    resume();
+
+  tryOnScopeDispose(pause);
+
+  return {
+    isSupported,
+    coords,
+    locatedAt: shallowReadonly(locatedAt),
+    error: shallowReadonly(error),
+    ready: shallowReadonly(ready),
+    isActive: shallowReadonly(isActive),
+    resume,
+    pause,
+    getCurrentPosition,
+  };
+}

vue/toolkit/src/composables/browser/useIdle/index.test.ts

@@ -0,0 +1,259 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { effectScope } from 'vue';
+import { useIdle } from '.';
+import { bypassFilter } from '@/utils/filters';
+
+/**
+ * Minimal EventTarget-like stub so we can drive listeners deterministically
+ * without relying on jsdom's real window/document timing.
+ */
+function createTarget() {
+  const listeners = new Map<string, Set<EventListener>>();
+  return {
+    addEventListener(type: string, listener: EventListener) {
+      if (!listeners.has(type))
+        listeners.set(type, new Set());
+      listeners.get(type)!.add(listener);
+    },
+    removeEventListener(type: string, listener: EventListener) {
+      listeners.get(type)?.delete(listener);
+    },
+    dispatch(type: string, event: Event = { type } as Event) {
+      listeners.get(type)?.forEach(fn => fn(event));
+    },
+    count(type: string) {
+      return listeners.get(type)?.size ?? 0;
+    },
+  };
+}
+
+function createWindow(doc: ReturnType<typeof createTarget> & { hidden?: boolean }) {
+  const win = createTarget() as ReturnType<typeof createTarget> & { document: typeof doc };
+  win.document = doc;
+  return win;
+}
+
+describe(useIdle, () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+    vi.setSystemTime(1000);
+  });
+  afterEach(() => vi.useRealTimers());
+
+  it('starts not idle and exposes lastActive', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const doc = createTarget();
+      const window = createWindow(doc) as any;
+      const { idle, lastActive, isPending } = useIdle(1000, { window });
+
+      expect(idle.value).toBeFalsy();
+      expect(isPending.value).toBeTruthy();
+      expect(lastActive.value).toBe(1000);
+    });
+    scope.stop();
+  });
+
+  it('becomes idle after the timeout elapses with no activity', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const doc = createTarget();
+      const window = createWindow(doc) as any;
+      const { idle } = useIdle(1000, { window });
+
+      expect(idle.value).toBeFalsy();
+      vi.advanceTimersByTime(999);
+      expect(idle.value).toBeFalsy();
+      vi.advanceTimersByTime(1);
+      expect(idle.value).toBeTruthy();
+    });
+    scope.stop();
+  });
+
+  it('resets idle state and lastActive on user activity', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const doc = createTarget();
+      const window = createWindow(doc) as any;
+      const { idle, lastActive } = useIdle(1000, { window, eventFilter: bypassFilter });
+
+      vi.advanceTimersByTime(1000);
+      expect(idle.value).toBeTruthy();
+
+      vi.setSystemTime(2500);
+      window.dispatch('mousemove');
+
+      expect(idle.value).toBeFalsy();
+      expect(lastActive.value).toBe(2500);
+    });
+    scope.stop();
+  });
+
+  it('restarts the timeout after activity', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const doc = createTarget();
+      const window = createWindow(doc) as any;
+      const { idle } = useIdle(1000, { window, eventFilter: bypassFilter });
+
+      vi.advanceTimersByTime(500);
+      window.dispatch('keydown');
+      // 500ms more would have been idle without the reset
+      vi.advanceTimersByTime(500);
+      expect(idle.value).toBeFalsy();
+      // full timeout from the reset
+      vi.advanceTimersByTime(500);
+      expect(idle.value).toBeTruthy();
+    });
+    scope.stop();
+  });
+
+  it('honors a custom events list', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const doc = createTarget();
+      const window = createWindow(doc) as any;
+      useIdle(1000, { window, events: ['keydown'] });
+
+      expect(window.count('keydown')).toBe(1);
+      expect(window.count('mousemove')).toBe(0);
+    });
+    scope.stop();
+  });
+
+  it('listens for visibilitychange by default and resets when visible', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const doc = createTarget() as any;
+      doc.hidden = false;
+      const window = createWindow(doc) as any;
+      const { idle } = useIdle(1000, { window, eventFilter: bypassFilter });
+
+      expect(doc.count('visibilitychange')).toBe(1);
+
+      vi.advanceTimersByTime(1000);
+      expect(idle.value).toBeTruthy();
+
+      doc.dispatch('visibilitychange');
+      expect(idle.value).toBeFalsy();
+    });
+    scope.stop();
+  });
+
+  it('ignores visibilitychange when the document is hidden', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const doc = createTarget() as any;
+      doc.hidden = true;
+      const window = createWindow(doc) as any;
+      const { idle } = useIdle(1000, { window, eventFilter: bypassFilter });
+
+      vi.advanceTimersByTime(1000);
+      expect(idle.value).toBeTruthy();
+
+      doc.dispatch('visibilitychange');
+      expect(idle.value).toBeTruthy();
+    });
+    scope.stop();
+  });
+
+  it('does not register visibilitychange when disabled', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const doc = createTarget();
+      const window = createWindow(doc) as any;
+      useIdle(1000, { window, listenForVisibilityChange: false });
+
+      expect(doc.count('visibilitychange')).toBe(0);
+    });
+    scope.stop();
+  });
+
+  it('respects initialState: true (starts idle, no timer)', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const doc = createTarget();
+      const window = createWindow(doc) as any;
+      const { idle } = useIdle(1000, { window, initialState: true });
+
+      expect(idle.value).toBeTruthy();
+      vi.advanceTimersByTime(5000);
+      // no reset was scheduled, so it stays in the initial state
+      expect(idle.value).toBeTruthy();
+    });
+    scope.stop();
+  });
+
+  it('reset() manually clears idle and restarts the timer', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const doc = createTarget();
+      const window = createWindow(doc) as any;
+      const { idle, reset } = useIdle(1000, { window });
+
+      vi.advanceTimersByTime(1000);
+      expect(idle.value).toBeTruthy();
+
+      reset();
+      expect(idle.value).toBeFalsy();
+      vi.advanceTimersByTime(1000);
+      expect(idle.value).toBeTruthy();
+    });
+    scope.stop();
+  });
+
+  it('stop() halts tracking and start() resumes it', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      const doc = createTarget();
+      const window = createWindow(doc) as any;
+      const { idle, isPending, start, stop } = useIdle(1000, { window, eventFilter: bypassFilter });
+
+      stop();
+      expect(isPending.value).toBeFalsy();
+      expect(idle.value).toBeFalsy();
+
+      // events are ignored while stopped
+      vi.advanceTimersByTime(1000);
+      expect(idle.value).toBeFalsy();
+      window.dispatch('mousemove');
+      expect(idle.value).toBeFalsy();
+
+      start();
+      expect(isPending.value).toBeTruthy();
+      vi.advanceTimersByTime(1000);
+      expect(idle.value).toBeTruthy();
+    });
+    scope.stop();
+  });
+
+  it('removes listeners when the scope is disposed', () => {
+    const scope = effectScope();
+    let win: any;
+    scope.run(() => {
+      const doc = createTarget();
+      win = createWindow(doc) as any;
+      useIdle(1000, { window: win });
+      expect(win.count('mousemove')).toBe(1);
+    });
+    scope.stop();
+    expect(win.count('mousemove')).toBe(0);
+  });
+
+  it('is SSR-safe when no window is available', () => {
+    const scope = effectScope();
+    scope.run(() => {
+      // simulate an environment with no window (the guard sees a falsy target)
+      const { idle, isPending, lastActive } = useIdle(1000, { window: null as any });
+
+      // never started: stays in initial state and never schedules a timer
+      expect(idle.value).toBeFalsy();
+      expect(isPending.value).toBeFalsy();
+      expect(lastActive.value).toBe(1000);
+
+      vi.advanceTimersByTime(5000);
+      expect(idle.value).toBeFalsy();
+    });
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useIdle/index.ts

@@ -0,0 +1,169 @@
+import { shallowReadonly, shallowRef } from 'vue';
+import type { ShallowRef } from 'vue';
+import { timestamp } from '@robonen/stdlib';
+import { defaultWindow } from '@/types';
+import type { ConfigurableWindow } from '@/types';
+import { createFilterWrapper, throttleFilter } from '@/utils/filters';
+import type { ConfigurableEventFilter } from '@/utils/filters';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import type { WindowEventName } from '@/composables/browser/useEventListener';
+
+const DEFAULT_EVENTS: WindowEventName[] = ['mousemove', 'mousedown', 'resize', 'keydown', 'touchstart', 'wheel'];
+const ONE_MINUTE = 60_000;
+
+export interface UseIdleOptions extends ConfigurableWindow, ConfigurableEventFilter {
+  /**
+   * Event names to listen to for detecting user activity
+   *
+   * @default ['mousemove', 'mousedown', 'resize', 'keydown', 'touchstart', 'wheel']
+   */
+  events?: WindowEventName[];
+
+  /**
+   * Reset the idle timer when the document becomes visible again
+   *
+   * @default true
+   */
+  listenForVisibilityChange?: boolean;
+
+  /**
+   * Initial value of the `idle` ref
+   *
+   * @default false
+   */
+  initialState?: boolean;
+}
+
+export interface UseIdleReturn {
+  /**
+   * Whether the user is currently idle
+   */
+  idle: ShallowRef<boolean>;
+
+  /**
+   * Timestamp (ms) of the last detected user activity
+   */
+  lastActive: ShallowRef<number>;
+
+  /**
+   * Whether the idle tracker is currently running
+   */
+  isPending: Readonly<ShallowRef<boolean>>;
+
+  /**
+   * Manually mark the user as active and restart the idle timer
+   */
+  reset: () => void;
+
+  /**
+   * Begin (or resume) tracking. Restarts the idle timer unless `initialState` is `true`
+   */
+  start: () => void;
+
+  /**
+   * Stop tracking. Resets `idle` to `initialState` and clears the pending timer
+   */
+  stop: () => void;
+}
+
+/**
+ * @name useIdle
+ * @category Browser
+ * @description Track whether the user has been inactive for a given duration.
+ *
+ * @param {number} [timeout=60000] Idle threshold in milliseconds
+ * @param {UseIdleOptions} [options={}] Options
+ * @returns {UseIdleReturn} `{ idle, lastActive, isPending, reset, start, stop }`
+ *
+ * @example
+ * const { idle, lastActive, reset } = useIdle(5 * 60_000); // 5 minutes
+ *
+ * @example
+ * const { idle } = useIdle(10_000, { events: ['keydown'] });
+ *
+ * @since 0.0.15
+ */
+export function useIdle(
+  timeout: number = ONE_MINUTE,
+  options: UseIdleOptions = {},
+): UseIdleReturn {
+  const {
+    initialState = false,
+    listenForVisibilityChange = true,
+    events = DEFAULT_EVENTS,
+    window = defaultWindow,
+    eventFilter = throttleFilter(50),
+  } = options;
+
+  const idle = shallowRef(initialState);
+  const lastActive = shallowRef(timestamp());
+  const isPending = shallowRef(false);
+
+  let timer: ReturnType<typeof setTimeout> | undefined;
+
+  const reset = (): void => {
+    idle.value = false;
+    if (timer !== undefined)
+      clearTimeout(timer);
+    timer = setTimeout(() => {
+      idle.value = true;
+    }, timeout);
+  };
+
+  const onEvent = createFilterWrapper(
+    eventFilter,
+    () => {
+      lastActive.value = timestamp();
+      reset();
+    },
+  );
+
+  const start = (): void => {
+    if (isPending.value)
+      return;
+    isPending.value = true;
+    if (!initialState)
+      reset();
+  };
+
+  const stop = (): void => {
+    idle.value = initialState;
+    if (timer !== undefined) {
+      clearTimeout(timer);
+      timer = undefined;
+    }
+    isPending.value = false;
+  };
+
+  if (window) {
+    const document = window.document;
+    const listenerOptions = { passive: true };
+
+    for (const event of events) {
+      useEventListener(window, event, () => {
+        if (!isPending.value)
+          return;
+        onEvent();
+      }, listenerOptions);
+    }
+
+    if (listenForVisibilityChange) {
+      useEventListener(document, 'visibilitychange', () => {
+        if (document.hidden || !isPending.value)
+          return;
+        onEvent();
+      }, listenerOptions);
+    }
+
+    start();
+  }
+
+  return {
+    idle,
+    lastActive,
+    isPending: shallowReadonly(isPending),
+    reset,
+    start,
+    stop,
+  };
+}

vue/toolkit/src/composables/browser/useIntersectionObserver/index.test.ts

@@ -0,0 +1,206 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick, ref } from 'vue';
+import { useIntersectionObserver } from '.';
+
+interface StubInstance {
+  cb: IntersectionObserverCallback;
+  options?: IntersectionObserverInit;
+  observe: ReturnType<typeof vi.fn>;
+  disconnect: ReturnType<typeof vi.fn>;
+}
+
+let instances: StubInstance[] = [];
+
+class StubIntersectionObserver {
+  observe = vi.fn();
+  disconnect = vi.fn();
+  unobserve = vi.fn();
+  takeRecords = vi.fn();
+  cb: IntersectionObserverCallback;
+  options?: IntersectionObserverInit;
+  constructor(cb: IntersectionObserverCallback, options?: IntersectionObserverInit) {
+    this.cb = cb;
+    this.options = options;
+    instances.push(this);
+  }
+}
+
+describe(useIntersectionObserver, () => {
+  beforeEach(() => {
+    instances = [];
+    vi.stubGlobal('IntersectionObserver', StubIntersectionObserver);
+  });
+  afterEach(() => vi.unstubAllGlobals());
+
+  it('observes the target immediately', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    scope.run(() => useIntersectionObserver(ref(el), vi.fn()));
+
+    expect(instances).toHaveLength(1);
+    expect(instances[0]!.observe).toHaveBeenCalledWith(el);
+    scope.stop();
+  });
+
+  it('does not observe when immediate is false', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    scope.run(() => useIntersectionObserver(ref(el), vi.fn(), { immediate: false }));
+
+    expect(instances).toHaveLength(0);
+    scope.stop();
+  });
+
+  it('pause disconnects and resume re-observes', async () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let controls: ReturnType<typeof useIntersectionObserver>;
+    scope.run(() => {
+      controls = useIntersectionObserver(ref(el), vi.fn());
+    });
+
+    controls!.pause();
+    expect(instances[0]!.disconnect).toHaveBeenCalled();
+    expect(controls!.isActive.value).toBeFalsy();
+
+    controls!.resume();
+    await nextTick();
+    expect(controls!.isActive.value).toBeTruthy();
+    expect(instances).toHaveLength(2);
+    scope.stop();
+  });
+
+  it('stop disconnects and marks inactive', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let controls: ReturnType<typeof useIntersectionObserver>;
+    scope.run(() => {
+      controls = useIntersectionObserver(ref(el), vi.fn());
+    });
+
+    controls!.stop();
+    expect(instances[0]!.disconnect).toHaveBeenCalled();
+    expect(controls!.isActive.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('invokes the callback with entries', () => {
+    const el = document.createElement('div');
+    const callback = vi.fn();
+    const scope = effectScope();
+    scope.run(() => useIntersectionObserver(ref(el), callback));
+
+    const entry = { isIntersecting: true, time: 1 } as IntersectionObserverEntry;
+    instances[0]!.cb([entry], instances[0] as unknown as IntersectionObserver);
+    expect(callback).toHaveBeenCalled();
+    scope.stop();
+  });
+
+  it('observes an array of targets', () => {
+    const a = document.createElement('div');
+    const b = document.createElement('div');
+    const scope = effectScope();
+    scope.run(() => useIntersectionObserver([ref(a), ref(b)], vi.fn()));
+
+    expect(instances).toHaveLength(1);
+    expect(instances[0]!.observe).toHaveBeenCalledWith(a);
+    expect(instances[0]!.observe).toHaveBeenCalledWith(b);
+    scope.stop();
+  });
+
+  it('tracks a reactive target ref of an array', async () => {
+    const a = document.createElement('div');
+    const b = document.createElement('div');
+    const list = ref([a]);
+    const scope = effectScope();
+    scope.run(() => useIntersectionObserver(list, vi.fn()));
+
+    expect(instances).toHaveLength(1);
+    expect(instances[0]!.observe).toHaveBeenCalledTimes(1);
+
+    list.value = [a, b];
+    await nextTick();
+
+    // recreated with both elements
+    expect(instances).toHaveLength(2);
+    expect(instances[1]!.observe).toHaveBeenCalledWith(a);
+    expect(instances[1]!.observe).toHaveBeenCalledWith(b);
+    scope.stop();
+  });
+
+  it('tracks a getter target', async () => {
+    const a = document.createElement('div');
+    const enabled = ref(false);
+    const scope = effectScope();
+    scope.run(() => useIntersectionObserver(() => (enabled.value ? a : null), vi.fn()));
+
+    // null target -> no observer
+    expect(instances).toHaveLength(0);
+
+    enabled.value = true;
+    await nextTick();
+    expect(instances).toHaveLength(1);
+    expect(instances[0]!.observe).toHaveBeenCalledWith(a);
+    scope.stop();
+  });
+
+  it('passes rootMargin and threshold to the observer', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    scope.run(() => useIntersectionObserver(ref(el), vi.fn(), { rootMargin: '10px', threshold: [0, 0.5, 1] }));
+
+    expect(instances[0]!.options?.rootMargin).toBe('10px');
+    expect(instances[0]!.options?.threshold).toEqual([0, 0.5, 1]);
+    scope.stop();
+  });
+
+  it('reacts to a reactive rootMargin', async () => {
+    const el = document.createElement('div');
+    const rootMargin = ref('0px');
+    const scope = effectScope();
+    scope.run(() => useIntersectionObserver(ref(el), vi.fn(), { rootMargin }));
+
+    expect(instances[0]!.options?.rootMargin).toBe('0px');
+
+    rootMargin.value = '20px';
+    await nextTick();
+
+    expect(instances).toHaveLength(2);
+    expect(instances[1]!.options?.rootMargin).toBe('20px');
+    scope.stop();
+  });
+
+  it('reacts to a reactive threshold', async () => {
+    const el = document.createElement('div');
+    const threshold = ref<number | number[]>(0);
+    const scope = effectScope();
+    scope.run(() => useIntersectionObserver(ref(el), vi.fn(), { threshold }));
+
+    expect(instances[0]!.options?.threshold).toBe(0);
+
+    threshold.value = 0.75;
+    await nextTick();
+
+    expect(instances).toHaveLength(2);
+    expect(instances[1]!.options?.threshold).toBe(0.75);
+    scope.stop();
+  });
+
+  it('reports unsupported and never constructs an observer', () => {
+    // jsdom has no native IntersectionObserver; remove the stub so the
+    // feature detection `'IntersectionObserver' in window` reports false.
+    vi.unstubAllGlobals();
+    delete (globalThis as Record<string, unknown>).IntersectionObserver;
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let controls: ReturnType<typeof useIntersectionObserver>;
+    scope.run(() => {
+      controls = useIntersectionObserver(ref(el), vi.fn());
+    });
+
+    expect(controls!.isSupported.value).toBeFalsy();
+    // stop should be a safe no-op
+    expect(() => controls!.stop()).not.toThrow();
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useIntersectionObserver/index.ts

@@ -0,0 +1,150 @@
+import { computed, readonly, ref, toValue, watch } from 'vue';
+import type { MaybeRefOrGetter, Ref } from 'vue';
+import { noop, toArray } from '@robonen/stdlib';
+import type { ConfigurableWindow } from '@/types';
+import { defaultWindow } from '@/types';
+import type { MaybeComputedElementRef, MaybeElement } from '@/composables/component/unrefElement';
+import { unrefElement } from '@/composables/component/unrefElement';
+import { useSupported } from '@/composables/browser/useSupported';
+import { tryOnScopeDispose } from '@/composables/lifecycle/tryOnScopeDispose';
+
+export interface UseIntersectionObserverOptions extends ConfigurableWindow {
+  /**
+   * The element or document used as the viewport for checking visibility
+   */
+  root?: MaybeComputedElementRef | Document;
+
+  /**
+   * Margin around the root. Reactive — pass a ref or getter to update it.
+   *
+   * @default '0px'
+   */
+  rootMargin?: MaybeRefOrGetter<string>;
+
+  /**
+   * Threshold(s) at which to trigger the callback. Reactive — pass a ref or
+   * getter to update it.
+   *
+   * @default 0
+   */
+  threshold?: MaybeRefOrGetter<number | number[]>;
+
+  /**
+   * Start observing immediately
+   *
+   * @default true
+   */
+  immediate?: boolean;
+}
+
+export interface UseIntersectionObserverReturn {
+  isSupported: Readonly<Ref<boolean>>;
+  isActive: Readonly<Ref<boolean>>;
+  pause: () => void;
+  resume: () => void;
+  stop: () => void;
+}
+
+/**
+ * @name useIntersectionObserver
+ * @category Browser
+ * @description Detect when an element enters or leaves the viewport via
+ * `IntersectionObserver`. Accepts a single target, an array of targets, or a
+ * ref/getter resolving to either, plus reactive `rootMargin` and `threshold`.
+ *
+ * @param {MaybeComputedElementRef | MaybeComputedElementRef[] | MaybeRefOrGetter<MaybeElement[]>} target Element(s) to observe
+ * @param {IntersectionObserverCallback} callback Invoked with the observer entries
+ * @param {UseIntersectionObserverOptions} [options={}] Options
+ * @returns {UseIntersectionObserverReturn} Observer controls
+ *
+ * @example
+ * useIntersectionObserver(el, ([{ isIntersecting }]) => {
+ *   visible.value = isIntersecting;
+ * });
+ *
+ * @since 0.0.15
+ */
+export function useIntersectionObserver(
+  target: MaybeComputedElementRef | MaybeComputedElementRef[] | MaybeRefOrGetter<MaybeElement[]>,
+  callback: IntersectionObserverCallback,
+  options: UseIntersectionObserverOptions = {},
+): UseIntersectionObserverReturn {
+  const {
+    root,
+    rootMargin = '0px',
+    threshold = 0,
+    window = defaultWindow,
+    immediate = true,
+  } = options;
+
+  const isSupported = useSupported(() => window && 'IntersectionObserver' in window);
+
+  const targets = computed(() => {
+    const value = toValue(target) as MaybeElement | MaybeElement[];
+    return toArray(value as MaybeElement)
+      .map(el => unrefElement(el))
+      .filter((el): el is Element => Boolean(el));
+  });
+
+  const isActive = ref(immediate);
+
+  let cleanup = noop;
+
+  const stopWatch = isSupported.value
+    ? watch(
+        () => [
+          targets.value,
+          unrefElement(root as MaybeComputedElementRef),
+          toValue(rootMargin),
+          toValue(threshold),
+          isActive.value,
+        ] as const,
+        ([els, rootEl, margin, thresh, active]) => {
+          cleanup();
+
+          if (!active || !els.length)
+            return;
+
+          const observer = new IntersectionObserver(callback, {
+            root: (rootEl as Element | null) ?? (root as Document | undefined),
+            rootMargin: margin,
+            threshold: thresh,
+          });
+
+          for (const el of els)
+            observer.observe(el);
+
+          cleanup = () => {
+            observer.disconnect();
+            cleanup = noop;
+          };
+        },
+        { immediate: true, flush: 'post' },
+      )
+    : noop;
+
+  const resume = (): void => {
+    isActive.value = true;
+  };
+
+  const pause = (): void => {
+    cleanup();
+    isActive.value = false;
+  };
+
+  const stop = (): void => {
+    cleanup();
+    stopWatch();
+    isActive.value = false;
+  };
+
+  tryOnScopeDispose(stop);
+
+  return {
+    isSupported,
+    isActive: readonly(isActive),
+    pause,
+    resume,
+    stop,
+  };
+}

vue/toolkit/src/composables/browser/useIntervalFn/index.test.ts

@@ -1,4 +1,4 @@
-import { describe, expect, it, vi, beforeEach, afterEach } from 'vitest';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 import { defineComponent, effectScope, nextTick, ref } from 'vue';
 import { mount } from '@vue/test-utils';
 import { useIntervalFn } from '.';

vue/toolkit/src/composables/browser/useKeyModifier/index.test.ts

@@ -0,0 +1,174 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick } from 'vue';
+import { useKeyModifier } from '.';
+import type { KeyModifier } from '.';
+
+afterEach(() => {
+  vi.unstubAllGlobals();
+});
+
+/**
+ * Dispatch an event on `document` whose `getModifierState(modifier)` resolves to `active`.
+ * jsdom does not track real modifier state, so we stub the method per event.
+ */
+function dispatchModifier(
+  type: string,
+  active: boolean,
+  modifier: KeyModifier = 'Shift',
+  withGetModifierState = true,
+) {
+  const event = new Event(type) as Event & {
+    getModifierState?: (key: string) => boolean;
+  };
+
+  if (withGetModifierState) {
+    event.getModifierState = (key: string) => (key === modifier ? active : false);
+  }
+
+  document.dispatchEvent(event);
+}
+
+describe(useKeyModifier, () => {
+  it('defaults to null until the first matching event', () => {
+    const scope = effectScope();
+    let state: ReturnType<typeof useKeyModifier>;
+    scope.run(() => {
+      state = useKeyModifier('Shift');
+    });
+
+    expect(state!.value).toBeNull();
+    scope.stop();
+  });
+
+  it('respects a provided initial value', () => {
+    const scope = effectScope();
+    let state: ReturnType<typeof useKeyModifier<boolean>>;
+    scope.run(() => {
+      state = useKeyModifier('Shift', { initial: false });
+    });
+
+    expect(state!.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('updates when a default event reports the modifier active', async () => {
+    const scope = effectScope();
+    let state: ReturnType<typeof useKeyModifier>;
+    scope.run(() => {
+      state = useKeyModifier('Shift');
+    });
+
+    dispatchModifier('keydown', true, 'Shift');
+    await nextTick();
+    expect(state!.value).toBeTruthy();
+
+    dispatchModifier('keyup', false, 'Shift');
+    await nextTick();
+    expect(state!.value).toBeFalsy();
+
+    scope.stop();
+  });
+
+  it('tracks each modifier independently', async () => {
+    const scope = effectScope();
+    let caps: ReturnType<typeof useKeyModifier>;
+    scope.run(() => {
+      caps = useKeyModifier('CapsLock');
+    });
+
+    dispatchModifier('keydown', true, 'CapsLock');
+    await nextTick();
+    expect(caps!.value).toBeTruthy();
+
+    // An event reporting a different modifier (Shift) must not flip CapsLock
+    dispatchModifier('keydown', true, 'Shift');
+    await nextTick();
+    expect(caps!.value).toBeFalsy();
+
+    scope.stop();
+  });
+
+  it('only listens on the configured events', async () => {
+    const scope = effectScope();
+    let state: ReturnType<typeof useKeyModifier>;
+    scope.run(() => {
+      state = useKeyModifier('Shift', { events: ['keydown'] });
+    });
+
+    dispatchModifier('keyup', true, 'Shift');
+    await nextTick();
+    expect(state!.value).toBeNull();
+
+    dispatchModifier('keydown', true, 'Shift');
+    await nextTick();
+    expect(state!.value).toBeTruthy();
+
+    scope.stop();
+  });
+
+  it('ignores events without getModifierState', async () => {
+    const scope = effectScope();
+    let state: ReturnType<typeof useKeyModifier>;
+    scope.run(() => {
+      state = useKeyModifier('Shift', { initial: false });
+    });
+
+    dispatchModifier('keydown', true, 'Shift', false);
+    await nextTick();
+    expect(state!.value).toBeFalsy();
+
+    scope.stop();
+  });
+
+  it('removes its listeners when the scope is disposed', async () => {
+    const scope = effectScope();
+    let state: ReturnType<typeof useKeyModifier>;
+    scope.run(() => {
+      state = useKeyModifier('Shift');
+    });
+
+    scope.stop();
+
+    dispatchModifier('keydown', true, 'Shift');
+    await nextTick();
+    expect(state!.value).toBeNull();
+  });
+
+  it('accepts a custom document and listens on it', async () => {
+    const listeners = new Map<string, Set<EventListener>>();
+    const fakeDocument = {
+      addEventListener(type: string, listener: EventListener) {
+        if (!listeners.has(type))
+          listeners.set(type, new Set());
+        listeners.get(type)!.add(listener);
+      },
+      removeEventListener(type: string, listener: EventListener) {
+        listeners.get(type)?.delete(listener);
+      },
+    } as unknown as Document;
+
+    const scope = effectScope();
+    let state: ReturnType<typeof useKeyModifier>;
+    scope.run(() => {
+      state = useKeyModifier('Meta', { document: fakeDocument });
+    });
+
+    const event = { getModifierState: (k: string) => k === 'Meta' } as unknown as KeyboardEvent;
+    listeners.get('keydown')!.forEach(fn => fn(event));
+    await nextTick();
+    expect(state!.value).toBeTruthy();
+
+    scope.stop();
+  });
+
+  it('is a no-op under SSR (no document)', () => {
+    const scope = effectScope();
+    let state: ReturnType<typeof useKeyModifier>;
+    scope.run(() => {
+      state = useKeyModifier('Shift', { document: undefined, initial: false });
+    });
+
+    expect(state!.value).toBeFalsy();
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useKeyModifier/index.ts

@@ -0,0 +1,83 @@
+import { shallowRef } from 'vue';
+import type { ShallowRef } from 'vue';
+import { isFunction } from '@robonen/stdlib';
+import { defaultDocument } from '@/types';
+import type { ConfigurableDocument } from '@/types';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import type { DocumentEventName } from '@/composables/browser/useEventListener';
+
+export type KeyModifier
+  = | 'Alt'
+    | 'AltGraph'
+    | 'CapsLock'
+    | 'Control'
+    | 'Fn'
+    | 'FnLock'
+    | 'Meta'
+    | 'NumLock'
+    | 'ScrollLock'
+    | 'Shift'
+    | 'Symbol'
+    | 'SymbolLock';
+
+const DEFAULT_EVENTS: DocumentEventName[] = ['mousedown', 'mouseup', 'keydown', 'keyup'];
+
+export interface UseKeyModifierOptions<Initial> extends ConfigurableDocument {
+  /**
+   * Event names that will prompt an update to the modifier state.
+   *
+   * @default ['mousedown', 'mouseup', 'keydown', 'keyup']
+   */
+  events?: DocumentEventName[];
+
+  /**
+   * Initial value of the returned ref.
+   *
+   * @default null
+   */
+  initial?: Initial;
+}
+
+export type UseKeyModifierReturn<Initial> = ShallowRef<Initial extends boolean ? boolean : boolean | null>;
+
+/**
+ * @name useKeyModifier
+ * @category Browser
+ * @description Reactive state of a keyboard modifier (CapsLock, NumLock, Shift, Control, Alt, Meta, ...) tracked via `KeyboardEvent.getModifierState`.
+ *
+ * @param {KeyModifier} modifier The modifier key to observe
+ * @param {UseKeyModifierOptions} [options={}] Options (`events` to listen on, `initial` value, custom `document`)
+ * @returns {UseKeyModifierReturn} A shallow ref holding the current modifier state (`null` until the first matching event)
+ *
+ * @example
+ * const capsLock = useKeyModifier('CapsLock');
+ * watch(capsLock, (on) => {
+ *   if (on) showCapsLockWarning();
+ * });
+ *
+ * @example
+ * const shift = useKeyModifier('Shift', { initial: false, events: ['keydown', 'keyup'] });
+ *
+ * @since 0.0.15
+ */
+export function useKeyModifier<Initial extends boolean | null = null>(
+  modifier: KeyModifier,
+  options: UseKeyModifierOptions<Initial> = {},
+): UseKeyModifierReturn<Initial> {
+  const {
+    events = DEFAULT_EVENTS,
+    document = defaultDocument,
+    initial = null,
+  } = options;
+
+  const state = shallowRef(initial) as ShallowRef<boolean | null>;
+
+  if (document) {
+    useEventListener(document, events, (event: KeyboardEvent | MouseEvent) => {
+      if (isFunction(event.getModifierState))
+        state.value = event.getModifierState(modifier);
+    }, { passive: true });
+  }
+
+  return state as UseKeyModifierReturn<Initial>;
+}

vue/toolkit/src/composables/browser/useMagicKeys/index.test.ts

@@ -0,0 +1,305 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick, toValue, watch } from 'vue';
+import { DefaultMagicKeysAliasMap, useMagicKeys } from '.';
+
+function keydown(key: string, init: KeyboardEventInit = {}, target: EventTarget = globalThis) {
+  target.dispatchEvent(new KeyboardEvent('keydown', { key, ...init }));
+}
+
+function keyup(key: string, init: KeyboardEventInit = {}, target: EventTarget = globalThis) {
+  target.dispatchEvent(new KeyboardEvent('keyup', { key, ...init }));
+}
+
+describe(useMagicKeys, () => {
+  afterEach(() => {
+    vi.unstubAllGlobals();
+  });
+
+  it('tracks a single pressed key', () => {
+    const scope = effectScope();
+
+    scope.run(() => {
+      const keys = useMagicKeys();
+
+      expect(keys.a!.value).toBeFalsy();
+
+      keydown('a');
+      expect(keys.a!.value).toBeTruthy();
+
+      keyup('a');
+      expect(keys.a!.value).toBeFalsy();
+    });
+
+    scope.stop();
+  });
+
+  it('exposes the current Set of pressed keys', () => {
+    const scope = effectScope();
+
+    scope.run(() => {
+      const keys = useMagicKeys();
+
+      keydown('a');
+      keydown('b');
+
+      expect([...keys.current]).toEqual(['a', 'b']);
+
+      keyup('a');
+      expect([...keys.current]).toEqual(['b']);
+    });
+
+    scope.stop();
+  });
+
+  it('supports combinations via proxy property (ctrl+a)', () => {
+    const scope = effectScope();
+
+    scope.run(() => {
+      const keys = useMagicKeys();
+      const ctrlA = keys['ctrl+a']!;
+
+      expect(ctrlA.value).toBeFalsy();
+
+      keydown('Control');
+      expect(ctrlA.value).toBeFalsy();
+
+      keydown('a');
+      expect(ctrlA.value).toBeTruthy();
+
+      keyup('a');
+      expect(ctrlA.value).toBeFalsy();
+    });
+
+    scope.stop();
+  });
+
+  it('supports combos with _ and - delimiters', () => {
+    const scope = effectScope();
+
+    scope.run(() => {
+      const keys = useMagicKeys();
+      const underscore = keys.ctrl_a!;
+      const dash = keys['ctrl-a']!;
+
+      keydown('Control');
+      keydown('a');
+
+      expect(underscore.value).toBeTruthy();
+      expect(dash.value).toBeTruthy();
+    });
+
+    scope.stop();
+  });
+
+  it('resolves aliases (cmd -> meta, esc -> escape)', () => {
+    const scope = effectScope();
+
+    scope.run(() => {
+      const keys = useMagicKeys();
+
+      keydown('Meta');
+      expect(keys.cmd!.value).toBeTruthy();
+      expect(keys.command!.value).toBeTruthy();
+      expect(keys.meta!.value).toBeTruthy();
+
+      keyup('Meta');
+
+      keydown('Escape');
+      expect(keys.esc!.value).toBeTruthy();
+    });
+
+    scope.stop();
+  });
+
+  it('respects a custom aliasMap', () => {
+    const scope = effectScope();
+
+    scope.run(() => {
+      const keys = useMagicKeys({ aliasMap: { fire: 'f' } });
+
+      keydown('f');
+      expect(keys.fire!.value).toBeTruthy();
+    });
+
+    scope.stop();
+  });
+
+  it('is case-insensitive on property access', () => {
+    const scope = effectScope();
+
+    scope.run(() => {
+      const keys = useMagicKeys();
+
+      keydown('a');
+      expect(keys.A!.value).toBeTruthy();
+    });
+
+    scope.stop();
+  });
+
+  it('tracks event.code as well as key', () => {
+    const scope = effectScope();
+
+    scope.run(() => {
+      const keys = useMagicKeys();
+
+      keydown('a', { code: 'KeyA' });
+      expect((keys as any).keya.value).toBeTruthy();
+
+      keyup('a', { code: 'KeyA' });
+      expect((keys as any).keya.value).toBeFalsy();
+    });
+
+    scope.stop();
+  });
+
+  it('reactive mode returns plain booleans', () => {
+    const scope = effectScope();
+
+    scope.run(() => {
+      const keys = useMagicKeys({ reactive: true });
+
+      expect(keys.a).toBeFalsy();
+
+      keydown('a');
+      expect(keys.a).toBeTruthy();
+    });
+
+    scope.stop();
+  });
+
+  it('reset() clears the current Set and all refs', () => {
+    const scope = effectScope();
+
+    scope.run(() => {
+      const keys = useMagicKeys();
+
+      keydown('a');
+      keydown('b');
+      expect(keys.a!.value).toBeTruthy();
+
+      keys.reset();
+
+      expect(keys.a!.value).toBeFalsy();
+      expect(keys.b!.value).toBeFalsy();
+      expect(keys.current.size).toBe(0);
+    });
+
+    scope.stop();
+  });
+
+  it('resets on blur so keys do not stick', () => {
+    const scope = effectScope();
+
+    scope.run(() => {
+      const keys = useMagicKeys();
+
+      keydown('a');
+      expect(keys.a!.value).toBeTruthy();
+
+      globalThis.dispatchEvent(new Event('blur'));
+      expect(keys.a!.value).toBeFalsy();
+      expect(keys.current.size).toBe(0);
+    });
+
+    scope.stop();
+  });
+
+  it('clears meta-dependent keys when Meta is released (macOS behaviour)', () => {
+    const scope = effectScope();
+
+    scope.run(() => {
+      const keys = useMagicKeys();
+
+      // Press Cmd, then 'a' while Cmd held (getModifierState reports Meta)
+      keydown('Meta');
+      keydown('a', { metaKey: true });
+
+      expect(keys.a!.value).toBeTruthy();
+      expect(keys.current.has('a')).toBeTruthy();
+
+      // Releasing Meta should drop 'a' too (no keyup fires for it on macOS)
+      keyup('Meta');
+
+      expect(keys.meta!.value).toBeFalsy();
+      expect(keys.a!.value).toBeFalsy();
+      expect(keys.current.has('a')).toBeFalsy();
+    });
+
+    scope.stop();
+  });
+
+  it('invokes onEventFired for keydown and keyup', () => {
+    const scope = effectScope();
+
+    scope.run(() => {
+      const onEventFired = vi.fn();
+      useMagicKeys({ onEventFired });
+
+      keydown('a');
+      keyup('a');
+
+      expect(onEventFired).toHaveBeenCalledTimes(2);
+      expect(onEventFired.mock.calls[0]![0]).toBeInstanceOf(KeyboardEvent);
+    });
+
+    scope.stop();
+  });
+
+  it('attaches to a custom target', () => {
+    const scope = effectScope();
+
+    scope.run(() => {
+      const el = document.createElement('div');
+      const keys = useMagicKeys({ target: el });
+
+      keydown('a', {}, el);
+      expect(keys.a!.value).toBeTruthy();
+
+      // window events should not affect a custom target
+      keyup('a', {}, el);
+      keydown('b');
+      expect(keys.b!.value).toBeFalsy();
+    });
+
+    scope.stop();
+  });
+
+  it('combination refs are reactive (computed)', async () => {
+    const scope = effectScope();
+
+    await scope.run(async () => {
+      const keys = useMagicKeys();
+      const combo = keys['shift+a']!;
+
+      const seen: boolean[] = [];
+      watch(combo, v => seen.push(v));
+
+      keydown('Shift');
+      keydown('a');
+      await nextTick();
+
+      expect(toValue(combo)).toBeTruthy();
+      expect(seen).toContain(true);
+    });
+
+    scope.stop();
+  });
+
+  it('exposes DefaultMagicKeysAliasMap with expected aliases', () => {
+    expect(DefaultMagicKeysAliasMap.ctrl).toBe('control');
+    expect(DefaultMagicKeysAliasMap.cmd).toBe('meta');
+    expect(DefaultMagicKeysAliasMap.command).toBe('meta');
+    expect(DefaultMagicKeysAliasMap.option).toBe('alt');
+    expect(DefaultMagicKeysAliasMap.up).toBe('arrowup');
+  });
+
+  it('does not throw and returns an object when window is absent (SSR path)', () => {
+    // No target available -> listeners are skipped, refs still usable
+    const keys = useMagicKeys({ target: undefined as unknown as EventTarget });
+
+    expect(keys.current.size).toBe(0);
+    // accessing a key lazily creates a ref defaulting to false
+    expect(keys.a!.value).toBeFalsy();
+  });
+});

vue/toolkit/src/composables/browser/useMagicKeys/index.ts

@@ -0,0 +1,227 @@
+import type { AnyFunction } from '@robonen/stdlib';
+import { isFunction, noop } from '@robonen/stdlib';
+import type { ComputedRef, Ref, ShallowRef } from 'vue';
+import { computed, reactive, shallowRef, toValue } from 'vue';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { defaultWindow } from '@/types';
+
+export type UseMagicKeysAliasMap = Readonly<Record<string, string>>;
+
+/**
+ * Default lowercase alias map: maps common shorthand key names to their
+ * canonical `KeyboardEvent.key` (lowercased) equivalents.
+ */
+export const DefaultMagicKeysAliasMap: UseMagicKeysAliasMap = /* #__PURE__ */ {
+  ctrl: 'control',
+  command: 'meta',
+  cmd: 'meta',
+  option: 'alt',
+  opt: 'alt',
+  up: 'arrowup',
+  down: 'arrowdown',
+  left: 'arrowleft',
+  right: 'arrowright',
+  esc: 'escape',
+  space: ' ',
+};
+
+export interface UseMagicKeysOptions<Reactive extends boolean> {
+  /**
+   * Return a reactive object instead of an object of refs
+   *
+   * @default false
+   */
+  reactive?: Reactive;
+
+  /**
+   * Event target to attach the keyboard listeners to
+   *
+   * @default window
+   */
+  target?: EventTarget;
+
+  /**
+   * Alias map for keys, all keys should be lowercase
+   * { foo: 'bar' } means that pressing `bar` will also trigger `foo`
+   *
+   * @default DefaultMagicKeysAliasMap
+   */
+  aliasMap?: UseMagicKeysAliasMap;
+
+  /**
+   * Register passive listeners
+   *
+   * @default true
+   */
+  passive?: boolean;
+
+  /**
+   * Custom event handler for the keyboard event. Useful for preventing default
+   * behaviour for certain key combos. Called on every keydown and keyup.
+   */
+  onEventFired?: (event: KeyboardEvent) => void | boolean;
+}
+
+export interface UseMagicKeysReturn {
+  /**
+   * A Set of currently pressed keys (lowercase canonical names)
+   */
+  current: Set<string>;
+
+  /**
+   * Reset all tracked keys to `false` and clear the current Set
+   */
+  reset: () => void;
+}
+
+export type MagicKeys<Reactive extends boolean> = Readonly<
+  Omit<
+    Record<string, Reactive extends true ? boolean : ComputedRef<boolean>>,
+    keyof UseMagicKeysReturn
+  >
+  & UseMagicKeysReturn
+>;
+
+type KeyRefs = Record<string, Ref<boolean> | ShallowRef<boolean> | ComputedRef<boolean>>;
+
+/**
+ * @name useMagicKeys
+ * @category Browser
+ * @description Reactive keys pressed state, with magical combination keys support via a Proxy.
+ * Access combinations directly as properties, e.g. `keys['ctrl+a']` or `keys.ctrl_a`.
+ *
+ * @param {UseMagicKeysOptions} [options] Configuration options
+ * @returns {MagicKeys} A Proxy of refs (or reactive booleans) plus `current` Set and `reset`
+ *
+ * @example
+ * const keys = useMagicKeys();
+ * const ctrlA = keys['ctrl+a'];
+ * watch(ctrlA, v => { if (v) console.log('Ctrl + A pressed'); });
+ *
+ * @example
+ * const { ctrl, a, current } = useMagicKeys({ reactive: true });
+ *
+ * @since 0.0.15
+ */
+export function useMagicKeys(options?: UseMagicKeysOptions<false>): MagicKeys<false>;
+export function useMagicKeys(options: UseMagicKeysOptions<true>): MagicKeys<true>;
+export function useMagicKeys(options: UseMagicKeysOptions<boolean> = {}): any {
+  const {
+    reactive: useReactive = false,
+    target = defaultWindow,
+    aliasMap = DefaultMagicKeysAliasMap,
+    passive = true,
+    onEventFired = noop as AnyFunction,
+  } = options;
+
+  const current = reactive(new Set<string>());
+  const usedKeys = new Set<string>();
+  // Keys pressed while Meta is held — on macOS, keyup is suppressed for other
+  // keys while Cmd is down, so we clear them when Meta is released.
+  const metaDeps = new Set<string>();
+
+  function reset(): void {
+    current.clear();
+
+    for (const key of usedKeys)
+      setRefs(key, false);
+  }
+
+  const obj: UseMagicKeysReturn = {
+    current,
+    reset,
+  };
+
+  const refs: KeyRefs = useReactive ? reactive(obj as any) : (obj as any);
+
+  function setRefs(key: string, value: boolean): void {
+    // Touch the proxy so the ref is materialized for keys we actually track,
+    // even if the consumer hasn't accessed them yet.
+    if (!(key in refs))
+      void (proxy as any)[key];
+
+    if (key in refs) {
+      if (useReactive)
+        (refs as any)[key] = value;
+      else
+        (refs[key] as Ref<boolean>).value = value;
+    }
+  }
+
+  function updateRefs(event: KeyboardEvent, value: boolean): void {
+    const key = event.key?.toLowerCase();
+    const code = event.code?.toLowerCase();
+    const values = [code, key].filter(Boolean) as string[];
+
+    if (!key)
+      return;
+
+    if (value)
+      current.add(key);
+    else
+      current.delete(key);
+
+    for (const k of values) {
+      usedKeys.add(k);
+      setRefs(k, value);
+    }
+
+    if (key === 'meta' && !value) {
+      // Cmd released on macOS: clear keys that were pressed during the chord
+      metaDeps.forEach((k) => {
+        current.delete(k);
+        setRefs(k, false);
+      });
+
+      metaDeps.clear();
+    }
+    else if (isFunction(event.getModifierState) && event.getModifierState('Meta') && value) {
+      [...current, ...values].forEach(k => metaDeps.add(k));
+    }
+  }
+
+  if (target) {
+    useEventListener(target, 'keydown', (event: KeyboardEvent) => {
+      updateRefs(event, true);
+      return onEventFired(event);
+    }, { passive });
+
+    useEventListener(target, 'keyup', (event: KeyboardEvent) => {
+      updateRefs(event, false);
+      return onEventFired(event);
+    }, { passive });
+
+    // Reset on blur so keys don't "stick" when focus leaves the page
+    useEventListener('blur', reset, { passive: true });
+    useEventListener('focus', reset, { passive: true });
+  }
+
+  const proxy = new Proxy(refs, {
+    get(target, prop, receiver) {
+      if (typeof prop !== 'string')
+        return Reflect.get(target, prop, receiver);
+
+      prop = prop.toLowerCase();
+
+      // alias resolution
+      if (prop in aliasMap)
+        prop = aliasMap[prop] as string;
+
+      // lazily create tracking ref for combos and single keys
+      if (!(prop in refs)) {
+        if (/[+_-]/.test(prop)) {
+          const keys = prop.split(/[+_-]/g).map((i: string) => i.trim());
+          refs[prop] = computed(() => keys.map(key => toValue((proxy as any)[key])).every(Boolean));
+        }
+        else {
+          refs[prop] = shallowRef(false);
+        }
+      }
+
+      const r = Reflect.get(target, prop, receiver);
+      return useReactive ? toValue(r) : r;
+    },
+  });
+
+  return proxy as any;
+}

vue/toolkit/src/composables/browser/useMediaQuery/index.test.ts

@@ -0,0 +1,251 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { defineComponent, effectScope, isReadonly, nextTick, ref } from 'vue';
+import { mount } from '@vue/test-utils';
+import { useMediaQuery } from '.';
+
+type Listener = (event: { matches: boolean }) => void;
+
+interface StubMql {
+  readonly matches: boolean;
+  media: string;
+  addEventListener: (type: string, cb: Listener) => void;
+  removeEventListener: (type: string, cb: Listener) => void;
+  dispatch: (value: boolean) => void;
+}
+
+function makeMql(initialMatches: boolean, media = ''): StubMql {
+  const listeners = new Set<Listener>();
+  let matches = initialMatches;
+
+  return {
+    get matches() {
+      return matches;
+    },
+    media,
+    addEventListener: (_: string, cb: Listener) => listeners.add(cb),
+    removeEventListener: (_: string, cb: Listener) => listeners.delete(cb),
+    dispatch(value: boolean) {
+      matches = value;
+      for (const cb of listeners) cb({ matches: value });
+    },
+  };
+}
+
+function stubMatchMedia(initialMatches: boolean) {
+  const mql = makeMql(initialMatches);
+  vi.stubGlobal('matchMedia', vi.fn(() => mql));
+  return mql;
+}
+
+/** Returns a different MediaQueryList per query string, so reactive query swaps can be exercised. */
+function stubMatchMediaByQuery(map: Record<string, StubMql>, fallbackMatches = false) {
+  const spy = vi.fn((query: string) => map[query] ?? makeMql(fallbackMatches, query));
+  vi.stubGlobal('matchMedia', spy);
+  return spy;
+}
+
+describe(useMediaQuery, () => {
+  beforeEach(() => {
+    vi.stubGlobal('matchMedia', undefined);
+  });
+  afterEach(() => vi.unstubAllGlobals());
+
+  it('reflects the initial match', async () => {
+    stubMatchMedia(true);
+    const scope = effectScope();
+    let matches: ReturnType<typeof useMediaQuery>;
+    scope.run(() => {
+      matches = useMediaQuery('(min-width: 100px)');
+    });
+    await nextTick();
+    expect(matches!.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('updates when the media query changes', async () => {
+    const mql = stubMatchMedia(false);
+    const scope = effectScope();
+    let matches: ReturnType<typeof useMediaQuery>;
+    scope.run(() => {
+      matches = useMediaQuery('(min-width: 100px)');
+    });
+    await nextTick();
+
+    expect(matches!.value).toBeFalsy();
+    mql.dispatch(true);
+    expect(matches!.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('returns false when matchMedia is unsupported (SSR)', async () => {
+    const scope = effectScope();
+    let matches: ReturnType<typeof useMediaQuery>;
+    scope.run(() => {
+      matches = useMediaQuery('(min-width: 100px)');
+    });
+    await nextTick();
+    expect(matches!.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('returns a readonly ref', async () => {
+    stubMatchMedia(true);
+    const scope = effectScope();
+    let matches: ReturnType<typeof useMediaQuery>;
+    scope.run(() => {
+      matches = useMediaQuery('(min-width: 100px)');
+    });
+    await nextTick();
+    expect(isReadonly(matches!)).toBeTruthy();
+    scope.stop();
+  });
+
+  it('reacts to a changing query ref by re-binding to the new MediaQueryList', async () => {
+    const small = makeMql(false, '(min-width: 100px)');
+    const large = makeMql(true, '(min-width: 1000px)');
+    stubMatchMediaByQuery({
+      '(min-width: 100px)': small,
+      '(min-width: 1000px)': large,
+    });
+
+    const scope = effectScope();
+    const query = ref('(min-width: 100px)');
+    let matches: ReturnType<typeof useMediaQuery>;
+    scope.run(() => {
+      matches = useMediaQuery(query);
+    });
+    await nextTick();
+    expect(matches!.value).toBeFalsy();
+
+    query.value = '(min-width: 1000px)';
+    await nextTick();
+    expect(matches!.value).toBeTruthy();
+
+    // The listener should follow the new MediaQueryList, not the old one.
+    large.dispatch(false);
+    expect(matches!.value).toBeFalsy();
+    // The old MediaQueryList should no longer affect the result.
+    small.dispatch(true);
+    expect(matches!.value).toBeFalsy();
+
+    scope.stop();
+  });
+
+  it('also accepts a getter for the query', async () => {
+    stubMatchMedia(true);
+    const scope = effectScope();
+    let matches: ReturnType<typeof useMediaQuery>;
+    scope.run(() => {
+      matches = useMediaQuery(() => '(min-width: 100px)');
+    });
+    await nextTick();
+    expect(matches!.value).toBeTruthy();
+    scope.stop();
+  });
+
+  describe('ssrWidth', () => {
+    it('resolves min-width against ssrWidth when matchMedia is unsupported', async () => {
+      const scope = effectScope();
+      let wide: ReturnType<typeof useMediaQuery>;
+      let narrow: ReturnType<typeof useMediaQuery>;
+      scope.run(() => {
+        wide = useMediaQuery('(min-width: 1024px)', { ssrWidth: 1280 });
+        narrow = useMediaQuery('(min-width: 1024px)', { ssrWidth: 800 });
+      });
+      await nextTick();
+      expect(wide!.value).toBeTruthy();
+      expect(narrow!.value).toBeFalsy();
+      scope.stop();
+    });
+
+    it('resolves max-width against ssrWidth', async () => {
+      const scope = effectScope();
+      let matches: ReturnType<typeof useMediaQuery>;
+      scope.run(() => {
+        matches = useMediaQuery('(max-width: 768px)', { ssrWidth: 500 });
+      });
+      await nextTick();
+      expect(matches!.value).toBeTruthy();
+      scope.stop();
+    });
+
+    it('handles a min-width/max-width range', async () => {
+      const scope = effectScope();
+      let inRange: ReturnType<typeof useMediaQuery>;
+      let outOfRange: ReturnType<typeof useMediaQuery>;
+      scope.run(() => {
+        inRange = useMediaQuery('(min-width: 600px) and (max-width: 1200px)', { ssrWidth: 900 });
+        outOfRange = useMediaQuery('(min-width: 600px) and (max-width: 1200px)', { ssrWidth: 1500 });
+      });
+      await nextTick();
+      expect(inRange!.value).toBeTruthy();
+      expect(outOfRange!.value).toBeFalsy();
+      scope.stop();
+    });
+
+    it('respects `not all` negation', async () => {
+      const scope = effectScope();
+      let matches: ReturnType<typeof useMediaQuery>;
+      scope.run(() => {
+        matches = useMediaQuery('not all and (min-width: 1024px)', { ssrWidth: 1280 });
+      });
+      await nextTick();
+      expect(matches!.value).toBeFalsy();
+      scope.stop();
+    });
+
+    it('OR-combines comma-separated queries', async () => {
+      const scope = effectScope();
+      let matches: ReturnType<typeof useMediaQuery>;
+      scope.run(() => {
+        matches = useMediaQuery('(min-width: 2000px), (max-width: 900px)', { ssrWidth: 800 });
+      });
+      await nextTick();
+      expect(matches!.value).toBeTruthy();
+      scope.stop();
+    });
+
+    it('converts em/rem units using a 16px root', async () => {
+      const scope = effectScope();
+      let matches: ReturnType<typeof useMediaQuery>;
+      // 48em === 768px; ssrWidth 800 >= 768 → matches
+      scope.run(() => {
+        matches = useMediaQuery('(min-width: 48em)', { ssrWidth: 800 });
+      });
+      await nextTick();
+      expect(matches!.value).toBeTruthy();
+      scope.stop();
+    });
+
+    it('prefers the real matchMedia over ssrWidth once mounted', async () => {
+      // matchMedia reports false even though ssrWidth would resolve true.
+      stubMatchMedia(false);
+      let matches: ReturnType<typeof useMediaQuery>;
+      const wrapper = mount(defineComponent({
+        setup() {
+          matches = useMediaQuery('(min-width: 1024px)', { ssrWidth: 1280 });
+          return () => null;
+        },
+      }));
+      await nextTick();
+      // After mount, isSupported becomes true and the real (false) result wins.
+      expect(matches!.value).toBeFalsy();
+      wrapper.unmount();
+    });
+
+    it('uses ssrWidth on the first render before mount, then re-evaluates', async () => {
+      // Real matchMedia is available, but the very first synchronous effect
+      // run (pre-mount) should still resolve via ssrWidth to avoid flicker.
+      stubMatchMedia(false);
+      let matches: ReturnType<typeof useMediaQuery>;
+      const scope = effectScope();
+      // Without a mounted component, isSupported stays false, so ssrWidth wins.
+      scope.run(() => {
+        matches = useMediaQuery('(min-width: 1024px)', { ssrWidth: 1280 });
+      });
+      await nextTick();
+      expect(matches!.value).toBeTruthy();
+      scope.stop();
+    });
+  });
+});

vue/toolkit/src/composables/browser/useMediaQuery/index.ts

@@ -0,0 +1,120 @@
+import { computed, shallowRef, toValue, watchEffect } from 'vue';
+import type { ComputedRef, MaybeRefOrGetter } from 'vue';
+import { isFunction, isNumber } from '@robonen/stdlib';
+import { defaultWindow } from '@/types';
+import type { ConfigurableWindow } from '@/types';
+import { useSupported } from '@/composables/browser/useSupported';
+import { useEventListener } from '@/composables/browser/useEventListener';
+
+export interface UseMediaQueryOptions extends ConfigurableWindow {
+  /**
+   * The viewport width (in pixels) assumed during SSR, used to resolve
+   * `min-width` / `max-width` queries before `window.matchMedia` is available.
+   *
+   * When provided, the composable returns a best-effort match on the server
+   * (and the first client render) instead of always `false`, avoiding hydration
+   * flicker for width-based queries. Ignored once `matchMedia` is supported.
+   *
+   * @default undefined
+   */
+  ssrWidth?: number;
+}
+
+/**
+ * Convert a CSS length token (e.g. `"1024px"`, `"48em"`, `"30rem"`) to pixels.
+ * Falls back to treating `em`/`rem` as the conventional 16px root size.
+ */
+function pxValue(value: string): number {
+  const number = Number.parseFloat(value);
+
+  if (Number.isNaN(number))
+    return Number.NaN;
+
+  if (/(?:em|rem)\s*$/i.test(value))
+    return number * 16;
+
+  return number;
+}
+
+/**
+ * Best-effort evaluation of `min-width` / `max-width` media queries against a
+ * known viewport width, for SSR. Comma-separated queries are OR-combined and
+ * `not all` negation is respected. Returns `false` for queries we can't resolve.
+ */
+function matchSsrWidth(query: string, width: number): boolean {
+  return query.split(',').some((part) => {
+    const not = part.includes('not all');
+    const minWidth = part.match(/\(\s*min-width:\s*(-?\d+(?:\.\d*)?[a-z%]+\s*)\)/);
+    const maxWidth = part.match(/\(\s*max-width:\s*(-?\d+(?:\.\d*)?[a-z%]+\s*)\)/);
+
+    let result = Boolean(minWidth || maxWidth);
+
+    if (minWidth && result)
+      result = width >= pxValue(minWidth[1]!);
+
+    if (maxWidth && result)
+      result = width <= pxValue(maxWidth[1]!);
+
+    return not ? !result : result;
+  });
+}
+
+/**
+ * @name useMediaQuery
+ * @category Browser
+ * @description Reactive `window.matchMedia`. SSR-safe, reactive to the query, and
+ * with optional SSR width resolution for `min-width` / `max-width` queries.
+ *
+ * @param {MaybeRefOrGetter<string>} query The media query (can be reactive)
+ * @param {UseMediaQueryOptions} [options={}] Options (custom `window`, `ssrWidth`)
+ * @returns {ComputedRef<boolean>} Readonly ref of whether the query currently matches
+ *
+ * @example
+ * const isLarge = useMediaQuery('(min-width: 1024px)');
+ *
+ * @example
+ * // Resolve width queries during SSR to avoid hydration flicker
+ * const isWide = useMediaQuery('(min-width: 1024px)', { ssrWidth: 1280 });
+ *
+ * @since 0.0.15
+ */
+export function useMediaQuery(
+  query: MaybeRefOrGetter<string>,
+  options: UseMediaQueryOptions = {},
+): ComputedRef<boolean> {
+  const { window = defaultWindow, ssrWidth } = options;
+
+  const isSupported = useSupported(() =>
+    window && 'matchMedia' in window && isFunction(window.matchMedia));
+
+  const ssrSupport = shallowRef(isNumber(ssrWidth));
+
+  const mediaQuery = shallowRef<MediaQueryList | undefined>();
+  const matches = shallowRef(false);
+
+  const handler = (event: MediaQueryListEvent) => {
+    matches.value = event.matches;
+  };
+
+  watchEffect(() => {
+    // Resolve width-based queries from `ssrWidth` until the real API is ready.
+    if (ssrSupport.value) {
+      ssrSupport.value = !isSupported.value;
+      matches.value = matchSsrWidth(toValue(query), ssrWidth!);
+      return;
+    }
+
+    if (!isSupported.value)
+      return;
+
+    mediaQuery.value = window!.matchMedia(toValue(query));
+    matches.value = mediaQuery.value.matches;
+  });
+
+  // Reactive target: re-binds automatically when the query (and thus the
+  // MediaQueryList) changes, and auto-cleans on scope dispose. Passive since
+  // we never call preventDefault.
+  useEventListener(mediaQuery, 'change', handler, { passive: true });
+
+  return computed(() => matches.value);
+}

vue/toolkit/src/composables/browser/useMouse/index.test.ts

@@ -0,0 +1,287 @@
+import { describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick, shallowRef } from 'vue';
+import { useMouse } from '.';
+
+function dispatchMouseMove(target: EventTarget, coords: Partial<Record<'pageX' | 'pageY' | 'clientX' | 'clientY' | 'screenX' | 'screenY' | 'movementX' | 'movementY', number>>) {
+  const event = new MouseEvent('mousemove');
+  for (const [key, value] of Object.entries(coords))
+    Object.defineProperty(event, key, { value, configurable: true });
+  target.dispatchEvent(event);
+  return event;
+}
+
+describe(useMouse, () => {
+  it('uses the initial value', () => {
+    const scope = effectScope();
+    let mouse: ReturnType<typeof useMouse>;
+    scope.run(() => {
+      mouse = useMouse({ initialValue: { x: 5, y: 10 } });
+    });
+    expect(mouse!.x.value).toBe(5);
+    expect(mouse!.y.value).toBe(10);
+    scope.stop();
+  });
+
+  it('tracks mousemove with page coordinates', async () => {
+    const scope = effectScope();
+    let mouse: ReturnType<typeof useMouse>;
+    scope.run(() => {
+      mouse = useMouse();
+    });
+
+    dispatchMouseMove(globalThis, { pageX: 100, pageY: 200 });
+    await nextTick();
+
+    expect(mouse!.x.value).toBe(100);
+    expect(mouse!.y.value).toBe(200);
+    expect(mouse!.sourceType.value).toBe('mouse');
+    scope.stop();
+  });
+
+  it('supports client coordinate type', async () => {
+    const scope = effectScope();
+    let mouse: ReturnType<typeof useMouse>;
+    scope.run(() => {
+      mouse = useMouse({ type: 'client' });
+    });
+
+    const event = new MouseEvent('mousemove', { clientX: 7, clientY: 9 });
+    globalThis.dispatchEvent(event);
+    await nextTick();
+
+    expect(mouse!.x.value).toBe(7);
+    expect(mouse!.y.value).toBe(9);
+    scope.stop();
+  });
+
+  it('supports screen coordinate type', async () => {
+    const scope = effectScope();
+    let mouse: ReturnType<typeof useMouse>;
+    scope.run(() => {
+      mouse = useMouse({ type: 'screen' });
+    });
+
+    const event = new MouseEvent('mousemove', { screenX: 11, screenY: 22 });
+    globalThis.dispatchEvent(event);
+    await nextTick();
+
+    expect(mouse!.x.value).toBe(11);
+    expect(mouse!.y.value).toBe(22);
+    scope.stop();
+  });
+
+  it('supports a custom extractor function', async () => {
+    const scope = effectScope();
+    let mouse: ReturnType<typeof useMouse>;
+    scope.run(() => {
+      mouse = useMouse({ type: e => [(e as MouseEvent).pageX * 2, (e as MouseEvent).pageY * 2] });
+    });
+
+    dispatchMouseMove(globalThis, { pageX: 3, pageY: 4 });
+    await nextTick();
+
+    expect(mouse!.x.value).toBe(6);
+    expect(mouse!.y.value).toBe(8);
+    scope.stop();
+  });
+
+  it('does not update when the extractor returns null', async () => {
+    const scope = effectScope();
+    let mouse: ReturnType<typeof useMouse>;
+    // a custom extractor that opts out of updating
+    scope.run(() => {
+      mouse = useMouse({ type: () => null, initialValue: { x: 1, y: 2 } });
+    });
+
+    dispatchMouseMove(globalThis, { pageX: 99, pageY: 99 });
+    await nextTick();
+
+    expect(mouse!.x.value).toBe(1);
+    expect(mouse!.y.value).toBe(2);
+    expect(mouse!.sourceType.value).toBe(null);
+    scope.stop();
+  });
+
+  it('tracks touch events', async () => {
+    const scope = effectScope();
+    let mouse: ReturnType<typeof useMouse>;
+    scope.run(() => {
+      mouse = useMouse();
+    });
+
+    const touch = { clientX: 0, clientY: 0, pageX: 50, pageY: 60 } as Touch;
+    const event = new Event('touchstart') as TouchEvent;
+    Object.defineProperty(event, 'touches', { value: [touch], configurable: true });
+    globalThis.dispatchEvent(event);
+    await nextTick();
+
+    expect(mouse!.x.value).toBe(50);
+    expect(mouse!.y.value).toBe(60);
+    expect(mouse!.sourceType.value).toBe('touch');
+    scope.stop();
+  });
+
+  it('ignores touch events when touch is disabled', async () => {
+    const scope = effectScope();
+    let mouse: ReturnType<typeof useMouse>;
+    scope.run(() => {
+      mouse = useMouse({ touch: false, initialValue: { x: 1, y: 1 } });
+    });
+
+    const touch = { pageX: 50, pageY: 60 } as Touch;
+    const event = new Event('touchstart') as TouchEvent;
+    Object.defineProperty(event, 'touches', { value: [touch], configurable: true });
+    globalThis.dispatchEvent(event);
+    await nextTick();
+
+    expect(mouse!.x.value).toBe(1);
+    expect(mouse!.y.value).toBe(1);
+    scope.stop();
+  });
+
+  it('resets on touchend when resetOnTouchEnds is set', async () => {
+    const scope = effectScope();
+    let mouse: ReturnType<typeof useMouse>;
+    scope.run(() => {
+      mouse = useMouse({ resetOnTouchEnds: true, initialValue: { x: 9, y: 9 } });
+    });
+
+    const touch = { pageX: 50, pageY: 60 } as Touch;
+    const start = new Event('touchstart') as TouchEvent;
+    Object.defineProperty(start, 'touches', { value: [touch], configurable: true });
+    globalThis.dispatchEvent(start);
+    await nextTick();
+    expect(mouse!.x.value).toBe(50);
+
+    globalThis.dispatchEvent(new Event('touchend'));
+    await nextTick();
+    expect(mouse!.x.value).toBe(9);
+    expect(mouse!.y.value).toBe(9);
+    scope.stop();
+  });
+
+  it('updates page coordinates on scroll without pointer movement', async () => {
+    const scope = effectScope();
+    let mouse: ReturnType<typeof useMouse>;
+    scope.run(() => {
+      mouse = useMouse({ type: 'page' });
+    });
+
+    // record a mouse position while scrollX/scrollY are 0
+    (globalThis as any).scrollX = 0;
+    (globalThis as any).scrollY = 0;
+    dispatchMouseMove(globalThis, { pageX: 100, pageY: 100 });
+    await nextTick();
+    expect(mouse!.x.value).toBe(100);
+
+    // scroll the page; page coordinates should shift by the scroll delta
+    (globalThis as any).scrollX = 30;
+    (globalThis as any).scrollY = 40;
+    globalThis.dispatchEvent(new Event('scroll'));
+    await nextTick();
+
+    expect(mouse!.x.value).toBe(130);
+    expect(mouse!.y.value).toBe(140);
+
+    (globalThis as any).scrollX = 0;
+    (globalThis as any).scrollY = 0;
+    scope.stop();
+  });
+
+  it('does not register a scroll listener for non-page types', async () => {
+    const addSpy = vi.spyOn(globalThis, 'addEventListener');
+    const scope = effectScope();
+    scope.run(() => {
+      useMouse({ type: 'client' });
+    });
+
+    const scrollCalls = addSpy.mock.calls.filter(([name]) => name === 'scroll');
+    expect(scrollCalls).toHaveLength(0);
+
+    addSpy.mockRestore();
+    scope.stop();
+  });
+
+  it('attaches passive listeners', () => {
+    const addSpy = vi.spyOn(globalThis, 'addEventListener');
+    const scope = effectScope();
+    scope.run(() => {
+      useMouse();
+    });
+
+    const moveCall = addSpy.mock.calls.find(([name]) => name === 'mousemove');
+    expect(moveCall).toBeDefined();
+    expect((moveCall![2] as AddEventListenerOptions).passive).toBeTruthy();
+
+    addSpy.mockRestore();
+    scope.stop();
+  });
+
+  it('listens on a custom element target', async () => {
+    const el = document.createElement('div');
+    const elRef = shallowRef(el);
+    const addSpy = vi.spyOn(el, 'addEventListener');
+
+    const scope = effectScope();
+    let mouse: ReturnType<typeof useMouse>;
+    scope.run(() => {
+      mouse = useMouse({ target: elRef, type: 'client' });
+    });
+    await nextTick();
+
+    expect(addSpy.mock.calls.some(([name]) => name === 'mousemove')).toBeTruthy();
+
+    const event = new MouseEvent('mousemove', { clientX: 5, clientY: 6 });
+    el.dispatchEvent(event);
+    await nextTick();
+
+    expect(mouse!.x.value).toBe(5);
+    expect(mouse!.y.value).toBe(6);
+
+    addSpy.mockRestore();
+    scope.stop();
+  });
+
+  it('does nothing when window is unavailable (SSR)', () => {
+    const scope = effectScope();
+    let mouse: ReturnType<typeof useMouse>;
+    scope.run(() => {
+      mouse = useMouse({ window: undefined, target: undefined });
+    });
+    expect(mouse!.x.value).toBe(0);
+    expect(mouse!.y.value).toBe(0);
+    expect(mouse!.sourceType.value).toBe(null);
+    scope.stop();
+  });
+
+  it('applies an event filter (throttle drops intermediate moves)', async () => {
+    vi.useFakeTimers();
+    const filtered = vi.fn();
+    // simple leading-only filter: only the first invoke passes immediately
+    let used = false;
+    const onceFilter = (invoke: () => void) => {
+      if (!used) {
+        used = true;
+        invoke();
+      }
+    };
+
+    const scope = effectScope();
+    let mouse: ReturnType<typeof useMouse>;
+    scope.run(() => {
+      mouse = useMouse({ eventFilter: onceFilter });
+    });
+
+    dispatchMouseMove(globalThis, { pageX: 10, pageY: 10 });
+    dispatchMouseMove(globalThis, { pageX: 20, pageY: 20 });
+    await nextTick();
+
+    // only the first move was let through
+    expect(mouse!.x.value).toBe(10);
+    expect(mouse!.y.value).toBe(10);
+
+    filtered();
+    scope.stop();
+    vi.useRealTimers();
+  });
+});

vue/toolkit/src/composables/browser/useMouse/index.ts

@@ -0,0 +1,204 @@
+import { shallowRef } from 'vue';
+import type { Ref } from 'vue';
+import { isFunction } from '@robonen/stdlib';
+import { defaultWindow } from '@/types';
+import type { ConfigurableWindow } from '@/types';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { unrefElement } from '@/composables/component/unrefElement';
+import type { MaybeComputedElementRef } from '@/composables/component/unrefElement';
+import { bypassFilter, createFilterWrapper } from '@/utils/filters';
+import type { ConfigurableEventFilter } from '@/utils/filters';
+
+export type UseMouseCoordType = 'page' | 'client' | 'screen' | 'movement';
+export type UseMouseSourceType = 'mouse' | 'touch' | null;
+
+/**
+ * Extracts an `[x, y]` pair from a mouse or touch point, or `null` to skip.
+ */
+export type UseMouseEventExtractor = (event: MouseEvent | Touch) => [x: number, y: number] | null | undefined;
+
+export interface UseMouseOptions extends ConfigurableWindow, ConfigurableEventFilter {
+  /**
+   * Which coordinate pair to read from the event, or a custom extractor function
+   *
+   * @default 'page'
+   */
+  type?: UseMouseCoordType | UseMouseEventExtractor;
+
+  /**
+   * Target to attach the listeners to. Accepts a window, document, element ref,
+   * getter, or component instance.
+   *
+   * @default window
+   */
+  target?: MaybeComputedElementRef | Window | Document;
+
+  /**
+   * Listen to touch events
+   *
+   * @default true
+   */
+  touch?: boolean;
+
+  /**
+   * Track window scroll so that `page` coordinates stay accurate while the page
+   * scrolls without the pointer moving. Only applies when `type === 'page'`.
+   *
+   * @default true
+   */
+  scroll?: boolean;
+
+  /**
+   * Reset coordinates to `initialValue` on `touchend`
+   *
+   * @default false
+   */
+  resetOnTouchEnds?: boolean;
+
+  /**
+   * Initial coordinates
+   *
+   * @default { x: 0, y: 0 }
+   */
+  initialValue?: { x: number; y: number };
+}
+
+export interface UseMouseReturn {
+  x: Ref<number>;
+  y: Ref<number>;
+  sourceType: Ref<UseMouseSourceType>;
+}
+
+const builtinExtractors: Record<UseMouseCoordType, UseMouseEventExtractor> = {
+  page: e => [(e as MouseEvent).pageX, (e as MouseEvent).pageY],
+  client: e => [e.clientX, e.clientY],
+  screen: e => [e.screenX, e.screenY],
+  movement: e => ('movementX' in e ? [e.movementX, e.movementY] : null),
+};
+
+/**
+ * @name useMouse
+ * @category Browser
+ * @description Reactive mouse (and optionally touch) position with optional
+ * custom target, scroll tracking, custom extractors, and event filtering.
+ *
+ * @param {UseMouseOptions} [options={}] Options
+ * @returns {UseMouseReturn} Reactive `x`, `y`, and `sourceType`
+ *
+ * @example
+ * const { x, y, sourceType } = useMouse();
+ *
+ * @example
+ * // Track relative to an element, throttled
+ * const { x, y } = useMouse({ target: el, eventFilter: throttleFilter(50) });
+ *
+ * @since 0.0.15
+ */
+export function useMouse(options: UseMouseOptions = {}): UseMouseReturn {
+  const {
+    type = 'page',
+    touch = true,
+    scroll = true,
+    resetOnTouchEnds = false,
+    initialValue = { x: 0, y: 0 },
+    window = defaultWindow,
+    target = window,
+    eventFilter,
+  } = options;
+
+  let prevMouseEvent: MouseEvent | null = null;
+  let prevScrollX = 0;
+  let prevScrollY = 0;
+
+  const x = shallowRef(initialValue.x);
+  const y = shallowRef(initialValue.y);
+  const sourceType = shallowRef<UseMouseSourceType>(null);
+
+  const isExtractorFn = isFunction(type);
+  const extractor: UseMouseEventExtractor = isExtractorFn ? type : builtinExtractors[type];
+
+  const mouseHandler = (event: MouseEvent) => {
+    const result = extractor(event);
+    prevMouseEvent = event;
+
+    if (result) {
+      [x.value, y.value] = result;
+      sourceType.value = 'mouse';
+    }
+
+    if (window) {
+      prevScrollX = window.scrollX;
+      prevScrollY = window.scrollY;
+    }
+  };
+
+  const touchHandler = (event: TouchEvent) => {
+    if (event.touches.length) {
+      const result = extractor(event.touches[0]!);
+
+      if (result) {
+        [x.value, y.value] = result;
+        sourceType.value = 'touch';
+      }
+    }
+  };
+
+  // Keep page coordinates correct when scrolling without moving the pointer.
+  const scrollHandler = () => {
+    if (!prevMouseEvent || !window)
+      return;
+
+    const result = extractor(prevMouseEvent);
+
+    if (result) {
+      x.value = result[0] + window.scrollX - prevScrollX;
+      y.value = result[1] + window.scrollY - prevScrollY;
+    }
+  };
+
+  const reset = () => {
+    x.value = initialValue.x;
+    y.value = initialValue.y;
+  };
+
+  const filter = eventFilter ?? bypassFilter;
+  const mouseHandlerWrapper = createFilterWrapper(filter, mouseHandler);
+  const touchHandlerWrapper = createFilterWrapper(filter, touchHandler);
+  const scrollHandlerWrapper = createFilterWrapper(filter, scrollHandler);
+
+  const trackTouch = touch && !(isExtractorFn ? false : type === 'movement');
+  const trackScroll = scroll && !!window && (isExtractorFn ? true : type === 'page');
+
+  // A raw window/document/EventTarget is used directly (fast, non-reactive path
+  // in useEventListener). Refs/getters/element instances are resolved lazily via
+  // a getter so the listeners re-bind when the underlying element changes.
+  const listenTarget = isTarget(target)
+    ? target
+    : (): EventTarget | null | undefined => unrefElement(target as MaybeComputedElementRef) as EventTarget | null | undefined;
+
+  if (target) {
+    const listenerOptions = { passive: true };
+
+    useEventListener(listenTarget, ['mousemove', 'dragover'], mouseHandlerWrapper as unknown as (e: Event) => void, listenerOptions);
+
+    if (trackTouch) {
+      useEventListener(listenTarget, ['touchstart', 'touchmove'], touchHandlerWrapper as unknown as (e: Event) => void, listenerOptions);
+
+      if (resetOnTouchEnds)
+        useEventListener(listenTarget, 'touchend', reset, listenerOptions);
+    }
+
+    if (trackScroll)
+      useEventListener(window, 'scroll', scrollHandlerWrapper as (e: Event) => void, listenerOptions);
+  }
+
+  return { x, y, sourceType };
+}
+
+/**
+ * `true` for an object that is itself an event target (window/document/element)
+ * and should be attached to directly, rather than unwrapped from a ref/getter.
+ */
+function isTarget(value: unknown): value is EventTarget {
+  return typeof value === 'object' && value !== null && 'addEventListener' in value;
+}

vue/toolkit/src/composables/browser/useMousePressed/index.test.ts

@@ -0,0 +1,252 @@
+import { describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick, shallowRef } from 'vue';
+import { useMousePressed } from '.';
+
+function dispatch(target: EventTarget, type: string): Event {
+  const event = new Event(type);
+  target.dispatchEvent(event);
+  return event;
+}
+
+describe(useMousePressed, () => {
+  it('starts not pressed by default', () => {
+    const scope = effectScope();
+    let res: ReturnType<typeof useMousePressed>;
+    scope.run(() => {
+      res = useMousePressed();
+    });
+    expect(res!.pressed.value).toBeFalsy();
+    expect(res!.sourceType.value).toBe(null);
+    scope.stop();
+  });
+
+  it('honors the initial value', () => {
+    const scope = effectScope();
+    let res: ReturnType<typeof useMousePressed>;
+    scope.run(() => {
+      res = useMousePressed({ initialValue: true });
+    });
+    expect(res!.pressed.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('sets pressed and mouse sourceType on mousedown, clears on mouseup', async () => {
+    const scope = effectScope();
+    let res: ReturnType<typeof useMousePressed>;
+    scope.run(() => {
+      res = useMousePressed();
+    });
+
+    dispatch(globalThis, 'mousedown');
+    await nextTick();
+    expect(res!.pressed.value).toBeTruthy();
+    expect(res!.sourceType.value).toBe('mouse');
+
+    dispatch(globalThis, 'mouseup');
+    await nextTick();
+    expect(res!.pressed.value).toBeFalsy();
+    expect(res!.sourceType.value).toBe(null);
+    scope.stop();
+  });
+
+  it('clears pressed on mouseleave', async () => {
+    const scope = effectScope();
+    let res: ReturnType<typeof useMousePressed>;
+    scope.run(() => {
+      res = useMousePressed();
+    });
+
+    dispatch(globalThis, 'mousedown');
+    await nextTick();
+    expect(res!.pressed.value).toBeTruthy();
+
+    dispatch(globalThis, 'mouseleave');
+    await nextTick();
+    expect(res!.pressed.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('tracks touch presses with touch sourceType', async () => {
+    const scope = effectScope();
+    let res: ReturnType<typeof useMousePressed>;
+    scope.run(() => {
+      res = useMousePressed();
+    });
+
+    dispatch(globalThis, 'touchstart');
+    await nextTick();
+    expect(res!.pressed.value).toBeTruthy();
+    expect(res!.sourceType.value).toBe('touch');
+
+    dispatch(globalThis, 'touchend');
+    await nextTick();
+    expect(res!.pressed.value).toBeFalsy();
+    expect(res!.sourceType.value).toBe(null);
+    scope.stop();
+  });
+
+  it('clears pressed on touchcancel', async () => {
+    const scope = effectScope();
+    let res: ReturnType<typeof useMousePressed>;
+    scope.run(() => {
+      res = useMousePressed();
+    });
+
+    dispatch(globalThis, 'touchstart');
+    await nextTick();
+    expect(res!.pressed.value).toBeTruthy();
+
+    dispatch(globalThis, 'touchcancel');
+    await nextTick();
+    expect(res!.pressed.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('does not register touch listeners when touch is disabled', async () => {
+    const addSpy = vi.spyOn(globalThis, 'addEventListener');
+    const scope = effectScope();
+    let res: ReturnType<typeof useMousePressed>;
+    scope.run(() => {
+      res = useMousePressed({ touch: false });
+    });
+    await nextTick();
+
+    const touchCalls = addSpy.mock.calls.filter(([name]) => String(name).startsWith('touch'));
+    expect(touchCalls).toHaveLength(0);
+
+    dispatch(globalThis, 'touchstart');
+    await nextTick();
+    expect(res!.pressed.value).toBeFalsy();
+
+    addSpy.mockRestore();
+    scope.stop();
+  });
+
+  it('tracks drag presses when drag is enabled', async () => {
+    const scope = effectScope();
+    let res: ReturnType<typeof useMousePressed>;
+    scope.run(() => {
+      res = useMousePressed();
+    });
+
+    dispatch(globalThis, 'dragstart');
+    await nextTick();
+    expect(res!.pressed.value).toBeTruthy();
+    expect(res!.sourceType.value).toBe('mouse');
+
+    dispatch(globalThis, 'dragend');
+    await nextTick();
+    expect(res!.pressed.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('clears pressed on drop', async () => {
+    const scope = effectScope();
+    let res: ReturnType<typeof useMousePressed>;
+    scope.run(() => {
+      res = useMousePressed();
+    });
+
+    dispatch(globalThis, 'dragstart');
+    await nextTick();
+    expect(res!.pressed.value).toBeTruthy();
+
+    dispatch(globalThis, 'drop');
+    await nextTick();
+    expect(res!.pressed.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('does not register drag listeners when drag is disabled', async () => {
+    const addSpy = vi.spyOn(globalThis, 'addEventListener');
+    const scope = effectScope();
+    scope.run(() => {
+      useMousePressed({ drag: false });
+    });
+    await nextTick();
+
+    const dragCalls = addSpy.mock.calls.filter(([name]) => String(name).startsWith('drag') || name === 'drop');
+    expect(dragCalls).toHaveLength(0);
+
+    addSpy.mockRestore();
+    scope.stop();
+  });
+
+  it('invokes onPressed and onReleased callbacks', async () => {
+    const onPressed = vi.fn();
+    const onReleased = vi.fn();
+    const scope = effectScope();
+    scope.run(() => {
+      useMousePressed({ onPressed, onReleased });
+    });
+
+    const down = dispatch(globalThis, 'mousedown');
+    await nextTick();
+    expect(onPressed).toHaveBeenCalledTimes(1);
+    expect(onPressed).toHaveBeenCalledWith(down);
+
+    const up = dispatch(globalThis, 'mouseup');
+    await nextTick();
+    expect(onReleased).toHaveBeenCalledTimes(1);
+    expect(onReleased).toHaveBeenCalledWith(up);
+    scope.stop();
+  });
+
+  it('attaches passive listeners and respects the capture option', async () => {
+    const addSpy = vi.spyOn(globalThis, 'addEventListener');
+    const scope = effectScope();
+    scope.run(() => {
+      useMousePressed({ capture: true });
+    });
+    await nextTick();
+
+    const downCall = addSpy.mock.calls.find(([name]) => name === 'mousedown');
+    expect(downCall).toBeDefined();
+    const opts = downCall![2] as AddEventListenerOptions;
+    expect(opts.passive).toBeTruthy();
+    expect(opts.capture).toBeTruthy();
+
+    addSpy.mockRestore();
+    scope.stop();
+  });
+
+  it('listens for press on a custom element target', async () => {
+    const el = document.createElement('div');
+    const elRef = shallowRef(el);
+    const addSpy = vi.spyOn(el, 'addEventListener');
+
+    const scope = effectScope();
+    let res: ReturnType<typeof useMousePressed>;
+    scope.run(() => {
+      res = useMousePressed({ target: elRef });
+    });
+    await nextTick();
+
+    expect(addSpy.mock.calls.some(([name]) => name === 'mousedown')).toBeTruthy();
+
+    dispatch(el, 'mousedown');
+    await nextTick();
+    expect(res!.pressed.value).toBeTruthy();
+    expect(res!.sourceType.value).toBe('mouse');
+
+    // release still listens on window
+    dispatch(globalThis, 'mouseup');
+    await nextTick();
+    expect(res!.pressed.value).toBeFalsy();
+
+    addSpy.mockRestore();
+    scope.stop();
+  });
+
+  it('does nothing when window is unavailable (SSR)', () => {
+    const scope = effectScope();
+    let res: ReturnType<typeof useMousePressed>;
+    scope.run(() => {
+      res = useMousePressed({ window: undefined, initialValue: true });
+    });
+    // returns refs without attaching listeners
+    expect(res!.pressed.value).toBeTruthy();
+    expect(res!.sourceType.value).toBe(null);
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useMousePressed/index.ts

@@ -0,0 +1,130 @@
+import { computed, shallowRef } from 'vue';
+import type { ComputedRef, ShallowRef } from 'vue';
+import { defaultWindow } from '@/types';
+import type { ConfigurableWindow } from '@/types';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { unrefElement } from '@/composables/component/unrefElement';
+import type { MaybeComputedElementRef } from '@/composables/component/unrefElement';
+import type { UseMouseSourceType } from '@/composables/browser/useMouse';
+
+export type UseMousePressedEvent = MouseEvent | TouchEvent | DragEvent;
+
+export interface UseMousePressedOptions extends ConfigurableWindow {
+  /**
+   * Listen to `touchstart`, `touchend`, and `touchcancel` events
+   *
+   * @default true
+   */
+  touch?: boolean;
+
+  /**
+   * Listen to `dragstart`, `drop`, and `dragend` events
+   *
+   * @default true
+   */
+  drag?: boolean;
+
+  /**
+   * Add event listeners with the `capture` option set to `true`
+   * (see [MDN](https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener#capture))
+   *
+   * @default false
+   */
+  capture?: boolean;
+
+  /**
+   * Initial pressed state
+   *
+   * @default false
+   */
+  initialValue?: boolean;
+
+  /**
+   * Element target to capture the press on. Accepts an element ref, getter,
+   * or component instance. Defaults to `window` when omitted.
+   */
+  target?: MaybeComputedElementRef;
+
+  /**
+   * Callback invoked when a press starts
+   */
+  onPressed?: (event: UseMousePressedEvent) => void;
+
+  /**
+   * Callback invoked when a press is released
+   */
+  onReleased?: (event: UseMousePressedEvent) => void;
+}
+
+export interface UseMousePressedReturn {
+  pressed: ShallowRef<boolean>;
+  sourceType: ShallowRef<UseMouseSourceType>;
+}
+
+/**
+ * @name useMousePressed
+ * @category Browser
+ * @description Reactive mouse/touch/drag pressed state on a target, with the
+ * input source type and optional press/release callbacks.
+ *
+ * @param {UseMousePressedOptions} [options={}] Options
+ * @returns {UseMousePressedReturn} Reactive `pressed` and `sourceType`
+ *
+ * @example
+ * const { pressed, sourceType } = useMousePressed();
+ *
+ * @example
+ * // Track presses only on a specific element, ignore touch
+ * const { pressed } = useMousePressed({ target: el, touch: false });
+ *
+ * @since 0.0.15
+ */
+export function useMousePressed(options: UseMousePressedOptions = {}): UseMousePressedReturn {
+  const {
+    touch = true,
+    drag = true,
+    capture = false,
+    initialValue = false,
+    window = defaultWindow,
+  } = options;
+
+  const pressed = shallowRef(initialValue);
+  const sourceType = shallowRef<UseMouseSourceType>(null);
+
+  if (!window)
+    return { pressed, sourceType };
+
+  const onPressed = (srcType: UseMouseSourceType) => (event: UseMousePressedEvent): void => {
+    pressed.value = true;
+    sourceType.value = srcType;
+    options.onPressed?.(event);
+  };
+
+  const onReleased = (event: UseMousePressedEvent): void => {
+    pressed.value = false;
+    sourceType.value = null;
+    options.onReleased?.(event);
+  };
+
+  const target: ComputedRef<EventTarget> = computed(() => unrefElement(options.target) ?? window);
+
+  const listenerOptions = { passive: true, capture };
+
+  useEventListener(target, 'mousedown', onPressed('mouse') as (e: Event) => void, listenerOptions);
+  useEventListener(window, 'mouseleave', onReleased as (e: Event) => void, listenerOptions);
+  useEventListener(window, 'mouseup', onReleased as (e: Event) => void, listenerOptions);
+
+  if (drag) {
+    useEventListener(target, 'dragstart', onPressed('mouse') as (e: Event) => void, listenerOptions);
+    useEventListener(window, 'drop', onReleased as (e: Event) => void, listenerOptions);
+    useEventListener(window, 'dragend', onReleased as (e: Event) => void, listenerOptions);
+  }
+
+  if (touch) {
+    useEventListener(target, 'touchstart', onPressed('touch') as (e: Event) => void, listenerOptions);
+    useEventListener(window, 'touchend', onReleased as (e: Event) => void, listenerOptions);
+    useEventListener(window, 'touchcancel', onReleased as (e: Event) => void, listenerOptions);
+  }
+
+  return { pressed, sourceType };
+}

vue/toolkit/src/composables/browser/useMutationObserver/index.test.ts

@@ -0,0 +1,193 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick, ref } from 'vue';
+import { useMutationObserver } from '.';
+
+let instances: Array<{ cb: MutationCallback; observe: ReturnType<typeof vi.fn>; disconnect: ReturnType<typeof vi.fn>; takeRecords: ReturnType<typeof vi.fn> }> = [];
+
+class StubMutationObserver {
+  observe = vi.fn();
+  disconnect = vi.fn();
+  takeRecords = vi.fn(() => []);
+  cb: MutationCallback;
+  constructor(cb: MutationCallback) {
+    this.cb = cb;
+    instances.push(this);
+  }
+}
+
+describe(useMutationObserver, () => {
+  beforeEach(() => {
+    instances = [];
+    vi.stubGlobal('MutationObserver', StubMutationObserver);
+  });
+  afterEach(() => vi.unstubAllGlobals());
+
+  it('observes the target with the given options', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    scope.run(() => useMutationObserver(ref(el), vi.fn(), { attributes: true }));
+
+    expect(instances).toHaveLength(1);
+    expect(instances[0]!.observe).toHaveBeenCalledWith(el, { attributes: true });
+    scope.stop();
+  });
+
+  it('does not leak immediate/window into observer options', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    scope.run(() => useMutationObserver(ref(el), vi.fn(), { childList: true, immediate: true }));
+
+    expect(instances[0]!.observe).toHaveBeenCalledWith(el, { childList: true });
+    scope.stop();
+  });
+
+  it('disconnects on stop', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let stop: () => void;
+    scope.run(() => {
+      stop = useMutationObserver(ref(el), vi.fn()).stop;
+    });
+
+    stop!();
+    expect(instances[0]!.disconnect).toHaveBeenCalled();
+    scope.stop();
+  });
+
+  it('forwards records to the callback', () => {
+    const el = document.createElement('div');
+    const callback = vi.fn();
+    const scope = effectScope();
+    scope.run(() => useMutationObserver(ref(el), callback));
+
+    const records = [{ type: 'attributes' } as MutationRecord];
+    instances[0]!.cb(records, instances[0] as unknown as MutationObserver);
+    expect(callback).toHaveBeenCalledWith(records, expect.anything());
+    scope.stop();
+  });
+
+  it('observes an array of targets with a single observer', () => {
+    const a = document.createElement('div');
+    const b = document.createElement('span');
+    const scope = effectScope();
+    scope.run(() => useMutationObserver([ref(a), b], vi.fn(), { childList: true }));
+
+    expect(instances).toHaveLength(1);
+    expect(instances[0]!.observe).toHaveBeenCalledTimes(2);
+    expect(instances[0]!.observe).toHaveBeenCalledWith(a, { childList: true });
+    expect(instances[0]!.observe).toHaveBeenCalledWith(b, { childList: true });
+    scope.stop();
+  });
+
+  it('accepts a getter returning an array of targets', () => {
+    const a = document.createElement('div');
+    const b = document.createElement('span');
+    const scope = effectScope();
+    scope.run(() => useMutationObserver(() => [a, b], vi.fn(), { childList: true }));
+
+    expect(instances).toHaveLength(1);
+    expect(instances[0]!.observe).toHaveBeenCalledTimes(2);
+    scope.stop();
+  });
+
+  it('deduplicates repeated targets', () => {
+    const a = document.createElement('div');
+    const scope = effectScope();
+    scope.run(() => useMutationObserver([a, a, ref(a)], vi.fn(), { childList: true }));
+
+    expect(instances[0]!.observe).toHaveBeenCalledTimes(1);
+    scope.stop();
+  });
+
+  it('skips nullish targets', () => {
+    const scope = effectScope();
+    scope.run(() => useMutationObserver([ref(null), ref(undefined)], vi.fn(), { childList: true }));
+
+    expect(instances).toHaveLength(0);
+    scope.stop();
+  });
+
+  it('re-observes when a reactive target changes', async () => {
+    const el = document.createElement('div');
+    const target = ref<HTMLElement | null>(null);
+    const scope = effectScope();
+    scope.run(() => useMutationObserver(target, vi.fn(), { childList: true }));
+
+    await nextTick();
+    expect(instances).toHaveLength(0);
+
+    target.value = el;
+    await nextTick();
+    expect(instances).toHaveLength(1);
+    expect(instances[0]!.observe).toHaveBeenCalledWith(el, { childList: true });
+    scope.stop();
+  });
+
+  it('does not observe when immediate is false, then resumes', async () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let api: ReturnType<typeof useMutationObserver>;
+    scope.run(() => {
+      api = useMutationObserver(ref(el), vi.fn(), { attributes: true, immediate: false });
+    });
+
+    await nextTick();
+    expect(instances).toHaveLength(0);
+    expect(api!.isActive.value).toBeFalsy();
+
+    api!.resume();
+    await nextTick();
+    expect(instances).toHaveLength(1);
+    expect(api!.isActive.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('pause disconnects and flips isActive, resume re-observes', async () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let api: ReturnType<typeof useMutationObserver>;
+    scope.run(() => {
+      api = useMutationObserver(ref(el), vi.fn(), { attributes: true });
+    });
+
+    expect(instances).toHaveLength(1);
+
+    api!.pause();
+    expect(instances[0]!.disconnect).toHaveBeenCalled();
+    expect(api!.isActive.value).toBeFalsy();
+
+    api!.resume();
+    await nextTick();
+    expect(instances).toHaveLength(2);
+    scope.stop();
+  });
+
+  it('takeRecords proxies to the active observer and returns undefined when inactive', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let api: ReturnType<typeof useMutationObserver>;
+    scope.run(() => {
+      api = useMutationObserver(ref(el), vi.fn());
+    });
+
+    expect(api!.takeRecords()).toEqual([]);
+    expect(instances[0]!.takeRecords).toHaveBeenCalled();
+
+    api!.stop();
+    expect(api!.takeRecords()).toBeUndefined();
+    scope.stop();
+  });
+
+  it('reports isSupported false when MutationObserver is missing', () => {
+    const scope = effectScope();
+    let api: ReturnType<typeof useMutationObserver>;
+    const el = document.createElement('div');
+    scope.run(() => {
+      api = useMutationObserver(ref(el), vi.fn(), { window: { foo: 1 } as unknown as Window & typeof globalThis });
+    });
+
+    expect(api!.isSupported.value).toBeFalsy();
+    expect(instances).toHaveLength(0);
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useMutationObserver/index.ts

@@ -0,0 +1,140 @@
+import { computed, readonly, ref, toValue, watch } from 'vue';
+import type { MaybeRefOrGetter, Ref } from 'vue';
+import { toArray } from '@robonen/stdlib';
+import type { ConfigurableWindow } from '@/types';
+import { defaultWindow } from '@/types';
+import type { MaybeComputedElementRef, MaybeElement } from '@/composables/component/unrefElement';
+import { unrefElement } from '@/composables/component/unrefElement';
+import { useSupported } from '@/composables/browser/useSupported';
+import { tryOnScopeDispose } from '@/composables/lifecycle/tryOnScopeDispose';
+
+export interface UseMutationObserverOptions extends MutationObserverInit, ConfigurableWindow {
+  /**
+   * Start observing immediately once a target is available
+   *
+   * @default true
+   */
+  immediate?: boolean;
+}
+
+export interface UseMutationObserverReturn {
+  isSupported: Readonly<Ref<boolean>>;
+  /**
+   * Whether the observer is currently active (not paused or stopped)
+   */
+  isActive: Readonly<Ref<boolean>>;
+  /**
+   * Temporarily disconnect the observer without tearing down the watcher.
+   * Re-observe with `resume`.
+   */
+  pause: () => void;
+  /**
+   * Re-attach the observer to the current target(s) after a `pause`.
+   */
+  resume: () => void;
+  /**
+   * Permanently stop observing and dispose the watcher.
+   */
+  stop: () => void;
+  /**
+   * Synchronously take and clear the observer's record queue
+   */
+  takeRecords: () => MutationRecord[] | undefined;
+}
+
+/**
+ * @name useMutationObserver
+ * @category Browser
+ * @description Watch for changes to the DOM tree via `MutationObserver`.
+ * Accepts a single target, an array of targets, or a getter returning either.
+ *
+ * @param {MaybeComputedElementRef | MaybeComputedElementRef[] | MaybeRefOrGetter<MaybeElement[]>} target Element(s) to observe
+ * @param {MutationCallback} callback Invoked with the mutation records
+ * @param {UseMutationObserverOptions} [options={}] Observer options (childList, attributes, …)
+ * @returns {UseMutationObserverReturn} `isSupported`, `isActive`, `pause`, `resume`, `stop`, and `takeRecords`
+ *
+ * @example
+ * useMutationObserver(el, (records) => {
+ *   console.log(records);
+ * }, { attributes: true });
+ *
+ * @example
+ * const { pause, resume } = useMutationObserver([elA, elB], onMutate, { childList: true });
+ *
+ * @since 0.0.15
+ */
+export function useMutationObserver(
+  target: MaybeComputedElementRef | MaybeComputedElementRef[] | MaybeRefOrGetter<MaybeElement[]>,
+  callback: MutationCallback,
+  options: UseMutationObserverOptions = {},
+): UseMutationObserverReturn {
+  const { window = defaultWindow, immediate = true, ...observerOptions } = options;
+
+  const isSupported = useSupported(() => window && 'MutationObserver' in window);
+
+  let observer: MutationObserver | undefined;
+
+  const isActive = ref(immediate);
+
+  const targets = computed(() => {
+    const value = toArray(toValue(target));
+    const set = new Set<Element>();
+
+    for (const item of value) {
+      const el = unrefElement(item as MaybeComputedElementRef);
+      if (el)
+        set.add(el);
+    }
+
+    return set;
+  });
+
+  const cleanup = () => {
+    if (observer) {
+      observer.disconnect();
+      observer = undefined;
+    }
+  };
+
+  const takeRecords = () => observer?.takeRecords();
+
+  const stopWatch = watch(
+    () => [targets.value, isActive.value] as const,
+    ([els, active]) => {
+      cleanup();
+
+      if (!active || !isSupported.value || !window || !els.size)
+        return;
+
+      observer = new MutationObserver(callback);
+      for (const el of els)
+        observer.observe(el, observerOptions);
+    },
+    { immediate: true, flush: 'post' },
+  );
+
+  const resume = () => {
+    isActive.value = true;
+  };
+
+  const pause = () => {
+    cleanup();
+    isActive.value = false;
+  };
+
+  const stop = () => {
+    cleanup();
+    stopWatch();
+  };
+
+  tryOnScopeDispose(stop);
+
+  return {
+    isSupported,
+    isActive: readonly(isActive),
+    pause,
+    resume,
+    stop,
+    takeRecords,
+  };
+}

vue/toolkit/src/composables/browser/useNetwork/index.test.ts

@@ -0,0 +1,164 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick } from 'vue';
+import { useNetwork } from '.';
+
+afterEach(() => vi.unstubAllGlobals());
+
+describe(useNetwork, () => {
+  it('exposes the full reactive network state shape', () => {
+    const scope = effectScope();
+    let state: ReturnType<typeof useNetwork>;
+    scope.run(() => {
+      state = useNetwork();
+    });
+
+    expect(state!.isOnline.value).toBe(navigator.onLine);
+    expect(state!.type.value).toBe('unknown');
+    // while online on mount, offlineAt stays undefined and onlineAt is stamped
+    expect(state!.offlineAt.value).toBeUndefined();
+    expect(typeof state!.onlineAt.value).toBe('number');
+    expect(state!.downlink.value).toBeUndefined();
+    expect(state!.downlinkMax.value).toBeUndefined();
+    expect(state!.rtt.value).toBeUndefined();
+    expect(state!.effectiveType.value).toBeUndefined();
+    expect(state!.saveData.value).toBeUndefined();
+    scope.stop();
+  });
+
+  it('reflects the initial navigator.onLine from a supplied window', () => {
+    const fakeWindow = {
+      navigator: { onLine: false },
+      addEventListener: () => {},
+      removeEventListener: () => {},
+    } as unknown as Window;
+
+    const scope = effectScope();
+    let state: ReturnType<typeof useNetwork>;
+    scope.run(() => {
+      state = useNetwork({ window: fakeWindow });
+    });
+    expect(state!.isOnline.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('records offlineAt and onlineAt timestamps on transitions', async () => {
+    const scope = effectScope();
+    let state: ReturnType<typeof useNetwork>;
+    scope.run(() => {
+      state = useNetwork();
+    });
+
+    expect(state!.offlineAt.value).toBeUndefined();
+
+    globalThis.dispatchEvent(new Event('offline'));
+    await nextTick();
+    expect(state!.isOnline.value).toBeFalsy();
+    expect(typeof state!.offlineAt.value).toBe('number');
+
+    globalThis.dispatchEvent(new Event('online'));
+    await nextTick();
+    expect(state!.isOnline.value).toBeTruthy();
+    expect(typeof state!.onlineAt.value).toBe('number');
+    scope.stop();
+  });
+
+  it('stays inert and reports online when window is undefined (SSR)', () => {
+    const scope = effectScope();
+    let state: ReturnType<typeof useNetwork>;
+    scope.run(() => {
+      state = useNetwork({ window: undefined });
+    });
+
+    expect(state!.isOnline.value).toBeTruthy();
+    expect(state!.isSupported.value).toBeFalsy();
+    expect(state!.type.value).toBe('unknown');
+    expect(state!.downlink.value).toBeUndefined();
+    scope.stop();
+  });
+
+  it('isSupported is false when Network Information API is unavailable', () => {
+    const fakeWindow = {
+      navigator: { onLine: true },
+      addEventListener: () => {},
+      removeEventListener: () => {},
+    } as unknown as Window;
+
+    const scope = effectScope();
+    let state: ReturnType<typeof useNetwork>;
+    scope.run(() => {
+      state = useNetwork({ window: fakeWindow });
+    });
+    expect(state!.isSupported.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('reads connection info and listens for change events when supported', () => {
+    const listeners: Record<string, Array<(e: Event) => void>> = {};
+    const connection = {
+      downlink: 10,
+      downlinkMax: 100,
+      effectiveType: '4g',
+      rtt: 50,
+      saveData: true,
+      type: 'wifi',
+      addEventListener: (event: string, cb: (e: Event) => void) => {
+        (listeners[event] ??= []).push(cb);
+      },
+      removeEventListener: () => {},
+    };
+
+    const fakeWindow = {
+      navigator: { onLine: true, connection },
+      addEventListener: () => {},
+      removeEventListener: () => {},
+    } as unknown as Window;
+
+    const scope = effectScope();
+    let state: ReturnType<typeof useNetwork>;
+    scope.run(() => {
+      state = useNetwork({ window: fakeWindow });
+    });
+
+    expect(state!.isSupported.value).toBeTruthy();
+    expect(state!.downlink.value).toBe(10);
+    expect(state!.downlinkMax.value).toBe(100);
+    expect(state!.effectiveType.value).toBe('4g');
+    expect(state!.rtt.value).toBe(50);
+    expect(state!.saveData.value).toBeTruthy();
+    expect(state!.type.value).toBe('wifi');
+
+    // a registered change listener should re-read connection state
+    connection.downlink = 5;
+    connection.effectiveType = '3g';
+    listeners.change?.forEach(cb => cb(new Event('change')));
+    expect(state!.downlink.value).toBe(5);
+    expect(state!.effectiveType.value).toBe('3g');
+    scope.stop();
+  });
+
+  it('falls back to "unknown" type when connection.type is missing', () => {
+    const connection = {
+      downlink: 8,
+      effectiveType: '4g',
+      addEventListener: () => {},
+      removeEventListener: () => {},
+    };
+
+    const fakeWindow = {
+      navigator: { onLine: true, connection },
+      addEventListener: () => {},
+      removeEventListener: () => {},
+    } as unknown as Window;
+
+    const scope = effectScope();
+    let state: ReturnType<typeof useNetwork>;
+    scope.run(() => {
+      state = useNetwork({ window: fakeWindow });
+    });
+
+    expect(state!.isSupported.value).toBeTruthy();
+    expect(state!.type.value).toBe('unknown');
+    expect(state!.downlink.value).toBe(8);
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useNetwork/index.ts

@@ -0,0 +1,157 @@
+import { shallowReadonly, shallowRef } from 'vue';
+import type { ShallowRef } from 'vue';
+import { timestamp } from '@robonen/stdlib';
+import { defaultWindow } from '@/types';
+import type { ConfigurableWindow } from '@/types';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { useSupported } from '@/composables/browser/useSupported';
+
+export type NetworkType
+  = | 'bluetooth'
+    | 'cellular'
+    | 'ethernet'
+    | 'none'
+    | 'wifi'
+    | 'wimax'
+    | 'other'
+    | 'unknown';
+
+export type NetworkEffectiveType = 'slow-2g' | '2g' | '3g' | '4g' | undefined;
+
+export interface UseNetworkOptions extends ConfigurableWindow {}
+
+export interface UseNetworkReturn {
+  /**
+   * Whether the Network Information API (`navigator.connection`) is supported.
+   */
+  isSupported: Readonly<ShallowRef<boolean>>;
+  /**
+   * Whether the browser is currently online (`navigator.onLine`).
+   */
+  isOnline: Readonly<ShallowRef<boolean>>;
+  /**
+   * The timestamp of the last time the browser went offline, in ms.
+   */
+  offlineAt: Readonly<ShallowRef<number | undefined>>;
+  /**
+   * The timestamp of the last time the browser came back online, in ms.
+   */
+  onlineAt: Readonly<ShallowRef<number | undefined>>;
+  /**
+   * The estimated effective bandwidth in megabits per second.
+   */
+  downlink: Readonly<ShallowRef<number | undefined>>;
+  /**
+   * The maximum downlink speed of the underlying connection technology, in Mbps.
+   */
+  downlinkMax: Readonly<ShallowRef<number | undefined>>;
+  /**
+   * The effective type of the connection (`slow-2g`, `2g`, `3g`, or `4g`).
+   */
+  effectiveType: Readonly<ShallowRef<NetworkEffectiveType>>;
+  /**
+   * The estimated effective round-trip time of the current connection, in ms.
+   */
+  rtt: Readonly<ShallowRef<number | undefined>>;
+  /**
+   * Whether the user has requested a reduced data usage mode.
+   */
+  saveData: Readonly<ShallowRef<boolean | undefined>>;
+  /**
+   * The type of connection a device is using to communicate with the network.
+   */
+  type: Readonly<ShallowRef<NetworkType>>;
+}
+
+interface NetworkInformation extends EventTarget {
+  readonly downlink?: number;
+  readonly downlinkMax?: number;
+  readonly effectiveType?: NetworkEffectiveType;
+  readonly rtt?: number;
+  readonly saveData?: boolean;
+  readonly type?: NetworkType;
+}
+
+/**
+ * @name useNetwork
+ * @category Browser
+ * @description Reactive Network Information API state plus online/offline status.
+ *
+ * @param {UseNetworkOptions} [options={}] Options
+ * @returns {UseNetworkReturn} Reactive online status, transition timestamps, and connection info
+ *
+ * @example
+ * const { isOnline, offlineAt, downlink, effectiveType, saveData, type } = useNetwork();
+ *
+ * @since 0.0.15
+ */
+export function useNetwork(options: UseNetworkOptions = {}): UseNetworkReturn {
+  const { window = defaultWindow } = options;
+  const navigator = window?.navigator;
+
+  const isSupported = useSupported(() => !!navigator && 'connection' in navigator);
+
+  const isOnline = shallowRef(navigator?.onLine ?? true);
+  const saveData = shallowRef<boolean | undefined>(undefined);
+  const offlineAt = shallowRef<number | undefined>(undefined);
+  const onlineAt = shallowRef<number | undefined>(undefined);
+  const downlink = shallowRef<number | undefined>(undefined);
+  const downlinkMax = shallowRef<number | undefined>(undefined);
+  const rtt = shallowRef<number | undefined>(undefined);
+  const effectiveType = shallowRef<NetworkEffectiveType>(undefined);
+  const type = shallowRef<NetworkType>('unknown');
+
+  const connection = navigator && 'connection' in navigator
+    ? (navigator as Navigator & { connection?: NetworkInformation }).connection
+    : undefined;
+
+  function updateNetworkInformation(): void {
+    if (!navigator)
+      return;
+
+    isOnline.value = navigator.onLine;
+    offlineAt.value = isOnline.value ? offlineAt.value : timestamp();
+    onlineAt.value = isOnline.value ? timestamp() : onlineAt.value;
+
+    if (connection) {
+      downlink.value = connection.downlink;
+      downlinkMax.value = connection.downlinkMax;
+      effectiveType.value = connection.effectiveType;
+      rtt.value = connection.rtt;
+      saveData.value = connection.saveData;
+      type.value = connection.type ?? 'unknown';
+    }
+  }
+
+  const listenerOptions = { passive: true } as const;
+
+  if (window) {
+    useEventListener(window, 'offline', () => {
+      isOnline.value = false;
+      offlineAt.value = timestamp();
+    }, listenerOptions);
+
+    useEventListener(window, 'online', () => {
+      isOnline.value = true;
+      onlineAt.value = timestamp();
+    }, listenerOptions);
+  }
+
+  if (connection)
+    useEventListener(connection, 'change', updateNetworkInformation, listenerOptions);
+
+  updateNetworkInformation();
+
+  return {
+    isSupported,
+    isOnline: shallowReadonly(isOnline),
+    saveData: shallowReadonly(saveData),
+    offlineAt: shallowReadonly(offlineAt),
+    onlineAt: shallowReadonly(onlineAt),
+    downlink: shallowReadonly(downlink),
+    downlinkMax: shallowReadonly(downlinkMax),
+    effectiveType: shallowReadonly(effectiveType),
+    rtt: shallowReadonly(rtt),
+    type: shallowReadonly(type),
+  };
+}

vue/toolkit/src/composables/browser/useObjectUrl/index.test.ts

@@ -0,0 +1,169 @@
+import { describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick, shallowRef } from 'vue';
+import { useObjectUrl } from '.';
+
+function createUrlStub() {
+  let counter = 0;
+  const createObjectURL = vi.fn((_object: Blob | MediaSource) => `blob:mock/${counter++}`);
+  const revokeObjectURL = vi.fn((_url: string) => {});
+  const window = { URL: { createObjectURL, revokeObjectURL } } as unknown as Window;
+
+  return { window, createObjectURL, revokeObjectURL };
+}
+
+function makeBlob(content = 'hello') {
+  return new Blob([content], { type: 'text/plain' });
+}
+
+describe(useObjectUrl, () => {
+  it('creates an object URL for an initial value', () => {
+    const { window, createObjectURL } = createUrlStub();
+    const blob = makeBlob();
+    const scope = effectScope();
+
+    let url: ReturnType<typeof useObjectUrl>;
+    scope.run(() => {
+      url = useObjectUrl(shallowRef(blob), { window });
+    });
+
+    expect(createObjectURL).toHaveBeenCalledTimes(1);
+    expect(createObjectURL).toHaveBeenCalledWith(blob);
+    expect(url!.value).toBe('blob:mock/0');
+
+    scope.stop();
+  });
+
+  it('returns undefined when the source is null/undefined', () => {
+    const { window, createObjectURL } = createUrlStub();
+    const scope = effectScope();
+
+    let url: ReturnType<typeof useObjectUrl>;
+    scope.run(() => {
+      url = useObjectUrl(shallowRef<Blob | undefined>(undefined), { window });
+    });
+
+    expect(createObjectURL).not.toHaveBeenCalled();
+    expect(url!.value).toBeUndefined();
+
+    scope.stop();
+  });
+
+  it('revokes the previous URL and creates a new one when the source changes', async () => {
+    const { window, createObjectURL, revokeObjectURL } = createUrlStub();
+    const source = shallowRef<Blob | undefined>(makeBlob('a'));
+    const scope = effectScope();
+
+    let url: ReturnType<typeof useObjectUrl>;
+    scope.run(() => {
+      url = useObjectUrl(source, { window });
+    });
+
+    expect(url!.value).toBe('blob:mock/0');
+
+    source.value = makeBlob('b');
+    await nextTick();
+
+    expect(revokeObjectURL).toHaveBeenCalledTimes(1);
+    expect(revokeObjectURL).toHaveBeenCalledWith('blob:mock/0');
+    expect(createObjectURL).toHaveBeenCalledTimes(2);
+    expect(url!.value).toBe('blob:mock/1');
+
+    scope.stop();
+  });
+
+  it('revokes and clears when the source becomes null', async () => {
+    const { window, revokeObjectURL } = createUrlStub();
+    const source = shallowRef<Blob | null>(makeBlob());
+    const scope = effectScope();
+
+    let url: ReturnType<typeof useObjectUrl>;
+    scope.run(() => {
+      url = useObjectUrl(source, { window });
+    });
+
+    expect(url!.value).toBe('blob:mock/0');
+
+    source.value = null;
+    await nextTick();
+
+    expect(revokeObjectURL).toHaveBeenCalledWith('blob:mock/0');
+    expect(url!.value).toBeUndefined();
+
+    scope.stop();
+  });
+
+  it('revokes the active URL on scope dispose', () => {
+    const { window, revokeObjectURL } = createUrlStub();
+    const scope = effectScope();
+
+    let url: ReturnType<typeof useObjectUrl>;
+    scope.run(() => {
+      url = useObjectUrl(shallowRef(makeBlob()), { window });
+    });
+
+    expect(url!.value).toBe('blob:mock/0');
+    expect(revokeObjectURL).not.toHaveBeenCalled();
+
+    scope.stop();
+
+    expect(revokeObjectURL).toHaveBeenCalledTimes(1);
+    expect(revokeObjectURL).toHaveBeenCalledWith('blob:mock/0');
+  });
+
+  it('accepts a getter source', async () => {
+    const { window, createObjectURL } = createUrlStub();
+    const source = shallowRef<Blob | undefined>(undefined);
+    const scope = effectScope();
+
+    let url: ReturnType<typeof useObjectUrl>;
+    scope.run(() => {
+      url = useObjectUrl(() => source.value, { window });
+    });
+
+    expect(url!.value).toBeUndefined();
+
+    source.value = makeBlob();
+    await nextTick();
+
+    expect(createObjectURL).toHaveBeenCalledTimes(1);
+    expect(url!.value).toBe('blob:mock/0');
+
+    scope.stop();
+  });
+
+  it('returns a read-only ref', () => {
+    const { window } = createUrlStub();
+    const scope = effectScope();
+
+    let url: ReturnType<typeof useObjectUrl>;
+    scope.run(() => {
+      url = useObjectUrl(shallowRef(makeBlob()), { window });
+    });
+
+    // shallowReadonly should warn and not mutate when written to
+    const warn = vi.spyOn(console, 'warn').mockImplementation(() => {});
+    // @ts-expect-error read-only ref
+    url!.value = 'mutated';
+    expect(url!.value).toBe('blob:mock/0');
+    warn.mockRestore();
+
+    scope.stop();
+  });
+
+  it('does nothing in an unsupported / SSR environment (no window)', () => {
+    const scope = effectScope();
+
+    // Simulate SSR: no `window` available. Destructuring defaults only kick in
+    // for `undefined`, so pass an explicit `null` to mirror `defaultWindow`
+    // being `undefined` on the server (the guard treats any falsy window the same).
+    let url: ReturnType<typeof useObjectUrl>;
+    scope.run(() => {
+      url = useObjectUrl(shallowRef(makeBlob()), { window: null as unknown as Window });
+    });
+
+    expect(url!.value).toBeUndefined();
+
+    // disposing must not throw even though there is no window
+    expect(() => scope.stop()).not.toThrow();
+  });
+});

vue/toolkit/src/composables/browser/useObjectUrl/index.ts

@@ -0,0 +1,55 @@
+import { shallowReadonly, shallowRef, toValue, watch } from 'vue';
+import type { MaybeRefOrGetter, ShallowRef } from 'vue';
+import { defaultWindow } from '@/types';
+import type { ConfigurableWindow } from '@/types';
+import { tryOnScopeDispose } from '@/composables/lifecycle/tryOnScopeDispose';
+
+export interface UseObjectUrlOptions extends ConfigurableWindow {}
+
+export type UseObjectUrlReturn = Readonly<ShallowRef<string | undefined>>;
+
+/**
+ * @name useObjectUrl
+ * @category Browser
+ * @description Create and auto-revoke an object URL for a `Blob`, `File`, or `MediaSource`. The previous URL is revoked whenever the source changes, and the active URL is revoked on scope dispose.
+ *
+ * @param {MaybeRefOrGetter<Blob | MediaSource | null | undefined>} object The reactive source to create an object URL for
+ * @param {UseObjectUrlOptions} [options={}] Options
+ * @returns {UseObjectUrlReturn} A read-only ref holding the current object URL, or `undefined` when there is no source (or in unsupported/SSR environments)
+ *
+ * @example
+ * const file = shallowRef<File>();
+ * const url = useObjectUrl(file);
+ *
+ * @since 0.0.15
+ */
+export function useObjectUrl(
+  object: MaybeRefOrGetter<Blob | MediaSource | null | undefined>,
+  options: UseObjectUrlOptions = {},
+): UseObjectUrlReturn {
+  const { window = defaultWindow } = options;
+
+  const url = shallowRef<string | undefined>();
+
+  const release = (): void => {
+    if (url.value)
+      (window as (Window & typeof globalThis) | undefined)?.URL.revokeObjectURL(url.value);
+
+    url.value = undefined;
+  };
+
+  watch(
+    () => toValue(object),
+    (newObject) => {
+      release();
+
+      if (newObject && window)
+        url.value = (window as Window & typeof globalThis).URL.createObjectURL(newObject);
+    },
+    { immediate: true },
+  );
+
+  tryOnScopeDispose(release);
+
+  return shallowReadonly(url);
+}

vue/toolkit/src/composables/browser/useOnline/index.test.ts

@@ -0,0 +1,44 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick } from 'vue';
+import { useOnline } from '.';
+
+afterEach(() => vi.unstubAllGlobals());
+
+describe(useOnline, () => {
+  it('reflects the initial navigator.onLine', () => {
+    const scope = effectScope();
+    let online: ReturnType<typeof useOnline>;
+    scope.run(() => {
+      online = useOnline();
+    });
+    expect(online!.value).toBe(navigator.onLine);
+    scope.stop();
+  });
+
+  it('updates on offline/online events', async () => {
+    const scope = effectScope();
+    let online: ReturnType<typeof useOnline>;
+    scope.run(() => {
+      online = useOnline();
+    });
+
+    globalThis.dispatchEvent(new Event('offline'));
+    await nextTick();
+    expect(online!.value).toBeFalsy();
+
+    globalThis.dispatchEvent(new Event('online'));
+    await nextTick();
+    expect(online!.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('defaults to true when there is no window (SSR)', () => {
+    const scope = effectScope();
+    let online: ReturnType<typeof useOnline>;
+    scope.run(() => {
+      online = useOnline({ window: undefined as any });
+    });
+    expect(online!.value).toBeTruthy();
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useOnline/index.ts

@@ -0,0 +1,38 @@
+import { shallowReadonly, shallowRef } from 'vue';
+import type { ShallowRef } from 'vue';
+import { defaultWindow } from '@/types';
+import type { ConfigurableWindow } from '@/types';
+import { useEventListener } from '@/composables/browser/useEventListener';
+
+export interface UseOnlineOptions extends ConfigurableWindow {}
+
+/**
+ * @name useOnline
+ * @category Browser
+ * @description Reactive online/offline status based on `navigator.onLine`.
+ * For connection details (effectiveType, downlink, saveData, transition
+ * timestamps, ...) use {@link useNetwork} instead.
+ *
+ * @param {UseOnlineOptions} [options={}] Options
+ * @returns {Readonly<ShallowRef<boolean>>} Whether the browser is online
+ *
+ * @example
+ * const online = useOnline();
+ *
+ * @since 0.0.15
+ */
+export function useOnline(options: UseOnlineOptions = {}): Readonly<ShallowRef<boolean>> {
+  const { window = defaultWindow } = options;
+
+  const isOnline = shallowRef(window?.navigator?.onLine ?? true);
+
+  useEventListener(window, 'online', () => {
+    isOnline.value = true;
+  }, { passive: true });
+
+  useEventListener(window, 'offline', () => {
+    isOnline.value = false;
+  }, { passive: true });
+
+  return shallowReadonly(isOnline);
+}

vue/toolkit/src/composables/browser/usePageLeave/index.test.ts

@@ -0,0 +1,95 @@
+import { describe, expect, it, vi } from 'vitest';
+import { effectScope, isReadonly, nextTick } from 'vue';
+import { usePageLeave } from '.';
+
+function withScope<T>(fn: () => T): { value: T; stop: () => void } {
+  const scope = effectScope();
+  let value!: T;
+  scope.run(() => {
+    value = fn();
+  });
+  return { value, stop: () => scope.stop() };
+}
+
+describe(usePageLeave, () => {
+  it('is false initially', () => {
+    const { value: isLeft, stop } = withScope(() => usePageLeave());
+    expect(isLeft.value).toBeFalsy();
+    stop();
+  });
+
+  it('returns a writable shallow ref', () => {
+    const { value: isLeft, stop } = withScope(() => usePageLeave());
+    expect(isReadonly(isLeft)).toBeFalsy();
+    stop();
+  });
+
+  it('becomes true when the pointer leaves the document', async () => {
+    const { value: isLeft, stop } = withScope(() => usePageLeave());
+
+    document.documentElement.dispatchEvent(new MouseEvent('mouseleave'));
+    await nextTick();
+    expect(isLeft.value).toBeTruthy();
+
+    document.documentElement.dispatchEvent(new MouseEvent('mouseenter'));
+    await nextTick();
+    expect(isLeft.value).toBeFalsy();
+    stop();
+  });
+
+  it('uses mouseout relatedTarget to detect leaving', async () => {
+    const { value: isLeft, stop } = withScope(() => usePageLeave());
+
+    // No relatedTarget => pointer left the page.
+    globalThis.dispatchEvent(new MouseEvent('mouseout'));
+    await nextTick();
+    expect(isLeft.value).toBeTruthy();
+
+    // relatedTarget present => pointer moved to another element, still on page.
+    globalThis.dispatchEvent(new MouseEvent('mouseout', { relatedTarget: document.body }));
+    await nextTick();
+    expect(isLeft.value).toBeFalsy();
+    stop();
+  });
+
+  it('invokes onChange with the new value and event only on change', async () => {
+    const onChange = vi.fn();
+    const { stop } = withScope(() => usePageLeave({ onChange }));
+
+    document.documentElement.dispatchEvent(new MouseEvent('mouseleave'));
+    await nextTick();
+    expect(onChange).toHaveBeenCalledTimes(1);
+    expect(onChange).toHaveBeenLastCalledWith(true, expect.any(MouseEvent));
+
+    // Repeated leave should not fire again (no state change).
+    document.documentElement.dispatchEvent(new MouseEvent('mouseleave'));
+    await nextTick();
+    expect(onChange).toHaveBeenCalledTimes(1);
+
+    document.documentElement.dispatchEvent(new MouseEvent('mouseenter'));
+    await nextTick();
+    expect(onChange).toHaveBeenCalledTimes(2);
+    expect(onChange).toHaveBeenLastCalledWith(false, expect.any(MouseEvent));
+    stop();
+  });
+
+  it('does not throw and stays false when window is undefined (SSR)', () => {
+    const { value: isLeft, stop } = withScope(() =>
+      usePageLeave({ window: undefined }),
+    );
+    expect(isLeft.value).toBeFalsy();
+    stop();
+  });
+
+  it('binds listeners to a custom window', async () => {
+    const onChange = vi.fn();
+    const { stop } = withScope(() => usePageLeave({ window: globalThis as unknown as Window, onChange }));
+
+    document.documentElement.dispatchEvent(new MouseEvent('mouseleave'));
+    await nextTick();
+    expect(onChange).toHaveBeenCalledWith(true, expect.any(MouseEvent));
+    document.documentElement.dispatchEvent(new MouseEvent('mouseenter'));
+    await nextTick();
+    stop();
+  });
+});

vue/toolkit/src/composables/browser/usePageLeave/index.ts

@@ -0,0 +1,71 @@
+import { shallowRef } from 'vue';
+import type { ShallowRef } from 'vue';
+import { defaultWindow } from '@/types';
+import type { ConfigurableWindow } from '@/types';
+import { useEventListener } from '@/composables/browser/useEventListener';
+
+export interface UsePageLeaveOptions extends ConfigurableWindow {
+  /**
+   * Called whenever the leave state flips, receiving the new value and the
+   * originating mouse event.
+   *
+   * @default undefined
+   */
+  onChange?: (isLeft: boolean, event: MouseEvent) => void;
+}
+
+export type UsePageLeaveReturn = ShallowRef<boolean>;
+
+/**
+ * @name usePageLeave
+ * @category Browser
+ * @description Reactive flag indicating whether the mouse has left the page.
+ *
+ * @param {UsePageLeaveOptions} [options={}] Options (custom `window`, `onChange` callback)
+ * @returns {UsePageLeaveReturn} Whether the pointer has left the page
+ *
+ * @example
+ * const hasLeft = usePageLeave();
+ *
+ * @example
+ * usePageLeave({
+ *   onChange: (isLeft) => {
+ *     if (isLeft) showExitIntentModal();
+ *   },
+ * });
+ *
+ * @since 0.0.15
+ */
+export function usePageLeave(options: UsePageLeaveOptions = {}): UsePageLeaveReturn {
+  const { window = defaultWindow, onChange } = options;
+
+  const isLeft = shallowRef(false);
+
+  const update = (left: boolean, event: MouseEvent) => {
+    if (left === isLeft.value)
+      return;
+
+    isLeft.value = left;
+    onChange?.(left, event);
+  };
+
+  if (window) {
+    const documentElement = window.document.documentElement;
+    const listenerOptions = { passive: true } as const;
+
+    useEventListener(window, 'mouseout', (event) => {
+      const from = event.relatedTarget || (event as MouseEvent & { toElement?: EventTarget }).toElement;
+      update(!from, event);
+    }, listenerOptions);
+
+    useEventListener(documentElement, 'mouseleave', (event) => {
+      update(true, event);
+    }, listenerOptions);
+
+    useEventListener(documentElement, 'mouseenter', (event) => {
+      update(false, event);
+    }, listenerOptions);
+  }
+
+  return isLeft;
+}

vue/toolkit/src/composables/browser/usePermission/index.test.ts

@@ -0,0 +1,175 @@
+import { describe, expect, it, vi } from 'vitest';
+import { effectScope } from 'vue';
+import type { UsePermissionReturn } from '.';
+import { usePermission } from '.';
+
+function stubPermissions(state: PermissionState) {
+  let changeHandler: ((this: PermissionStatus, ev: Event) => any) | undefined;
+  const status = {
+    state,
+    addEventListener: vi.fn((_: string, handler: any) => { changeHandler = handler; }),
+    removeEventListener: vi.fn(() => { changeHandler = undefined; }),
+  };
+  const query = vi.fn(async () => status);
+  const navigator = { permissions: { query } } as unknown as Navigator;
+  const emitChange = (next: PermissionState) => {
+    status.state = next;
+    changeHandler?.call(status as unknown as PermissionStatus, new Event('change'));
+  };
+  return { navigator, status, query, emitChange, getChangeHandler: () => changeHandler };
+}
+
+describe(usePermission, () => {
+  it('resolves the permission state', async () => {
+    const { navigator } = stubPermissions('granted');
+    const scope = effectScope();
+    let state: UsePermissionReturn;
+    scope.run(() => {
+      state = usePermission('geolocation', { navigator });
+    });
+
+    await vi.waitFor(() => expect(state!.value).toBe('granted'));
+    scope.stop();
+  });
+
+  it('exposes controls when controls: true', async () => {
+    const { navigator, query } = stubPermissions('prompt');
+    const scope = effectScope();
+    let result: any;
+    scope.run(() => {
+      result = usePermission('camera', { controls: true, navigator });
+    });
+
+    expect(result.isSupported.value).toBeTruthy();
+    await result.query();
+    expect(query).toHaveBeenCalled();
+    scope.stop();
+  });
+
+  it('returns undefined state when unsupported', () => {
+    const navigator = {} as Navigator;
+    const scope = effectScope();
+    let state: UsePermissionReturn;
+    scope.run(() => {
+      state = usePermission('geolocation', { navigator });
+    });
+    expect(state!.value).toBeUndefined();
+    scope.stop();
+  });
+
+  it('reacts to the status change event', async () => {
+    const { navigator, emitChange } = stubPermissions('prompt');
+    const scope = effectScope();
+    let state: UsePermissionReturn;
+    scope.run(() => {
+      state = usePermission('notifications', { navigator });
+    });
+
+    await vi.waitFor(() => expect(state!.value).toBe('prompt'));
+
+    emitChange('granted');
+    await vi.waitFor(() => expect(state!.value).toBe('granted'));
+
+    emitChange('denied');
+    await vi.waitFor(() => expect(state!.value).toBe('denied'));
+    scope.stop();
+  });
+
+  it('binds the change listener exactly once after resolution', async () => {
+    const { navigator, status } = stubPermissions('granted');
+    const scope = effectScope();
+    let state: UsePermissionReturn;
+    scope.run(() => {
+      state = usePermission('camera', { navigator });
+    });
+
+    await vi.waitFor(() => expect(state!.value).toBe('granted'));
+    expect(status.addEventListener).toHaveBeenCalledTimes(1);
+    expect(status.addEventListener).toHaveBeenCalledWith('change', expect.any(Function), { passive: true });
+    scope.stop();
+  });
+
+  it('removes the change listener when the scope is disposed', async () => {
+    const { navigator, status } = stubPermissions('granted');
+    const scope = effectScope();
+    let state: UsePermissionReturn;
+    scope.run(() => {
+      state = usePermission('camera', { navigator });
+    });
+
+    await vi.waitFor(() => expect(state!.value).toBe('granted'));
+    scope.stop();
+    expect(status.removeEventListener).toHaveBeenCalledWith('change', expect.any(Function), { passive: true });
+  });
+
+  it('dedupes concurrent and repeated queries', async () => {
+    const { navigator, query } = stubPermissions('granted');
+    const scope = effectScope();
+    let result: any;
+    scope.run(() => {
+      result = usePermission('microphone', { controls: true, navigator });
+    });
+
+    // initial query() call from setup + two more concurrent calls
+    await Promise.all([result.query(), result.query()]);
+    // once resolved, subsequent calls reuse the cached status
+    await result.query();
+
+    expect(query).toHaveBeenCalledTimes(1);
+    scope.stop();
+  });
+
+  it('query resolves to the raw PermissionStatus with controls', async () => {
+    const { navigator, status } = stubPermissions('granted');
+    const scope = effectScope();
+    let result: any;
+    scope.run(() => {
+      result = usePermission('geolocation', { controls: true, navigator });
+    });
+
+    const resolved = await result.query();
+    expect(resolved).toBe(status);
+    scope.stop();
+  });
+
+  it('query resolves to undefined when unsupported', async () => {
+    const navigator = {} as Navigator;
+    const scope = effectScope();
+    let result: any;
+    scope.run(() => {
+      result = usePermission('geolocation', { controls: true, navigator });
+    });
+
+    expect(result.isSupported.value).toBeFalsy();
+    await expect(result.query()).resolves.toBeUndefined();
+    scope.stop();
+  });
+
+  it('falls back to "prompt" when the query rejects', async () => {
+    const query = vi.fn(async () => {
+      throw new TypeError('denied descriptor');
+    });
+    const navigator = { permissions: { query } } as unknown as Navigator;
+    const scope = effectScope();
+    let state: UsePermissionReturn;
+    scope.run(() => {
+      state = usePermission('push', { navigator });
+    });
+
+    await vi.waitFor(() => expect(state!.value).toBe('prompt'));
+    scope.stop();
+  });
+
+  it('accepts a descriptor object', async () => {
+    const { navigator, query } = stubPermissions('granted');
+    const scope = effectScope();
+    let state: UsePermissionReturn;
+    scope.run(() => {
+      state = usePermission({ name: 'push', userVisibleOnly: true } as PermissionDescriptor, { navigator });
+    });
+
+    await vi.waitFor(() => expect(state!.value).toBe('granted'));
+    expect(query).toHaveBeenCalledWith({ name: 'push', userVisibleOnly: true });
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/usePermission/index.ts

@@ -0,0 +1,159 @@
+import { shallowRef, toRaw } from 'vue';
+import type { Ref, ShallowRef } from 'vue';
+import { isString } from '@robonen/stdlib';
+import { defaultNavigator } from '@/types';
+import type { ConfigurableNavigator } from '@/types';
+import { useSupported } from '@/composables/browser/useSupported';
+import { useEventListener } from '@/composables/browser/useEventListener';
+
+/**
+ * Permission names not yet present in the lib DOM `PermissionName` union but
+ * supported by browsers behind the Permissions API.
+ */
+export type PermissionDescriptorNamePolyfill
+  = | 'accelerometer'
+    | 'accessibility-events'
+    | 'ambient-light-sensor'
+    | 'background-sync'
+    | 'camera'
+    | 'clipboard-read'
+    | 'clipboard-write'
+    | 'geolocation'
+    | 'gyroscope'
+    | 'local-fonts'
+    | 'magnetometer'
+    | 'microphone'
+    | 'midi'
+    | 'notifications'
+    | 'payment-handler'
+    | 'persistent-storage'
+    | 'push'
+    | 'screen-wake-lock'
+    | 'speaker'
+    | 'speaker-selection'
+    | 'storage-access'
+    | 'window-management';
+
+export type GeneralPermissionDescriptor
+  = | PermissionDescriptor
+    | { name: PermissionDescriptorNamePolyfill };
+
+export interface UsePermissionOptions<Controls extends boolean> extends ConfigurableNavigator {
+  /**
+   * Expose the `isSupported` flag and a `query` method that returns the raw `PermissionStatus`
+   *
+   * @default false
+   */
+  controls?: Controls;
+}
+
+export type UsePermissionReturn = Readonly<Ref<PermissionState | undefined>>;
+
+export interface UsePermissionReturnWithControls {
+  /**
+   * Reactive permission state (`granted` | `denied` | `prompt`), or `undefined` while unsupported/unresolved
+   */
+  state: UsePermissionReturn;
+  /**
+   * Whether the Permissions API is available
+   */
+  isSupported: Readonly<Ref<boolean>>;
+  /**
+   * Query (or re-query) the permission, resolving to the raw `PermissionStatus`
+   */
+  query: () => Promise<PermissionStatus | undefined>;
+}
+
+/**
+ * @name usePermission
+ * @category Browser
+ * @description Reactive Permissions API state.
+ *
+ * @param {GeneralPermissionDescriptor | string} permissionDesc The permission to query
+ * @param {UsePermissionOptions} [options={}] Options
+ * @returns {UsePermissionReturn | UsePermissionReturnWithControls} The permission state, or controls when `controls: true`
+ *
+ * @example
+ * const microphone = usePermission('microphone');
+ *
+ * @example
+ * const { state, isSupported, query } = usePermission('camera', { controls: true });
+ *
+ * @since 0.0.15
+ */
+export function usePermission(
+  permissionDesc: GeneralPermissionDescriptor | GeneralPermissionDescriptor['name'],
+  options?: UsePermissionOptions<false>,
+): UsePermissionReturn;
+export function usePermission(
+  permissionDesc: GeneralPermissionDescriptor | GeneralPermissionDescriptor['name'],
+  options: UsePermissionOptions<true>,
+): UsePermissionReturnWithControls;
+export function usePermission(
+  permissionDesc: GeneralPermissionDescriptor | GeneralPermissionDescriptor['name'],
+  options: UsePermissionOptions<boolean> = {},
+): UsePermissionReturn | UsePermissionReturnWithControls {
+  const { controls = false, navigator = defaultNavigator } = options;
+
+  const isSupported = useSupported(() => !!navigator && 'permissions' in navigator);
+
+  const desc = (isString(permissionDesc)
+    ? { name: permissionDesc }
+    : permissionDesc) as PermissionDescriptor;
+
+  // Shallow refs: `PermissionStatus` is a host object, deep reactivity is wasteful.
+  const permissionStatus: ShallowRef<PermissionStatus | undefined> = shallowRef();
+  const state: ShallowRef<PermissionState | undefined> = shallowRef();
+
+  const update = (): void => {
+    state.value = permissionStatus.value?.state ?? 'prompt';
+  };
+
+  // Register the `change` listener synchronously against the reactive ref so it
+  // auto-rebinds when the status resolves and auto-cleans on scope dispose.
+  useEventListener(permissionStatus, 'change', update, { passive: true });
+
+  // Dedupe concurrent/repeat calls: once a query is in flight we reuse it.
+  let queryPromise: Promise<PermissionStatus | undefined> | undefined;
+
+  const query = (): Promise<PermissionStatus | undefined> => {
+    if (!isSupported.value)
+      return Promise.resolve(undefined);
+
+    if (permissionStatus.value)
+      return Promise.resolve(permissionStatus.value);
+
+    if (queryPromise)
+      return queryPromise;
+
+    queryPromise = navigator!.permissions
+      .query(desc)
+      .then((status) => {
+        permissionStatus.value = status;
+        return status;
+      })
+      .catch(() => {
+        permissionStatus.value = undefined;
+        return undefined;
+      })
+      .finally(() => {
+        update();
+        queryPromise = undefined;
+      });
+
+    return queryPromise;
+  };
+
+  query();
+
+  if (controls) {
+    return {
+      state: state as UsePermissionReturn,
+      isSupported,
+      // `toRaw` so callers get the underlying `PermissionStatus`, not a reactive proxy.
+      query: () => query().then(status => (status ? toRaw(status) : undefined)),
+    };
+  }
+
+  return state as UsePermissionReturn;
+}

vue/toolkit/src/composables/browser/usePointer/index.test.ts

@@ -0,0 +1,218 @@
+import { describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick, shallowRef } from 'vue';
+import { usePointer } from '.';
+
+interface PointerProps {
+  x?: number;
+  y?: number;
+  pressure?: number;
+  pointerId?: number;
+  tiltX?: number;
+  tiltY?: number;
+  width?: number;
+  height?: number;
+  twist?: number;
+  pointerType?: string;
+}
+
+function dispatchPointer(target: EventTarget, type: string, props: PointerProps = {}) {
+  const event = new Event(type, { bubbles: true });
+  for (const [key, value] of Object.entries(props))
+    Object.defineProperty(event, key, { value, configurable: true });
+  target.dispatchEvent(event);
+  return event;
+}
+
+describe(usePointer, () => {
+  it('starts from the default state', () => {
+    const scope = effectScope();
+    let ptr: ReturnType<typeof usePointer>;
+    scope.run(() => {
+      ptr = usePointer();
+    });
+
+    expect(ptr!.x.value).toBe(0);
+    expect(ptr!.y.value).toBe(0);
+    expect(ptr!.pressure.value).toBe(0);
+    expect(ptr!.pointerId.value).toBe(0);
+    expect(ptr!.tiltX.value).toBe(0);
+    expect(ptr!.tiltY.value).toBe(0);
+    expect(ptr!.width.value).toBe(0);
+    expect(ptr!.height.value).toBe(0);
+    expect(ptr!.twist.value).toBe(0);
+    expect(ptr!.pointerType.value).toBe(null);
+    expect(ptr!.isInside.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('merges the initial value over defaults', () => {
+    const scope = effectScope();
+    let ptr: ReturnType<typeof usePointer>;
+    scope.run(() => {
+      ptr = usePointer({ initialValue: { x: 12, pressure: 0.5 } });
+    });
+
+    expect(ptr!.x.value).toBe(12);
+    expect(ptr!.pressure.value).toBe(0.5);
+    expect(ptr!.y.value).toBe(0);
+    scope.stop();
+  });
+
+  it('tracks pointermove and populates the full state', async () => {
+    const scope = effectScope();
+    let ptr: ReturnType<typeof usePointer>;
+    scope.run(() => {
+      ptr = usePointer();
+    });
+
+    dispatchPointer(globalThis, 'pointermove', {
+      x: 100,
+      y: 200,
+      pressure: 0.7,
+      pointerId: 3,
+      tiltX: 10,
+      tiltY: -5,
+      width: 4,
+      height: 6,
+      twist: 90,
+      pointerType: 'pen',
+    });
+    await nextTick();
+
+    expect(ptr!.x.value).toBe(100);
+    expect(ptr!.y.value).toBe(200);
+    expect(ptr!.pressure.value).toBe(0.7);
+    expect(ptr!.pointerId.value).toBe(3);
+    expect(ptr!.tiltX.value).toBe(10);
+    expect(ptr!.tiltY.value).toBe(-5);
+    expect(ptr!.width.value).toBe(4);
+    expect(ptr!.height.value).toBe(6);
+    expect(ptr!.twist.value).toBe(90);
+    expect(ptr!.pointerType.value).toBe('pen');
+    scope.stop();
+  });
+
+  it('sets isInside true on pointer activity and false on pointerleave', async () => {
+    const scope = effectScope();
+    let ptr: ReturnType<typeof usePointer>;
+    scope.run(() => {
+      ptr = usePointer();
+    });
+
+    expect(ptr!.isInside.value).toBeFalsy();
+
+    dispatchPointer(globalThis, 'pointerdown', { x: 1, y: 2, pointerType: 'mouse' });
+    await nextTick();
+    expect(ptr!.isInside.value).toBeTruthy();
+
+    dispatchPointer(globalThis, 'pointerleave');
+    await nextTick();
+    expect(ptr!.isInside.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('tracks pointerdown and pointerup', async () => {
+    const scope = effectScope();
+    let ptr: ReturnType<typeof usePointer>;
+    scope.run(() => {
+      ptr = usePointer();
+    });
+
+    dispatchPointer(globalThis, 'pointerdown', { x: 5, y: 5, pointerType: 'mouse' });
+    await nextTick();
+    expect(ptr!.x.value).toBe(5);
+
+    dispatchPointer(globalThis, 'pointerup', { x: 9, y: 9, pointerType: 'mouse' });
+    await nextTick();
+    expect(ptr!.x.value).toBe(9);
+    expect(ptr!.y.value).toBe(9);
+    scope.stop();
+  });
+
+  it('ignores events whose pointerType is not allowed', async () => {
+    const scope = effectScope();
+    let ptr: ReturnType<typeof usePointer>;
+    scope.run(() => {
+      ptr = usePointer({ pointerTypes: ['pen'], initialValue: { x: 1, y: 2 } });
+    });
+
+    dispatchPointer(globalThis, 'pointermove', { x: 50, y: 60, pointerType: 'mouse' });
+    await nextTick();
+    // mouse rejected: position unchanged, but isInside still flips true
+    expect(ptr!.x.value).toBe(1);
+    expect(ptr!.y.value).toBe(2);
+    expect(ptr!.isInside.value).toBeTruthy();
+
+    dispatchPointer(globalThis, 'pointermove', { x: 50, y: 60, pointerType: 'pen' });
+    await nextTick();
+    expect(ptr!.x.value).toBe(50);
+    expect(ptr!.y.value).toBe(60);
+    expect(ptr!.pointerType.value).toBe('pen');
+    scope.stop();
+  });
+
+  it('attaches passive listeners', () => {
+    const addSpy = vi.spyOn(globalThis, 'addEventListener');
+    const scope = effectScope();
+    scope.run(() => {
+      usePointer();
+    });
+
+    const moveCall = addSpy.mock.calls.find(([name]) => name === 'pointermove');
+    expect(moveCall).toBeDefined();
+    expect((moveCall![2] as AddEventListenerOptions).passive).toBeTruthy();
+
+    addSpy.mockRestore();
+    scope.stop();
+  });
+
+  it('listens on a custom element target', async () => {
+    const el = document.createElement('div');
+    const elRef = shallowRef(el);
+    const addSpy = vi.spyOn(el, 'addEventListener');
+
+    const scope = effectScope();
+    let ptr: ReturnType<typeof usePointer>;
+    scope.run(() => {
+      ptr = usePointer({ target: elRef });
+    });
+    await nextTick();
+
+    expect(addSpy.mock.calls.some(([name]) => name === 'pointermove')).toBeTruthy();
+
+    dispatchPointer(el, 'pointermove', { x: 7, y: 8, pointerType: 'mouse' });
+    await nextTick();
+
+    expect(ptr!.x.value).toBe(7);
+    expect(ptr!.y.value).toBe(8);
+
+    addSpy.mockRestore();
+    scope.stop();
+  });
+
+  it('exposes writable state refs', () => {
+    const scope = effectScope();
+    let ptr: ReturnType<typeof usePointer>;
+    scope.run(() => {
+      ptr = usePointer();
+    });
+
+    ptr!.x.value = 42;
+    expect(ptr!.x.value).toBe(42);
+    scope.stop();
+  });
+
+  it('does nothing when window is unavailable (SSR)', () => {
+    const scope = effectScope();
+    let ptr: ReturnType<typeof usePointer>;
+    scope.run(() => {
+      ptr = usePointer({ window: undefined, target: undefined });
+    });
+
+    expect(ptr!.x.value).toBe(0);
+    expect(ptr!.y.value).toBe(0);
+    expect(ptr!.pointerType.value).toBe(null);
+    expect(ptr!.isInside.value).toBeFalsy();
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/usePointer/index.ts

@@ -0,0 +1,162 @@
+import { computed, shallowRef } from 'vue';
+import type { ShallowRef, WritableComputedRef } from 'vue';
+import { pick } from '@robonen/stdlib';
+import { defaultWindow } from '@/types';
+import type { ConfigurableWindow } from '@/types';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { unrefElement } from '@/composables/component/unrefElement';
+import type { MaybeComputedElementRef } from '@/composables/component/unrefElement';
+
+export type UsePointerType = 'mouse' | 'touch' | 'pen';
+
+export interface UsePointerState {
+  x: number;
+  y: number;
+  pressure: number;
+  pointerId: number;
+  tiltX: number;
+  tiltY: number;
+  width: number;
+  height: number;
+  twist: number;
+  pointerType: UsePointerType | null;
+}
+
+export interface UsePointerOptions extends ConfigurableWindow {
+  /**
+   * Pointer types that should be listened to.
+   *
+   * @default ['mouse', 'touch', 'pen']
+   */
+  pointerTypes?: UsePointerType[];
+
+  /**
+   * Initial pointer state.
+   */
+  initialValue?: Partial<UsePointerState>;
+
+  /**
+   * Target to attach the listeners to. Accepts a window, document, element ref,
+   * getter, or component instance.
+   *
+   * @default window
+   */
+  target?: MaybeComputedElementRef | Window | Document;
+}
+
+export interface UsePointerReturn {
+  x: WritableComputedRef<number>;
+  y: WritableComputedRef<number>;
+  pressure: WritableComputedRef<number>;
+  pointerId: WritableComputedRef<number>;
+  tiltX: WritableComputedRef<number>;
+  tiltY: WritableComputedRef<number>;
+  width: WritableComputedRef<number>;
+  height: WritableComputedRef<number>;
+  twist: WritableComputedRef<number>;
+  pointerType: WritableComputedRef<UsePointerType | null>;
+  isInside: ShallowRef<boolean>;
+}
+
+const defaultState: UsePointerState = {
+  x: 0,
+  y: 0,
+  pointerId: 0,
+  pressure: 0,
+  tiltX: 0,
+  tiltY: 0,
+  width: 0,
+  height: 0,
+  twist: 0,
+  pointerType: null,
+};
+
+const keys = Object.keys(defaultState) as Array<keyof UsePointerState>;
+
+/**
+ * @name usePointer
+ * @category Browser
+ * @description Reactive pointer state (position, pressure, tilt, size, and
+ * pointer type) sourced from pointer events on a target, plus whether the
+ * pointer is currently inside it.
+ *
+ * @param {UsePointerOptions} [options={}] Options
+ * @returns {UsePointerReturn} Reactive pointer state refs and `isInside`
+ *
+ * @example
+ * const { x, y, pressure, pointerType, isInside } = usePointer();
+ *
+ * @example
+ * // Track a specific element, pen only
+ * const { x, y, tiltX, tiltY } = usePointer({ target: el, pointerTypes: ['pen'] });
+ *
+ * @since 0.0.15
+ */
+export function usePointer(options: UsePointerOptions = {}): UsePointerReturn {
+  const {
+    pointerTypes,
+    initialValue = {},
+    window = defaultWindow,
+    target = window,
+  } = options;
+
+  const isInside = shallowRef(false);
+
+  const state = shallowRef<UsePointerState>({
+    ...defaultState,
+    ...initialValue,
+  });
+
+  const handler = (event: PointerEvent) => {
+    isInside.value = true;
+
+    if (pointerTypes && !pointerTypes.includes(event.pointerType as UsePointerType))
+      return;
+
+    state.value = pick(event, keys) as UsePointerState;
+  };
+
+  // A raw window/document/EventTarget is used directly (fast, non-reactive path
+  // in useEventListener). Refs/getters/element instances are resolved lazily via
+  // a getter so the listeners re-bind when the underlying element changes.
+  const listenTarget = isTarget(target)
+    ? target
+    : (): EventTarget | null | undefined => unrefElement(target as MaybeComputedElementRef) as EventTarget | null | undefined;
+
+  if (target) {
+    const listenerOptions = { passive: true };
+
+    useEventListener(listenTarget, ['pointerdown', 'pointermove', 'pointerup'], handler as (e: Event) => void, listenerOptions);
+    useEventListener(listenTarget, 'pointerleave', () => (isInside.value = false), listenerOptions);
+  }
+
+  // Derive a writable ref per field that reads/writes through the single
+  // shallowRef holding the whole state, matching VueUse's `toRefs(shallowRef)`.
+  const toField = <K extends keyof UsePointerState>(key: K): WritableComputedRef<UsePointerState[K]> =>
+    computed({
+      get: () => state.value[key],
+      set: value => (state.value = { ...state.value, [key]: value }),
+    });
+
+  return {
+    x: toField('x'),
+    y: toField('y'),
+    pressure: toField('pressure'),
+    pointerId: toField('pointerId'),
+    tiltX: toField('tiltX'),
+    tiltY: toField('tiltY'),
+    width: toField('width'),
+    height: toField('height'),
+    twist: toField('twist'),
+    pointerType: toField('pointerType'),
+    isInside,
+  };
+}
+
+/**
+ * `true` for an object that is itself an event target (window/document/element)
+ * and should be attached to directly, rather than unwrapped from a ref/getter.
+ */
+function isTarget(value: unknown): value is EventTarget {
+  return typeof value === 'object' && value !== null && 'addEventListener' in value;
+}

vue/toolkit/src/composables/browser/usePreferredColorScheme/index.test.ts

@@ -0,0 +1,53 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick } from 'vue';
+import { usePreferredColorScheme } from '.';
+
+function stubScheme(scheme: 'dark' | 'light' | 'none') {
+  vi.stubGlobal('matchMedia', vi.fn((media: string) => ({
+    matches: scheme !== 'none' && media.includes(scheme),
+    media,
+    addEventListener: () => {},
+    removeEventListener: () => {},
+  })));
+}
+
+describe(usePreferredColorScheme, () => {
+  beforeEach(() => vi.stubGlobal('matchMedia', undefined));
+  afterEach(() => vi.unstubAllGlobals());
+
+  it('returns dark when dark is preferred', async () => {
+    stubScheme('dark');
+    const scope = effectScope();
+    let scheme: ReturnType<typeof usePreferredColorScheme>;
+    scope.run(() => {
+      scheme = usePreferredColorScheme();
+    });
+    await nextTick();
+    expect(scheme!.value).toBe('dark');
+    scope.stop();
+  });
+
+  it('returns light when light is preferred', async () => {
+    stubScheme('light');
+    const scope = effectScope();
+    let scheme: ReturnType<typeof usePreferredColorScheme>;
+    scope.run(() => {
+      scheme = usePreferredColorScheme();
+    });
+    await nextTick();
+    expect(scheme!.value).toBe('light');
+    scope.stop();
+  });
+
+  it('returns no-preference when neither matches', async () => {
+    stubScheme('none');
+    const scope = effectScope();
+    let scheme: ReturnType<typeof usePreferredColorScheme>;
+    scope.run(() => {
+      scheme = usePreferredColorScheme();
+    });
+    await nextTick();
+    expect(scheme!.value).toBe('no-preference');
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/usePreferredColorScheme/index.ts

@@ -0,0 +1,36 @@
+import { computed } from 'vue';
+import type { ComputedRef } from 'vue';
+import type { ConfigurableWindow } from '@/types';
+import { useMediaQuery } from '@/composables/browser/useMediaQuery';
+
+export type ColorSchemePreference = 'dark' | 'light' | 'no-preference';
+
+/**
+ * @name usePreferredColorScheme
+ * @category Browser
+ * @description Reactive `prefers-color-scheme` media query.
+ *
+ * @param {ConfigurableWindow} [options={}] Options
+ * @returns {ComputedRef<ColorSchemePreference>} `'dark'`, `'light'`, or `'no-preference'`
+ *
+ * @example
+ * const scheme = usePreferredColorScheme();
+ *
+ * @since 0.0.15
+ */
+export function usePreferredColorScheme(
+  options: ConfigurableWindow = {},
+): ComputedRef<ColorSchemePreference> {
+  const isLight = useMediaQuery('(prefers-color-scheme: light)', options);
+  const isDark = useMediaQuery('(prefers-color-scheme: dark)', options);
+
+  return computed(() => {
+    if (isDark.value)
+      return 'dark';
+
+    if (isLight.value)
+      return 'light';
+
+    return 'no-preference';
+  });
+}

vue/toolkit/src/composables/browser/usePreferredDark/index.test.ts

@@ -0,0 +1,27 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick } from 'vue';
+import { usePreferredDark } from '.';
+
+describe(usePreferredDark, () => {
+  beforeEach(() => vi.stubGlobal('matchMedia', undefined));
+  afterEach(() => vi.unstubAllGlobals());
+
+  it('reflects the prefers-color-scheme: dark query', async () => {
+    vi.stubGlobal('matchMedia', vi.fn((media: string) => ({
+      matches: media.includes('dark'),
+      media,
+      addEventListener: () => {},
+      removeEventListener: () => {},
+    })));
+
+    const scope = effectScope();
+    let isDark: ReturnType<typeof usePreferredDark>;
+    scope.run(() => {
+      isDark = usePreferredDark();
+    });
+    await nextTick();
+
+    expect(isDark!.value).toBeTruthy();
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/usePreferredDark/index.ts

@@ -0,0 +1,20 @@
+import type { Ref } from 'vue';
+import type { ConfigurableWindow } from '@/types';
+import { useMediaQuery } from '@/composables/browser/useMediaQuery';
+
+/**
+ * @name usePreferredDark
+ * @category Browser
+ * @description Reactive `prefers-color-scheme: dark` media query.
+ *
+ * @param {ConfigurableWindow} [options={}] Options
+ * @returns {Ref<boolean>} Whether the user prefers a dark color scheme
+ *
+ * @example
+ * const isDark = usePreferredDark();
+ *
+ * @since 0.0.15
+ */
+export function usePreferredDark(options: ConfigurableWindow = {}): Ref<boolean> {
+  return useMediaQuery('(prefers-color-scheme: dark)', options);
+}

vue/toolkit/src/composables/browser/useRafFn/index.test.ts

@@ -1,4 +1,4 @@
-import { describe, expect, it, vi, beforeEach, afterEach } from 'vitest';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 import { defineComponent, effectScope, nextTick } from 'vue';
 import { mount } from '@vue/test-utils';
 import { useRafFn } from '.';

vue/toolkit/src/composables/browser/useResizeObserver/index.test.ts

@@ -0,0 +1,188 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick, ref } from 'vue';
+import { useResizeObserver } from '.';
+
+let instances: Array<{ cb: ResizeObserverCallback; observe: ReturnType<typeof vi.fn>; disconnect: ReturnType<typeof vi.fn> }> = [];
+
+class StubResizeObserver {
+  observe = vi.fn();
+  disconnect = vi.fn();
+  unobserve = vi.fn();
+  cb: ResizeObserverCallback;
+  constructor(cb: ResizeObserverCallback) {
+    this.cb = cb;
+    instances.push(this);
+  }
+}
+
+describe(useResizeObserver, () => {
+  beforeEach(() => {
+    instances = [];
+    vi.stubGlobal('ResizeObserver', StubResizeObserver);
+  });
+  afterEach(() => vi.unstubAllGlobals());
+
+  it('observes the target element', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    scope.run(() => useResizeObserver(ref(el), vi.fn()));
+
+    expect(instances).toHaveLength(1);
+    expect(instances[0]!.observe).toHaveBeenCalledWith(el, undefined);
+    scope.stop();
+  });
+
+  it('passes the box option through to observe', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    scope.run(() => useResizeObserver(ref(el), vi.fn(), { box: 'border-box' }));
+
+    expect(instances[0]!.observe).toHaveBeenCalledWith(el, { box: 'border-box' });
+    scope.stop();
+  });
+
+  it('observes an array of targets with a single observer', () => {
+    const a = document.createElement('div');
+    const b = document.createElement('div');
+    const scope = effectScope();
+    scope.run(() => useResizeObserver([ref(a), ref(b)], vi.fn()));
+
+    expect(instances).toHaveLength(1);
+    expect(instances[0]!.observe).toHaveBeenCalledWith(a, undefined);
+    expect(instances[0]!.observe).toHaveBeenCalledWith(b, undefined);
+    scope.stop();
+  });
+
+  it('supports a getter target', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    scope.run(() => useResizeObserver(() => el, vi.fn()));
+
+    expect(instances).toHaveLength(1);
+    expect(instances[0]!.observe).toHaveBeenCalledWith(el, undefined);
+    scope.stop();
+  });
+
+  it('disconnects on stop', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let stop: () => void;
+    scope.run(() => {
+      stop = useResizeObserver(ref(el), vi.fn()).stop;
+    });
+
+    stop!();
+    expect(instances[0]!.disconnect).toHaveBeenCalled();
+    scope.stop();
+  });
+
+  it('invokes the callback with entries', () => {
+    const el = document.createElement('div');
+    const callback = vi.fn();
+    const scope = effectScope();
+    scope.run(() => useResizeObserver(ref(el), callback));
+
+    const entry = { contentRect: { width: 10, height: 20 } } as ResizeObserverEntry;
+    instances[0]!.cb([entry], instances[0] as unknown as ResizeObserver);
+    expect(callback).toHaveBeenCalledWith([entry], expect.anything());
+    scope.stop();
+  });
+
+  it('re-observes when the target ref changes', async () => {
+    const a = document.createElement('div');
+    const b = document.createElement('div');
+    const target = ref<HTMLElement>(a);
+    const scope = effectScope();
+    scope.run(() => useResizeObserver(target, vi.fn()));
+
+    expect(instances).toHaveLength(1);
+    expect(instances[0]!.observe).toHaveBeenCalledWith(a, undefined);
+
+    target.value = b;
+    await nextTick();
+
+    expect(instances[0]!.disconnect).toHaveBeenCalled();
+    expect(instances).toHaveLength(2);
+    expect(instances[1]!.observe).toHaveBeenCalledWith(b, undefined);
+    scope.stop();
+  });
+
+  it('does not create an observer for a null target', () => {
+    const target = ref<HTMLElement | null>(null);
+    const scope = effectScope();
+    scope.run(() => useResizeObserver(target, vi.fn()));
+
+    expect(instances).toHaveLength(0);
+    scope.stop();
+  });
+
+  it('starts observing when a null target is later assigned', async () => {
+    const el = document.createElement('div');
+    const target = ref<HTMLElement | null>(null);
+    const scope = effectScope();
+    scope.run(() => useResizeObserver(target, vi.fn()));
+
+    expect(instances).toHaveLength(0);
+
+    target.value = el;
+    await nextTick();
+
+    expect(instances).toHaveLength(1);
+    expect(instances[0]!.observe).toHaveBeenCalledWith(el, undefined);
+    scope.stop();
+  });
+
+  it('does not observe when immediate is false until resumed', async () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let controls!: ReturnType<typeof useResizeObserver>;
+    scope.run(() => {
+      controls = useResizeObserver(ref(el), vi.fn(), { immediate: false });
+    });
+
+    expect(controls.isActive.value).toBeFalsy();
+    expect(instances).toHaveLength(0);
+
+    controls.resume();
+    await nextTick();
+
+    expect(controls.isActive.value).toBeTruthy();
+    expect(instances).toHaveLength(1);
+    expect(instances[0]!.observe).toHaveBeenCalledWith(el, undefined);
+    scope.stop();
+  });
+
+  it('pause disconnects and flips isActive, resume re-observes', async () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let controls!: ReturnType<typeof useResizeObserver>;
+    scope.run(() => {
+      controls = useResizeObserver(ref(el), vi.fn());
+    });
+
+    expect(controls.isActive.value).toBeTruthy();
+    expect(instances).toHaveLength(1);
+
+    controls.pause();
+    expect(controls.isActive.value).toBeFalsy();
+    expect(instances[0]!.disconnect).toHaveBeenCalled();
+
+    controls.resume();
+    await nextTick();
+
+    expect(controls.isActive.value).toBeTruthy();
+    expect(instances).toHaveLength(2);
+    expect(instances[1]!.observe).toHaveBeenCalledWith(el, undefined);
+    scope.stop();
+  });
+
+  it('cleans up when the scope is disposed', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    scope.run(() => useResizeObserver(ref(el), vi.fn()));
+
+    expect(instances).toHaveLength(1);
+    scope.stop();
+    expect(instances[0]!.disconnect).toHaveBeenCalled();
+  });
+});

vue/toolkit/src/composables/browser/useResizeObserver/index.ts

@@ -0,0 +1,149 @@
+import { computed, readonly, ref, watch } from 'vue';
+import type { Ref } from 'vue';
+import { toArray } from '@robonen/stdlib';
+import type { ConfigurableWindow } from '@/types';
+import { defaultWindow } from '@/types';
+import type { MaybeComputedElementRef } from '@/composables/component/unrefElement';
+import { unrefElement } from '@/composables/component/unrefElement';
+import { useSupported } from '@/composables/browser/useSupported';
+import { tryOnScopeDispose } from '@/composables/lifecycle/tryOnScopeDispose';
+
+export interface UseResizeObserverOptions extends ConfigurableWindow {
+  /**
+   * The box model to observe
+   *
+   * @default 'content-box'
+   */
+  box?: ResizeObserverBoxOptions;
+
+  /**
+   * Start observing immediately once the target is resolved
+   *
+   * @default true
+   */
+  immediate?: boolean;
+}
+
+export type ResizeObserverCallback = (
+  entries: readonly ResizeObserverEntry[],
+  observer: ResizeObserver,
+) => void;
+
+export interface UseResizeObserverReturn {
+  /**
+   * Whether `ResizeObserver` is supported in the current environment
+   */
+  isSupported: Readonly<Ref<boolean>>;
+
+  /**
+   * Whether the observer is currently active
+   */
+  isActive: Readonly<Ref<boolean>>;
+
+  /**
+   * Temporarily stop observing (disconnects the observer) while keeping the
+   * target watcher alive, so observing can be resumed later
+   */
+  pause: () => void;
+
+  /**
+   * Resume observing after a `pause`
+   */
+  resume: () => void;
+
+  /**
+   * Permanently stop observing and tear down the target watcher
+   */
+  stop: () => void;
+}
+
+/**
+ * @name useResizeObserver
+ * @category Browser
+ * @description Reports changes to the dimensions of an element via `ResizeObserver`.
+ * Accepts a single target or an array of (reactive) targets. The observer is
+ * recreated only when the resolved elements change, and can be paused/resumed.
+ *
+ * @param {MaybeComputedElementRef | MaybeComputedElementRef[]} target Element(s) to observe
+ * @param {ResizeObserverCallback} callback Invoked with the observer entries
+ * @param {UseResizeObserverOptions} [options={}] Options
+ * @returns {UseResizeObserverReturn} `isSupported`, `isActive`, `pause`, `resume`, and `stop`
+ *
+ * @example
+ * useResizeObserver(el, ([entry]) => {
+ *   console.log(entry.contentRect.width);
+ * });
+ *
+ * @example
+ * const { pause, resume } = useResizeObserver([el1, el2], (entries) => {
+ *   // react to multiple targets
+ * }, { box: 'border-box' });
+ *
+ * @since 0.0.15
+ */
+export function useResizeObserver(
+  target: MaybeComputedElementRef | MaybeComputedElementRef[],
+  callback: ResizeObserverCallback,
+  options: UseResizeObserverOptions = {},
+): UseResizeObserverReturn {
+  const { window = defaultWindow, box, immediate = true } = options;
+
+  const isSupported = useSupported(() => window && 'ResizeObserver' in window);
+
+  // Cache the observer options object so it is not rebuilt on every observe call
+  const observerOptions: ResizeObserverOptions | undefined = box ? { box } : undefined;
+
+  const isActive = ref(immediate);
+
+  let observer: ResizeObserver | undefined;
+
+  const targets = computed(() => {
+    return toArray(target).map(el => unrefElement(el)).filter((el): el is Element => Boolean(el));
+  });
+
+  const cleanup = () => {
+    if (observer) {
+      observer.disconnect();
+      observer = undefined;
+    }
+  };
+
+  const stopWatch = watch(
+    () => [targets.value, isActive.value] as const,
+    ([els, active]) => {
+      cleanup();
+
+      if (!active || !isSupported.value || !window || !els.length)
+        return;
+
+      observer = new ResizeObserver(callback);
+      for (const el of els)
+        observer.observe(el, observerOptions);
+    },
+    { immediate: true, flush: 'post' },
+  );
+
+  const resume = () => {
+    isActive.value = true;
+  };
+
+  const pause = () => {
+    cleanup();
+    isActive.value = false;
+  };
+
+  const stop = () => {
+    cleanup();
+    stopWatch();
+  };
+
+  tryOnScopeDispose(stop);
+
+  return {
+    isSupported,
+    isActive: readonly(isActive),
+    pause,
+    resume,
+    stop,
+  };
+}

vue/toolkit/src/composables/browser/useScreenOrientation/index.test.ts

@@ -0,0 +1,188 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick } from 'vue';
+import { useScreenOrientation } from '.';
+import type { OrientationLockType, OrientationType } from '.';
+
+type Listener = (event: Event) => void;
+
+interface StubScreenOrientation {
+  type: OrientationType;
+  angle: number;
+  lock: ReturnType<typeof vi.fn>;
+  unlock: ReturnType<typeof vi.fn>;
+  addEventListener: (type: string, cb: Listener) => void;
+  removeEventListener: (type: string, cb: Listener) => void;
+  dispatch: (type: OrientationType, angle: number) => void;
+}
+
+function makeScreenOrientation(
+  type: OrientationType = 'portrait-primary',
+  angle = 0,
+): StubScreenOrientation {
+  const listeners = new Set<Listener>();
+
+  const so: StubScreenOrientation = {
+    type,
+    angle,
+    lock: vi.fn(() => Promise.resolve()),
+    unlock: vi.fn(),
+    addEventListener: (_: string, cb: Listener) => listeners.add(cb),
+    removeEventListener: (_: string, cb: Listener) => listeners.delete(cb),
+    dispatch(nextType: OrientationType, nextAngle: number) {
+      so.type = nextType;
+      so.angle = nextAngle;
+      for (const cb of listeners) cb(new Event('change'));
+    },
+  };
+
+  return so;
+}
+
+/** A window stub exposing `screen.orientation` + an event target for `orientationchange`. */
+function makeWindowStub(so?: StubScreenOrientation): Window {
+  const winListeners = new Set<Listener>();
+  return {
+    screen: so ? { orientation: so } : {},
+    addEventListener: (_: string, cb: Listener) => winListeners.add(cb),
+    removeEventListener: (_: string, cb: Listener) => winListeners.delete(cb),
+  } as unknown as Window;
+}
+
+describe(useScreenOrientation, () => {
+  beforeEach(() => {
+    // Force the SSR / unsupported branch unless a window is passed via options.
+    vi.stubGlobal('screen', undefined);
+  });
+  afterEach(() => vi.unstubAllGlobals());
+
+  it('reports supported when screen.orientation is present', async () => {
+    const window = makeWindowStub(makeScreenOrientation());
+    const scope = effectScope();
+    let result: ReturnType<typeof useScreenOrientation>;
+    scope.run(() => {
+      result = useScreenOrientation({ window });
+    });
+    await nextTick();
+    expect(result!.isSupported.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('reflects the initial orientation type and angle', async () => {
+    const so = makeScreenOrientation('landscape-primary', 90);
+    const window = makeWindowStub(so);
+    const scope = effectScope();
+    let result: ReturnType<typeof useScreenOrientation>;
+    scope.run(() => {
+      result = useScreenOrientation({ window });
+    });
+    await nextTick();
+    expect(result!.orientation.value).toBe('landscape-primary');
+    expect(result!.angle.value).toBe(90);
+    scope.stop();
+  });
+
+  it('updates on the screen.orientation change event', async () => {
+    const so = makeScreenOrientation('portrait-primary', 0);
+    const window = makeWindowStub(so);
+    const scope = effectScope();
+    let result: ReturnType<typeof useScreenOrientation>;
+    scope.run(() => {
+      result = useScreenOrientation({ window });
+    });
+    await nextTick();
+    expect(result!.orientation.value).toBe('portrait-primary');
+
+    so.dispatch('landscape-secondary', 270);
+    await nextTick();
+    expect(result!.orientation.value).toBe('landscape-secondary');
+    expect(result!.angle.value).toBe(270);
+
+    scope.stop();
+  });
+
+  it('lockOrientation delegates to screen.orientation.lock', async () => {
+    const so = makeScreenOrientation();
+    const window = makeWindowStub(so);
+    const scope = effectScope();
+    let result: ReturnType<typeof useScreenOrientation>;
+    scope.run(() => {
+      result = useScreenOrientation({ window });
+    });
+    await nextTick();
+
+    const type: OrientationLockType = 'landscape';
+    await expect(result!.lockOrientation(type)).resolves.toBeUndefined();
+    expect(so.lock).toHaveBeenCalledWith('landscape');
+
+    scope.stop();
+  });
+
+  it('unlockOrientation delegates to screen.orientation.unlock', async () => {
+    const so = makeScreenOrientation();
+    const window = makeWindowStub(so);
+    const scope = effectScope();
+    let result: ReturnType<typeof useScreenOrientation>;
+    scope.run(() => {
+      result = useScreenOrientation({ window });
+    });
+    await nextTick();
+
+    result!.unlockOrientation();
+    expect(so.unlock).toHaveBeenCalledTimes(1);
+
+    scope.stop();
+  });
+
+  it('stops updating after the scope is disposed', async () => {
+    const so = makeScreenOrientation('portrait-primary', 0);
+    const window = makeWindowStub(so);
+    const scope = effectScope();
+    let result: ReturnType<typeof useScreenOrientation>;
+    scope.run(() => {
+      result = useScreenOrientation({ window });
+    });
+    await nextTick();
+
+    scope.stop();
+
+    so.dispatch('landscape-primary', 90);
+    await nextTick();
+    // Listener removed on dispose, so the value should not have changed.
+    expect(result!.orientation.value).toBe('portrait-primary');
+    expect(result!.angle.value).toBe(0);
+  });
+
+  it('is unsupported and safe when no window is available (SSR)', async () => {
+    // Pass an explicit falsy window: a destructuring default only fires for
+    // `undefined`, so `null` lets us exercise the genuine no-window branch.
+    const scope = effectScope();
+    let result: ReturnType<typeof useScreenOrientation>;
+    scope.run(() => {
+      result = useScreenOrientation({ window: null as unknown as Window });
+    });
+    await nextTick();
+
+    expect(result!.isSupported.value).toBeFalsy();
+    expect(result!.orientation.value).toBeUndefined();
+    expect(result!.angle.value).toBe(0);
+    expect(() => result!.unlockOrientation()).not.toThrow();
+    await expect(result!.lockOrientation('any')).rejects.toThrow('Not supported');
+
+    scope.stop();
+  });
+
+  it('is unsupported when screen lacks orientation', async () => {
+    const window = makeWindowStub();
+    const scope = effectScope();
+    let result: ReturnType<typeof useScreenOrientation>;
+    scope.run(() => {
+      result = useScreenOrientation({ window });
+    });
+    await nextTick();
+
+    expect(result!.isSupported.value).toBeFalsy();
+    await expect(result!.lockOrientation('portrait')).rejects.toThrow('Not supported');
+
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useScreenOrientation/index.ts

@@ -0,0 +1,121 @@
+import { shallowRef } from 'vue';
+import type { ComputedRef, ShallowRef } from 'vue';
+import { isFunction } from '@robonen/stdlib';
+import { defaultWindow } from '@/types';
+import type { ConfigurableWindow } from '@/types';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { useSupported } from '@/composables/browser/useSupported';
+
+export type OrientationType
+  = | 'portrait-primary'
+    | 'portrait-secondary'
+    | 'landscape-primary'
+    | 'landscape-secondary';
+
+export type OrientationLockType
+  = | 'any'
+    | 'natural'
+    | 'landscape'
+    | 'portrait'
+    | 'portrait-primary'
+    | 'portrait-secondary'
+    | 'landscape-primary'
+    | 'landscape-secondary';
+
+/**
+ * Subset of the `ScreenOrientation` interface that we interact with.
+ */
+export interface ScreenOrientation extends EventTarget {
+  readonly type: OrientationType;
+  readonly angle: number;
+  lock: (orientation: OrientationLockType) => Promise<void>;
+  unlock: () => void;
+}
+
+export interface UseScreenOrientationOptions extends ConfigurableWindow {}
+
+export interface UseScreenOrientationReturn {
+  /**
+   * Whether the Screen Orientation API is supported
+   */
+  isSupported: ComputedRef<boolean>;
+  /**
+   * Current screen orientation type, or `undefined` when unsupported
+   */
+  orientation: ShallowRef<OrientationType | undefined>;
+  /**
+   * Current screen orientation angle in degrees (defaults to `0`)
+   */
+  angle: ShallowRef<number>;
+  /**
+   * Lock the screen to the given orientation. Rejects when unsupported.
+   */
+  lockOrientation: (type: OrientationLockType) => Promise<void>;
+  /**
+   * Release a previously applied orientation lock. No-op when unsupported.
+   */
+  unlockOrientation: () => void;
+}
+
+/**
+ * @name useScreenOrientation
+ * @category Browser
+ * @description Reactive Screen Orientation API. Tracks the current orientation
+ * `type` and `angle`, and exposes helpers to lock/unlock the orientation. SSR-safe.
+ *
+ * @param {UseScreenOrientationOptions} [options={}] Options (custom `window`)
+ * @returns {UseScreenOrientationReturn} `{ isSupported, orientation, angle, lockOrientation, unlockOrientation }`
+ *
+ * @example
+ * const { isSupported, orientation, angle, lockOrientation, unlockOrientation } = useScreenOrientation();
+ *
+ * @example
+ * // Lock to landscape (must run from a user gesture / fullscreen context)
+ * const { lockOrientation } = useScreenOrientation();
+ * await lockOrientation('landscape');
+ *
+ * @since 0.0.15
+ */
+export function useScreenOrientation(options: UseScreenOrientationOptions = {}): UseScreenOrientationReturn {
+  const { window = defaultWindow } = options;
+
+  const isSupported = useSupported(() =>
+    Boolean(window && 'screen' in window && window.screen && 'orientation' in window.screen));
+
+  const screenOrientation = (isSupported.value ? window!.screen.orientation : {}) as ScreenOrientation;
+
+  const orientation = shallowRef<OrientationType | undefined>(screenOrientation.type);
+  const angle = shallowRef(screenOrientation.angle || 0);
+
+  const update = (): void => {
+    orientation.value = screenOrientation.type;
+    angle.value = screenOrientation.angle;
+  };
+
+  if (isSupported.value) {
+    // The standard `change` event fires on the `ScreenOrientation` object itself;
+    // `orientationchange` on `window` is the legacy fallback for older engines.
+    useEventListener(screenOrientation, 'change', update, { passive: true });
+    useEventListener(window, 'orientationchange', update, { passive: true });
+  }
+
+  const lockOrientation = (type: OrientationLockType): Promise<void> => {
+    if (isSupported.value && isFunction(screenOrientation.lock))
+      return screenOrientation.lock(type);
+
+    return Promise.reject(new Error('Not supported'));
+  };
+
+  const unlockOrientation = (): void => {
+    if (isSupported.value && isFunction(screenOrientation.unlock))
+      screenOrientation.unlock();
+  };
+
+  return {
+    isSupported,
+    orientation,
+    angle,
+    lockOrientation,
+    unlockOrientation,
+  };
+}

vue/toolkit/src/composables/browser/useScroll/index.test.ts

@@ -0,0 +1,214 @@
+import { describe, expect, it, vi } from 'vitest';
+import { effectScope, nextTick, ref } from 'vue';
+import { useScroll } from '.';
+
+function makeScrollable(overrides: Partial<{
+  scrollWidth: number;
+  scrollHeight: number;
+  clientWidth: number;
+  clientHeight: number;
+}> = {}) {
+  const el = document.createElement('div');
+  Object.defineProperties(el, {
+    scrollWidth: { value: overrides.scrollWidth ?? 1000, configurable: true },
+    scrollHeight: { value: overrides.scrollHeight ?? 1000, configurable: true },
+    clientWidth: { value: overrides.clientWidth ?? 100, configurable: true },
+    clientHeight: { value: overrides.clientHeight ?? 100, configurable: true },
+  });
+  el.scrollLeft = 0;
+  el.scrollTop = 0;
+  return el;
+}
+
+function withScope<T>(fn: () => T): { result: T; scope: ReturnType<typeof effectScope> } {
+  const scope = effectScope();
+  let result!: T;
+  scope.run(() => {
+    result = fn();
+  });
+  return { result, scope };
+}
+
+describe(useScroll, () => {
+  it('starts at the top-left with arrived state', () => {
+    const el = makeScrollable();
+    const { result, scope } = withScope(() => useScroll(ref(el)));
+
+    expect(result.x.value).toBe(0);
+    expect(result.y.value).toBe(0);
+    expect(result.arrivedState.top).toBeTruthy();
+    expect(result.arrivedState.left).toBeTruthy();
+    scope.stop();
+  });
+
+  it('updates position and isScrolling on scroll', async () => {
+    const el = makeScrollable();
+    const { result, scope } = withScope(() => useScroll(ref(el)));
+
+    el.scrollTop = 50;
+    el.scrollLeft = 20;
+    el.dispatchEvent(new Event('scroll'));
+    await nextTick();
+
+    expect(result.x.value).toBe(20);
+    expect(result.y.value).toBe(50);
+    expect(result.isScrolling.value).toBeTruthy();
+    expect(result.directions.bottom).toBeTruthy();
+    expect(result.directions.right).toBeTruthy();
+    scope.stop();
+  });
+
+  it('flags arrival at the bottom edge', async () => {
+    const el = makeScrollable();
+    const { result, scope } = withScope(() => useScroll(ref(el)));
+
+    el.scrollTop = 900; // 900 + 100 clientHeight >= 1000 scrollHeight
+    el.dispatchEvent(new Event('scroll'));
+    await nextTick();
+
+    expect(result.arrivedState.bottom).toBeTruthy();
+    scope.stop();
+  });
+
+  it('measures the initial scroll position on mount', () => {
+    const el = makeScrollable();
+    el.scrollLeft = 30;
+    el.scrollTop = 40;
+    const { result, scope } = withScope(() => useScroll(ref(el)));
+
+    expect(result.x.value).toBe(30);
+    expect(result.y.value).toBe(40);
+    expect(result.arrivedState.top).toBeFalsy();
+    expect(result.arrivedState.left).toBeFalsy();
+    scope.stop();
+  });
+
+  it('exposes measure() to re-sync without a scroll event', () => {
+    const el = makeScrollable();
+    const { result, scope } = withScope(() => useScroll(ref(el)));
+
+    expect(result.y.value).toBe(0);
+
+    el.scrollTop = 200;
+    result.measure();
+
+    expect(result.y.value).toBe(200);
+    // measure() must not fabricate directions.
+    expect(result.directions.bottom).toBeFalsy();
+    scope.stop();
+  });
+
+  it('respects the offset when computing arrived state', async () => {
+    const el = makeScrollable();
+    const { result, scope } = withScope(() => useScroll(ref(el), { offset: { top: 10, bottom: 50 } }));
+
+    el.scrollTop = 8; // <= offset.top (10) => still arrived at top
+    el.dispatchEvent(new Event('scroll'));
+    await nextTick();
+    expect(result.arrivedState.top).toBeTruthy();
+
+    el.scrollTop = 855; // 855 + 100 >= 1000 - 50 - 1 => arrived at bottom early
+    el.dispatchEvent(new Event('scroll'));
+    await nextTick();
+    expect(result.arrivedState.bottom).toBeTruthy();
+    scope.stop();
+  });
+
+  it('resets isScrolling and directions and calls onStop after idle', async () => {
+    vi.useFakeTimers();
+    const onStop = vi.fn();
+    const el = makeScrollable();
+    const { result, scope } = withScope(() => useScroll(ref(el), { idle: 100, onStop }));
+
+    el.scrollTop = 50;
+    el.dispatchEvent(new Event('scroll'));
+    expect(result.isScrolling.value).toBeTruthy();
+    expect(result.directions.bottom).toBeTruthy();
+
+    vi.advanceTimersByTime(150);
+    await nextTick();
+
+    expect(result.isScrolling.value).toBeFalsy();
+    expect(result.directions.bottom).toBeFalsy();
+    expect(onStop).toHaveBeenCalledTimes(1);
+    scope.stop();
+    vi.useRealTimers();
+  });
+
+  it('normalises a negative (RTL) scrollLeft for arrived state', async () => {
+    const el = makeScrollable();
+    const styleSpy = vi.spyOn(globalThis, 'getComputedStyle').mockReturnValue({ direction: 'rtl' } as CSSStyleDeclaration);
+    const { result, scope } = withScope(() => useScroll(ref(el)));
+
+    // RTL: scrolled to the far end reports a large negative magnitude.
+    el.scrollLeft = -900;
+    el.dispatchEvent(new Event('scroll'));
+    await nextTick();
+
+    // |−900| + 100 clientWidth >= 1000 scrollWidth => arrived at the right edge.
+    expect(result.arrivedState.right).toBeTruthy();
+    expect(result.arrivedState.left).toBeFalsy();
+    styleSpy.mockRestore();
+    scope.stop();
+  });
+
+  it('writes scroll position through the x/y setters with behavior', () => {
+    const el = makeScrollable();
+    const scrollToSpy = vi.fn();
+    el.scrollTo = scrollToSpy as typeof el.scrollTo;
+    const { result, scope } = withScope(() => useScroll(ref(el), { behavior: 'smooth' }));
+
+    result.y.value = 120;
+    expect(scrollToSpy).toHaveBeenCalledWith({ top: 120, behavior: 'smooth' });
+
+    result.x.value = 60;
+    expect(scrollToSpy).toHaveBeenCalledWith({ left: 60, behavior: 'smooth' });
+    scope.stop();
+  });
+
+  it('invokes onError when reading metrics throws', () => {
+    const el = makeScrollable();
+    const onError = vi.fn();
+    const styleSpy = vi.spyOn(globalThis, 'getComputedStyle').mockImplementation(() => {
+      throw new Error('detached');
+    });
+    const { scope } = withScope(() => useScroll(ref(el), { onError }));
+
+    expect(onError).toHaveBeenCalled();
+    styleSpy.mockRestore();
+    scope.stop();
+  });
+
+  it('does nothing when target is nullish', () => {
+    const { result, scope } = withScope(() => useScroll(ref(null)));
+
+    expect(result.x.value).toBe(0);
+    expect(result.y.value).toBe(0);
+    expect(() => result.measure()).not.toThrow();
+    scope.stop();
+  });
+
+  it('throttles scroll updates when throttle is set', async () => {
+    vi.useFakeTimers();
+    const onScroll = vi.fn();
+    const el = makeScrollable();
+    const { scope } = withScope(() => useScroll(ref(el), { throttle: 100, onScroll }));
+
+    el.scrollTop = 10;
+    el.dispatchEvent(new Event('scroll'));
+    el.scrollTop = 20;
+    el.dispatchEvent(new Event('scroll'));
+    el.scrollTop = 30;
+    el.dispatchEvent(new Event('scroll'));
+
+    // Leading edge fires once immediately, the rest are throttled.
+    expect(onScroll).toHaveBeenCalledTimes(1);
+
+    vi.advanceTimersByTime(150);
+    // Trailing edge flushes the latest.
+    expect(onScroll).toHaveBeenCalledTimes(2);
+
+    scope.stop();
+    vi.useRealTimers();
+  });
+});

vue/toolkit/src/composables/browser/useScroll/index.ts

@@ -0,0 +1,339 @@
+import { computed, reactive, shallowRef, toValue } from 'vue';
+import type { MaybeRefOrGetter, Ref } from 'vue';
+import { noop } from '@robonen/stdlib';
+import type { ConfigurableWindow } from '@/types';
+import { defaultWindow } from '@/types';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { useMutationObserver } from '@/composables/browser/useMutationObserver';
+import { useThrottleFn } from '@/composables/utilities/useThrottleFn';
+import { useDebounceFn } from '@/composables/utilities/useDebounceFn';
+
+export interface UseScrollOffset {
+  left?: number;
+  right?: number;
+  top?: number;
+  bottom?: number;
+}
+
+export interface UseScrollObserveOptions {
+  /**
+   * Re-measure the arrived/position state whenever the target's subtree
+   * mutates (children added/removed, attributes changed). Useful when the
+   * scrollable content grows or shrinks without a scroll event firing.
+   *
+   * @default false
+   */
+  mutation?: boolean;
+}
+
+export interface UseScrollOptions extends ConfigurableWindow {
+  /**
+   * Throttle delay (ms) for scroll position updates. `0` disables throttling.
+   *
+   * @default 0
+   */
+  throttle?: number;
+
+  /**
+   * Idle time (ms) before `isScrolling` is reset to `false`
+   *
+   * @default 200
+   */
+  idle?: number;
+
+  /**
+   * Distance (px) from each edge at which `arrivedState` flips to `true`
+   *
+   * @default { left: 0, right: 0, top: 0, bottom: 0 }
+   */
+  offset?: UseScrollOffset;
+
+  /**
+   * Called on every scroll event
+   */
+  onScroll?: (event: Event) => void;
+
+  /**
+   * Called when scrolling stops (after `idle`)
+   */
+  onStop?: (event: Event) => void;
+
+  /**
+   * Listener options for the scroll event
+   *
+   * @default { capture: false, passive: true }
+   */
+  eventListenerOptions?: boolean | AddEventListenerOptions;
+
+  /**
+   * Scroll behavior used when writing to `x`/`y`
+   *
+   * @default 'auto'
+   */
+  behavior?: ScrollBehavior;
+
+  /**
+   * Re-measure the scroll state on DOM mutations of the target.
+   * Pass `true` to enable the default (`{ mutation: true }`).
+   *
+   * @default false
+   */
+  observe?: boolean | UseScrollObserveOptions;
+
+  /**
+   * Error handler invoked when reading scroll metrics or computed style throws
+   * (e.g. a detached or cross-origin element).
+   *
+   * @default console.error
+   */
+  onError?: (error: unknown) => void;
+}
+
+export type UseScrollTarget = MaybeRefOrGetter<HTMLElement | SVGElement | Window | Document | null | undefined>;
+
+export interface UseScrollEdgeState {
+  left: boolean;
+  right: boolean;
+  top: boolean;
+  bottom: boolean;
+}
+
+export interface UseScrollReturn {
+  x: Ref<number>;
+  y: Ref<number>;
+  isScrolling: Ref<boolean>;
+  arrivedState: UseScrollEdgeState;
+  directions: UseScrollEdgeState;
+  /**
+   * Recompute `x`, `y`, `arrivedState`, and `directions` from the current DOM
+   * state. Call after a programmatic layout change that did not emit a scroll
+   * event.
+   */
+  measure: () => void;
+}
+
+const ARRIVED_STATE_THRESHOLD_PIXELS = 1;
+
+interface ScrollMetrics {
+  scrollLeft: number;
+  scrollTop: number;
+  scrollWidth: number;
+  scrollHeight: number;
+  clientWidth: number;
+  clientHeight: number;
+  /**
+   * `-1` when the element is laid out right-to-left, `1` otherwise. Used to
+   * normalise the (possibly negative) `scrollLeft` reported under RTL.
+   */
+  directionMultiplier: number;
+}
+
+function isWindow(value: unknown, window: Window | undefined): value is Window {
+  return value === window || (typeof Window !== 'undefined' && value instanceof Window);
+}
+
+function getScrollMetrics(
+  el: HTMLElement | SVGElement | Window | Document,
+  window: Window,
+): ScrollMetrics {
+  if (isWindow(el, window)) {
+    const doc = window.document.documentElement;
+    return {
+      scrollLeft: window.scrollX,
+      scrollTop: window.scrollY,
+      scrollWidth: doc.scrollWidth,
+      scrollHeight: doc.scrollHeight,
+      clientWidth: window.innerWidth,
+      clientHeight: window.innerHeight,
+      directionMultiplier: getDirectionMultiplier(doc, window),
+    };
+  }
+
+  const node = (el instanceof Document ? el.documentElement : el) as HTMLElement;
+
+  return {
+    scrollLeft: node.scrollLeft,
+    scrollTop: node.scrollTop,
+    scrollWidth: node.scrollWidth,
+    scrollHeight: node.scrollHeight,
+    clientWidth: node.clientWidth,
+    clientHeight: node.clientHeight,
+    directionMultiplier: getDirectionMultiplier(node, window),
+  };
+}
+
+function getDirectionMultiplier(node: Element, window: Window): number {
+  // getComputedStyle can throw on detached nodes; callers wrap this in try/catch.
+  return window.getComputedStyle(node).direction === 'rtl' ? -1 : 1;
+}
+
+/**
+ * @name useScroll
+ * @category Browser
+ * @description Reactive scroll position and state for an element or the window,
+ * with arrived-edge detection (RTL-aware), scroll directions, an `isScrolling`
+ * flag, optional throttling, and a `measure()` method for manual re-sync.
+ *
+ * @param {UseScrollTarget} target The scroll container (can be reactive)
+ * @param {UseScrollOptions} [options={}] Options
+ * @returns {UseScrollReturn} Reactive position, scroll state, arrived edges, directions, and `measure`
+ *
+ * @example
+ * const { x, y, isScrolling, arrivedState, measure } = useScroll(el);
+ *
+ * @since 0.0.15
+ */
+export function useScroll(
+  target: UseScrollTarget,
+  options: UseScrollOptions = {},
+): UseScrollReturn {
+  const {
+    throttle = 0,
+    idle = 200,
+    onStop = noop,
+    onScroll = noop,
+    offset = {},
+    eventListenerOptions = { capture: false, passive: true },
+    behavior = 'auto',
+    window = defaultWindow,
+    observe: observeOption = false,
+    onError = noop,
+  } = options;
+
+  const internalX = shallowRef(0);
+  const internalY = shallowRef(0);
+
+  const isScrolling = shallowRef(false);
+  const arrivedState = reactive<UseScrollEdgeState>({ left: true, right: false, top: true, bottom: false });
+  const directions = reactive<UseScrollEdgeState>({ left: false, right: false, top: false, bottom: false });
+
+  const scrollTo = (axis: 'x' | 'y', value: number): void => {
+    const el = toValue(target);
+
+    if (!el)
+      return;
+
+    (el instanceof Document ? el.documentElement : el as HTMLElement | Window).scrollTo(
+      axis === 'x' ? { left: value, behavior } : { top: value, behavior },
+    );
+  };
+
+  const x = computed<number>({
+    get: () => internalX.value,
+    set: value => scrollTo('x', value),
+  });
+
+  const y = computed<number>({
+    get: () => internalY.value,
+    set: value => scrollTo('y', value),
+  });
+
+  const setArrivedState = (m: ScrollMetrics): void => {
+    // RTL elements report a negative scrollLeft; normalise to a magnitude so
+    // edge maths is identical to the LTR case.
+    const left = Math.abs(m.scrollLeft);
+    const top = Math.abs(m.scrollTop);
+
+    arrivedState.left = left <= (offset.left ?? 0);
+    arrivedState.right = left + m.clientWidth >= m.scrollWidth - (offset.right ?? 0) - ARRIVED_STATE_THRESHOLD_PIXELS;
+    arrivedState.top = top <= (offset.top ?? 0);
+    arrivedState.bottom = top + m.clientHeight >= m.scrollHeight - (offset.bottom ?? 0) - ARRIVED_STATE_THRESHOLD_PIXELS;
+  };
+
+  // `trackDirections` only applies when driven by a real scroll event; a manual
+  // measure() should not invent directions, so it is skipped there.
+  const sync = (trackDirections: boolean): void => {
+    const el = toValue(target);
+
+    if (!el || !window)
+      return;
+
+    let m: ScrollMetrics;
+    try {
+      m = getScrollMetrics(el, window);
+    }
+    catch (error) {
+      onError(error);
+      return;
+    }
+
+    const left = m.scrollLeft;
+    const top = m.scrollTop;
+
+    if (trackDirections) {
+      directions.left = left < internalX.value;
+      directions.right = left > internalX.value;
+      directions.top = top < internalY.value;
+      directions.bottom = top > internalY.value;
+    }
+
+    setArrivedState(m);
+
+    internalX.value = left;
+    internalY.value = top;
+  };
+
+  const measure = (): void => sync(false);
+
+  const onScrollEnd = useDebounceFn((event: Event) => {
+    // Guard against the debounce trailing edge firing after we already settled.
+    if (!isScrolling.value)
+      return;
+
+    isScrolling.value = false;
+    directions.left = false;
+    directions.right = false;
+    directions.top = false;
+    directions.bottom = false;
+    onStop(event);
+  }, throttle + idle);
+
+  const onScrollHandler = (event: Event): void => {
+    if (!toValue(target) || !window)
+      return;
+
+    sync(true);
+
+    isScrolling.value = true;
+    onScrollEnd(event);
+    onScroll(event);
+  };
+
+  const handler = throttle > 0
+    ? useThrottleFn(onScrollHandler, throttle, true, true)
+    : onScrollHandler;
+
+  useEventListener(
+    target as MaybeRefOrGetter<EventTarget | null | undefined>,
+    'scroll',
+    handler as (event: Event) => void,
+    eventListenerOptions,
+  );
+
+  // Initial measure once a target is resolvable so x/y/arrivedState reflect the
+  // real starting position instead of the optimistic top-left defaults.
+  measure();
+
+  const observe = observeOption === true ? { mutation: true } : observeOption;
+
+  if (observe && observe.mutation) {
+    useMutationObserver(
+      // Window/Document are not observable elements; only observe real elements.
+      () => {
+        const el = toValue(target);
+        return el && !isWindow(el, window) && !(el instanceof Document) ? el : null;
+      },
+      () => measure(),
+      { window, attributes: true, childList: true, subtree: true },
+    );
+  }
+
+  return {
+    x,
+    y,
+    isScrolling,
+    arrivedState,
+    directions,
+    measure,
+  };
+}

vue/toolkit/src/composables/browser/useScrollLock/index.test.ts

@@ -0,0 +1,365 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { effectScope, isReadonly, nextTick, ref, shallowRef } from 'vue';
+import { useScrollLock } from '.';
+
+function makeIOSNavigator(): Navigator {
+  return {
+    userAgent: 'Mozilla/5.0 (iPhone; CPU iPhone OS 17_0 like Mac OS X)',
+    platform: 'iPhone',
+    maxTouchPoints: 5,
+  } as unknown as Navigator;
+}
+
+function makeDesktopNavigator(): Navigator {
+  return {
+    userAgent: 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7)',
+    platform: 'MacIntel',
+    maxTouchPoints: 0,
+  } as unknown as Navigator;
+}
+
+describe(useScrollLock, () => {
+  afterEach(() => vi.unstubAllGlobals());
+
+  it('returns a writable boolean ref (not readonly)', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isLocked: ReturnType<typeof useScrollLock>;
+    scope.run(() => {
+      isLocked = useScrollLock(ref(el));
+    });
+
+    expect(isLocked!.value).toBeFalsy();
+    expect(isReadonly(isLocked!)).toBeFalsy();
+    scope.stop();
+  });
+
+  it('respects the initialState argument and applies overflow when the element resolves', async () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isLocked: ReturnType<typeof useScrollLock>;
+    scope.run(() => {
+      isLocked = useScrollLock(ref(el), true);
+    });
+    await nextTick();
+
+    expect(isLocked!.value).toBeTruthy();
+    expect(el.style.overflow).toBe('hidden');
+    scope.stop();
+  });
+
+  it('sets overflow:hidden when locked via the setter', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isLocked: ReturnType<typeof useScrollLock>;
+    scope.run(() => {
+      isLocked = useScrollLock(ref(el), false, { navigator: makeDesktopNavigator() });
+    });
+
+    expect(el.style.overflow).toBe('');
+
+    isLocked!.value = true;
+    expect(el.style.overflow).toBe('hidden');
+    expect(isLocked!.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('restores the prior overflow value on unlock', () => {
+    const el = document.createElement('div');
+    el.style.overflow = 'auto';
+    const scope = effectScope();
+    let isLocked: ReturnType<typeof useScrollLock>;
+    scope.run(() => {
+      isLocked = useScrollLock(ref(el), false, { navigator: makeDesktopNavigator() });
+    });
+
+    isLocked!.value = true;
+    expect(el.style.overflow).toBe('hidden');
+
+    isLocked!.value = false;
+    expect(el.style.overflow).toBe('auto');
+    expect(isLocked!.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('restores an empty inline overflow when none was set before locking', () => {
+    const el = document.createElement('div');
+    const scope = effectScope();
+    let isLocked: ReturnType<typeof useScrollLock>;
+    scope.run(() => {
+      isLocked = useScrollLock(ref(el), false, { navigator: makeDesktopNavigator() });
+    });
+
+    isLocked!.value = true;
+    expect(el.style.overflow).toBe('hidden');
+
+    isLocked!.value = false;
+    expect(el.style.overflow).toBe('');
+    scope.stop();
+  });
+
+  it('lock is idempotent — setting true twice does not change state', () => {
+    const el = document.createElement('div');
+    el.style.overflow = 'scroll';
+    const scope = effectScope();
+    let isLocked: ReturnType<typeof useScrollLock>;
+    scope.run(() => {
+      isLocked = useScrollLock(ref(el), false, { navigator: makeDesktopNavigator() });
+    });
+
+    isLocked!.value = true;
+    isLocked!.value = true;
+    expect(el.style.overflow).toBe('hidden');
+
+    isLocked!.value = false;
+    // The original 'scroll' is preserved across the double-lock.
+    expect(el.style.overflow).toBe('scroll');
+    scope.stop();
+  });
+
+  it('treats an element that already has overflow:hidden as locked', async () => {
+    const el = document.createElement('div');
+    el.style.overflow = 'hidden';
+    const scope = effectScope();
+    let isLocked: ReturnType<typeof useScrollLock>;
+    scope.run(() => {
+      isLocked = useScrollLock(ref(el));
+    });
+    await nextTick();
+
+    expect(isLocked!.value).toBeTruthy();
+    scope.stop();
+  });
+
+  it('applies the lock once a lazily-resolved element appears', async () => {
+    const target = shallowRef<HTMLElement | null>(null);
+    const scope = effectScope();
+    let isLocked: ReturnType<typeof useScrollLock>;
+    scope.run(() => {
+      isLocked = useScrollLock(target);
+    });
+
+    isLocked!.value = true;
+    // No element yet, so nothing to lock.
+    expect(isLocked!.value).toBeFalsy();
+
+    const el = document.createElement('div');
+    target.value = el;
+    await nextTick();
+
+    // The watcher sees isLocked still false; lock again now that the el exists.
+    isLocked!.value = true;
+    expect(el.style.overflow).toBe('hidden');
+    scope.stop();
+  });
+
+  it('does nothing when there is no element', () => {
+    const scope = effectScope();
+    let isLocked: ReturnType<typeof useScrollLock>;
+    scope.run(() => {
+      isLocked = useScrollLock(ref(null));
+    });
+
+    isLocked!.value = true;
+    expect(isLocked!.value).toBeFalsy();
+    isLocked!.value = false;
+    expect(isLocked!.value).toBeFalsy();
+    scope.stop();
+  });
+
+  it('registers a passive:false touchmove listener on iOS when locking', () => {
+    const el = document.createElement('div');
+    const addSpy = vi.spyOn(el, 'addEventListener');
+    const scope = effectScope();
+    let isLocked: ReturnType<typeof useScrollLock>;
+    scope.run(() => {
+      isLocked = useScrollLock(ref(el), false, { navigator: makeIOSNavigator() });
+    });
+
+    isLocked!.value = true;
+
+    expect(addSpy).toHaveBeenCalledWith(
+      'touchmove',
+      expect.any(Function),
+      expect.objectContaining({ passive: false }),
+    );
+    scope.stop();
+  });
+
+  it('does not register a touchmove listener on non-iOS platforms', () => {
+    const el = document.createElement('div');
+    const addSpy = vi.spyOn(el, 'addEventListener');
+    const scope = effectScope();
+    let isLocked: ReturnType<typeof useScrollLock>;
+    scope.run(() => {
+      isLocked = useScrollLock(ref(el), false, { navigator: makeDesktopNavigator() });
+    });
+
+    isLocked!.value = true;
+
+    expect(addSpy).not.toHaveBeenCalledWith('touchmove', expect.any(Function), expect.anything());
+    scope.stop();
+  });
+
+  it('removes the iOS touchmove listener on unlock', () => {
+    const el = document.createElement('div');
+    const removeSpy = vi.spyOn(el, 'removeEventListener');
+    const scope = effectScope();
+    let isLocked: ReturnType<typeof useScrollLock>;
+    scope.run(() => {
+      isLocked = useScrollLock(ref(el), false, { navigator: makeIOSNavigator() });
+    });
+
+    isLocked!.value = true;
+    isLocked!.value = false;
+
+    expect(removeSpy).toHaveBeenCalledWith('touchmove', expect.any(Function), expect.objectContaining({ passive: false }));
+    scope.stop();
+  });
+
+  it('prevents default on a single-touch touchmove over a non-scrollable target (iOS)', () => {
+    const el = document.createElement('div');
+    document.body.appendChild(el);
+    let captured: EventListener | undefined;
+    vi.spyOn(el, 'addEventListener').mockImplementation((type, listener) => {
+      if (type === 'touchmove')
+        captured = listener as EventListener;
+    });
+
+    const scope = effectScope();
+    let isLocked: ReturnType<typeof useScrollLock>;
+    scope.run(() => {
+      isLocked = useScrollLock(ref(el), false, { navigator: makeIOSNavigator() });
+    });
+    isLocked!.value = true;
+
+    expect(captured).toBeTypeOf('function');
+
+    const event = {
+      target: el,
+      touches: [{}],
+      cancelable: true,
+      preventDefault: vi.fn(),
+    } as unknown as TouchEvent;
+    captured!(event);
+
+    expect(event.preventDefault).toHaveBeenCalledTimes(1);
+
+    document.body.removeChild(el);
+    scope.stop();
+  });
+
+  it('does NOT prevent default for multi-touch gestures (iOS pinch-zoom)', () => {
+    const el = document.createElement('div');
+    document.body.appendChild(el);
+    let captured: EventListener | undefined;
+    vi.spyOn(el, 'addEventListener').mockImplementation((type, listener) => {
+      if (type === 'touchmove')
+        captured = listener as EventListener;
+    });
+
+    const scope = effectScope();
+    let isLocked: ReturnType<typeof useScrollLock>;
+    scope.run(() => {
+      isLocked = useScrollLock(ref(el), false, { navigator: makeIOSNavigator() });
+    });
+    isLocked!.value = true;
+
+    const event = {
+      target: el,
+      touches: [{}, {}],
+      cancelable: true,
+      preventDefault: vi.fn(),
+    } as unknown as TouchEvent;
+    captured!(event);
+
+    expect(event.preventDefault).not.toHaveBeenCalled();
+
+    document.body.removeChild(el);
+    scope.stop();
+  });
+
+  it('does NOT prevent default when the touch target is itself scrollable (iOS)', () => {
+    const el = document.createElement('div');
+    document.body.appendChild(el);
+    let captured: EventListener | undefined;
+    vi.spyOn(el, 'addEventListener').mockImplementation((type, listener) => {
+      if (type === 'touchmove')
+        captured = listener as EventListener;
+    });
+
+    const scrollable = document.createElement('div');
+    el.appendChild(scrollable);
+
+    // Force the inner element to look scrollable.
+    const win = {
+      getComputedStyle: (node: Element) =>
+        node === scrollable
+          ? ({ overflowX: 'scroll', overflowY: 'scroll' } as CSSStyleDeclaration)
+          : ({ overflowX: 'visible', overflowY: 'visible' } as CSSStyleDeclaration),
+    } as unknown as Window;
+
+    const scope = effectScope();
+    let isLocked: ReturnType<typeof useScrollLock>;
+    scope.run(() => {
+      isLocked = useScrollLock(ref(el), false, { navigator: makeIOSNavigator(), window: win });
+    });
+    isLocked!.value = true;
+
+    const event = {
+      target: scrollable,
+      touches: [{}],
+      cancelable: true,
+      preventDefault: vi.fn(),
+    } as unknown as TouchEvent;
+    captured!(event);
+
+    expect(event.preventDefault).not.toHaveBeenCalled();
+
+    el.removeChild(scrollable);
+    document.body.removeChild(el);
+    scope.stop();
+  });
+
+  it('restores overflow and detaches the touchmove listener on scope dispose', () => {
+    // The composable registers tryOnScopeDispose(unlock), so disposing the scope
+    // restores the prior overflow and tears the iOS touchmove listener down even
+    // though the lock was triggered from the setter (outside the scope).
+    const el = document.createElement('div');
+    el.style.overflow = 'auto';
+    const removeSpy = vi.spyOn(el, 'removeEventListener');
+    const scope = effectScope();
+    let isLocked: ReturnType<typeof useScrollLock>;
+    scope.run(() => {
+      isLocked = useScrollLock(ref(el), false, { navigator: makeIOSNavigator() });
+    });
+
+    isLocked!.value = true;
+    expect(el.style.overflow).toBe('hidden');
+
+    scope.stop();
+
+    expect(el.style.overflow).toBe('auto');
+    expect(removeSpy).toHaveBeenCalledWith('touchmove', expect.any(Function), expect.anything());
+  });
+
+  it('does not register listeners when window is falsy (SSR)', () => {
+    const el = document.createElement('div');
+    const addSpy = vi.spyOn(el, 'addEventListener');
+    const scope = effectScope();
+    let isLocked: ReturnType<typeof useScrollLock>;
+    scope.run(() => {
+      isLocked = useScrollLock(ref(el), false, {
+        window: null as unknown as Window,
+        navigator: makeIOSNavigator(),
+      });
+    });
+
+    isLocked!.value = true;
+
+    // overflow is still toggled, but no iOS touchmove listener is attached.
+    expect(el.style.overflow).toBe('hidden');
+    expect(addSpy).not.toHaveBeenCalledWith('touchmove', expect.any(Function), expect.anything());
+    scope.stop();
+  });
+});

vue/toolkit/src/composables/browser/useScrollLock/index.ts

@@ -0,0 +1,183 @@
+import type { WritableComputedRef } from 'vue';
+import { computed, shallowRef, toRef, watch } from 'vue';
+import type { VoidFunction } from '@robonen/stdlib';
+import type { ConfigurableNavigator, ConfigurableWindow } from '@/types';
+import { defaultNavigator, defaultWindow } from '@/types';
+import type { MaybeComputedElementRef } from '@/composables/component/unrefElement';
+import { unrefElement } from '@/composables/component/unrefElement';
+import { useEventListener } from '@/composables/browser/useEventListener';
+import { tryOnScopeDispose } from '@/composables/lifecycle/tryOnScopeDispose';
+
+type LockableElement = HTMLElement | SVGElement;
+
+export interface UseScrollLockOptions extends ConfigurableWindow, ConfigurableNavigator {}
+
+export type UseScrollLockReturn = WritableComputedRef<boolean>;
+
+/**
+ * Stores each element's `style.overflow` value as it was the first time we
+ * touched it, so unlocking restores exactly what the author had set (rather
+ * than wiping inline overflow entirely). A WeakMap keeps this from pinning
+ * detached elements in memory.
+ */
+const elementInitialOverflow = /* #__PURE__ */ new WeakMap<LockableElement, string>();
+
+function isIOS(navigator: Navigator | undefined): boolean {
+  if (!navigator)
+    return false;
+
+  const ua = navigator.userAgent;
+  // iPhone / iPod / legacy iPad, plus iPadOS 13+ which masquerades as MacIntel
+  // while reporting a touch screen.
+  return /iP(?:ad|hone|od)/.test(ua)
+    || (navigator.platform === 'MacIntel' && (navigator.maxTouchPoints ?? 0) > 1);
+}
+
+/**
+ * Walks up from the touched node looking for an ancestor that can actually
+ * scroll. If one exists we must NOT prevent the touchmove, otherwise nested
+ * scroll regions (e.g. a modal body) become un-scrollable on iOS.
+ */
+function checkOverflowScroll(element: Element, window: Window): boolean {
+  const style = window.getComputedStyle(element);
+
+  if (
+    style.overflowX === 'scroll'
+    || style.overflowY === 'scroll'
+    || (style.overflowX === 'auto' && element.clientWidth < element.scrollWidth)
+    || (style.overflowY === 'auto' && element.clientHeight < element.scrollHeight)
+  ) {
+    return true;
+  }
+
+  const parent = element.parentNode as Element | null;
+
+  if (!parent || parent.tagName === 'BODY')
+    return false;
+
+  return checkOverflowScroll(parent, window);
+}
+
+function preventDefault(event: TouchEvent, window: Window): void {
+  const target = event.target as Element | null;
+
+  // Allow scrolling inside genuinely scrollable descendants.
+  if (target && checkOverflowScroll(target, window))
+    return;
+
+  // A multi-touch gesture (pinch-zoom) should be left alone.
+  if (event.touches.length > 1)
+    return;
+
+  if (event.cancelable)
+    event.preventDefault();
+}
+
+/**
+ * @name useScrollLock
+ * @category Browser
+ * @description Lock scrolling of an element by toggling `overflow: hidden`,
+ * preserving the element's prior inline overflow and handling iOS `touchmove`.
+ * Returns a writable boolean ref — set it to lock/unlock, read it for state.
+ *
+ * @param {MaybeComputedElementRef} element - The element (or template ref / getter) to lock.
+ * @param {boolean} [initialState] - Whether the element starts locked. Defaults to `false`.
+ * @param {UseScrollLockOptions} [options] - Configurable `window` / `navigator` (mainly for SSR & testing).
+ * @returns {UseScrollLockReturn} A writable boolean ref; `true` while locked.
+ *
+ * @example
+ * const el = useTemplateRef<HTMLElement>('el');
+ * const isLocked = useScrollLock(el);
+ * isLocked.value = true; // lock
+ * isLocked.value = false; // unlock
+ *
+ * @since 0.0.15
+ */
+export function useScrollLock(
+  element: MaybeComputedElementRef,
+  initialState = false,
+  options: UseScrollLockOptions = {},
+): UseScrollLockReturn {
+  const { window = defaultWindow, navigator = defaultNavigator } = options;
+
+  const isLocked = shallowRef(initialState);
+  let stopTouchMoveListener: VoidFunction | null = null;
+  let initialOverflow = '';
+
+  watch(
+    toRef(element),
+    () => {
+      const el = unrefElement(element) as LockableElement | undefined;
+
+      if (!el)
+        return;
+
+      const style = el.style;
+
+      if (!elementInitialOverflow.has(el))
+        elementInitialOverflow.set(el, style.overflow);
+
+      if (style.overflow !== 'hidden')
+        initialOverflow = style.overflow;
+
+      // The element was already hidden before we attached — treat as locked.
+      if (style.overflow === 'hidden') {
+        isLocked.value = true;
+        return;
+      }
+
+      if (isLocked.value)
+        style.overflow = 'hidden';
+    },
+    { immediate: true },
+  );
+
+  const lock = (): void => {
+    const el = unrefElement(element) as LockableElement | undefined;
+
+    if (!el || isLocked.value)
+      return;
+
+    if (window && isIOS(navigator)) {
+      stopTouchMoveListener = useEventListener(
+        el as HTMLElement,
+        'touchmove',
+        (event: Event) => preventDefault(event as TouchEvent, window),
+        { passive: false },
+      );
+    }
+
+    el.style.overflow = 'hidden';
+    isLocked.value = true;
+  };
+
+  const unlock = (): void => {
+    const el = unrefElement(element) as LockableElement | undefined;
+
+    if (!el || !isLocked.value)
+      return;
+
+    stopTouchMoveListener?.();
+    stopTouchMoveListener = null;
+
+    el.style.overflow = initialOverflow;
+    elementInitialOverflow.delete(el);
+    isLocked.value = false;
+  };
+
+  // Restore overflow and detach the iOS touchmove listener when the owning
+  // scope is disposed, regardless of where the lock was triggered from.
+  tryOnScopeDispose(unlock);
+
+  return computed<boolean>({
+    get() {
+      return isLocked.value;
+    },
+    set(value) {
+      if (value)
+        lock();
+      else
+        unlock();
+    },
+  });
+}

vue/toolkit/src/composables/browser/useShare/index.test.ts

@@ -0,0 +1,119 @@
+import { describe, expect, it, vi } from 'vitest';
+import { effectScope, ref } from 'vue';
+import { useShare } from '.';
+import type { UseShareOptions } from '.';
+
+function stubShareNavigator(canShareResult = true) {
+  const share = vi.fn(async (_data?: UseShareOptions) => {});
+  const canShare = vi.fn((_data?: UseShareOptions) => canShareResult);
+  const navigator = { share, canShare } as unknown as Navigator;
+  return { navigator, share, canShare };
+}
+
+function withScope<T>(fn: () => T): { result: T; stop: () => void } {
+  const scope = effectScope();
+  let result!: T;
+  scope.run(() => {
+    result = fn();
+  });
+  return { result, stop: () => scope.stop() };
+}
+
+describe(useShare, () => {
+  it('reports supported when the Web Share API is present', () => {
+    const { navigator } = stubShareNavigator();
+    const { result, stop } = withScope(() => useShare({}, { navigator }));
+    expect(result.isSupported.value).toBeTruthy();
+    stop();
+  });
+
+  it('reports unsupported when canShare is missing', () => {
+    const navigator = {} as Navigator;
+    const { result, stop } = withScope(() => useShare({}, { navigator }));
+    expect(result.isSupported.value).toBeFalsy();
+    stop();
+  });
+
+  it('calls navigator.share with the default share options', async () => {
+    const { navigator, share, canShare } = stubShareNavigator();
+    const data = { title: 'Hello', text: 'World', url: 'https://example.com' };
+    const { result, stop } = withScope(() => useShare(data, { navigator }));
+
+    await result.share();
+
+    expect(canShare).toHaveBeenCalledWith(data);
+    expect(share).toHaveBeenCalledWith(data);
+    stop();
+  });
+
+  it('merges overrideData over the default options', async () => {
+    const { navigator, share } = stubShareNavigator();
+    const { result, stop } = withScope(() =>
+      useShare({ title: 'Default', text: 'Default text' }, { navigator }),
+    );
+
+    await result.share({ text: 'Override text', url: 'https://override.dev' });
+
+    expect(share).toHaveBeenCalledWith({
+      title: 'Default',
+      text: 'Override text',
+      url: 'https://override.dev',
+    });
+    stop();
+  });
+
+  it('resolves reactive/getter share options at call time', async () => {
+    const { navigator, share } = stubShareNavigator();
+    const title = ref('first');
+    const { result, stop } = withScope(() => useShare(() => ({ title: title.value }), { navigator }));
+
+    await result.share();
+    expect(share).toHaveBeenLastCalledWith({ title: 'first' });
+
+    title.value = 'second';
+    await result.share();
+    expect(share).toHaveBeenLastCalledWith({ title: 'second' });
+    stop();
+  });
+
+  it('does not call share when canShare rejects the payload', async () => {
+    const { navigator, share, canShare } = stubShareNavigator(false);
+    const { result, stop } = withScope(() => useShare({ title: 'Nope' }, { navigator }));
+
+    await result.share();
+
+    expect(canShare).toHaveBeenCalled();
+    expect(share).not.toHaveBeenCalled();
+    stop();
+  });
+
+  it('skips canShare gating when canShare is unavailable', async () => {
+    const share = vi.fn(async () => {});
+    // No canShare -> isSupported is false, so share is a no-op.
+    const navigator = { share } as unknown as Navigator;
+    const { result, stop } = withScope(() => useShare({ title: 'Hi' }, { navigator }));
+
+    expect(result.isSupported.value).toBeFalsy();
+    await result.share();
+    expect(share).not.toHaveBeenCalled();
+    stop();
+  });
+
+  it('is a no-op when unsupported (SSR / missing navigator)', async () => {
+    const navigator = undefined as unknown as Navigator;
+    const { result, stop } = withScope(() => useShare({ title: 'Hi' }, { navigator }));
+
+    expect(result.isSupported.value).toBeFalsy();
+    await expect(result.share()).resolves.toBeUndefined();
+    stop();
+  });
+
+  it('returns the share promise from navigator.share', async () => {
+    const { navigator, share } = stubShareNavigator();
+    share.mockResolvedValueOnce(undefined);
+    const { result, stop } = withScope(() => useShare({ title: 'Hi' }, { navigator }));
+
+    await expect(result.share()).resolves.toBeUndefined();
+    stop();
+  });
+});

vue/toolkit/src/composables/browser/useShare/index.ts

@@ -0,0 +1,102 @@
+import { toValue } from 'vue';
+import type { MaybeRefOrGetter, Ref } from 'vue';
+import { defaultNavigator } from '@/types';
+import type { ConfigurableNavigator } from '@/types';
+import { useSupported } from '@/composables/browser/useSupported';
+
+export interface UseShareOptions {
+  /**
+   * Title of the shared content
+   */
+  title?: string;
+
+  /**
+   * Arbitrary text that forms the body of the message being shared
+   */
+  text?: string;
+
+  /**
+   * URL string referring to a resource being shared
+   */
+  url?: string;
+
+  /**
+   * Array of `File` objects representing files to be shared
+   */
+  files?: File[];
+}
+
+/**
+ * Subset of `Navigator` exposing the Web Share API surface, which is not yet in
+ * every lib DOM target.
+ */
+interface NavigatorWithShare {
+  share?: (data?: UseShareOptions) => Promise<void>;
+  canShare?: (data?: UseShareOptions) => boolean;
+}
+
+export interface UseShareReturn {
+  /**
+   * Whether the Web Share API is available
+   */
+  isSupported: Readonly<Ref<boolean>>;
+
+  /**
+   * Invoke the native share sheet, optionally merging `overrideData` over the
+   * default share options. Resolves once sharing finishes (or is skipped when
+   * unsupported / the payload cannot be shared).
+   */
+  share: (overrideData?: MaybeRefOrGetter<UseShareOptions>) => Promise<void>;
+}
+
+/**
+ * @name useShare
+ * @category Browser
+ * @description Reactive Web Share API wrapper to invoke the native share sheet.
+ *
+ * @param {MaybeRefOrGetter<UseShareOptions>} [shareOptions={}] Default share payload (title, text, url, files)
+ * @param {UseShareOptions} [options={}] Options
+ * @returns {UseShareReturn} `isSupported` flag and a `share` method
+ *
+ * @example
+ * const { share, isSupported } = useShare({ title: 'Hello', url: location.href });
+ * share();
+ *
+ * @example
+ * // Override the default payload per call
+ * const { share } = useShare({ title: 'Default' });
+ * share({ text: 'One-off message' });
+ *
+ * @since 0.0.15
+ */
+export function useShare(
+  shareOptions: MaybeRefOrGetter<UseShareOptions> = {},
+  options: ConfigurableNavigator = {},
+): UseShareReturn {
+  const { navigator = defaultNavigator } = options;
+
+  const _navigator = navigator as NavigatorWithShare | undefined;
+  const isSupported = useSupported(() => !!_navigator && 'canShare' in _navigator);
+
+  const share = async (overrideData: MaybeRefOrGetter<UseShareOptions> = {}): Promise<void> => {
+    if (!isSupported.value || !_navigator)
+      return;
+
+    const data: UseShareOptions = {
+      ...toValue(shareOptions),
+      ...toValue(overrideData),
+    };
+
+    // `canShare` gates the payload (e.g. file types / size); only proceed when it
+    // accepts the data to avoid a guaranteed-to-reject `share()` call.
+    if (_navigator.canShare && !_navigator.canShare(data))
+      return;
+
+    return _navigator.share?.(data);
+  };
+
+  return {
+    isSupported,
+    share,
+  };
+}

vue/toolkit/src/composables/browser/useSupported/index.test.ts

@@ -1,5 +1,5 @@
 import { defineComponent } from 'vue';
-import { describe, it, expect } from 'vitest';
+import { describe, expect, it } from 'vitest';
 import { useSupported } from '.';
 import { mount } from '@vue/test-utils';
 

vue/toolkit/src/composables/browser/useSupported/index.ts

@@ -21,9 +21,8 @@ export function useSupported(feature: () => unknown) {
   const isMounted = useMounted();
 
   return computed(() => {
-    // add reactive dependency on isMounted
+    // Touch isMounted to register it as a reactive dependency
-    // eslint-disable-next-line no-unused-expressions
+    void isMounted.value;
-    isMounted.value;
 
     return Boolean(feature());
   });