[lexical] Bug Fix: Don't scroll or steal focus when an IME composition is force-committed - #8835

…n is force-committed

Clicking outside the editor mid-composition makes the browser force-commit and
fire compositionend. Because the commit happens before focus actually moves, the
editor is still the active element, so every activeElement guard in
$updateDOMSelection passes and reconciliation scrolls the caret back into view —
undoing the scrolling the user just did to reach whatever they clicked. A plain
contenteditable keeps its scroll position under the same gesture.

Distinguish keyboard-driven commits from browser-forced ones: a commit typed by
the user (Space/Enter, next-syllable, arrows) is always preceded by a keydown on
the editor, and one caused by clicking away is not. When the keydown is missing,
tag the update with SKIP_SELECTION_FOCUS_TAG and SKIP_SCROLL_INTO_VIEW_TAG,
reusing the lastKeyDownTimeStamp heuristic $handleCompositionStart already uses.
The committed text is still synced and the selection still reconciled; only the
focus grab and the scroll-into-view are suppressed. Android Chrome zeroes
lastKeyDownTimeStamp while composing, so the zero check leaves it unchanged.

Both routes into compositionend are covered: the immediate one and Firefox's,
which defers the commit to the input event that follows.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

…ionEndImpl

Follow-up to the force-committed-composition scroll fix, addressing review
feedback that the tag-setting should belong to $onCompositionEndImpl rather
than trail after each of its callers.

Moving the tagging inside the function — right after $setCompositionKey(null),
before any exit — makes the tag follow from ending the composition instead of
from each caller remembering to add it. That closes two gaps the caller-side
tagging had left open, both intended:

- The token-redirect path in $handleInput only tagged when it actually
  redirected onto a token node. An ordinary multi-character commit (the common
  CJK case) ended untagged. It is now tagged.
- Safari's deferred 'ending-safari' commit, processed on the following keydown,
  was never tagged at all. It is now tagged. Because that path finishes the
  commit later, the compositionend timeStamp is stashed in the new
  InputState.compositionEndTimeStamp so the classification reads when the
  composition actually ended, not when we got around to it.

Also separates RECENT_KEYDOWN_WINDOW from ANDROID_COMPOSITION_LATENCY. They
held the same value but answer different questions — one is how late Android's
keyboard delivers events, the other is whether a keystroke is behind a
composition event at all — so tuning one must not silently move the other. No
value change; the $handleCompositionStart site that was already asking the
keydown-recency question is switched to the new name.

The scroll-suppression comment now records that SKIP_SCROLL_INTO_VIEW_TAG only
suppresses Lexical's own reconciliation scroll (the Chromium case), and does
nothing where the browser natively scrolls the caret on commit (observed on
Firefox, where a plain contentEditable jumps identically).

Adds a Firefox unit test for the multi-character-commit path that the
token-redirect gap left untagged.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

## Description

Merge upstream/main at 0e9a9f5 into the IME forced-commit branch. The PR's
keydown-recency constant conflicts with main's lazy initialization of root
event handlers. Keep both the constant and the lazy event list so the
existing composition-end behavior and main's tree-shaking fix are preserved.

## Test plan

### Before

`git merge --no-commit upstream/main`

```text
Auto-merging packages/lexical/src/LexicalEditor.ts
Auto-merging packages/lexical/src/LexicalEvents.ts
CONFLICT (content): Merge conflict in packages/lexical/src/LexicalEvents.ts
Automatic merge failed; fix conflicts and then commit the result.
```

### After

Checks ran with Node v24.21.0 and pnpm v11.24.0 after a frozen-lockfile install.
`pnpm_config_verify_deps_before_run=false` used the installed dependencies
without repeating pnpm's automatic install check in the sandbox.

```sh
pnpm_config_verify_deps_before_run=false pnpm run test-unit \
  packages/lexical/src/__tests__/unit/LexicalAndroidChromeComposition.test.ts \
  packages/lexical/src/__tests__/unit/LexicalFirefoxCompositionEndTag.test.ts \
  packages/lexical/src/__tests__/unit/LexicalEventsKeyDown.test.ts \
  packages/lexical/src/__tests__/unit/LexicalEventsKeyDownApple.test.ts \
  packages/lexical/src/__tests__/unit/LexicalIosKoreanIME.test.ts \
  packages/lexical/src/__tests__/unit/IosKeyboardSuggestions.test.ts \
  scripts/__tests__/unit/treeShakingSource.test.ts
```

```text
 Test Files  7 passed (7)
      Tests  150 passed (150)
```

```sh
pnpm_config_verify_deps_before_run=false VITEST_BROWSER=chromium,firefox,webkit \
  pnpm run test-browser \
  packages/lexical/src/__tests__/browser/LexicalCompositionForcedCommit.test.ts \
  packages/lexical/src/__tests__/browser/LexicalComposition.test.ts
```

```text
 Test Files  6 passed (6)
      Tests  70 passed | 2 skipped (72)
```

`node_modules/.bin/tsc` and `git diff --cached --check upstream/main` exited 0.
ESLint exited 0 for all six PR files. Prettier checked the same files:

```sh
pnpm_config_verify_deps_before_run=false pnpm exec eslint \
  packages/lexical/src/LexicalEditor.ts \
  packages/lexical/src/LexicalEvents.ts \
  packages/lexical/src/__tests__/browser/LexicalCompositionForcedCommit.test.ts \
  packages/lexical/src/__tests__/browser/utils/compose.ts \
  packages/lexical/src/__tests__/unit/LexicalAndroidChromeComposition.test.ts \
  packages/lexical/src/__tests__/unit/LexicalFirefoxCompositionEndTag.test.ts
pnpm_config_verify_deps_before_run=false pnpm exec prettier --check \
  packages/lexical/src/LexicalEditor.ts \
  packages/lexical/src/LexicalEvents.ts \
  packages/lexical/src/__tests__/browser/LexicalCompositionForcedCommit.test.ts \
  packages/lexical/src/__tests__/browser/utils/compose.ts \
  packages/lexical/src/__tests__/unit/LexicalAndroidChromeComposition.test.ts \
  packages/lexical/src/__tests__/unit/LexicalFirefoxCompositionEndTag.test.ts
```

```text
Checking formatting...
All matched files use Prettier code style!
```

Chromium, Firefox, and WebKit ran on macOS. Real OS IME input and Android
devices were not exercised. The existing WebKit forced-commit tests still
have their documented limitation: deferred composition-end processing is
not reached without a subsequent keydown.