fix(desktop): flush DOM to draft before submit to avoid IME character drop

[szzhangkkk]

What

Fix Korean IME input dropping the final character or word when sending immediately after composition without a trailing space.

Why

submitDraft read the draft React state variable (line 1241), which is updated asynchronously via aui.composer().setText(). When the user pressed Enter right after IME compositionend, the React re-render from the async state update hadn't committed yet — so draft held a stale value missing the last composed character.

The sequence:

1. User types "안녕" with Korean IME → composition is active
2. First Enter → consumed by IME to finalize composition
3. compositionend fires → flushEditorToDraft sets draftRef.current = "안녕" (sync) and calls aui.composer().setText("안녕") (async, queued)
4. Second Enter → submitDraft() reads draft → still "안" or "" (stale React state) → final character dropped

The hasComposerPayload check also read stale state, so in the worst case (first composition, no prior text) the submit path was skipped entirely.

How

At the top of submitDraft, call flushEditorToDraft(editorRef.current) to pull the live DOM text into draftRef.current synchronously, then read draftRef.current (via a local currentDraft) for all submit-path decisions instead of the stale React draft variable.

This is safe because flushEditorToDraft is idempotent — if the DOM already matches draftRef.current, it's a no-op.

How to test

1. Launch Hermes Desktop on macOS
2. Switch to Korean IME (Hangul)
3. Type a Korean sentence (e.g. "안녕하세요")
4. Press Enter to finalize composition, then immediately press Enter again to send
5. The full sentence should be sent — no dropped final character
6. Also test: type Korean text and send without adding a trailing space — should work correctly

Platforms tested

• macOS (primary target per issue reporter)
• The fix is IME-framework-level — no platform-specific code, applies to all CJK IMEs (Korean, Japanese, Chinese)

Related issues

Fixes #40633
Regression-safe companion to the #39614 IME fix that added flushEditorToDraft in onCompositionEnd

🤖 Generated with Claude Code

[szzhangkkk]

Update: added regression test

Added apps/desktop/src/app/chat/composer/ime-submit-race.test.tsx with 4 test cases covering the IME submit race condition:

Test	Scenario
Korean IME	안녕 → immediate Enter → full text submitted
Chinese IME	你好世界 → immediate Enter → full text submitted
Japanese IME	こんにちは → immediate Enter → full text submitted
Empty composition	compositionend with no text → Enter → no submit

All 4 tests pass. Existing ime-composition-dom-repro.test.tsx (2 tests, #39614) also passes — no regression.

Verification results

$ vitest run --environment jsdom apps/desktop/src/app/chat/composer/ime-submit-race.test.tsx
 ✓ 4 passed (36ms)

$ vitest run --environment jsdom apps/desktop/src/app/chat/composer/ime-composition-dom-repro.test.tsx
 ✓ 2 passed (no regression)

$ tsc --noEmit
  6 errors — all pre-existing (findLast/findLastIndex es2023 lib), none from this change

[teknium1]

Thanks for the IME investigation and regression coverage. The reported stale-draft behavior is already fixed on current main by an independent implementation, so this PR is now redundant.

• 8b84d82227a3b637a26ba5f4f41bb08281e2ab84 (fix(desktop): send on Enter from live editor text, not stale composer state) synchronizes draftRef from the live editor before submit decisions.
• apps/desktop/src/app/chat/composer/hooks/use-composer-submit.ts:110–167 now sends, queues, and drains from that synchronized value rather than render-lagged composer state.
• apps/desktop/src/app/chat/composer/index.tsx:558–589 also makes the Enter-path decision from live DOM text.
• apps/desktop/src/app/chat/composer/enter-submit-dom-race.test.tsx:129 covers the stale-DOM-state submission and queueing cases.

This is an automated hermes-sweeper review.