fix(desktop): recover from a stale IME composition flag that silently blocks all sends

apps/desktop/src/app/chat/composer/enter-stale-ime-flag.test.tsx

@@ -0,0 +1,129 @@
+import { act, cleanup, fireEvent, render } from '@testing-library/react'
+import { useRef } from 'react'
+import { afterEach, describe, expect, it, vi } from 'vitest'
+
+afterEach(cleanup)
+
+// Faithful mirror of index.tsx's IME wiring: the composition guard at the top
+// of handleEditorKeyDown (self-heal + swallow), the compositionstart/end
+// handlers, and the blur reset.
+//
+// Regression repro for #44135: compositionend can be missed (focus jumps,
+// input-source switches, programmatic DOM swaps mid-preedit), leaving
+// composingRef wedged true. Before the fix, a wedged flag silently swallowed
+// every Enter — and, via the form onSubmit guard, the Send button — until the
+// composer remounted, which read as "Enter has no effect, no error, nothing
+// reaches the gateway". The fix trusts Chromium's per-keydown isComposing flag
+// to clear a stale ref, and clears it on blur (a composition never survives
+// focus loss).
+function Harness({ onSubmit, wedgeComposing }: { onSubmit: (text: string) => void; wedgeComposing?: boolean }) {
+  const editorRef = useRef<HTMLDivElement>(null)
+  const composingRef = useRef(Boolean(wedgeComposing))
+
+  const submitDraft = () => {
+    onSubmit(editorRef.current?.textContent ?? '')
+  }
+
+  const handleKeyDown = (event: React.KeyboardEvent<HTMLDivElement>) => {
+    if (composingRef.current && !event.nativeEvent.isComposing) {
+      composingRef.current = false
+    }
+
+    if (composingRef.current || event.nativeEvent.isComposing) {
+      return
+    }
+
+    if (event.key === 'Enter' && !event.shiftKey) {
+      event.preventDefault()
+      submitDraft()
+    }
+  }
+
+  return (
+    <div>
+      <div
+        contentEditable
+        data-testid="editor"
+        onBlur={() => {
+          composingRef.current = false
+        }}
+        onCompositionEnd={() => {
+          composingRef.current = false
+        }}
+        onCompositionStart={() => {
+          composingRef.current = true
+        }}
+        onKeyDown={handleKeyDown}
+        ref={editorRef}
+        suppressContentEditableWarning
+      />
+      <button
+        data-testid="send"
+        onClick={() => {
+          // Mirrors the form onSubmit guard in index.tsx.
+          if (composingRef.current) {
+            return
+          }
+
+          submitDraft()
+        }}
+        type="button"
+      />
+    </div>
+  )
+}
+
+describe('composer Enter — stale IME composition flag recovery (#44135)', () => {
+  it('sends on Enter despite a wedged composing flag when the native event says not composing', async () => {
+    const onSubmit = vi.fn()
+    const { getByTestId } = render(<Harness onSubmit={onSubmit} wedgeComposing />)
+    const editor = getByTestId('editor')
+
+    await act(async () => {
+      editor.textContent = 'hello after wedge'
+      fireEvent.keyDown(editor, { key: 'Enter', isComposing: false })
+    })
+
+    expect(onSubmit).toHaveBeenCalledWith('hello after wedge')
+  })
+
+  it('still swallows Enter during a genuine composition (isComposing keydown)', async () => {
+    const onSubmit = vi.fn()
+    const { getByTestId } = render(<Harness onSubmit={onSubmit} />)
+    const editor = getByTestId('editor')
+
+    await act(async () => {
+      fireEvent.compositionStart(editor)
+      editor.textContent = '你好'
+      // The Enter that confirms the preedit: Chromium stamps isComposing=true.
+      fireEvent.keyDown(editor, { key: 'Enter', isComposing: true })
+    })
+
+    expect(onSubmit).not.toHaveBeenCalled()
+
+    // After compositionend, the next Enter sends normally.
+    await act(async () => {
+      fireEvent.compositionEnd(editor)
+      fireEvent.keyDown(editor, { key: 'Enter', isComposing: false })
+    })
+
+    expect(onSubmit).toHaveBeenCalledWith('你好')
+  })
+
+  it('unblocks the Send button after blur even when compositionend was missed', async () => {
+    const onSubmit = vi.fn()
+    const { getByTestId } = render(<Harness onSubmit={onSubmit} />)
+    const editor = getByTestId('editor')
+
+    await act(async () => {
+      fireEvent.compositionStart(editor)
+      editor.textContent = '发送'
+      // compositionend never fires (the wedge) — the user mouses to Send,
+      // blurring the editor.
+      fireEvent.blur(editor)
+      fireEvent.click(getByTestId('send'))
+    })
+
+    expect(onSubmit).toHaveBeenCalledWith('发送')
+  })
+})

apps/desktop/src/app/chat/composer/index.tsx

@@ -762,6 +762,18 @@ export function ChatBar({
   }
 
   const handleEditorKeyDown = (event: KeyboardEvent<HTMLDivElement>) => {
+    // Self-heal a stale composition flag before the guard below reads it.
+    // compositionend can be missed (focus jumps, input-source switches, or a
+    // programmatic DOM swap mid-preedit abort the composition without the
+    // event reaching us), and a wedged composingRef silently swallows every
+    // Enter — and, via the form onSubmit guard, the Send button — until the
+    // component remounts (#44135). Chromium stamps isComposing on every
+    // keydown of a genuine composition, so when the native flag says we're
+    // not composing, trust it and recover.
+    if (composingRef.current && !event.nativeEvent.isComposing) {
+      composingRef.current = false
+    }
+
     // IME composition: Enter confirms composed text, not a message submission.
     // We check both composingRef (set by compositionstart/compositionend, robust
     // across browsers) and nativeEvent.isComposing (Chromium fallback).  Without
@@ -1604,7 +1616,15 @@ export function ChatBar({
         contentEditable={!disabled}
         data-placeholder={placeholder}
         data-slot={RICH_INPUT_SLOT}
-        onBlur={() => window.setTimeout(closeTrigger, 80)}
+        onBlur={() => {
+          // A composition never survives focus loss (Chromium commits the
+          // preedit and fires compositionend on blur) — but if that event is
+          // missed, the wedged flag would block the Send button's form-submit
+          // guard forever (#44135). Clear unconditionally: by the time blur
+          // runs there is nothing left composing in this editor.
+          composingRef.current = false
+          window.setTimeout(closeTrigger, 80)
+        }}
         onCompositionEnd={event => {
           composingRef.current = false