diff --git a/packages/ui/src/components/comments/InlineCommentInput.ime.test.ts b/packages/ui/src/components/comments/InlineCommentInput.ime.test.ts
new file mode 100644
index 00000000..91b025b6
--- /dev/null
+++ b/packages/ui/src/components/comments/InlineCommentInput.ime.test.ts
@@ -0,0 +1,24 @@
+import { describe, expect, test } from 'bun:test';
+import { readFileSync } from 'node:fs';
+import { dirname, join } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const inputSource = readFileSync(join(__dirname, 'InlineCommentInput.tsx'), 'utf-8');
+
+describe('InlineCommentInput IME handling', () => {
+  test('ignores composition keydown events before handling save shortcuts', () => {
+    expect(inputSource).toContain("import { isIMECompositionEvent } from '@/lib/ime';");
+
+    const handlerStart = inputSource.indexOf('const handleKeyDown');
+    const handlerEnd = inputSource.indexOf('const handleSaveClick', handlerStart);
+    expect(handlerStart).toBeGreaterThan(-1);
+    expect(handlerEnd).toBeGreaterThan(handlerStart);
+
+    const handler = inputSource.slice(handlerStart, handlerEnd);
+    const imeGuard = handler.indexOf('if (isIMECompositionEvent(e)) return;');
+    const saveShortcut = handler.indexOf("e.key === 'Enter'");
+    expect(imeGuard).toBeGreaterThan(-1);
+    expect(saveShortcut).toBeGreaterThan(imeGuard);
+  });
+});
diff --git a/packages/ui/src/components/comments/InlineCommentInput.tsx b/packages/ui/src/components/comments/InlineCommentInput.tsx
index c9abd28d..0fb1ef61 100644
--- a/packages/ui/src/components/comments/InlineCommentInput.tsx
+++ b/packages/ui/src/components/comments/InlineCommentInput.tsx
@@ -3,6 +3,7 @@ import { cn } from '@/lib/utils';
 import { Icon } from '@/components/icon/Icon';
 import { useDeviceInfo } from '@/lib/device';
 import { useI18n } from '@/lib/i18n';
+import { isIMECompositionEvent } from '@/lib/ime';
 import { formatShortcutForDisplay } from '@/lib/shortcuts';
 
 export interface InlineCommentInputProps {
@@ -121,6 +122,8 @@ export function InlineCommentInput({
   };
 
   const handleKeyDown = (e: React.KeyboardEvent) => {
+    if (isIMECompositionEvent(e)) return;
+
     // As the placeholder promises: Cmd/Ctrl+Enter attaches, plain Enter
     // breaks the line, Escape cancels.
     if ((e.metaKey || e.ctrlKey) && e.key === 'Enter') {
diff --git a/packages/ui/src/lib/browser/annotationOverlay.test.ts b/packages/ui/src/lib/browser/annotationOverlay.test.ts
index b737e480..c1869813 100644
--- a/packages/ui/src/lib/browser/annotationOverlay.test.ts
+++ b/packages/ui/src/lib/browser/annotationOverlay.test.ts
@@ -67,6 +67,19 @@ describe('annotation overlay script', () => {
     expect(script).toContain('event.stopPropagation();');
   });
 
+  test('does not attach a comment while IME composition is active', () => {
+    const handlerStart = script.indexOf('var onCommentKeyDown = function (event) {');
+    const handlerEnd = script.indexOf('};', handlerStart);
+    expect(handlerStart).toBeGreaterThan(-1);
+    expect(handlerEnd).toBeGreaterThan(handlerStart);
+
+    const handler = script.slice(handlerStart, handlerEnd);
+    const imeGuard = handler.indexOf('event.isComposing || event.keyCode === 229');
+    const attachCall = handler.indexOf('attach();');
+    expect(imeGuard).toBeGreaterThan(-1);
+    expect(attachCall).toBeGreaterThan(imeGuard);
+  });
+
   test('escapes a label that would otherwise close the script', () => {
     const hostile = buildAnnotationOverlayScript(theme, {
       ...labels,
diff --git a/packages/ui/src/lib/browser/annotationOverlay.ts b/packages/ui/src/lib/browser/annotationOverlay.ts
index d752fb94..012daf19 100644
--- a/packages/ui/src/lib/browser/annotationOverlay.ts
+++ b/packages/ui/src/lib/browser/annotationOverlay.ts
@@ -545,6 +545,8 @@ export const buildAnnotationOverlayScript = (
   var onCommentKeyDown = function (event) {
     // Do not let the annotated page treat typed letters as its own shortcuts.
     event.stopPropagation();
+    // WebKit can report the composition-confirming Enter as keyCode 229.
+    if (event.isComposing || event.keyCode === 229) return;
     if (event.key === 'Enter' && !event.shiftKey) {
       event.preventDefault();
       attach();