fix(dashboard): defer IME fallback until xterm input settles

web/src/lib/pty-composition.test.ts

@@ -1,24 +1,40 @@
-import { describe, expect, it, vi } from "vitest";
+import { afterEach, describe, expect, it, vi } from "vitest";
 
 import { createPtyCompositionForwarder } from "./pty-composition";
 
 describe("createPtyCompositionForwarder", () => {
-  it("forwards committed dead-key text and suppresses xterm's duplicate onData", () => {
+  afterEach(() => vi.useRealTimers());
+
+  it("forwards committed dead-key text when xterm emits no onData", () => {
+    vi.useFakeTimers();
     const send = vi.fn();
     const forwarder = createPtyCompositionForwarder(send);
 
     forwarder.onCompositionEnd("ä");
+    vi.runAllTimers();
 
     expect(send).toHaveBeenCalledExactlyOnceWith("ä");
-    expect(forwarder.shouldForwardTerminalData("ä")).toBe(false);
-    expect(forwarder.shouldForwardTerminalData("x")).toBe(true);
+  });
+
+  it("leaves xterm's committed input alone when it arrives before the fallback", () => {
+    vi.useFakeTimers();
+    const send = vi.fn();
+    const forwarder = createPtyCompositionForwarder(send);
+
+    forwarder.onCompositionEnd("ä");
+    forwarder.noteTerminalData("äx");
+    vi.runAllTimers();
+
+    expect(send).not.toHaveBeenCalled();
   });
 
   it("does not send an empty cancelled composition", () => {
+    vi.useFakeTimers();
     const send = vi.fn();
     const forwarder = createPtyCompositionForwarder(send);
 
     forwarder.onCompositionEnd("");
+    vi.runAllTimers();
 
     expect(send).not.toHaveBeenCalled();
   });

web/src/lib/pty-composition.ts

@@ -1,25 +1,37 @@
 /**
- * Sends committed IME/dead-key text when xterm does not emit onData.
+ * Delays an IME/dead-key commit just long enough for xterm to emit onData.
  *
- * Some browser/layout combinations leave xterm's CompositionHelper without an
- * onData callback. The DOM compositionend event is the authoritative commit.
- * If xterm does emit the same bytes afterwards, consume that one duplicate.
+ * xterm is authoritative when it emits the commit. Browsers/layouts where it
+ * does not emit onData still forward the compositionend text on the next turn.
  */
 export function createPtyCompositionForwarder(send: (data: string) => void) {
-  let pendingDuplicate: string | null = null;
+  let pending: string | null = null;
+  let timer: ReturnType<typeof setTimeout> | null = null;
+
+  const clearPending = () => {
+    pending = null;
+    if (timer) {
+      clearTimeout(timer);
+      timer = null;
+    }
+  };
 
   return {
-    onCompositionEnd(data: string) {
+    onCompositionEnd(data: string | null) {
       if (!data) return;
-      pendingDuplicate = data;
-      send(data);
+      clearPending();
+      pending = data;
+      timer = setTimeout(() => {
+        const committed = pending;
+        clearPending();
+        if (committed) send(committed);
+      }, 0);
     },
-    shouldForwardTerminalData(data: string) {
-      if (data === pendingDuplicate) {
-        pendingDuplicate = null;
-        return false;
+    noteTerminalData(data: string) {
+      if (pending && data.startsWith(pending)) {
+        clearPending();
       }
-      return true;
     },
+    dispose: clearPending,
   };
 }

web/src/pages/ChatPage.tsx

@@ -36,8 +36,8 @@ import { usePageHeader } from "@/contexts/usePageHeader";
 import { useI18n } from "@/i18n";
 import { api } from "@/lib/api";
 import { latchChatActivation } from "@/lib/chat-activation";
-import { createPtyCompositionForwarder } from "@/lib/pty-composition";
 import { normalizeSessionTitle } from "@/lib/chat-title";
+import { createPtyCompositionForwarder } from "@/lib/pty-composition";
 import { PtyResumeSanitizer } from "@/lib/pty-resume-sanitizer";
 import {
   PTY_CONNECTING_TIMEOUT_MS,
@@ -801,9 +801,9 @@ export default function ChatPage({ isActive = true }: { isActive?: boolean }) {
           mobileReplacementInputUntilRef.current = Date.now() + MOBILE_REPLACEMENT_WINDOW_MS;
         }
       };
-      const markCompositionEnd = (ev: Event) => {
+      const markCompositionEnd = (ev: CompositionEvent) => {
         mobileReplacementInputUntilRef.current = Date.now() + MOBILE_REPLACEMENT_WINDOW_MS;
-        compositionForwarder.onCompositionEnd((ev as CompositionEvent).data);
+        compositionForwarder.onCompositionEnd(ev.data);
       };
 
       textarea.addEventListener("beforeinput", markReplacementInput, true);
@@ -1278,7 +1278,7 @@ export default function ChatPage({ isActive = true }: { isActive?: boolean }) {
     // behave normally.
       // eslint-disable-next-line no-control-regex -- intentional ESC byte in xterm SGR mouse report parser
       const SGR_MOUSE_RE = /^\x1b\[<(\d+);(\d+);(\d+)([Mm])$/;
-      const forwardPtyData = (data: string) => {
+      const forwardPtyData = (data: string, useMobileReplacement = true) => {
         // Mouse reports (scroll wheel etc.) are not typed input — swallow
         // them before the blocked-input check so scrolling a disconnected
         // terminal doesn't trip the "reconnecting" notice.
@@ -1302,7 +1302,7 @@ export default function ChatPage({ isActive = true }: { isActive?: boolean }) {
         const normalized = normalizePtyMobileInput(
           data,
           ptyInputLineRef.current,
-          Date.now() <= mobileReplacementInputUntilRef.current,
+          useMobileReplacement && Date.now() <= mobileReplacementInputUntilRef.current,
         );
         ptyInputLineRef.current = normalized.nextLine;
         if (normalized.normalized) {
@@ -1310,11 +1310,13 @@ export default function ChatPage({ isActive = true }: { isActive?: boolean }) {
         }
         ws.send(normalized.data);
       };
-      sendComposedText = forwardPtyData;
+      // The deferred composition fallback is already committed text, so it
+      // must not consume the mobile replacement window intended for xterm's
+      // normal onData path.
+      sendComposedText = (data) => forwardPtyData(data, false);
       onDataDisposable = term.onData((data) => {
-        if (compositionForwarder.shouldForwardTerminalData(data)) {
-          forwardPtyData(data);
-        }
+        compositionForwarder.noteTerminalData(data);
+        forwardPtyData(data);
       });
 
       onResizeDisposable = term.onResize(({ cols, rows }) => {
@@ -1344,6 +1346,7 @@ export default function ChatPage({ isActive = true }: { isActive?: boolean }) {
       onResizeDisposable?.dispose();
       onScrollDisposable?.dispose();
       mobileInputCleanup?.();
+      compositionForwarder.dispose();
       host.removeEventListener("paste", handleBrowserPaste, true);
       host.removeEventListener("dragover", handleBrowserDragOver, true);
       host.removeEventListener("drop", handleBrowserDrop, true);