fix: dedupe Windows notification quick replies (#3467)

AGENTS.md

@@ -36,7 +36,9 @@ yarn workspaces:build        # Build all workspaces
 - `release/X.Y.x` branches are patch lines for a shipped stable version.
   Fixes land on `dev` first and are cherry-picked onto the release branch.
   A hotfix authored directly on a release branch must be forward-ported to
-  `dev` immediately via a cherry-pick PR.
+  `dev` in the same change or immediately after (cherry-pick PR). Do not
+  ship a stable cut from `dev` that is missing a hotfix that already
+  shipped on a release line.
 - Never back-merge `master` or a `release/X.Y.x` branch into `dev`.
 - Tags are created only via `yarn release:tag` (channel-aware guard).
   Release builds trigger on semver tag pushes only and always produce a
@@ -135,6 +137,15 @@ yarn workspaces:build        # Build all workspaces
   semantics and traps, Fuselage geometry/timing facts, the button-dimming and
   SVG transform-origin pitfalls, and layout rules learned in PRs #3441/#3443.
 
+## Desktop Notifications
+
+- Windows / Electron 42 can emit `reply` twice for one toast (WinRT + COM
+  activation paths). Guard `NOTIFICATIONS_NOTIFICATION_REPLIED` with a
+  per-notification `Set`; re-arm (delete the id) on `show`; never clear on
+  `close` — the duplicate can arrive after dismiss, and clearing there
+  reopens the race. If Windows replies are routed through
+  `Notification.handleActivation`, that path must use the same `Set`.
+
 ## Testing
 
 - Renderer specs use `*.spec.ts` / `*.spec.tsx`.

src/notifications/main.ts

@@ -48,6 +48,7 @@ const resolveIcon = async (
 const notifications = new Map();
 const notificationTypes = new Map<string, 'voice' | 'text'>();
 const notificationCategories = new Map<string, 'DOWNLOADS' | 'SERVER'>();
+const repliedNotifications = new Set<string>();
 
 const createNotification = async (
   id: string,
@@ -79,6 +80,8 @@ const createNotification = async (
   });
 
   notification.addListener('show', () => {
+    repliedNotifications.delete(id);
+
     dispatchSingle({
       type: NOTIFICATIONS_NOTIFICATION_SHOWN,
       payload: { id },
@@ -126,6 +129,12 @@ const createNotification = async (
   });
 
   notification.addListener('reply', (_event, reply) => {
+    // Electron 42 on Windows can dispatch a single toast reply twice (WinRT+COM activation paths)
+    if (repliedNotifications.has(id)) {
+      return;
+    }
+    repliedNotifications.add(id);
+
     dispatchSingle({
       type: NOTIFICATIONS_NOTIFICATION_REPLIED,
       payload: { id, reply },

src/notifications/main/setup.main.spec.ts

@@ -233,4 +233,68 @@ describe('notifications/main setupNotifications', () => {
     expect(dispatch).not.toHaveBeenCalled();
     expect(notificationInstances).toHaveLength(0);
   });
+
+  const repliedCalls = () =>
+    dispatchSingle.mock.calls.filter(
+      ([action]) => action.type === NOTIFICATIONS_NOTIFICATION_REPLIED
+    );
+
+  it('dispatches REPLIED exactly once when the same reply event fires twice', async () => {
+    await create({
+      title: 'Hello',
+      body: 'World',
+      tag: 'dedup-1',
+      canReply: true,
+    });
+    const n = notificationInstances[0];
+
+    n.emit('reply', {}, 'hi there');
+    n.emit('reply', {}, 'hi there');
+
+    expect(repliedCalls()).toHaveLength(1);
+    expect(repliedCalls()[0][0].payload).toEqual({
+      id: 'dedup-1',
+      reply: 'hi there',
+    });
+  });
+
+  it('re-arms the guard after another show event, allowing a subsequent reply to dispatch', async () => {
+    await create({
+      title: 'Hello',
+      body: 'World',
+      tag: 'dedup-2',
+      canReply: true,
+    });
+    const n = notificationInstances[0];
+
+    n.emit('reply', {}, 'first reply');
+    n.emit('show');
+    n.emit('reply', {}, 'second reply');
+
+    expect(repliedCalls()).toHaveLength(2);
+    expect(repliedCalls()[1][0].payload).toEqual({
+      id: 'dedup-2',
+      reply: 'second reply',
+    });
+  });
+
+  it('does not re-arm the reply guard on close (duplicate can arrive after dismiss)', async () => {
+    await create({
+      title: 'Hello',
+      body: 'World',
+      tag: 'dedup-3',
+      canReply: true,
+    });
+    const n = notificationInstances[0];
+
+    n.emit('reply', {}, 'once');
+    n.emit('close');
+    n.emit('reply', {}, 'late duplicate');
+
+    expect(repliedCalls()).toHaveLength(1);
+    expect(repliedCalls()[0][0].payload).toEqual({
+      id: 'dedup-3',
+      reply: 'once',
+    });
+  });
 });