fix(extension): harden chat and target tab lifecycle

extension/chat-session.test.mjs

@@ -1,10 +1,14 @@
 import { describe, expect, it } from 'vitest';
+import { CHAT_MESSAGE_RATE_LIMIT } from '../server/rate-limiter.js';
 import {
+    CHAT_ECHO_TIMEOUT_MS,
     CHAT_SEND_LIMIT,
+    createChatEchoTracker,
     createChatSendLimiter,
     createLatestTaskQueue,
     MAX_ROOM_ID_LENGTH,
-    normalizeRoomId
+    normalizeRoomId,
+    shouldShowChatNotification
 } from './chat-session.js';
 
 describe('chat session boundaries', () => {
@@ -14,7 +18,8 @@ describe('chat session boundaries', () => {
         expect(normalizeRoomId(null)).toBe('');
     });
 
-    it('keeps client chat bursts below the relay disconnect threshold', () => {
+    it('allows ten-message client bursts without exceeding the relay threshold', () => {
+        expect(CHAT_SEND_LIMIT).toBe(CHAT_MESSAGE_RATE_LIMIT);
         let current = 1000;
         const limiter = createChatSendLimiter({ now: () => current });
         for (let index = 0; index < CHAT_SEND_LIMIT; index++) {
@@ -27,6 +32,49 @@ describe('chat session boundaries', () => {
         expect(limiter.take()).toEqual({ allowed: true, retryAfterMs: 0 });
     });
 
+    it('waits for the matching relay echo and clears pending sends on reset or timeout', async () => {
+        const timers = new Map();
+        let nextTimerId = 1;
+        const tracker = createChatEchoTracker({
+            setTimer(callback, timeoutMs) {
+                const id = nextTimerId++;
+                timers.set(id, { callback, timeoutMs });
+                return id;
+            },
+            clearTimer(id) {
+                timers.delete(id);
+            }
+        });
+
+        const acknowledged = tracker.waitFor('ciphertext-1');
+        expect(tracker.acknowledge('ciphertext-1')).toBe(true);
+        await expect(acknowledged).resolves.toBe(true);
+
+        const reset = tracker.waitFor('ciphertext-2');
+        tracker.reset();
+        await expect(reset).resolves.toBe(false);
+
+        const timedOut = tracker.waitFor('ciphertext-3');
+        const timeout = [...timers.values()][0];
+        expect(timeout.timeoutMs).toBe(CHAT_ECHO_TIMEOUT_MS);
+        timeout.callback();
+        await expect(timedOut).resolves.toBe(false);
+    });
+
+    it('suppresses chat notifications only while the target tab and its window are focused', () => {
+        const focused = {
+            enabled: true,
+            targetTabId: 7,
+            tab: { id: 7, active: true, windowId: 3 },
+            windowInfo: { id: 3, focused: true }
+        };
+        expect(shouldShowChatNotification(focused)).toBe(false);
+        expect(shouldShowChatNotification({ ...focused, windowInfo: { id: 3, focused: false } })).toBe(true);
+        expect(shouldShowChatNotification({ ...focused, tab: { id: 7, active: false, windowId: 3 } })).toBe(true);
+        expect(shouldShowChatNotification({ ...focused, targetTabId: 8 })).toBe(true);
+        expect(shouldShowChatNotification({ ...focused, enabled: false })).toBe(false);
+    });
+
     it('serializes join work and prevents an older request from winning storage races', async () => {
         const queue = createLatestTaskQueue();
         let releaseFirst;