diff --git a/packages/server/test/fs-watch.e2e.test.ts b/packages/server/test/fs-watch.e2e.test.ts
index 6535443be..cabeb86e5 100644
--- a/packages/server/test/fs-watch.e2e.test.ts
+++ b/packages/server/test/fs-watch.e2e.test.ts
@@ -255,56 +255,7 @@ describe('WS fs watch (W12 / Chain 14)', () => {
     conn.ws.close();
   });
 
-  it('AC #2: burst > 500 changes inside 200ms window → truncated:true', async () => {
-    const r = await bootDaemon();
-    const sid = await createSession(r);
-    const conn = await openConn(wsUrl(r.address));
-    await helloAndSubscribe(conn, 'A', sid);
-
-    // Watch the whole workspace root so every new file lands in scope.
-    conn.ws.send(
-      JSON.stringify({
-        type: 'watch_fs_add',
-        id: 'w2',
-        payload: { session_id: sid, paths: ['.'] },
-      }),
-    );
-    await receiveType(conn, 'ack', 1000);
-
-    await sleep(WATCH_SETTLE_MS);
-
-    // Slam 600 files into a fresh dir; chokidar emits >500 add events well
-    // inside one 200ms window.
-    const burstDir = join(workspace, 'burst');
-    mkdirSync(burstDir, { recursive: true });
-    for (let i = 0; i < 600; i++) {
-      writeFileSync(join(burstDir, `f${i}.txt`), `x${i}`);
-    }
-
-    // Drain frames until we see truncated:true OR run out of time.
-    const deadline = Date.now() + 4000;
-    let sawTruncated = false;
-    while (Date.now() < deadline) {
-      const remaining = deadline - Date.now();
-      let frame: WsFrame;
-      try {
-        frame = await receive(conn, remaining);
-      } catch {
-        break;
-      }
-      if (frame.type !== 'event.fs.changed') continue;
-      const payload = frame.payload as { truncated?: boolean; count?: number };
-      if (payload.truncated === true) {
-        expect(payload.count).toBeGreaterThan(500);
-        sawTruncated = true;
-        break;
-      }
-    }
-    expect(sawTruncated).toBe(true);
-    conn.ws.close();
-  });
-
-  it('AC #3: two clients on disjoint paths receive only their own changes', async () => {
+  it('AC #2: two clients on disjoint paths receive only their own changes', async () => {
     const r = await bootDaemon();
     const sid = await createSession(r);
     const a = await openConn(wsUrl(r.address));
@@ -368,7 +319,7 @@ describe('WS fs watch (W12 / Chain 14)', () => {
     b.ws.close();
   });
 
-  it('AC #4: > 100 paths on one connection → 42902 fs.watch_limit_exceeded', async () => {
+  it('AC #3: > 100 paths on one connection → 42902 fs.watch_limit_exceeded', async () => {
     const r = await bootDaemon();
     const sid = await createSession(r);
     const conn = await openConn(wsUrl(r.address));
diff --git a/packages/server/test/services.test.ts b/packages/server/test/services.test.ts
index 5444f7667..18607f16d 100644
--- a/packages/server/test/services.test.ts
+++ b/packages/server/test/services.test.ts
@@ -1,5 +1,6 @@
 
 
+import { EventEmitter } from 'node:events';
 import { mkdtempSync, rmSync } from 'node:fs';
 import { mkdtemp, rm } from 'node:fs/promises';
 import { tmpdir } from 'node:os';
@@ -7,7 +8,7 @@ import { join } from 'node:path';
 
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 
-import { InstantiationService, ServiceCollection, EventService, FsWatcherService, IApprovalService, IEventService, ILogService, IQuestionService, type ApprovalResponse, type QuestionResult, type FsWatcherServiceOptions, type IEnvironmentService, type ILogService as ILoggerT, type ISessionService } from '@moonshot-ai/agent-core';
+import { InstantiationService, ServiceCollection, EventService, FsWatcherService, IApprovalService, IEventService, ILogService, IQuestionService, type ApprovalResponse, type FsWatcherServiceOptions, type IEnvironmentService, type ILogService as ILoggerT, type ISessionService, type QuestionResult, type FsChangedFrame } from '@moonshot-ai/agent-core';
 import type { Event } from '@moonshot-ai/protocol';
 
 import { ApprovalService } from '#/services/approval/approvalService';
@@ -105,7 +106,7 @@ function captureThrown(fn: () => void): unknown {
   }
 }
 
-class FakeWatcher {
+class FakeWatcher extends EventEmitter {
   readonly added: string[][] = [];
   readonly unwatched: string[][] = [];
   readonly unwatchErrors = new Map<string, Error>();
@@ -124,10 +125,6 @@ class FakeWatcher {
     return this;
   }
 
-  on(): this {
-    return this;
-  }
-
   async close(): Promise<void> {
     this.closeCalls += 1;
   }
@@ -516,6 +513,37 @@ describe('FsWatcherService', () => {
     expect(watcher.closeCalls).toBe(0);
     service.dispose();
   });
+
+  it('truncates when more than maxChangesPerWindow changes arrive in one debounce window', async () => {
+    const watcher = new FakeWatcher();
+    const sent: FsChangedFrame[] = [];
+    const service = new FsWatcherService(
+      { resolve: () => ({ send: (frame: FsChangedFrame) => sent.push(frame) }) },
+      {
+        watcherFactory: () => watcher as unknown as TestFsWatcher,
+        debounceMs: 10,
+        maxChangesPerWindow: 50,
+      },
+      testLogger,
+      {} as ISessionService,
+    );
+
+    service.addPaths('sid', 'conn', ['/workspace']);
+    service.bindSessionCwd('sid', '/workspace');
+
+    for (let i = 0; i < 60; i++) {
+      watcher.emit('all', 'add', `/workspace/f${i}.txt`);
+    }
+
+    await new Promise((r) => setTimeout(r, 30));
+
+    expect(sent.length).toBe(1);
+    expect(sent[0].type).toBe('event.fs.changed');
+    expect(sent[0].payload.truncated).toBe(true);
+    expect(sent[0].payload.count).toBe(60);
+
+    service.dispose();
+  });
 });
 
 describe('ApprovalService (broadcasts + resolve-by-approval_id)', () => {
diff --git a/packages/server/test/start.test.ts b/packages/server/test/start.test.ts
index cd25d5750..15f6f8cb1 100644
--- a/packages/server/test/start.test.ts
+++ b/packages/server/test/start.test.ts
@@ -161,7 +161,7 @@ describe('startServer — lock + healthz smoke', () => {
     expect(existsSync(lockPath)).toBe(false);
   });
 
-  it('retries on port+1 and updates the lock when the requested port is held by a third party', async () => {
+  it('retries to a higher port and updates the lock when the requested port is held by a third party', async () => {
     // Occupy the requested port with a raw TCP server (a "third-party" process
     // from the server's point of view — it does NOT hold the lock).
     const { port, next } = await allocateAdjacentFreePair();
@@ -179,10 +179,17 @@ describe('startServer — lock + healthz smoke', () => {
       });
       running.push(r);
 
-      // Bound to the next port, and the lock advertises it so status/kill/ps work.
-      expect(r.address).toBe(`http://127.0.0.1:${String(next)}`);
+      // The server must bind to a higher port because `port` is occupied.
+      // The exact port can be `next` or higher: in a concurrent test run another
+      // listener may grab `next` before the server does. The +1 retry strategy is
+      // covered by unit tests for listenWithPortRetry.
+      expect(r.address).toMatch(/^http:\/\/127\.0\.0\.1:\d+$/);
+      const actualPort = Number(new URL(r.address).port);
+      expect(actualPort).toBeGreaterThanOrEqual(next);
+
+      // The lock advertises the real bound port so status/kill/ps work.
       const stored = JSON.parse(readFileSync(thirdPartyLockPath, 'utf8')) as LockContents;
-      expect(stored.port).toBe(next);
+      expect(stored.port).toBe(actualPort);
     } finally {
       await closeNetServer(occupant);
     }