diff --git a/.project-docs/30-worklog/tasks/20260901-agent-received-stall-8b6d4c21.md b/.project-docs/30-worklog/tasks/20260901-agent-received-stall-8b6d4c21.md
new file mode 100644
index 0000000..eae4691
--- /dev/null
+++ b/.project-docs/30-worklog/tasks/20260901-agent-received-stall-8b6d4c21.md
@@ -0,0 +1,53 @@
+# Task: Diagnose local Agent received-message stall
+
+## Identity
+
+- Task ID: 20260901-agent-received-stall-8b6d4c21
+- Mode: Feature
+- Branch: codex/20260901-agent-received-stall-8b6d4c21-agent-received-stall
+- Worktree: D:\Datas\OthersProjects\makelore-worktrees\agent-received-stall-8b6d4c21
+- Base commit: 850947c092892cb647c4191b6d8bbf37a763e1ad
+- Owner: codex
+- Status: Ready for Integration
+
+## Scope
+
+- Diagnose the installed-app state where a prompt is acknowledged locally but remains optimistic indefinitely.
+- Fix the background-sleep versus Agent Server start race without replaying accepted prompts.
+- Add focused regression coverage for both lifecycle race windows.
+
+## Intent And Constraints
+
+- Preserve the single shared Pi Agent Server and per-conversation logical thread architecture.
+- Background sleep must not stop work that begins while idle worker cleanup is in flight.
+- A start racing an already-started stop must wait for the stop and then create a fresh server process.
+- Do not auto-replay an accepted or uncertain prompt.
+
+## Outcome
+
+- Confirmed installed-state evidence: the accepted UI state was newer than the latest Pi session write, and no Agent Server process remained live, so the prompt had not reached Provider generation.
+- Confirmed regression: `PiAgentServerProcess.start()` returned immediately when the old child still existed during an in-flight stop; after that stop completed, no server remained. The real-process race test failed before the fix and passed afterward.
+- Confirmed regression: composition checked for active work only before asynchronous background cleanup, then stopped the shared Agent Server even when a new run began during cleanup. The composition race test failed before the fix and passed afterward.
+- Fixed both lifecycle windows: background sleep rechecks active work after worker cleanup, and a start racing a stop waits for that stop before creating a fresh server.
+- The installed-app symptom maps directly to these two confirmed races, although the exact renderer/Main interleaving of the reported occurrence was not captured live.
+- Accepted and uncertain prompts are still never auto-replayed.
+
+## Verification
+
+- Installed-state red loop: accepted screenshot timestamp is newer than the latest Pi session write while no Agent Server process is live.
+- Red phase: the two focused race tests both failed against the original implementation.
+- `pnpm exec vitest run tests/unit/pi-agent-server-process-real.test.ts tests/unit/coding-composition-background-sleep.test.ts --maxWorkers=1` — 2 files, 4 tests passed.
+- `pnpm exec vitest run tests/unit/background-lifecycle.test.ts tests/unit/pi-background-lifecycle.test.ts tests/unit/pi-agent-server-process-real.test.ts tests/unit/coding-composition-background-sleep.test.ts --maxWorkers=1` — 4 files, 9 tests passed.
+- `pnpm run typecheck` — passed.
+- `pnpm run lint:check` — passed with 5 pre-existing warnings and no errors.
+- `pnpm test` — 216 files passed; 1,764 tests passed and 2 skipped.
+- `pnpm run build:vite` — Renderer, Main, Preload, and utility production builds passed.
+- Existing Electron E2E fixtures mock prompt acceptance and do not exercise the real Main-owned Agent Server lifecycle; the real-process regression test is the relevant product-path coverage.
+
+## Follow-ups
+
+- Integrate the feature commit into `main`, then produce/reinstall a Windows package before validating the original installed-app reproduction; the currently installed binary does not contain this source fix.
+
+## Promotion Candidates
+
+- None. The change enforces existing background-lease and single-Agent-Server architecture rather than changing canonical product behavior.
diff --git a/electron/api/coding-composition.ts b/electron/api/coding-composition.ts
index 1210947..8d55ac3 100644
--- a/electron/api/coding-composition.ts
+++ b/electron/api/coding-composition.ts
@@ -498,6 +498,7 @@ export function createCodingComposition(
       await Promise.allSettled(conversationIds.map((conversationId) => (
         runtime.dispose(conversationId, reason)
       )));
+      if (reason === 'background_sleep' && runtime.hasActiveWork()) return;
       await agentServer.stop();
     },
     async shutdown() {
diff --git a/electron/coding-runtime/pi/agent-server-process.ts b/electron/coding-runtime/pi/agent-server-process.ts
index 15c6075..41ed00b 100644
--- a/electron/coding-runtime/pi/agent-server-process.ts
+++ b/electron/coding-runtime/pi/agent-server-process.ts
@@ -490,6 +490,7 @@ export class PiAgentServerProcess {
   }
 
   start(): Promise<void> {
+    if (this.stopFlight) return this.stopFlight.then(() => this.start());
     if (this.startFlight) return this.startFlight;
     if (this.child && !this.failure) return Promise.resolve();
     this.startFlight = this.startServer().finally(() => {
diff --git a/tests/unit/coding-composition-background-sleep.test.ts b/tests/unit/coding-composition-background-sleep.test.ts
new file mode 100644
index 0000000..d969cd3
--- /dev/null
+++ b/tests/unit/coding-composition-background-sleep.test.ts
@@ -0,0 +1,62 @@
+// @vitest-environment node
+
+import { mkdtemp, rm } from 'node:fs/promises';
+import { tmpdir } from 'node:os';
+import path from 'node:path';
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import type { AgentBrowserModule } from '../../electron/agent-browser';
+import { createCodingComposition } from '../../electron/api/coding-composition';
+import { PiAgentServerProcess } from '../../electron/coding-runtime/pi/agent-server-process';
+import { createMemoryCodingProjectStorage } from '../../electron/coding-projects/project-store';
+
+const roots: string[] = [];
+
+afterEach(async () => {
+  vi.restoreAllMocks();
+  await Promise.all(roots.splice(0).map((root) => rm(root, { recursive: true, force: true })));
+});
+
+describe('coding composition background sleep', () => {
+  it('does not stop the shared Agent Server when work starts during worker cleanup', async () => {
+    const projectPath = await mkdtemp(path.join(tmpdir(), 'makelore-sleep-race-project-'));
+    const userDataDir = await mkdtemp(path.join(tmpdir(), 'makelore-sleep-race-user-'));
+    roots.push(projectPath, userDataDir);
+    const composition = createCodingComposition({
+      storage: createMemoryCodingProjectStorage(),
+      browser: { close: vi.fn(async () => undefined) } as unknown as AgentBrowserModule,
+      paths: {
+        executablePath: process.execPath,
+        cliPath: path.join(projectPath, 'unused-cli.js'),
+        serverPath: path.join(projectPath, 'unused-server.mjs'),
+        userDataDir,
+        bundledSkillsDir: path.resolve('resources/coding-skills'),
+      },
+    });
+    const stopAgentServer = vi.spyOn(PiAgentServerProcess.prototype, 'stop')
+      .mockResolvedValue(undefined);
+    let activeWork = false;
+    const hasActiveWork = vi.spyOn(composition.runtime, 'hasActiveWork')
+      .mockImplementation(() => activeWork);
+    const getDiagnostics = vi.spyOn(composition.runtime, 'getDiagnostics')
+      .mockReturnValue({
+        workers: [{ conversationId: 'conversation-a' }],
+      } as ReturnType<typeof composition.runtime.getDiagnostics>);
+    const dispose = vi.spyOn(composition.runtime, 'dispose').mockImplementation(async () => {
+      activeWork = true;
+    });
+
+    try {
+      await composition.sleep('background_sleep');
+
+      expect(dispose).toHaveBeenCalledWith('conversation-a', 'background_sleep');
+      expect(hasActiveWork).toHaveBeenCalledTimes(2);
+      expect(stopAgentServer).not.toHaveBeenCalled();
+    } finally {
+      dispose.mockRestore();
+      getDiagnostics.mockRestore();
+      hasActiveWork.mockRestore();
+      stopAgentServer.mockRestore();
+      await composition.shutdown();
+    }
+  });
+});
diff --git a/tests/unit/pi-agent-server-process-real.test.ts b/tests/unit/pi-agent-server-process-real.test.ts
index f835674..17a95f6 100644
--- a/tests/unit/pi-agent-server-process-real.test.ts
+++ b/tests/unit/pi-agent-server-process-real.test.ts
@@ -133,6 +133,30 @@ describe('Pi Agent Server real process', () => {
     }
   }, 10_000);
 
+  it('restarts when start races with a graceful background stop', async () => {
+    const root = await mkdtemp(path.join(tmpdir(), 'makelore-pi-agent-server-restart-'));
+    roots.push(root);
+    const layout = await materializePackagedAgentServerLayout(root);
+    const server = new PiAgentServerProcess({
+      executablePath: electronExecutable,
+      ...layout,
+    });
+
+    try {
+      await server.start();
+      const firstProcessId = server.processId;
+      expect(firstProcessId).toBeTypeOf('number');
+
+      const stopping = server.stop();
+      const restarting = server.start();
+      await Promise.all([stopping, restarting]);
+      expect(server.processId).toBeTypeOf('number');
+      expect(server.processId).not.toBe(firstProcessId);
+    } finally {
+      await server.stop();
+    }
+  }, 20_000);
+
   it('hosts isolated Conversation threads in one long-lived process', async () => {
     const root = await mkdtemp(path.join(tmpdir(), 'makelore-pi-agent-server-'));
     roots.push(root);