fix(acp): recover from persist() failure instead of cascading (#3366)

src/__tests__/fix-3366-acp-persist-cascade.test.ts

@@ -0,0 +1,120 @@
+/**
+ * Regression tests for #3366: ACP local storage persist() failure cascade.
+ *
+ * Bug: FileAcpLocalStorageProfile.persist() chains writes onto writeChain
+ * without error recovery. A single failed write poisons all subsequent writes
+ * because every .then() chains onto the rejected promise.
+ *
+ * Fix: persist() now catches errors, resets the chain, and logs the failure.
+ * Subsequent writes get a fresh attempt.
+ */
+import { readFile } from 'node:fs/promises';
+import fs from 'node:fs';
+import path from 'node:path';
+import os from 'node:os';
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+
+import { createFileAcpLocalStorageProfile } from '../services/acp/local-storage.js';
+
+function makeSession(id: string) {
+  const now = Date.now();
+  return {
+    id,
+    conversationId: `conv-${id}`,
+    transcriptId: `transcript-${id}`,
+    tenantId: 'test-tenant',
+    ownerKeyId: 'test-key',
+    runnerType: 'acp' as const,
+    status: 'initializing' as const,
+    createdAt: now,
+    updatedAt: now,
+    metadata: {},
+  };
+}
+
+describe('Issue #3366: ACP local storage persist() failure cascade', () => {
+  let tmpDir: string;
+  let filePath: string;
+
+  beforeEach(async () => {
+    tmpDir = await fs.promises.mkdtemp(path.join(os.tmpdir(), 'aegis-3366-'));
+    filePath = path.join(tmpDir, 'acp-local-storage.json');
+  });
+
+  afterEach(async () => {
+    // Restore permissions so cleanup can succeed
+    await fs.promises.chmod(tmpDir, 0o755).catch(() => {});
+    await fs.promises.rm(tmpDir, { recursive: true, force: true }).catch(() => {});
+  });
+
+  it('recovers from a failed persist — subsequent writes succeed', async () => {
+    const profile = createFileAcpLocalStorageProfile({ filePath });
+    await profile.start();
+    expect(profile.getPersistError()).toBeNull();
+
+    // Make the directory read-only to force a write failure
+    await fs.promises.chmod(tmpDir, 0o444);
+
+    // Trigger persist via a mutation — should fail silently
+    await profile.sessionStore.create(makeSession('fail-1'));
+    expect(profile.getPersistError()).not.toBeNull();
+
+    // Restore write permissions
+    await fs.promises.chmod(tmpDir, 0o755);
+
+    // Trigger another mutation — this should SUCCEED (not cascade!)
+    await profile.sessionStore.create(makeSession('recover-1'));
+    expect(profile.getPersistError()).toBeNull();
+
+    // Verify the file actually contains the data
+    const content = await readFile(filePath, 'utf8');
+    const parsed = JSON.parse(content);
+    expect(parsed.sessions).toHaveLength(2);
+
+    await profile.stop();
+  });
+
+  it('does NOT cascade rejection across multiple sequential failures', async () => {
+    const profile = createFileAcpLocalStorageProfile({ filePath });
+    await profile.start();
+
+    // Make dir read-only
+    await fs.promises.chmod(tmpDir, 0o444);
+
+    // First failed persist
+    await profile.sessionStore.create(makeSession('fail-1'));
+    expect(profile.getPersistError()).not.toBeNull();
+
+    // Second failed persist — should NOT be chained to rejected promise
+    await profile.sessionStore.create(makeSession('fail-2'));
+    expect(profile.getPersistError()).not.toBeNull();
+
+    // Third failed persist — still no cascade
+    await profile.sessionStore.create(makeSession('fail-3'));
+    expect(profile.getPersistError()).not.toBeNull();
+
+    // Now restore and verify recovery
+    await fs.promises.chmod(tmpDir, 0o755);
+    await profile.sessionStore.create(makeSession('recover'));
+    expect(profile.getPersistError()).toBeNull();
+
+    const content = await readFile(filePath, 'utf8');
+    const parsed = JSON.parse(content);
+    expect(parsed.sessions).toHaveLength(4);
+
+    await profile.stop();
+  });
+
+  it('stop() does not throw even when writeChain has a rejection', async () => {
+    const profile = createFileAcpLocalStorageProfile({ filePath });
+    await profile.start();
+
+    // Make dir read-only so persist fails
+    await fs.promises.chmod(tmpDir, 0o444);
+    await profile.sessionStore.create(makeSession('doomed'));
+
+    // stop() should NOT throw — it catches the chain rejection
+    await fs.promises.chmod(tmpDir, 0o755);
+    await expect(profile.stop()).resolves.toBeUndefined();
+  });
+});

src/services/acp/local-storage.ts

@@ -1,6 +1,7 @@
-import { mkdir, readFile, writeFile, rename } from 'node:fs/promises';
+import { mkdir, readFile, writeFile, rename, unlink } from 'node:fs/promises';
 import path from 'node:path';
 
+import { logger } from '../../logger.js';
 import type { ServiceHealth } from '../../container.js';
 import {
   AcpDurableIdentityError,
@@ -48,6 +49,7 @@ export interface AcpLocalStorageProfile {
   start(): Promise<void>;
   stop(signal?: AbortSignal): Promise<void>;
   health(): Promise<ServiceHealth>;
+  getPersistError(): Error | null;
 }
 
 export interface FileAcpLocalStorageProfileConfig {
@@ -101,12 +103,17 @@ export class MemoryAcpLocalStorageProfile implements AcpLocalStorageProfile {
   async health(): Promise<ServiceHealth> {
     return { healthy: true, details: 'memory ACP local storage profile ok' };
   }
+
+  getPersistError(): Error | null {
+    return null;
+  }
 }
 
 export class FileAcpLocalStorageProfile implements AcpLocalStorageProfile {
   private state = createEmptyState();
   private started = false;
   private writeChain: Promise<void> = Promise.resolve();
+  private persistError: Error | null = null;
   private readonly memorySessionStore: MemoryAcpSessionStore;
   private readonly memoryEventStore: MemoryAcpEventStore;
   private readonly memoryActionQueue: MemoryAcpActionQueue;
@@ -143,7 +150,8 @@ export class FileAcpLocalStorageProfile implements AcpLocalStorageProfile {
 
   async stop(_signal?: AbortSignal): Promise<void> {
     if (!this.started) return;
-    await this.writeChain;
+    // Best-effort final persist — swallow errors so shutdown completes
+    await this.writeChain.catch(() => {});
     this.started = false;
   }
 
@@ -156,16 +164,48 @@ export class FileAcpLocalStorageProfile implements AcpLocalStorageProfile {
 
   private async persist(): Promise<void> {
     if (!this.started) {
-      throw new Error('FileAcpLocalStorageProfile: start() must be called before use');
+      throw new Error('FileAcpLocalStorageProfile: persist() called before start()');
     }
     // Issue #3045: atomic write to prevent truncation on SIGTERM/OOM kill
+    // Issue #3366: error recovery — a failed write must not poison subsequent writes
     const content = `${JSON.stringify(serializeState(this.state), null, 2)}\n`;
     const tmpFile = `${this.config.filePath}.tmp.${process.pid}`;
-    this.writeChain = this.writeChain.then(
-      () => writeFile(tmpFile, content, 'utf8').then(() => rename(tmpFile, this.config.filePath)),
-    );
+
+    const prevChain = this.writeChain;
+    this.writeChain = prevChain
+      .then(
+        // Previous write succeeded — do this write
+        () => writeFile(tmpFile, content, 'utf8').then(() => rename(tmpFile, this.config.filePath)),
+        // Previous write failed — still attempt this write
+        () => writeFile(tmpFile, content, 'utf8').then(() => rename(tmpFile, this.config.filePath)),
+      )
+      .then(() => {
+        this.persistError = null;
+      })
+      .catch((err: Error) => {
+        this.persistError = err;
+        logger.error({
+          component: 'acp-local-storage',
+          operation: 'persist',
+          errorCode: 'PERSIST_FAILED',
+          attributes: { error: err.message, filePath: this.config.filePath },
+        });
+        // Clean up stale tmp file if it exists
+        unlink(tmpFile).catch(() => {});
+        // Reset chain so next persist() is not chained to a rejected promise
+        this.writeChain = Promise.resolve();
+      });
+
     await this.writeChain;
   }
+
+  /**
+   * Returns the last persist error, or null if all writes succeeded.
+   * Useful for diagnostics and health checks.
+   */
+  getPersistError(): Error | null {
+    return this.persistError;
+  }
 }
 
 export class MemoryAcpSessionStore implements AcpSessionStore {