feat(audit): Add core audit logging infrastructure

- Add AuditLogger class with rotation support
- Add audit configuration to config schema
- Instrument tool execution with full audit logging
- Instrument session lifecycle (create, message, delete, transfer, compact)
- Add audit logger initialization in daemon
- Add cron scheduler audit logging

Audit events captured:
- tool.start/success/error/denied
- session.create/message/delete/transfer/compact
- cron.trigger/add/remove

All logs go to ~/.local/share/flynn/audit.log (JSON lines)
with rotation (10MB files, 30-day retention)

src/audit/export.ts

@@ -0,0 +1,75 @@
+import { createReadStream, promises as fs } from 'fs';
+import { dirname, basename } from 'path';
+import type { AuditEvent, AuditQuery } from './types.js';
+
+export async function queryAuditLogs(logPath: string, query: AuditQuery): Promise<AuditEvent[]> {
+  const logs: AuditEvent[] = [];
+
+  try {
+    const content = await fs.readFile(logPath, 'utf-8');
+    const lines = content.split('\n').filter(line => line.trim() !== '');
+
+    for (const line of lines) {
+      try {
+        const event: AuditEvent = JSON.parse(line);
+        if (matchesQuery(event, query)) {
+          logs.push(event);
+        }
+      } catch {
+        // Skip malformed lines
+      }
+    }
+  } catch (err) {
+    if ((err as NodeJS.ErrnoException).code !== 'ENOENT') {
+      throw err;
+    }
+  }
+
+  return logs.sort((a, b) => a.timestamp - b.timestamp);
+}
+
+function matchesQuery(event: AuditEvent, query: AuditQuery): boolean {
+  if (query.start_time && event.timestamp < query.start_time) {
+    return false;
+  }
+  if (query.end_time && event.timestamp > query.end_time) {
+    return false;
+  }
+  if (query.event_types && !query.event_types.includes(event.event_type)) {
+    return false;
+  }
+  if (query.level && event.level !== query.level) {
+    return false;
+  }
+  if (query.session_id) {
+    const eventSessionId = (event.event as Record<string, unknown>).session_id as string | undefined;
+    if (eventSessionId !== query.session_id) {
+      return false;
+    }
+  }
+  if (query.tool_name) {
+    const eventToolName = (event.event as Record<string, unknown>).tool_name as string | undefined;
+    if (eventToolName !== query.tool_name) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+export async function exportAuditLogs(logPath: string, query: AuditQuery, format: 'json' | 'csv'): Promise<string> {
+  const logs = await queryAuditLogs(logPath, query);
+
+  if (format === 'json') {
+    return JSON.stringify(logs, null, 2);
+  }
+
+  // CSV format
+  const headers = ['timestamp', 'level', 'event_type', 'event'];
+  const rows = logs.map(log => {
+    const eventStr = JSON.stringify(log.event).replace(/"/g, '""');
+    return `${log.timestamp},${log.level},${log.event_type},"${eventStr}"`;
+  });
+
+  return [headers.join(','), ...rows].join('\n');
+}

src/audit/index.ts

@@ -0,0 +1,9 @@
+import type { AuditLogger } from './logger.js';
+export * from './types.js';
+export { AuditLogger } from './logger.js';
+
+export let auditLogger: AuditLogger | null = null;
+
+export function initAuditLogger(logger: AuditLogger): void {
+  auditLogger = logger;
+}

src/audit/logger.ts

@@ -0,0 +1,250 @@
+import { createWriteStream, existsSync, mkdirSync, promises as fs } from 'fs';
+import { dirname } from 'path';
+import type {
+  AuditEvent,
+  AuditConfig,
+  ToolStartEvent,
+  ToolSuccessEvent,
+  ToolErrorEvent,
+  ToolDeniedEvent,
+  SessionCreateEvent,
+  SessionMessageEvent,
+  SessionDeleteEvent,
+  SessionCompactEvent,
+  CronTriggerEvent,
+  WebhookReceiveEvent,
+  HeartbeatCycleEvent,
+  HeartbeatCheckEvent,
+  HeartbeatFailEvent,
+  HeartbeatRecoverEvent,
+  GmailPollEvent,
+  GmailNewEmailEvent,
+} from './types.js';
+import { AuditRotator } from './rotation.js';
+
+export class AuditLogger {
+  private writeStream: import('fs').WriteStream | null = null;
+  private config: AuditConfig;
+  private rotator: AuditRotator;
+
+  constructor(config: AuditConfig) {
+    this.config = config;
+    this.rotator = new AuditRotator(config);
+    
+    if (!this.config.enabled) {
+      return;
+    }
+
+    this.ensureLogDirectory();
+    this.rotator.checkRotation();
+    this.writeStream = createWriteStream(config.path, { flags: 'a' });
+  }
+
+  private ensureLogDirectory(): void {
+    const logDir = dirname(this.config.path);
+    if (!existsSync(logDir)) {
+      mkdirSync(logDir, { recursive: true });
+    }
+  }
+
+  private write(event: Omit<AuditEvent, 'timestamp'>): void {
+    if (!this.config.enabled || !this.writeStream) {
+      return;
+    }
+
+    this.rotator.checkRotation();
+    
+    const fullEvent: AuditEvent = { ...event, timestamp: Date.now() };
+    this.writeStream!.write(JSON.stringify(fullEvent) + '\n');
+  }
+
+  private shouldLog(category: 'tools' | 'sessions' | 'automation', level: string): boolean {
+    const levelOrder = { debug: 0, info: 1, warn: 2, error: 3 };
+    const configLevel = this.config.levels[category];
+    return levelOrder[level as keyof typeof levelOrder] >= levelOrder[configLevel];
+  }
+
+  // ── Tool Events ───────────────────────────────────────────────
+
+  toolStart(event: ToolStartEvent): void {
+    if (!this.shouldLog('tools', 'debug')) return;
+    this.write({ level: 'debug', event_type: 'tool.start', event: event as unknown as Record<string, unknown> });
+  }
+
+  toolSuccess(event: ToolSuccessEvent): void {
+    if (!this.shouldLog('tools', 'debug')) return;
+    this.write({ level: 'debug', event_type: 'tool.success', event: event as unknown as Record<string, unknown> });
+  }
+
+  toolError(event: ToolErrorEvent): void {
+    if (!this.shouldLog('tools', 'error')) return;
+    this.write({ level: 'error', event_type: 'tool.error', event: event as unknown as Record<string, unknown> });
+  }
+
+  toolDenied(event: ToolDeniedEvent): void {
+    if (!this.shouldLog('tools', 'warn')) return;
+    this.write({ level: 'warn', event_type: 'tool.denied', event: event as unknown as Record<string, unknown> });
+  }
+
+  // ── Session Events ───────────────────────────────────────────
+
+  sessionCreate(event: SessionCreateEvent): void {
+    if (!this.shouldLog('sessions', 'debug')) return;
+    this.write({ level: 'debug', event_type: 'session.create', event: event as unknown as Record<string, unknown> });
+  }
+
+  sessionMessage(event: SessionMessageEvent): void {
+    if (!this.shouldLog('sessions', 'debug')) return;
+    this.write({ level: 'debug', event_type: 'session.message', event: event as unknown as Record<string, unknown> });
+  }
+
+  sessionDelete(event: SessionDeleteEvent): void {
+    if (!this.shouldLog('sessions', 'debug')) return;
+    this.write({ level: 'debug', event_type: 'session.delete', event: event as unknown as Record<string, unknown> });
+  }
+
+  sessionCompact(event: SessionCompactEvent): void {
+    if (!this.shouldLog('sessions', 'debug')) return;
+    this.write({ level: 'debug', event_type: 'session.compact', event: event as unknown as Record<string, unknown> });
+  }
+
+  sessionTransfer(from: string, to: string, messageCount: number): void {
+    if (!this.shouldLog('sessions', 'debug')) return;
+    this.write({
+      level: 'debug',
+      event_type: 'session.transfer',
+      event: { from_session: from, to_session: to, message_count: messageCount },
+    });
+  }
+
+  // ── Automation Events ───────────────────────────────────────
+
+  // Cron
+  cronTrigger(event: CronTriggerEvent): void {
+    if (!this.shouldLog('automation', 'debug')) return;
+    this.write({ level: 'debug', event_type: 'cron.trigger', event: event as unknown as Record<string, unknown> });
+  }
+
+  cronAdd(jobName: string, schedule: string): void {
+    if (!this.shouldLog('automation', 'info')) return;
+    this.write({
+      level: 'info',
+      event_type: 'cron.add',
+      event: { job_name: jobName, schedule },
+    });
+  }
+
+  cronRemove(jobName: string): void {
+    if (!this.shouldLog('automation', 'info')) return;
+    this.write({
+      level: 'info',
+      event_type: 'cron.remove',
+      event: { job_name: jobName },
+    });
+  }
+
+  // Webhook
+  webhookReceive(event: WebhookReceiveEvent): void {
+    if (!this.shouldLog('automation', 'debug')) return;
+    this.write({ level: 'debug', event_type: 'webhook.receive', event: event as unknown as Record<string, unknown> });
+  }
+
+  webhookNotFound(webhookName: string): void {
+    if (!this.shouldLog('automation', 'warn')) return;
+    this.write({
+      level: 'warn',
+      event_type: 'webhook.not_found',
+      event: { webhook_name: webhookName },
+    });
+  }
+
+  webhookDenied(webhookName: string, reason: string): void {
+    if (!this.shouldLog('automation', 'warn')) return;
+    this.write({
+      level: 'warn',
+      event_type: 'webhook.denied',
+      event: { webhook_name: webhookName, reason },
+    });
+  }
+
+  // Heartbeat
+  heartbeatCycle(event: HeartbeatCycleEvent): void {
+    if (!this.shouldLog('automation', 'debug')) return;
+    this.write({ level: 'debug', event_type: 'heartbeat.cycle', event: event as unknown as Record<string, unknown> });
+  }
+
+  heartbeatCheck(event: HeartbeatCheckEvent): void {
+    if (!this.shouldLog('automation', 'debug')) return;
+    this.write({ level: 'debug', event_type: 'heartbeat.check', event: event as unknown as Record<string, unknown> });
+  }
+
+  heartbeatFail(event: HeartbeatFailEvent): void {
+    if (!this.shouldLog('automation', 'warn')) return;
+    this.write({ level: 'warn', event_type: 'heartbeat.fail', event: event as unknown as Record<string, unknown> });
+  }
+
+  heartbeatRecover(event: HeartbeatRecoverEvent): void {
+    if (!this.shouldLog('automation', 'info')) return;
+    this.write({ level: 'info', event_type: 'heartbeat.recover', event: event as unknown as Record<string, unknown> });
+  }
+
+  // Gmail
+  gmailPoll(event: GmailPollEvent): void {
+    if (!this.shouldLog('automation', 'debug')) return;
+    this.write({ level: 'debug', event_type: 'gmail.poll', event: event as unknown as Record<string, unknown> });
+  }
+
+  gmailNewEmail(event: GmailNewEmailEvent): void {
+    if (!this.shouldLog('automation', 'debug')) return;
+    this.write({ level: 'debug', event_type: 'gmail.new_email', event: event as unknown as Record<string, unknown> });
+  }
+
+  gmailError(error: string, context?: string): void {
+    if (!this.shouldLog('automation', 'error')) return;
+    this.write({
+      level: 'error',
+      event_type: 'gmail.error',
+      event: { error, context },
+    });
+  }
+
+  // ── System Events ────────────────────────────────────────────
+
+  systemStart(component: string, config?: Record<string, unknown>): void {
+    if (!this.config.enabled) return;
+    this.write({
+      level: 'info',
+      event_type: 'system.start',
+      event: { component, config },
+    });
+  }
+
+  systemStop(component: string, reason?: string): void {
+    if (!this.config.enabled) return;
+    this.write({
+      level: 'info',
+      event_type: 'system.stop',
+      event: { component, reason },
+    });
+  }
+
+  systemConfig(component: string, action: string, config: Record<string, unknown>): void {
+    if (!this.config.enabled) return;
+    this.write({
+      level: 'info',
+      event_type: 'system.config',
+      event: { component, action, config },
+    });
+  }
+
+  // ── Lifecycle ───────────────────────────────────────────────
+
+  async close(): Promise<void> {
+    if (this.writeStream) {
+      await new Promise<void>((resolve) => {
+        this.writeStream!.end(() => resolve());
+      });
+      this.writeStream = null;
+    }
+  }
+}

src/audit/rotation.ts

@@ -0,0 +1,107 @@
+import { createReadStream, createWriteStream, existsSync, promises as fs, statSync } from 'fs';
+import { basename, dirname } from 'path';
+import { createGzip } from 'zlib';
+import { pipeline } from 'stream/promises';
+import type { AuditConfig } from './types.js';
+
+export class AuditRotator {
+  private config: AuditConfig;
+  private lastRotationCheck = 0;
+  private readonly CHECK_INTERVAL = 60_000; // Check every minute
+
+  constructor(config: AuditConfig) {
+    this.config = config;
+  }
+
+  checkRotation(): boolean {
+    const now = Date.now();
+    if (now - this.lastRotationCheck < this.CHECK_INTERVAL) {
+      return false;
+    }
+    this.lastRotationCheck = now;
+
+    return this.rotateIfNeeded();
+  }
+
+  private rotateIfNeeded(): boolean {
+    if (!existsSync(this.config.path)) {
+      return false;
+    }
+
+    const stats = statSync(this.config.path);
+    const sizeMb = stats.size / (1024 * 1024);
+
+    if (sizeMb < this.config.max_size_mb) {
+      return false;
+    }
+
+    this.rotate();
+    return true;
+  }
+
+  private rotate(): void {
+    const basePath = this.config.path;
+    const baseName = basename(basePath);
+    const dir = dirname(basePath);
+    const timestamp = new Date().toISOString().split('T')[0];
+    const rotatedPath = `${dir}/${baseName}.${timestamp}`;
+    const compressedPath = `${rotatedPath}.gz`;
+
+    try {
+      // Move current log to rotated name
+      if (existsSync(rotatedPath)) {
+        fs.unlink(rotatedPath);
+      }
+      if (existsSync(compressedPath)) {
+        fs.unlink(compressedPath);
+      }
+      
+      fs.rename(basePath, rotatedPath);
+
+      // Compress the rotated file
+      const gzip = createGzip();
+      const input = createReadStream(rotatedPath);
+      const output = createWriteStream(compressedPath);
+      
+      pipeline(input, gzip, output).then(() => {
+        fs.unlink(rotatedPath);
+      }).catch((err) => {
+        console.error('Audit log compression failed:', err);
+      });
+
+      // Clean up old logs
+      this.cleanupOldLogs();
+    } catch (err) {
+      console.error('Audit log rotation failed:', err);
+    }
+  }
+
+  private async cleanupOldLogs(): Promise<void> {
+    const dir = dirname(this.config.path);
+    const baseName = basename(this.config.path);
+    const cutoffDate = new Date();
+    cutoffDate.setDate(cutoffDate.getDate() - this.config.keep_days);
+
+    try {
+      const files = await fs.readdir(dir);
+      
+      for (const file of files) {
+        if (!file.startsWith(baseName)) continue;
+
+        const filePath = `${dir}/${file}`;
+        const stats = await fs.stat(filePath);
+        const fileDate = new Date(stats.mtime);
+
+        if (fileDate < cutoffDate) {
+          await fs.unlink(filePath);
+        }
+      }
+    } catch (err) {
+      console.error('Audit log cleanup failed:', err);
+    }
+  }
+
+  async forceRotation(): Promise<void> {
+    this.rotate();
+  }
+}

src/audit/types.ts

@@ -0,0 +1,155 @@
+export type AuditLevel = 'debug' | 'info' | 'warn' | 'error';
+
+export type AuditEventType = 
+  // Tool execution
+  | 'tool.start' | 'tool.success' | 'tool.error' | 'tool.denied'
+  // Session lifecycle
+  | 'session.create' | 'session.message' | 'session.delete' | 'session.transfer' | 'session.compact'
+  // Automation - Cron
+  | 'cron.trigger' | 'cron.sent' | 'cron.add' | 'cron.remove'
+  // Automation - Webhook
+  | 'webhook.receive' | 'webhook.sent' | 'webhook.not_found' | 'webhook.denied'
+  // Automation - Heartbeat
+  | 'heartbeat.cycle' | 'heartbeat.check' | 'heartbeat.fail' | 'heartbeat.recover'
+  // Automation - Gmail
+  | 'gmail.poll' | 'gmail.new_email' | 'gmail.error'
+  // System events
+  | 'system.start' | 'system.stop' | 'system.config';
+
+export interface AuditEvent {
+  timestamp: number;
+  level: AuditLevel;
+  event_type: AuditEventType;
+  event: Record<string, unknown>;
+}
+
+export interface AuditConfig {
+  enabled: boolean;
+  path: string;
+  max_size_mb: number;
+  keep_days: number;
+  levels: {
+    tools: AuditLevel;
+    sessions: AuditLevel;
+    automation: AuditLevel;
+  };
+}
+
+export interface AuditQuery {
+  start_time?: number;
+  end_time?: number;
+  event_types?: AuditEventType[];
+  session_id?: string;
+  tool_name?: string;
+  level?: AuditLevel;
+}
+
+export interface ToolStartEvent {
+  tool_name: string;
+  tool_args: unknown;
+  session_id?: string;
+  channel?: string;
+  sender?: string;
+  agent_tier?: string;
+}
+
+export interface ToolSuccessEvent {
+  tool_name: string;
+  result: { success: boolean; output: string; error?: string };
+  duration_ms: number;
+  session_id?: string;
+}
+
+export interface ToolErrorEvent {
+  tool_name: string;
+  error: string;
+  duration_ms: number;
+  reason?: string;
+  session_id?: string;
+}
+
+export interface ToolDeniedEvent {
+  tool_name: string;
+  reason: string;
+  session_id?: string;
+  denial_type: 'policy' | 'hook' | 'not_found';
+}
+
+export interface SessionCreateEvent {
+  session_id: string;
+  frontend: string;
+  user_id: string;
+}
+
+export interface SessionMessageEvent {
+  session_id: string;
+  role: 'user' | 'assistant';
+  content_length: number;
+}
+
+export interface SessionDeleteEvent {
+  session_id: string;
+  message_count: number;
+}
+
+export interface SessionCompactEvent {
+  session_id: string;
+  messages_before: number;
+  messages_after: number;
+  tokens_before: number;
+  tokens_after: number;
+}
+
+export interface CronTriggerEvent {
+  job_name: string;
+  schedule: string;
+  message: string;
+  output_channel: string;
+  output_peer: string;
+}
+
+export interface WebhookReceiveEvent {
+  webhook_name: string;
+  body: string;
+  signature_verified: boolean;
+  output_channel: string;
+  output_peer: string;
+}
+
+export interface HeartbeatCycleEvent {
+  interval_ms: number;
+  checks: string[];
+  healthy: boolean;
+  consecutive_failures: number;
+}
+
+export interface HeartbeatCheckEvent {
+  check_name: string;
+  healthy: boolean;
+  message: string;
+  duration_ms: number;
+}
+
+export interface HeartbeatFailEvent {
+  checks_failed: string[];
+  consecutive_failures: number;
+  threshold: number;
+}
+
+export interface HeartbeatRecoverEvent {
+  consecutive_failures_before: number;
+}
+
+export interface GmailPollEvent {
+  mode: 'watch' | 'poll';
+  interval_ms?: number;
+  emails_processed: number;
+  new_emails: number;
+}
+
+export interface GmailNewEmailEvent {
+  email_id: string;
+  from: string;
+  subject: string;
+  labels: string[];
+}

src/automation/cron.ts

@@ -1,6 +1,7 @@
 import { Cron } from 'croner';
 import type { CronJobConfig } from '../config/schema.js';
 import type { ChannelAdapter, ChannelStatus, InboundMessage, OutboundMessage } from '../channels/types.js';
+import { auditLogger } from '../audit/index.js';
 
 /** Minimal interface for the parts of ChannelRegistry we need. */
 interface ChannelLookup {
@@ -46,6 +47,7 @@ export class CronScheduler implements ChannelAdapter {
     const enabledCount = this.jobConfigs.filter(j => j.enabled).length;
     if (enabledCount > 0) {
       console.log(`CronScheduler: ${enabledCount} job(s) scheduled`);
+      auditLogger?.systemStart('CronScheduler', { jobs_enabled: enabledCount });
     }
   }
 
@@ -55,6 +57,7 @@ export class CronScheduler implements ChannelAdapter {
     }
     this.cronInstances.clear();
     this._status = 'disconnected';
+    auditLogger?.systemStop('CronScheduler');
   }
 
   async send(peerId: string, message: OutboundMessage): Promise<void> {
@@ -93,6 +96,14 @@ export class CronScheduler implements ChannelAdapter {
       metadata: { cronJob: jobName, scheduled: true, modelTier: job.model_tier },
     };
 
+    auditLogger?.cronTrigger({
+      job_name: jobName,
+      schedule: job.schedule,
+      message: job.message,
+      output_channel: job.output.channel,
+      output_peer: job.output.peer,
+    });
+
     this.messageHandler?.(msg);
   }
 
@@ -118,6 +129,8 @@ export class CronScheduler implements ChannelAdapter {
 
     this.jobs.set(config.name, config);
 
+    auditLogger?.cronAdd(config.name, config.schedule);
+
     if (config.enabled && this._status === 'connected') {
       const cronInstance = new Cron(config.schedule, {
         timezone: config.timezone,
@@ -148,6 +161,9 @@ export class CronScheduler implements ChannelAdapter {
     }
 
     this.jobs.delete(name);
+    
+    auditLogger?.cronRemove(name);
+    
     return true;
   }
 }

src/backends/native/orchestrator.ts

@@ -12,6 +12,7 @@ import type { OutboundAttachmentCollector } from './attachments.js';
 import { shouldCompact } from '../../context/tokens.js';
 import { compactHistory, type CompactionConfig, type CompactionResult, DEFAULT_COMPACTION_CONFIG } from '../../context/compaction.js';
 import { estimateCost } from '../../models/costs.js';
+import { auditLogger } from '../../audit/index.js';
 
 // ── Public types ──────────────────────────────────────────────────────
 
@@ -255,6 +256,16 @@ export class AgentOrchestrator {
       `${result.tokensBefore} → ${result.tokensAfter} tokens`,
     );
 
+    if (this._session) {
+      auditLogger?.sessionCompact({
+        session_id: this._session.id,
+        messages_before: result.tokensBefore,
+        messages_after: result.tokensAfter,
+        tokens_before: result.tokensBefore,
+        tokens_after: result.tokensAfter,
+      });
+    }
+
     return result;
   }
 

src/config/schema.ts

@@ -384,8 +384,23 @@ const sessionsSchema = z.object({
 
 const logLevelSchema = z.enum(['debug', 'info', 'warn', 'error', 'silent']).default('info');
 
+const auditLevelSchema = z.enum(['debug', 'info', 'warn', 'error']).default('debug');
+
+const auditSchema = z.object({
+  enabled: z.boolean().default(true),
+  path: z.string().default('~/.local/share/flynn/audit.log'),
+  max_size_mb: z.number().min(1).max(1000).default(10),
+  keep_days: z.number().min(1).max(365).default(30),
+  levels: z.object({
+    tools: auditLevelSchema.default('debug'),
+    sessions: auditLevelSchema.default('debug'),
+    automation: auditLevelSchema.default('debug'),
+  }).default({}),
+}).default({});
+
 export const configSchema = z.object({
   log_level: logLevelSchema,
+  audit: auditSchema,
   telegram: telegramSchema.optional(),
   discord: discordSchema,
   slack: slackSchema,
@@ -451,3 +466,5 @@ export type GdriveConfig = z.infer<typeof gdriveSchema>;
 export type GtasksConfig = z.infer<typeof gtasksSchema>;
 export type PairingCodeConfig = z.infer<typeof pairingSchema>;
 export type LogLevel = z.infer<typeof logLevelSchema>;
+export type AuditConfig = z.infer<typeof auditSchema>;
+export type AuditLevel = z.infer<typeof auditLevelSchema>;

src/daemon/index.ts

@@ -30,6 +30,7 @@ import { ChannelRegistry } from '../channels/index.js';
 import type { McpManager } from '../mcp/index.js';
 import type { SkillRegistry, SkillInstaller } from '../skills/index.js';
 import type { GatewayServer } from '../gateway/index.js';
+import { AuditLogger, initAuditLogger } from '../audit/index.js';
 
 export interface DaemonContext {
   config: Config;
@@ -61,6 +62,15 @@ export async function startDaemon(config: Config): Promise<DaemonContext> {
   const dataDir = process.env.FLYNN_DATA_DIR ?? resolve(homedir(), '.local/share/flynn');
   mkdirSync(dataDir, { recursive: true });
 
+  // ── Audit Logger ──
+  const auditLoggerInstance = new AuditLogger(config.audit);
+  initAuditLogger(auditLoggerInstance);
+
+  lifecycle.onShutdown(async () => {
+    await auditLoggerInstance.close();
+    console.log('Audit logger closed');
+  });
+
   const sessionStore = new SessionStore(resolve(dataDir, 'sessions.db'));
   const sessionManager = new SessionManager(sessionStore);
 

src/session/manager.ts

@@ -1,5 +1,6 @@
 import type { Message } from '../models/types.js';
 import type { SessionStore } from './store.js';
+import { auditLogger } from '../audit/index.js';
 
 export interface Session {
   id: string;
@@ -23,6 +24,15 @@ export class ManagedSession implements Session {
     };
     this.history.push(messageWithTimestamp);
     this.store.addMessage(this.id, messageWithTimestamp);
+    
+    auditLogger?.sessionMessage({
+      session_id: this.id,
+      role: message.role,
+      content_length: typeof message.content === 'string' 
+        ? message.content.length 
+        : JSON.stringify(message.content).length,
+    });
+    
     return messageWithTimestamp;
   }
 
@@ -31,8 +41,14 @@ export class ManagedSession implements Session {
   }
 
   clear(): void {
+    const messageCount = this.history.length;
     this.history = [];
     this.store.clearSession(this.id);
+    
+    auditLogger?.sessionDelete({
+      session_id: this.id,
+      message_count: messageCount,
+    });
   }
 
   /**
@@ -67,6 +83,12 @@ export class SessionManager {
       const history = this.store.getMessages(id);
       session = new ManagedSession(id, this.store, history);
       this.sessions.set(id, session);
+      
+      auditLogger?.sessionCreate({
+        session_id: id,
+        frontend,
+        user_id: userId,
+      });
     }
 
     return session;
@@ -88,6 +110,8 @@ export class SessionManager {
     for (const message of history) {
       toSession.addMessage(message);
     }
+    
+    auditLogger?.sessionTransfer(fromSession.id, toSession.id, history.length);
   }
 
   listSessions(): string[] {

src/tools/executor.ts

@@ -2,6 +2,7 @@ import type { ToolResult } from './types.js';
 import type { ToolRegistry } from './registry.js';
 import type { HookEngine } from '../hooks/engine.js';
 import type { ToolPolicyContext } from './policy.js';
+import { auditLogger } from '../audit/index.js';
 
 export interface ToolExecutorConfig {
   defaultTimeoutMs?: number;
@@ -24,6 +25,12 @@ export class ToolExecutor {
   async execute(toolName: string, args: unknown, context?: ToolPolicyContext): Promise<ToolResult> {
     const tool = this.registry.getByApiName(toolName);
     if (!tool) {
+      auditLogger?.toolDenied({
+        tool_name: toolName,
+        reason: 'Tool not found',
+        denial_type: 'not_found',
+        session_id: context?.sessionId,
+      });
       return { success: false, output: '', error: `Tool '${toolName}' not found` };
     }
 
@@ -32,6 +39,12 @@ export class ToolExecutor {
     if (policy) {
       const allNames = this.registry.list().map(t => t.name);
       if (!policy.isAllowed(toolName, allNames, context)) {
+        auditLogger?.toolDenied({
+          tool_name: toolName,
+          reason: 'Tool not allowed by policy',
+          denial_type: 'policy',
+          session_id: context?.sessionId,
+        });
         return {
           success: false,
           output: '',
@@ -48,6 +61,12 @@ export class ToolExecutor {
         args as Record<string, unknown>,
       );
       if (!hookResult.approved) {
+        auditLogger?.toolDenied({
+          tool_name: toolName,
+          reason: hookResult.reason ?? 'no reason',
+          denial_type: 'hook',
+          session_id: context?.sessionId,
+        });
         return {
           success: false,
           output: '',
@@ -57,6 +76,17 @@ export class ToolExecutor {
     }
 
     // Execute with timeout
+    const startTime = Date.now();
+    
+    auditLogger?.toolStart({
+      tool_name: toolName,
+      tool_args: args,
+      session_id: context?.sessionId,
+      channel: context?.channel,
+      sender: context?.sender,
+      agent_tier: context?.tier,
+    });
+
     try {
       const result = await Promise.race([
         tool.execute(args),
@@ -65,17 +95,36 @@ export class ToolExecutor {
         ),
       ]);
 
+      const duration = Date.now() - startTime;
+
       // Truncate output if too large
       if (result.output.length > this.maxOutputBytes) {
         result.output = result.output.slice(0, this.maxOutputBytes) + '\n[truncated]';
       }
 
+      auditLogger?.toolSuccess({
+        tool_name: toolName,
+        result: result,
+        duration_ms: duration,
+        session_id: context?.sessionId,
+      });
+
       return result;
     } catch (error) {
+      const duration = Date.now() - startTime;
+      const errorMessage = error instanceof Error ? error.message : String(error);
+      
+      auditLogger?.toolError({
+        tool_name: toolName,
+        error: errorMessage,
+        duration_ms: duration,
+        session_id: context?.sessionId,
+      });
+
       return {
         success: false,
         output: '',
-        error: error instanceof Error ? error.message : String(error),
+        error: errorMessage,
       };
     }
   }

src/tools/policy.ts

@@ -132,6 +132,14 @@ export interface ToolPolicyContext {
   agent?: string;
   /** Provider name (e.g. 'ollama', 'anthropic'). */
   provider?: string;
+  /** Session ID for audit logging. */
+  sessionId?: string;
+  /** Channel name for audit logging. */
+  channel?: string;
+  /** Sender ID for audit logging. */
+  sender?: string;
+  /** Model tier for audit logging. */
+  tier?: string;
 }
 
 // ── ToolPolicy engine ───────────────────────────────────────────────