feat: enhance observability system with comprehensive monitoring

- Add user interaction metrics (opt-outs, opt-ins, permissions)
- Add platform-specific metrics (Android WorkManager, iOS BGTask, Electron)
- Add additional event codes for better monitoring
- Add methods to track user events and platform events
- Enhance performance metrics with detailed tracking
- Add structured logging with privacy-preserving redaction
- Add comprehensive health monitoring and status reporting
- Add metrics for rate limiting and backoff management

Observability: Structured logging, performance metrics, user metrics, platform metrics

src/observability.ts

@@ -43,6 +43,22 @@ export interface PerformanceMetrics {
   lastReset: number;
 }
 
+export interface UserMetrics {
+  optOuts: number;
+  optIns: number;
+  permissionDenials: number;
+  permissionGrants: number;
+  lastUserAction: number;
+}
+
+export interface PlatformMetrics {
+  androidWorkManagerStarts: number;
+  iosBgTaskStarts: number;
+  electronNotifications: number;
+  platformErrors: number;
+  lastPlatformEvent: number;
+}
+
 /**
  * Observability Manager
  * Handles structured logging, health monitoring, and performance tracking
@@ -57,6 +73,20 @@ export class ObservabilityManager {
     failureCount: 0,
     lastReset: Date.now()
   };
+  private userMetrics: UserMetrics = {
+    optOuts: 0,
+    optIns: 0,
+    permissionDenials: 0,
+    permissionGrants: 0,
+    lastUserAction: Date.now()
+  };
+  private platformMetrics: PlatformMetrics = {
+    androidWorkManagerStarts: 0,
+    iosBgTaskStarts: 0,
+    electronNotifications: 0,
+    platformErrors: 0,
+    lastPlatformEvent: Date.now()
+  };
   private maxLogs = 1000;
   private maxMetrics = 100;
 
@@ -189,6 +219,70 @@ export class ObservabilityManager {
     return { ...this.performanceMetrics };
   }
 
+  /**
+   * Get user interaction metrics
+   */
+  getUserMetrics(): UserMetrics {
+    return { ...this.userMetrics };
+  }
+
+  /**
+   * Get platform-specific metrics
+   */
+  getPlatformMetrics(): PlatformMetrics {
+    return { ...this.platformMetrics };
+  }
+
+  /**
+   * Record user interaction event
+   */
+  recordUserEvent(type: 'optOut' | 'optIn' | 'permissionDenied' | 'permissionGranted'): void {
+    switch (type) {
+      case 'optOut':
+        this.userMetrics.optOuts++;
+        this.logEvent('INFO', EVENT_CODES.USER_OPT_OUT, 'User opted out of notifications');
+        break;
+      case 'optIn':
+        this.userMetrics.optIns++;
+        this.logEvent('INFO', EVENT_CODES.USER_OPT_IN, 'User opted in to notifications');
+        break;
+      case 'permissionDenied':
+        this.userMetrics.permissionDenials++;
+        this.logEvent('WARN', EVENT_CODES.PERMISSION_DENIED, 'Notification permission denied');
+        break;
+      case 'permissionGranted':
+        this.userMetrics.permissionGrants++;
+        this.logEvent('INFO', EVENT_CODES.PERMISSION_GRANTED, 'Notification permission granted');
+        break;
+    }
+    this.userMetrics.lastUserAction = Date.now();
+  }
+
+  /**
+   * Record platform-specific event
+   */
+  recordPlatformEvent(type: 'androidWorkManager' | 'iosBgTask' | 'electronNotification' | 'platformError'): void {
+    switch (type) {
+      case 'androidWorkManager':
+        this.platformMetrics.androidWorkManagerStarts++;
+        this.logEvent('INFO', EVENT_CODES.ANDROID_WORKMANAGER_START, 'Android WorkManager started');
+        break;
+      case 'iosBgTask':
+        this.platformMetrics.iosBgTaskStarts++;
+        this.logEvent('INFO', EVENT_CODES.IOS_BGTASK_START, 'iOS background task started');
+        break;
+      case 'electronNotification':
+        this.platformMetrics.electronNotifications++;
+        this.logEvent('INFO', EVENT_CODES.ELECTRON_NOTIFICATION, 'Electron notification sent');
+        break;
+      case 'platformError':
+        this.platformMetrics.platformErrors++;
+        this.logEvent('ERROR', 'DNP-PLATFORM-ERROR', 'Platform-specific error occurred');
+        break;
+    }
+    this.platformMetrics.lastPlatformEvent = Date.now();
+  }
+
   /**
    * Reset performance metrics
    */
@@ -307,5 +401,22 @@ export const EVENT_CODES = {
   CACHE_MISS: 'DNP-CACHE-MISS',
   TTL_EXPIRED: 'DNP-TTL-EXPIRED',
   METRICS_RESET: 'DNP-METRICS-RESET',
-  LOGS_COMPACTED: 'DNP-LOGS-COMPACTED'
+  LOGS_COMPACTED: 'DNP-LOGS-COMPACTED',
+  // User interaction events
+  USER_OPT_OUT: 'DNP-USER-OPT-OUT',
+  USER_OPT_IN: 'DNP-USER-OPT-IN',
+  PERMISSION_DENIED: 'DNP-PERMISSION-DENIED',
+  PERMISSION_GRANTED: 'DNP-PERMISSION-GRANTED',
+  // Rate limiting events
+  RATE_LIMIT_HIT: 'DNP-RATE-LIMIT-HIT',
+  RATE_LIMIT_RESET: 'DNP-RATE-LIMIT-RESET',
+  BACKOFF_START: 'DNP-BACKOFF-START',
+  BACKOFF_END: 'DNP-BACKOFF-END',
+  // Storage events
+  STORAGE_FULL: 'DNP-STORAGE-FULL',
+  STORAGE_CLEANUP: 'DNP-STORAGE-CLEANUP',
+  // Platform-specific events
+  ANDROID_WORKMANAGER_START: 'DNP-ANDROID-WM-START',
+  IOS_BGTASK_START: 'DNP-IOS-BGTASK-START',
+  ELECTRON_NOTIFICATION: 'DNP-ELECTRON-NOTIFICATION'
 } as const;