enhance: Improve background data fetching plan with TimeSafari insights

- Integrated TimeSafari authentication patterns (DID-based JWT + Passkey JWANT)
- Added batch processing optimization (100ms delays, 10-item batches)
- Enhanced cross-platform logging with database persistence
- Incorporated @capacitor-community/sqlite for unified storage
- Added performance monitoring with operation timing
- Included structured notification patterns and error handling
- Enhanced Android/iOS native implementation strategies
- Expanded success criteria and technical requirements

Based on analysis of TimeSafari crowdsourcing application architecture.

doc/BACKGROUND_DATA_FETCHING_PLAN.md

@@ -2,8 +2,8 @@
 
 **Author**: Matthew Raymer  
 **Version**: 1.0.0  
-**Created**: 2025-01-27 12:00:00 UTC  
-**Last Updated**: 2025-01-27 12:00:00 UTC  
+**Created**: 2025-10-02 07:47:04 UTC  
+**Last Updated**: 2025-10-02 10:15:00 UTC  
 
 ## Overview
 
@@ -36,12 +36,33 @@ JavaScript Layer → Native Bridge → Native Background Executor
 ### B. Authentication Implementation
 
 ```kotlin
-// JWT Generation in Android
+// JWT Generation in Android - Enhanced with DID support
 class JWTHelper {
     fun generateJWT(userDid: String, expiresInSeconds: Int): String {
         val payload = mapOf(
             "exp" to (System.currentTimeMillis() / 1000 + expiresInSeconds),
-            "iat" to (System.currentTimeMillis() / 1000)?
+            "iat" to (System.currentTimeMillis() / 1000),
+            "iss" to userDid,
+            // Include DID-specific claims for verification
+            "aud" to "timesafari.notifications",
+            "sub" to userDid
+        )
+        return signWithDID(payload, userDid)
+    }
+    
+    // Enhanced authentication with Passkey support
+    fun generateJWANT(userDid: String, biometricData: ByteArray): String {
+        val payload = mapOf(
+            "exp" to (System.currentTimeMillis() / 1000 + 3600), // 1 hour
+            "iat" to (System.currentTimeMillis() / 1000),
+            "iss" to userDid,
+            "aud" to "timesafari.notifications",
+            "sub" to userDid,
+            "auth_data" to android.util.Base64.encodeToString(biometricData, android.util.Base64.NO_WRAP)
+        )
+        return signWithDIDPasskey(payload, userDid, biometricData)
+    }
+}
 
 ### C. HTTP Request Implementation
 
@@ -184,13 +205,27 @@ interface PluginConfig {
 
 - **Android Room database** for caching API responses
 - **iOS Core Data** for persistent storage
+- **Web IndexedDB** for web platform caching
 - **TTL enforcement** for cached data freshness
+- **SQLite integration** via @capacitor-community/sqlite for unified storage across platforms
 
 ### State Synchronization
 
 - **JavaScript → Native** configuration updates
 - **Native → JavaScript** status reporting
 - **Cross-platform state consistency**
+- **Background ↔ Foreground** state synchronization
+- **Database logging** for audit trails and debugging
+
+### Enhanced Caching Strategy
+
+Based on TimeSafari's optimization patterns:
+
+- **Batch-oriented processing** for API requests to reduce overhead
+- **Intelligent batching** with configurable timing (max 100ms wait, max 10 items)
+- **Memory-optimized caching** with automatic cleanup (keep last 1000 log entries)
+- **Request deduplication** to prevent redundant API calls
+- **Performance monitoring** with operation timing and metrics collection
 
 ## Performance Optimizations
 
@@ -273,6 +308,8 @@ GET {apiServer}/api/v2/report/offersToPlansOwnedByMe?afterId={jwtId}&beforeId={j
 - Generate traditional JWT using DID signing
 - Short-lived tokens (60 seconds)
 - Suitable for basic notification data fetching
+- Use `did-jwt` library for token generation and verification
+- Based on TimeSafari's existing JWT implementation patterns
 
 ### Option 2: Enhanced Passkey Authentication (Advanced)
 
@@ -280,6 +317,8 @@ GET {apiServer}/api/v2/report/offersToPlansOwnedByMe?afterId={jwtId}&beforeId={j
 - Longer-lived tokens with automatic refresh
 - Support for cached authentication state
 - Better user experience for frequent polling
+- Integrate with SimpleWebAuthn for cross-platform biometric support
+- Support JWANT tokens (JWT + WebAuthn) for enhanced security
 
 ## Platform-Specific Considerations
 
@@ -296,6 +335,9 @@ GET {apiServer}/api/v2/report/offersToPlansOwnedByMe?afterId={jwtId}&beforeId={j
 - Support iOS Keychain for authentication tokens
 - Handle Face ID/Touch ID integration for passkeys
 - Support certificate pinning if required
+- Use BGTaskScheduler for reliable background execution
+- Handle iOS-specific background refresh restrictions
+- Support Core Data for notification metadata persistence
 
 ## Data Flow Integration Points
 
@@ -356,6 +398,10 @@ GET {apiServer}/api/v2/report/offersToPlansOwnedByMe?afterId={jwtId}&beforeId={j
 - [ ] **Reliability Requirements**: Handles network failures and offline scenarios
 - [ ] **Integration Requirements**: Seamless integration with existing plugin APIs
 - [ ] **Testing Requirements**: Comprehensive test coverage for all platforms
+- [ ] **Authentication Requirements**: Support both DID-based JWT and Passkey JWANT tokens
+- [ ] **Optimization Requirements**: Implement batch processing with sub-100ms delays
+- [ ] **Logging Requirements**: Structured logging with database persistence for debugging
+- [ ] **Cross-Platform Requirements**: Unified SQLite/IndexedDB storage across platforms
 
 ## Risks & Mitigation
 
@@ -373,6 +419,7 @@ GET {apiServer}/api/v2/report/offersToPlansOwnedByMe?afterId={jwtId}&beforeId={j
 
 ---
 
-**Status**: Planning document - Ready for implementation  
+**Status**: Enhanced planning document - Ready for implementation  
 **Next Steps**: Begin Phase 1 implementation with Android HTTP client setup  
-**Dependencies**: Android Studio, Xcode, Capacitor CLI, existing plugin infrastructure
+**Dependencies**: Android Studio, Xcode, Capacitor CLI, existing plugin infrastructure, @capacitor-community/sqlite, @simplewebauthn packages  
+**Enhanced Features**: DID authentication, batch processing, structured logging, cross-platform storage optimization