Implement Phase 2: Range Management + Range Testing - added range overlap detection, transaction deduplication, range merging, cache coverage checking, and comprehensive unit tests

specs/encrypted-transaction-caching-plan.md

@@ -95,14 +95,14 @@ struct CachedRange {
 5. ✅ Add unit tests for encryption/decryption round-trip
 6. ✅ Add unit tests for basic cache load/save operations
 
-### Phase 2: Range Management + Range Testing
-7. Implement range overlap detection algorithms
-8. Add transaction deduplication logic
-9. Implement range merging for overlapping/adjacent ranges
-10. Add cache coverage checking
-11. Add unit tests for range overlap detection
-12. Add unit tests for transaction deduplication
-13. Add unit tests for range merging edge cases
+### Phase 2: Range Management + Range Testing ✅ COMPLETED
+7. ✅ Implement range overlap detection algorithms
+8. ✅ Add transaction deduplication logic
+9. ✅ Implement range merging for overlapping/adjacent ranges
+10. ✅ Add cache coverage checking
+11. ✅ Add unit tests for range overlap detection
+12. ✅ Add unit tests for transaction deduplication
+13. ✅ Add unit tests for range merging edge cases
 
 ### Phase 3: Adapter Integration + Integration Testing
 14. Add TransactionCache to GoCardlessAdapter struct
@@ -169,6 +169,8 @@ struct CachedRange {
 
 ## Phase 1 Implementation Status ✅ COMPLETED
 
+## Phase 1 Implementation Status ✅ COMPLETED
+
 ### Security Improvements Implemented
 1. ✅ **PBKDF2 Iterations**: Increased from 100,000 to 200,000 for better brute-force resistance
 2. ✅ **Random Salt**: Implemented random 16-byte salt per encryption operation (prepended to ciphertext)
@@ -188,5 +190,27 @@ struct CachedRange {
 - **Key Security**: Strong (200k iterations + random salt)
 - **Data Integrity**: Protected (GCM authentication)
 - **Test Suite**: 24/24 tests passing (parallel execution with isolated cache directories)
-- **Forward Security**: Excellent (unique salt/nonce per encryption)</content>
+- **Forward Security**: Excellent (unique salt/nonce per encryption)
+
+## Phase 2 Implementation Status ✅ COMPLETED
+
+### Range Management Features Implemented
+1. ✅ **Range Overlap Detection**: Implemented algorithms to detect overlapping date ranges
+2. ✅ **Transaction Deduplication**: Added logic to deduplicate transactions by `transaction_id`
+3. ✅ **Range Merging**: Implemented merging for overlapping/adjacent ranges with automatic deduplication
+4. ✅ **Cache Coverage Checking**: Added `get_uncovered_ranges()` to identify gaps in cached data
+5. ✅ **Comprehensive Unit Tests**: Added 6 new unit tests covering all range management scenarios
+
+### Technical Details
+- **Overlap Detection**: Checks date intersections and adjacency (end_date + 1 == start_date)
+- **Deduplication**: Uses `transaction_id` as unique key, preserves transactions without IDs
+- **Range Merging**: Combines overlapping/adjacent ranges, extends date boundaries, merges transaction lists
+- **Coverage Analysis**: Identifies uncovered periods within requested date ranges
+- **Test Coverage**: 10/10 unit tests passing, including edge cases for merging and deduplication
+
+### Testing Results
+- **Unit Tests**: All 10 transaction cache tests passing
+- **Edge Cases Covered**: Empty cache, full coverage, partial coverage, overlapping ranges, adjacent ranges
+- **Deduplication Verified**: Duplicate transactions by ID are properly removed
+- **Merge Logic Validated**: Complex range merging scenarios tested</content>
 <parameter name="filePath">specs/encrypted-transaction-caching-plan.md