Cache Busting Impact Analysis on Note Storage

Executive Summary

✅ SAFE: The cache busting implementation has been analyzed and enhanced to ensure it does NOT affect note storage, retrieval, deletion, or any other note-related functionality.

Analysis Results

Current Cache Busting Implementation

The cache busting system in js/cache-buster.js is designed to:

1. Detect when users have outdated cached versions
2. Show notifications prompting refresh
3. Clear only cache-related localStorage items during refresh
4. Force page reload to get latest version

Note Storage Patterns Identified

The web application uses the following localStorage patterns for note storage:

Note Storage Keys (WebStorage class in js/lib/storage.js):

• anchored_notes_* - Individual note caches (prefix pattern)
• anchored_sync_queue - Queue of notes pending sync to cloud
• anchored_last_sync - Timestamp of last successful sync
• anchored_change_count - Counter for batching sync operations
• anchored_meta - Metadata for storage system

Authentication & User Data Keys:

• supabase_session - User authentication session
• userTier - User subscription tier (free/premium)
• profileLastChecked - Profile verification timestamp
• subscriptionLastChecked - Subscription check timestamp
• cachedSubscription - Cached subscription data
• subscriptionCacheTime - Subscription cache timestamp
• encryptionKeyLastChecked - Encryption key check timestamp
• cachedKeyMaterial - Cached encryption key material
• cachedSalt - Encryption salt for key derivation
• auth_token - Authentication bearer token

UI Preferences:

• theme - User theme preference (dark/light)
• upgradeBannerDismissed - Banner dismissal timestamp

Monitoring & Debug:

• anchored_debug - Debug mode flag
• anchored_errors - Error logs for troubleshooting
• anchored_health_checks - Health check logs

Protection Implementation

The cache buster has been enhanced with comprehensive protection:

1. Explicit Protection List

All user data keys are explicitly listed as protected and will never be removed.

2. Double-Check Validation

Before removing any key, the system verifies it’s not in the protection list.

3. Minimal Removal Scope

Only the anchored-cache-version key is removed during cache refresh.

4. Safety Logging

All preserved keys are logged for verification and debugging.

5. Test Function

A comprehensive test function window.CacheBuster.testNoteStorageProtection() verifies protection works correctly.

Impact Assessment

✅ What IS Affected (Safe):

• anchored-cache-version - Cache version tracking (removed as intended)
• Browser cache (CSS/JS files) - Cleared to force fresh downloads
• Service worker caches - Cleared to ensure latest code

✅ What is NOT Affected (Protected):

• Note Storage: All note data remains intact
• Sync Queue: Pending sync operations preserved
• Authentication: User sessions maintained
• Encryption: Keys and materials preserved
• User Preferences: Theme and settings maintained
• Monitoring Data: Debug and error logs preserved

Testing Results

Automated Test Results:

🎉 Overall Result: ALL TESTS PASSED
✨ Cache buster correctly preserves all note storage and user data!

Test Coverage:

• ✅ Note data preservation
• ✅ Sync queue preservation
• ✅ Authentication data preservation
• ✅ Encryption material preservation
• ✅ User preferences preservation
• ✅ Monitoring data preservation
• ✅ Cache version removal (as intended)

Recommendations

For Users:

• Cache refresh is completely safe to use
• No risk of losing notes, settings, or authentication
• Refresh when prompted for best experience

For Developers:

• Run window.CacheBuster.testNoteStorageProtection() after any changes
• Monitor console logs during cache refresh for verification
• Use scripts/test-cache-busting-protection.js for automated testing

For Maintenance:

• If adding new localStorage keys for user data, add them to the protection list
• Always test protection after modifying cache buster logic
• Document any new storage patterns in this analysis

Conclusion

The cache busting system is completely safe for note storage and retrieval. The implementation includes multiple layers of protection to ensure user data is never affected by cache refresh operations. All tests pass and the system correctly preserves all note-related functionality while only clearing the intended cache version tracking.