Three fixes for high 4xx alert rate:
1. Catch urllib.error.HTTPError (not just RuntimeError) for 404 on
DELETE in pending_ops — was causing infinite retry loop for
already-deleted memories
2. try_sync_delete: treat 404 as success instead of enqueuing
a retry that will also 404 forever
3. URL-encode the `since` query param to prevent `+` in timezone
offset being decoded to a space (the asyncpg-string-timestamp
pattern applied to the sync client)
- Add SyncEngine for background sync between local SQLite cache and
remote API with pending_ops queue for offline resilience
- Refactor MCP server to support three modes: SQLite-only, hybrid
(local cache + sync, new default), and HTTP-only (legacy)
- Add GET /api/memories/sync endpoint for incremental sync
- Change DELETE to soft delete (set deleted_at) for sync support
- Add deleted_at IS NULL filters to all read queries
- Scale API deployment to 2 replicas with pod anti-affinity, PDB,
and startup probe for high availability
- Add migration 003 for deleted_at column and updated_at index
- Add comprehensive tests for sync engine and API sync endpoint
