**Motivations:**
- Avoid unnecessary re-anchoring of already anchored hashes
- Improve performance by using database as source of truth
- Return consistent information without additional RPC calls
**Evolutions:**
- Added optional skipIfExists parameter to /api/anchor/document endpoint
- Check database for existing anchors before creating new transaction
- Automatically store anchors in database after transaction creation
- Return old: true/false flag and ok: true in all responses
- Enrich anchors table with all necessary information for retrieval without RPC calls
**Pages affectées:**
- api-anchorage/src/routes/anchor.js: Added skipIfExists parameter and database check
- api-anchorage/src/bitcoin-rpc.js: Store anchor in database after transaction creation
- api-anchorage/README.md: Updated documentation with new parameter and response format
- features/api-anchorage-skip-if-exists.md: Evolution documentation
