Document the dual HTTP surface everywhere integrators look: OpenAPI intro and servers, ARCHITECTURE, REST_API, API_VERSIONING (deprecated vs internal routes, shared modules), and CONTRIBUTING (v1-first rule).
Session JSON routes in app/routes/api.py that overlap REST v1 now return X-API-Deprecated and a Link header with rel successor-version, implemented via app/utils/api_deprecation.py.
Extract shared global search into app/services/global_search_service.py for both GET /api/search and GET /api/v1/search while preserving legacy short-query 200 empty responses and v1 400 validation.
Refactor legacy POST /api/timer/start, /api/timer/stop, and the start path of /api/timer/resume to use TimeTrackingService; keep existing socketio emits for the web UI.
Add tests/test_api_deprecation_headers.py and adjust search partial-failure tests to patch Project.query on the service module.
Dries Peeters