Elasticsearch’s PUT /<index>/_create/<id> and POST /<index>/_create/<id> endpoints are deliberately stricter than the ordinary index API: they create a missing document but return HTTP 409 rather than replace an existing ID. This matters for importers and job processors that use create-only writes as an idempotency guard.

The gateway already enforced that distinction for bulk create, but the standalone endpoint was not routed. Both standalone forms now reuse the same existence check. A new document returns HTTP 201 with result: "created"; an existing document returns version_conflict_engine_exception, and the regression test verifies that Qdrant receives no write. Both success and error responses include the Elasticsearch product header expected by official clients. The test covers both embedded-source and dedicated document-projection storage:

cargo test standalone_create

This adds one point lookup before each create-only write. The lookup and write are serialized inside one gateway process, but they are not an atomic compare-and-insert across replicas or independently running gateway processes. Deployments that require distributed exactly-once creation still need a stronger coordination mechanism; the endpoint should not be treated as a substitute for Qdrant-side conditional insertion.