## Goal Split the Artifact Registry's single `container` artifact format into two user-facing formats, `docker` and `oci`, at the management-API and metadata layer. The `/v2/` OCI backend and the `container_*` tables stay unified. This gives strictly typed Docker and OCI repositories without a later breaking reclassification, while there is no data to migrate. ## Workflow 1. **Spec amendments (S17, S12).** S17 widens the repository `format` enum to `docker, oci, maven, npm`, and S12 adds strict per-repository media-type enforcement at manifest push. Tracked in gitlab-org/ops/artifact-registry#254+s. 1. **Implementation plan.** A `docs/plans/` plan and plan MR that sequences the phases below and lands before any implementation MR. 1. **Phase 1: enum split and typed repository creation.** Widen the `format` enum (migration), retire `container` for `docker` and `oci` across the three coupled enum sites, flip the OpenAPI contract, and route both formats to the shared `container_repositories` child. No enforcement yet. Independently shippable and client-reversible. 1. **Phase 2: per-repository media-type enforcement.** Surface the repository format in the OCI resolution result and reject cross-family manifest pushes with `MANIFEST_INVALID` (400). Gated on resolving the OCI conformance-suite interaction. This is the client-visible, irreversible step. 1. **Phase 3 (deferrable): image-config metadata.** Extract `architecture`, `os`, and `os_variant` on manifest push to power list-view filter and sort. A fast-follow, not required for the split to be correct. ## Boundaries - Frontend Path A (format-specific detail views, icons, names) is a separate monolith frontend workstream and a consumer of this backend work. - Enforcement modes (advisory, none) and migration or import tooling are deferred. - OCI subtypes (Helm OCI, WASM OCI) are future format values on the same tables.