api-endpoint-serializer-authoring

Apply this skill when adding an endpoint to apps/api/, authoring a mutation-ack serializer, wiring ManagerFactory, resolving Phase 5A routing collisions, or diagnosing the validate_manifest or test_resource_route_coverage CI gates. Covers: resource vs. action classification (409 vs. 200+envelope); Cursor + paginate() pagination in services/pagination.py; ManagerFactory concurrency scoping; apps/api → unifi-core-only dependency rule; Phase 5A patterns (capability-aware dispatch on product_kinds, dual-kind stats, wrapper-dict unwrap, path disambiguation, TOOL_ROUTE_OVERRIDES in test_resource_route_coverage.py); @register_serializer(tools={...}) decorator; seven RenderKind values; field-curation discipline; _reset_registry_for_tests() isolation; and the two CI gates. Post-Phase 6: read tools use Strawberry types (graphql-api-extension skill); serializers cover mutation acks only. Activate even without explicit serializer mention — any apps/api/ PR may need CI-gate alignment.