This P0 makes a Node prove it can serve its selected Model Artifact and Shard before the Tracker treats it as routable. It is deliberately model-agnostic: Qwen3.6 is only a development integration fixture, never a hardcoded runtime target.

Locked decisions

A Node explicitly asked to serve a Model Preset fails closed when no validated recipe can execute it; it must not register as ready or accept paid inference.
Default validation covers the selected model/shard only. meshnet-node doctor --all-recipes is reserved for support and CI.
A Model Preset may have multiple named recipes. Each independently proves a real forward; the Tracker schedules only validated recipes while considering measured performance.
Compatibility schemas are generic. A future Tracker may publish signed, data-only Model Artifact Manifests, but executable recipes arrive only through signed Node releases.
P0 ships a local versioned recipe manifest and reports its version. It does not build a self-updater, download executable recipes, or install system dependencies.
Every story requires pytest; release CI additionally runs an integration-marked real-model doctor smoke test on each certified hardware lane.

Ralph order

NCA-001 generic capability/report contract
NCA-002 generic doctor command and real-forward validation
NCA-003 startup admission lifecycle and fail-closed behavior
NCA-004 tracker registration/routing enforcement
NCA-005 operator documentation and hardware-lane integration contract

Run serially. Stories 3 and 4 both change registration/startup behavior and must not be executed in parallel.

Quality gates

Targeted pytest tests named by the issue.
Full pytest before marking a story done, or record the unrelated blocker.
No default test downloads a model or requires a GPU.
pytest -m integration / the real-model doctor test remains explicit and environment-gated.