The proxy's data-plane entry point: the handlers for packument merges (GET /{pkg}), artifact relays (GET /{pkg}/-/{file}.tgz), and first-party publishes (PUT /{pkg}). An ecosystem's route table names them one module at a time, so nothing but its own spec imports this hub.

The handlers name no ecosystem. A registry's metadata client, packument assembly, and artifact-request formation reach them as injected capabilities on PackumentDeps, so a router maps its own routes onto whichever handlers apply and names its own actions for the rest.