The composition root's worker bundle construction: the one function that turns the served mounts, the resolved publish targets, and the adapter registry into the per-ecosystem WorkerPolicies the mirror worker dispatches every job through.

runProxy consumes this, and a worker-only binary is a thin entry over the same function: everything the worker's dispatch needs (the re-evaluation inputs, the artifact request formation, and the married mirror-write capability) is assembled here rather than threaded through the proxy's own wiring. The adapter registry is consumed only here, at the composition root, per the standing rule: the worker itself receives plain handles and never resolves an adapter.

Each bundle reuses its mount's own PackumentDeps (the same prepared rules, floors, host gate, and request formation the serve path gates with, so the ingest decision cannot diverge from the serve decision) and marries its ecosystem's publish codec to the shared publish transport at the mount's declared mirror target. A mount that serves no packument, or an ecosystem without a resolved publish target or adapter, contributes no bundle: a job for it is fail-closed at the worker rather than half-wired here.