Mutation triage (StrykerJS, 81 survivors on the first full run) showed worker.model was
written and never read. The new tests pin the survivors that were behaviour: the loopback
default, --host, stray flags, the models-root resolution, the SIGTERM grace, a worker that
dies while the daemon waits for its health, the POST route, and lastError after a
requested stop.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>