A module-level companion to the layering spec: what each ring holds, why
the model is a package, where each timestamp's truth source is, and how
the three drivers (HTTP, poller, run-completion callback) reach the same
service through the same ports.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Queue comments received while a run is active, then submit one deduplicated follow-up after it finishes. Failed drains are requeued and watcher tasks stop cleanly with the channel manager.