Addresses operator reports: Stop never finishes, the agent polls curator
constantly, and stale-cached pages get mistaken for a failed deploy.
- Stop is prompt: flip _running BEFORE any lock so /status + worker loops see
"stopped" immediately, and add a stop/shrink checkpoint in _process (after
decode, before the expensive detect+embed) that releases the job and bails —
so a Stop doesn't wait out heavy GPU work.
- Lazy curator polling: the queue snapshot is fetched only while a browser is
actually watching (a /status hit within UI_IDLE_GRACE) and on a 5s cadence,
not a constant background loop. The work loop's own lease/submit is curator's
only visitor otherwise — nothing polls just to poll.
- Build marker: VERSION is embedded in the page and reported on /status; the UI
shows a "reload" banner when they differ, so a browser-cached page can't be
mistaken for "the new image didn't deploy" (complements the no-store header).
CI: the lint lane now also `ruff check`s agent/ and compileall-parses it, so the
GPU agent is linted + syntax-checked before its image builds (build.yml only
`docker build`s it). Fixed the agent's pre-existing UP037/B905 so it passes.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ttrj5P7upUTueSfoJcxEqa
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