Arm a PR watch automatically when a turn ends with pending checks and no watch

[ceolinwill]

Note

🤖 Claude Opus 5.5 opening this discussion on behalf of Will

Problem. A thread stays in Working while it watches its PR, which is great. But the watch only exists if the agent remembers to call watch_pull_request, and sometimes it doesn't. The thread then ends its turn with CI still running on a PR it just pushed to, and the sidebar shows Done. I find out later that checks failed and nobody looked.

It goes wrong most often on a later turn. I checked the 188 PRs my threads opened over the last two weeks in statev2.sqlite:

• 174 were watched on their final head, which is the happy path.
• 6 were never watched at all.
• 8 got a later push after their watch had ended, and no new watch was armed.

A typical case: the watch ends, I come back later with "main is fixed, go ahead". The agent merges main, pushes, writes "I'm watching the PR and will hand it back once every check passes", and ends its turn without calling watch_pull_request. The thread shows Done while the new head's checks run for another 12 minutes. The runtime instructions already say to watch "even after an earlier unwatch", so this is the model not following them, but it happens often enough to matter.

Idea. Let T3 arm the watch itself instead of relying on the agent:

• When a turn ends and a PR the thread created or pushed to has pending checks on its current head with no active watch, T3 starts the watch automatically, as if the agent had called watch_pull_request. A project or global setting could turn this on or off.
• The thread stays Working until checks settle, and wakes the agent on failures, comments or conflicts like any other watch.
• If auto-arming is too much, a smaller version would help too: when a turn ends right after a push to a linked PR with no watch, send the agent a one-line nudge ("PR #N has pending checks and no watch") before the thread settles.

T3 already knows everything this needs: the linked PRs, their head SHA and checks, and whether a watch is active. That makes it more reliable than asking every agent to remember on every follow-up turn.

Related, not duplicates: #31921 (show what a waiting thread is waiting on), #25764 (delegated children are told never to watch their PR), #22183 (watches ending silently). Seen on T3 Code 0.1.7 (Beta), macOS, with Claude agents.