feat(status): acknowledge a pull request the moment automatic commands start

[dwin-gharibi]

Implements #3090.

Description

An automatic command sets config.is_auto_command, which suppresses the "Preparing review…"
progress comment. Between opening a pull request and the model answering — often a minute or more
on a large diff — nothing tells the author that PR-Agent is running, or whether the webhook arrived
at all.

What changed

A provider primitive. GitProvider.publish_run_status(state, description) where state is
pending, success or failure. The base implementation returns False, so providers without a
commit-status API are a no-op.

• GitHub — a commit status on the PR head (create_status), truncating the description to the
  140 characters GitHub accepts.
• GitLab — a commit status too, mapping failure to GitLab's spelling, failed.

A commit status was chosen over a comment because it is not part of the conversation: it appears
in the PR's checks area immediately and is replaced in place, so re-running adds no noise. It also
needs no extra permission beyond what PR-Agent already has, unlike the Checks API.

Wiring. _perform_auto_commands_github publishes pending before the command loop and
success / failure after it, tracking both a command that returns False and one that raises.

Configuration, off by default:

[config]
publish_run_status = false
run_status_context = "pr-agent"   # the status name shown on the commit

Behaviour change

Configuration	Result
shipped default	nothing — byte-identical to today
publish_run_status = true	pending when the PR is opened, then success or failure
a command returns False or raises	failure, and the remaining commands still run
provider without statuses	no-op, no error

Testing

$ PYTHONPATH=. pytest tests/unittest
3698 passed, 1 skipped, 1 xfailed, 91 warnings in 53.69s

New file tests/unittest/test_run_status_acknowledgment.py (13 tests), written first (12 failed /
1 passed before, 13 passed after). Covers all three states on GitHub, the configured context,
description truncation, a missing commit SHA, an API failure, GitLab's failed mapping, and the
four wiring outcomes including the default-off control.

Also checked: ruff check clean on every file touched.

Risk / compatibility

Nothing happens unless the setting is turned on. Every provider call is wrapped, so a repository
where the token cannot write statuses logs a warning and continues.

Scope

Wired into the GitHub automatic-command runner in this PR. The primitive lives on the base
provider, so the GitLab and Gitea runners are a two-line follow-up each.

[Copilot]

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[IsmaelMartinez]

Thanks, and the gap is real: the check run added in #2492 only ever publishes completed/neutral, so there is no in-progress signal today.

I cannot take this as written though. propagate_tool_errors is false by default, so a review that fails internally is swallowed at pr_reviewer.py:347 and handle_request still returns True, which publishes success. And because _perform_auto_commands_github sets is_auto_command, the failure comment at line 358 is suppressed as well, so a failed automatic review gets no comment and a green tick.

Before fixing that, a design question. Rather than a second mechanism in the checks area, could this move the existing check run from completed to in_progress and back? Two parallel ways to report on the same commit seems worse than extending the one that already merged.

[qodo-code-review]

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[IsmaelMartinez]

Thanks for the fix at f694088, that closes the swallowed-error half. The open question is still the shape: move the #2492 check run through in_progress and back rather than add a commit status beside it, so there is one mechanism on the commit. If the status API is the better fit for a reason I am missing, say so and I will review the head as it stands.