feat(pr-review): let a PR comment trigger a reconcile round

[Troublor]

Fix A — answering a question without a push

Follow-up to #7. Before this, the pr-review action only ran on pull_request events, so answering an open question in a PR comment did nothing until the next push. This lets a repo opt a comment into driving a review round — while making sure routine chatter doesn't burn a review.

How it works

• prepare accepts --event-name. On an issue_comment event, a comment never adds code to review, so it can only ever produce a reconcile-only incremental round or a skip — never a full review.
• Cheap gate (manifest_has_open_items): it skips unless the manifest still has an open question or open finding — something a comment could answer, justify, or invalidate (per the design discussion, findings count too, not just questions). Most comments skip for the cost of a few API calls; no Opus run.
• History preserved: when it does run, it's incremental and reuses the same sticky-comment manifest, so the reviewer keeps full prior context — the reason not to use @claude (which starts fresh). Runs on the cheaper incremental tier.
• Silent when irrelevant: if the round changes nothing, the publisher posts nothing (no new review/notification).
• Head unchanged → empty delta, reconcile-only; a comment that races a push reviews the new delta too.

Consumer opt-in

Per-repo, in claude.yml (documented in actions/README.md):

on:
  pull_request: { types: [opened, synchronize, ready_for_review, reopened] }
  issue_comment: { types: [created] }
jobs:
  pr-review:
    if: >-
      github.event_name != 'issue_comment' ||
      (github.event.issue.pull_request != null &&
       github.event.comment.user.type != 'Bot')
    concurrency:
      group: claude-pr-review-${{ github.event.pull_request.number || github.event.issue.number }}
      cancel-in-progress: false

Without the issue_comment trigger, behaviour is unchanged.

Tests

Gate helper + action wiring covered; full suite green (80 tests). YAML valid, pipeline compiles.

Follow-up (separate PR)

Wiring the issue_comment trigger into grafana-dashboard's claude.yml (the repo where this was observed) so the flow is live there.

🤖 Generated with Claude Code