Arc Pr Review Loop

PR Review Loop

Iterate a PR to plan-alignment through review comments. The leading word is converge: every round must either approve or produce actionable comments that shrink the gap to the plan — never a rubber stamp, never vague feedback.

This is the review counterpart to arc-work-issue --ship pr: implementation produces an open PR, then this loop supplies the judgment. Merge authority stays with the caller unless --merge-on-approve is passed.

Orchestrator route guidance

• Route a bounded correctness, regression, security, or acceptance-criteria review to codex-check.
• Route high-taste UI/UX, API, architecture, copy, docs, prompt, or skill critique to opus-review. This is a content-triggered review route, distinct from availability fallback.
• Route a bounded read-only investigation needed before review to codex-explore.
• Route clear mechanical comment fixes to composer-implement (the Cursor/Composer implementation lane) and difficult or debugging-heavy fixes to codex-implement.
• When Codex is unavailable, opus-check and opus-implement are the matching availability fallbacks; opus-explore is available if a read-only investigation phase is needed. There is no separate cursor-implement route.

Review workers return structured findings; they never approve, request changes, post comments, or otherwise mutate GitHub. The parent judges those findings and retains the approval decision. It delegates GitHub review comments and replies to mechanical-post-comment. Fix workers operate only in the PR branch's isolated worktree and never commit, push, comment, merge, deploy, edit secrets, or touch unrelated files. Under orchestration, accepted fixes are committed and pushed via mechanical-commit-push, and an explicitly authorized merge or auto-merge runs via mechanical-merge. Outside orchestration, preserve the standalone commands and arc-git-pr-check behavior below.

Input

• PR number or URL (required). If absent, ask and stop.
• --plan <file|issue> — plan source override.
• --max-rounds <N> — review rounds before escalating (default 3).
• --merge-on-approve — squash-merge on approval; under orchestration this uses mechanical-merge, while standalone use retains arc-git-pr-check --ship merge. Without it, approval is reported and the caller decides whether to merge.

Steps

1. Resolve the PR and its plan.

   • gh pr view <n> --json title,body,headRefName,url,files plus the diff (gh pr diff <n>).
   • Find the plan: --plan if given; else the issue referenced by Closes #<n> and any implementation-plan comment on it (per arc-planning-work); else the PR body's stated intent.
   • Locate the working copy for fixes: the branch's existing worktree (git worktree list) or check the branch out fresh.

   Completion criterion: the loop has a diff, a plan with acceptance criteria (or the explicit note that none exists), and a writable checkout of the PR branch.

2. Review round: diff vs plan.

   • Under an orchestrator, select codex-check or opus-review using the route guidance above; the parent remains responsible for the verdict.
   • Judge only what the plan and acceptance criteria require plus correctness/safety of the changed code; do not expand scope.
   • Classify each finding blocking (violates plan, acceptance criterion, or correctness) or nit (better, not required).
   • Verdict: approve when no blocking findings remain.

   Completion criterion: a verdict plus a findings list where every blocking finding names the file, the problem, and what done looks like.

3. Post the round to the PR.

   • Under orchestration, the parent converts accepted findings into the final approval or change-request decision and delegates the round summary and independently addressable GitHub comments to mechanical-post-comment.
   • Outside orchestration, approve with gh pr review <n> --approve --body "<summary>", then go to step 6; request revisions with gh pr review <n> --request-changes --body "<round summary>" and one gh pr comment (or inline review comments) per blocking finding.

   Completion criterion: every blocking finding exists as a PR comment an agent can act on without reading this conversation.

4. Address the comments.

   • Apply fixes in the PR branch's worktree — directly or by delegating with the comments as the bounded task contract. Use composer-implement for clear mechanical fixes and codex-implement for difficult fixes or escalation.
   • Fix only what the comments name; unrelated improvements are new work items.
   • The fix worker runs the repo's test/lint commands and reports evidence. The parent inspects the diff and chooses a conventional message referencing the round (e.g. fix: address review round 2). Under orchestration, delegate the scoped commit and push to mechanical-commit-push; outside orchestration, retain the standalone commit and push workflow.

   Completion criterion: every blocking comment has a corresponding pushed change or a reply explaining why it is not actionable.

5. Loop.

   • Return to step 2. After --max-rounds rounds without approval, stop: summarize the unresolved blocking findings to the caller and publish them through mechanical-post-comment under orchestration (or the standalone PR comment flow), then recommend escalation (stronger implementation model, or human decision).

   Completion criterion: the loop exits only via approval or the round limit — never by silently accepting unresolved blocking findings.

6. Hand off.

   • With --merge-on-approve: delegate the merge to mechanical-merge under orchestration; standalone use runs arc-git-pr-check with --ship merge. Then confirm the result.
   • Otherwise: report verdict, rounds used, findings resolved, and the PR URL; the caller retains the merge decision.

   Completion criterion: the caller receives verdict, round count, and PR URL, and the merge happened only if explicitly requested.

Boundaries

• Use arc-work-issue --ship pr to produce the PR this loop consumes; this skill never implements the original issue from scratch.
• Under orchestration use mechanical-merge for an authorized merge; standalone use retains arc-git-pr-check. Never run gh pr merge directly.
• Use arc-bug-finder for defects discovered outside the PR's scope — file them, don't fix them here.
• Do not force-push or rewrite the PR branch's history; reviewers' comment anchors must survive.