PR Review

Use this skill when the user provides a GitHub PR URL or number and asks to review it. This covers the full review lifecycle: data gathering, code review, CI verification, and posting the result.

Prerequisites

• Read AGENTS.md for the repository's adversarial validation policy and change-style rules.
• The adversarial-validation skill handles the review role playbooks; this skill orchestrates the workflow around it.

Workflow

1. Gather PR context

gh pr view <N> --json title,author,state,body,additions,deletions,changedFiles,commits,baseRefName,headRefName
gh pr diff <N> --name-only

Read the PR body and linked issues to understand the change's purpose. If the PR references an issue, fetch that too:

gh issue view <ISSUE> --json title,body,state

2. Fetch the diff and classify the change

git fetch origin pull/<N>/head:pr-<N>
git diff main...pr-<N> --stat

Classify the change by risk tier (per AGENTS.md):

• Exempt: docs/comments/instruction-only, formatting, typos.
• Mechanical: renames, file moves, test-only or tooling changes.
• Standard (default): any behavior change.
• High risk: locking, erasure coding, quorum/heal, replication, multipart, RPC, lifecycle/tiering, metadata formats, persistence/fsync, IAM/KMS/auth, on-disk/on-wire formats, S3 API-visible behavior.

3. Cluster changed files and delegate review

Group the changed files into logical clusters (by crate or functional area). For each cluster, spawn a subagent with a focused review prompt that includes:

• The cluster's changed files and their diffs.
• The applicable adversarial role probes (from the adversarial-validation skill).
• The repository's AGENTS.md rules relevant to that domain.

For standard-tier changes: correctness adversary + simplicity adversary + test-coverage skeptic, plus every role whose domain the diff touches. For high-risk changes: run all seven roles.

Each subagent must produce findings (concrete failure scenario with file:line) or a null report ("attacked X, Y, Z — no break found").

4. Check CI status

gh pr checks <N>

If any checks fail, investigate:

gh run view --log-failed --job=<JOB_ID>

Determine whether failures are pre-existing (on main), flaky, or caused by the PR.

5. Synthesize findings

Combine all subagent findings into a structured review:

• Summary: one-paragraph overview of the change and overall assessment.
• Findings: each finding with severity (critical/major/minor/nit), file:line, concrete failure scenario, and suggested fix.
• CI status: pass/fail with notes on any failures.
• Verdict: APPROVE, REQUEST_CHANGES, or COMMENT.

6. Post the review

Write the review body to a temp file and post via CLI:

# Request changes
gh pr review <N> --request-changes --body-file /tmp/pr_review.md

# Approve
gh pr review <N> --approve --body-file /tmp/pr_review.md

# Comment only (no verdict)
gh pr review <N> --comment --body-file /tmp/pr_review.md

For inline comments on specific lines, use the GitHub API:

cat > /tmp/pr_review.json <<'EOF'
{
  "body": "review body",
  "event": "REQUEST_CHANGES",
  "comments": [
    {
      "path": "crates/foo/src/bar.rs",
      "line": 42,
      "body": "finding description"
    }
  ]
}
EOF
gh api --method POST /repos/{owner}/{repo}/pulls/<N>/reviews --input /tmp/pr_review.json

Always use --body-file or --input, never inline multiline --body.

7. Handle follow-up

If the review requests changes:

• Monitor for new commits: gh pr view <N> --json commits
• Re-review changed files only: git diff pr-<N>..origin/pull/<N>/head
• Update the review when findings are addressed.

If CI was failing due to pre-existing main breakage:

• Comment on the PR noting the failure is pre-existing.
• Suggest updating the branch: gh pr update-branch <N>

Output format

PR Review: #<N> — <title>

Author: Risk tier: exempt | mechanical | standard | high-risk Changed files: across clusters

Summary