PR Review

Review a pull request.

PR to review: $ARGUMENTS

Workflow

Follow these steps in order.

0. Load environment skills

Load /tend-ci-runner:running-in-ci first — it contains CI security rules, polling conventions, and comment formatting guidance. It will also prompt you to load any repo-specific skills (e.g., running-tend).

1. Pre-flight checks

Before reading the diff, run cheap checks to avoid redundant work. Shell state doesn't persist between tool calls — re-derive REPO in each bash invocation or combine commands.

REPO=$(gh repo view --json nameWithOwner --jq '.nameWithOwner')
BOT_LOGIN=$(gh api user --jq '.login')
HEAD_SHA=$(gh pr view <number> --json commits --jq '.commits[-1].oid')
PR_AUTHOR=$(gh pr view <number> --json author --jq '.author.login')

# Find the bot's most recent review (any state counts — COMMENTED reviews carry
# inline comments even when the body is empty).
# IMPORTANT: `gh pr view --json reviews` returns `.commit.oid` (NOT `.commit_id`).
# The REST API (`gh api .../reviews`) uses `.commit_id` — don't confuse the two.
LAST_REVIEW_SHA=$(gh pr view <number> --json reviews \
  --jq "[.reviews[] | select(.author.login == \"$BOT_LOGIN\")] | last | .commit.oid // empty")

If LAST_REVIEW_SHA == HEAD_SHA, this commit has already been reviewed — exit silently. The only exception: an unanswered conversation question directed at the bot (check below).

If the bot reviewed a previous commit (LAST_REVIEW_SHA exists but differs from HEAD_SHA), check the incremental changes:

REPO=$(gh repo view --json nameWithOwner --jq '.nameWithOwner')
gh api "repos/$REPO/compare/$LAST_REVIEW_SHA...$HEAD_SHA" \
  --jq '{total: ([.files[] | .additions + .deletions] | add), files: [.files[] | "\(.filename)\t+\(.additions)/-\(.deletions)"]}'

If the incremental changes are trivial, skip the full review — go directly to step 7 to resolve any bot threads addressed by the new changes. After resolving threads: if the most recent bot review was a COMMENT that flagged issues, and those issues are now addressed, submit an APPROVE with an empty body so the PR isn't left in limbo. Otherwise do not submit a new review — the existing one stands. Do NOT proceed to steps 2–6. Rough heuristic: changes under ~20 added+deleted lines that don't introduce new functions, types, or control flow are typically trivial.

Commit and PR authorship do not affect review behavior. Apply the same trivial-vs-substantive heuristic regardless of who pushed the new commits. When tend-notifications or tend-ci-fix pushes a fix to a human-authored PR, reviewing (and re-approving) the updated state is expected — the reviewer role is independent of commit authorship.

Then read all previous bot feedback and conversation:

REPO=$(gh repo view --json nameWithOwner --jq '.nameWithOwner')
BOT_LOGIN=$(gh api user --jq '.login')
# Previous review bodies
gh api "repos/$REPO/pulls/<number>/reviews" \
  --jq ".[] | select(.user.login == \"$BOT_LOGIN\" and (.body | length > 0)) | {state, body}"
# Inline review comments
gh api "repos/$REPO/pulls/<number>/comments" --paginate \
  --jq ".[] | select(.user.login == \"$BOT_LOGIN\") | {path, line, body}"
# Conversation (catch questions directed at the bot)
gh api "repos/$REPO/issues/<number>/comments" --paginate \
  --jq '.[] | {author: .user.login, body: .body}'

Do not repeat any point from previous reviews — cross-reference previous bot comments before posting inline comments. When concurrent runs race (a new push while the first run is still responding), both see the same unanswered question — check whether a bot reply exists after the question's timestamp before answering. Address unanswered questions in the review body (not via gh pr comment).

2. Check for overlapping PRs

Before reading the diff, scan other open PRs for file overlap. If another PR touches the same files with a similar fix, flag it in the review so one can be closed as a duplicate.

3. Read and understand the change

1. Read the PR diff with gh pr diff <number>.
2. Before going deeper, look at the PR as a reader would — not just the code, but the shape: what files are being added/changed, and does anything look off?
3. Read the changed files in full (not just the diff) to understand context.

4. Review

Scale depth to the change. A docs-only PR or a mechanical rename needs a skim for correctness, not the full checklist. A new algorithm or state-management change needs trace analysis. Don't over-analyze trivial changes.

Check the project's CLAUDE.md for language-specific review criteria and conventions. Load any project-specific review skill if available.

Code quality:

• Is the code clear and well-structured?
• Are there simpler ways to express the same logic?
• Does it avoid unnecessary complexity, feature flags, or compatibility layers?

Correctness:

• Are there edge cases that aren't handled?
• Could the changes break existing functionality?
• Are error messages helpful and consistent with the project style?
• Trace failure paths, don't just note error handling exists. For code that modifies state through multiple fallible steps, walk through what happens when each error fires. What has already been mutated? Is the system left in a recoverable state?

Testing:

• Are the changes adequately tested?

Same pattern elsewhere:

When a PR fixes a bug or changes a pattern, search for the same pattern in other files. If found in the diff, add inline suggestions; if found outside the diff, offer to push a fix commit.

Duplication check (for new functions/types):

For every new public or module-level function added in the diff, search the codebase for existing functions that do the same thing. LLM-generated code frequently reinvents internal APIs — this is the highest-value check for externally contributed PRs.

Two search strategies, both required:

1. Similar names and signatures. Search for functions with similar names, return types, or parameter types.
2. Overlapping subgoals. Identify the intermediate steps the new code performs and search for existing code that does the same sub-tasks.

Flag duplicates — reuse is almost always better than a parallel implementation.

5. Submit

If there are no issues, approve with an empty body — silence means correct.

gh pr review <number> --approve -b ""

If there are actionable findings, submit as a review with inline suggestions for concrete fixes. Every comment must give the author something to act on:

Don't explain what the code does — the author wrote it. Don't nitpick formatting — that's what linters are for. Explain why something should change, not just what.

Form your own opinion independently. Do not factor in other reviewers' comments or approvals when deciding whether to approve — the value of this review is as an uncorrelated signal.

When confidence is low, go beyond checking the implementation — question the approach: "Does this bypass or duplicate an existing API?" "What does this change not handle?" If the design involves a judgment call, flag it for human review as a COMMENT.

Self-authored PRs (PR_AUTHOR == BOT_LOGIN): Still perform the full review (steps 2-3) — self-review catches real issues (lint failures, edge cases) and is intentionally valuable. Do NOT attempt gh pr review --approve — GitHub rejects self-approvals. Submit as COMMENT when there are concerns, or stay silent and skip to step 6. Always post CI failure analysis as a COMMENT, even on self-authored PRs.

Not confident enough to approve (unfamiliar module, subtle logic): Add a +1 reaction instead — no review needed unless there are specific observations.

gh api "repos/$REPO/issues/<number>/reactions" -f content="+1"

Posting mechanics

Before posting, verify HEAD hasn't moved and no review was already posted for this commit:

REPO=$(gh repo view --json nameWithOwner --jq '.nameWithOwner')
BOT_LOGIN=$(gh api user --jq '.login')
CURRENT_HEAD=$(gh pr view <number> --json commits --jq '.commits[-1].oid')
[ "$CURRENT_HEAD" != "$HEAD_SHA" ] && echo "HEAD moved — skipping" && exit 0

# NOTE: REST API uses .commit_id (not .commit.oid from gh pr view --json)
ALREADY_POSTED=$(gh api "repos/$REPO/pulls/<number>/reviews" \
  --jq "[.[] | select(.user.login == \"$BOT_LOGIN\" and .commit_id == \"$HEAD_SHA\")] | last | .submitted_at // empty")
[ -n "$ALREADY_POSTED" ] && echo "Already reviewed — skipping" && exit 0

Post exactly one review per run. Always give a verdict: approve or comment (never "request changes"). Use gh pr review for reviews, not gh pr comment. Note: --comment requires a non-empty body — if there's nothing to say, use the approve-with-empty-body pattern.

Inline suggestions are mandatory for concrete fixes. Whenever there's a concrete fix (typos, doc updates, naming, missing imports, minor refactors), post it as an inline suggestion on the exact line — never as a code block in the review body. Inline suggestions let the author apply with one click; code blocks force them to find the line and copy-paste manually.

For fixes targeting lines outside the diff, offer to push a fix commit instead.

Post inline suggestions via the review API:

cat > /tmp/review-body.md << 'EOF'
Summary of suggestions
EOF

cat > /tmp/review-payload.json << 'ENDJSON'
{
  "event": "COMMENT",
  "comments": [
    {
      "path": "example/file.txt",
      "line": 3,
      "body": "```suggestion\nnew text here\n```"
    }
  ]
}
ENDJSON

BODY=$(cat /tmp/review-body.md)
jq --arg body "$BODY" '.body = $body' /tmp/review-payload.json > /tmp/review-final.json

gh api "repos/$REPO/pulls/<number>/reviews" \
  --method POST \
  --input /tmp/review-final.json

Do not use -f 'comments[0][path]=...' flag syntax — gh api converts array indices to object keys, which GitHub rejects.

• If a review has both suggestions and prose observations, put the suggestions as inline comments and the prose in the review body.

• Multi-line suggestions: set start_line and line to define the range. GitHub replaces every line in that range with the suggestion content — any line in the range that isn't reproduced in the replacement is deleted.

  Before posting any multi-line suggestion, verify it:

  1. Read the exact lines start_line through line from the diff hunk.
  2. Diff mentally: every line in that range must either appear (possibly modified) in the replacement text, or be a line you intend to delete. If any line would be silently dropped, shrink the range or include the line in the replacement.
  3. Cap the range at ~10 lines. Larger suggestions are error-prone and hard to review. For changes spanning more than 10 lines, split into multiple suggestions or push a fix commit instead.
  4. Never span markdown fences. If the range includes a ``` line, GitHub's suggestion parser may consume it as a delimiter, corrupting the result. Either shrink the range to avoid the fence or push a commit.

Recovering from inline comment 422 errors

GitHub returns 422 Unprocessable Entity with "Line could not be resolved" when inline comment line numbers don't map to valid positions in the diff. Two failure modes produce the same error message but differ in whether a review record is persisted:

• (a) Large / complex diff: the body is persisted first, then the inline comments are rejected — leaving an orphan body-only review on the PR. A blind retry creates a duplicate.
• (b) Line outside the diff entirely: the entire POST is rejected up front — no review is persisted. Retrying without inline comments is correct; editing a non-existent review will fail.

Check which case you are in before deciding how to recover — query for an orphan review on the current HEAD first, then branch on the result.

ORPHAN_ID=$(gh api "repos/$REPO/pulls/<number>/reviews" \
  --jq "[.[] | select(.user.login == \"$BOT_LOGIN\" and .commit_id == \"$HEAD_SHA\")] | last | .id // empty")

Then, in either case, move the failed inline comments into the review body as fenced code blocks with file paths, and:

• If ORPHAN_ID is non-empty (case a): edit the existing review instead of creating a duplicate.

  bashCopy

  gh api "repos/$REPO/pulls/<number>/reviews/$ORPHAN_ID" \
    -X PUT -F body=@/tmp/updated-review-body.md
  

  If the edit itself fails, do not post another review — the body-only review is sufficient.

• If ORPHAN_ID is empty (case b): retry the POST with comments omitted (body-only), since no duplicate is possible.

Prevention: before writing any inline comment, verify the target line falls inside one of the PR's diff hunks. For fixes outside the diff, use the "push a fix commit" path instead of an inline suggestion (see above).

6. Monitor CI

After approving or staying silent, poll CI in a single background loop — do not launch individual sleep commands. Use the Bash tool with run_in_background: true and the loop below. Exclude your own run (/runs/$GITHUB_RUN_ID/) — your own job check will always show as pending while you're running. Filter on the run URL, not the check name: gh pr checks shows the job name (review), which does not match $GITHUB_WORKFLOW (tend-review). NEVER use --watch flags — they hang forever.

# Run with Bash tool's run_in_background: true.
# Use `||` rather than if-based negation. The Bash tool escapes the
# exclamation mark to a literal backslash-exclamation, which prevents bash
# from recognizing the pipeline-negation reserved word and leaves the loop
# stuck until the 10-minute timeout.
for i in $(seq 1 10); do
  sleep 60
  gh pr checks <number> --required 2>&1 \
       | grep -v "/runs/$GITHUB_RUN_ID/" | grep -q 'pending\|queued\|in_progress' || {
    gh pr checks <number> --required
    exit 0
  }
done
echo "CI still running after 10 minutes"
exit 1

• All required checks passed -> done.
• A check failed and it's related to the PR -> post a follow-up COMMENT review with analysis and inline suggestions, then dismiss the bot's approval:
  bashCopy

  # Use PUT, not POST — the dismiss endpoint requires it
  gh api "repos/$REPO/pulls/<number>/reviews/$REVIEW_ID/dismissals" \
    -X PUT -f message="CI failed — <reason>"
  

  Skip if already dismissed. Do not push fixes on human-authored PRs — post the analysis and offer to fix, then wait for the author to accept.
• A check was cancelled (conclusion cancelled) -> do nothing. Cancellations are almost always caused by concurrency groups — a new workflow run (often triggered by your own approval event) replaces the in-progress one. The replacement run will cover the cancelled checks. Do not re-run cancelled jobs — that creates another run that gets cancelled again, wasting time in a loop.
• A check failed (conclusion failure, not cancelled) and it's a transient flake (unrelated to the PR changes) ->
  1. Re-run the failed jobs:
     bashCopy

     gh run rerun <run-id> --failed
     

  2. Report the flake. Search for an open issue about the specific flaky test. If found, append to an existing bot comment rather than posting a new one.

7. Resolve handled suggestions

After submitting the review, check if any unresolved bot threads have been addressed by the new changes. Resolve threads where the suggestion was applied.

Only resolve if the substance was addressed. Read both the suggestion and the new code — if the author took a different approach, verify its technical accuracy before resolving. "Different wording" is not "addressed" when the new wording is less accurate than the suggestion. When in doubt, leave the thread open for a human reviewer.

Self-authored PRs are especially risky. When the bot is both author and reviewer, there is a bias toward accepting the code's own claims. Treat self-authored thread resolution with extra skepticism — read the code and verify the claim independently rather than trusting the doc comment or commit message.

cat > /tmp/review-threads.graphql << 'GRAPHQL'
query($owner: String!, $repo: String!, $number: Int!) {
  repository(owner: $owner, name: $repo) {
    pullRequest(number: $number) {
      reviewThreads(first: 100) {
        nodes {
          id
          isResolved
          comments(first: 1) {
            nodes {
              author { login }
              path
              line
              body
            }
          }
        }
      }
    }
  }
}
GRAPHQL

REPO=$(gh repo view --json nameWithOwner --jq '.nameWithOwner')
BOT_LOGIN=$(gh api user --jq '.login')
OWNER=$(echo "$REPO" | cut -d/ -f1)
NAME=$(echo "$REPO" | cut -d/ -f2)

gh api graphql -F query=@/tmp/review-threads.graphql \
  -f owner="$OWNER" -f repo="$NAME" -F number=<number> \
  | jq --arg bot "$BOT_LOGIN" '
    .data.repository.pullRequest.reviewThreads.nodes[]
    | select(.isResolved == false)
    | select(.comments.nodes[0].author.login == $bot)
    | {id, path: .comments.nodes[0].path, line: .comments.nodes[0].line, body: .comments.nodes[0].body}'

# Resolve a thread that has been addressed
cat > /tmp/resolve-thread.graphql << 'GRAPHQL'
mutation($threadId: ID!) {
  resolveReviewThread(input: {threadId: $threadId}) {
    thread { id }
  }
}
GRAPHQL

gh api graphql -F query=@/tmp/resolve-thread.graphql -f threadId="THREAD_ID"

Outdated comments (null line) are best-effort — skip if the original context can't be located.

8. Push mechanical fixes

Bot PRs (Dependabot, renovate, etc.): If the review found concrete, fixable issues and there's no human author to act on feedback, commit and push the fix directly to the PR branch.

Human PRs: Post inline suggestions first. Additionally, offer to push a commit when the fixes are mechanical and correctness is obvious. Only push after the author accepts.

gh pr checkout <number>
git add <files>
git commit -m "fix: <description>

Co-Authored-By: Claude <[email protected]>"
git push