Review Pr

Perform a code review of an ArcticDB pull request.

Context variables

When invoked from a GitHub Actions workflow the following variables are injected before this prompt: PR_NUMBER, REPO, EVENT_ACTION, BEFORE_SHA, AFTER_SHA. When invoked locally as a slash command the PR number is $ARGUMENTS (e.g. /review-pr 2933). If $ARGUMENTS is empty, detect from the current branch.

Step 1 — Resolve PR number and repository

# If PR_NUMBER is not set and $ARGUMENTS is empty, detect from current branch:
gh pr view --json number -q .number

# If REPO is not set, detect:
gh repo view --json nameWithOwner -q .nameWithOwner

Step 2 — Fetch diffs

If EVENT_ACTION is synchronize and both BEFORE_SHA and AFTER_SHA are set:

Attempt to produce the delta diff (new commits only):

git fetch --depth=1 origin <BEFORE_SHA>
git diff <BEFORE_SHA>..<AFTER_SHA>

• If the delta diff is non-empty, use it as the delta diff. Do not fetch the full diff — it is not needed (the existing sticky summary covers the earlier commits).
• If the fetch fails (e.g. force-push removed BEFORE_SHA) or the result is empty, fall back: fetch the full diff and use it for both inline comments and summary.

gh pr diff <PR_NUMBER>   # fallback only

Otherwise (event is opened, reopened, ready_for_review, or this is a local run):

Fetch the full diff and use it as both the full diff and the delta diff:

gh pr diff <PR_NUMBER>

Step 3 — Fetch existing inline review comments and sticky summary

Fetch all existing inline review comments (for deduplication):

gh api --paginate "repos/<REPO>/pulls/<PR_NUMBER>/comments" \
  --jq '[.[] | {path: .path, line: (.line // .original_line), author: .user.login, body: (.body | .[0:300])}]'

Also fetch the existing sticky summary comment, if any (for incremental updates):

gh api "repos/<REPO>/issues/<PR_NUMBER>/comments" \
  --jq '[.[] | select(.body | startswith("## ArcticDB Code Review Summary"))] | last | {id: .id, body: .body}'

Step 4 — Deduplication rule

Before posting any inline comment, check the existing comments for an entry with the same path and line:

• Human comment exists: skip the inline comment. Note the finding in the summary checklist if relevant.
• Previous Claude comment exists: skip the inline comment. Ensure the finding is still reflected in the summary checklist.
• No existing comment: post the inline comment normally.

Step 5 — Review outputs

Only make remarks about things that must be changed. Do not make minor or nit comments. Focus on important issues. Do not mention things that are fine at all - you never need to say "no issue found in X". You do not need a section for "items reviewed and OK" or similar. Make your output concise.

Inline comments

Post only on lines present in the delta diff, subject to the deduplication rule above.

Summary

Do not include items that do not need attention in the summary.

If EVENT_ACTION is synchronize and a previous sticky summary exists:

• Evaluate only the delta diff against the guidelines.
• Read the previous summary.
• Update individual items that are affected by the delta:
  • A new commit that introduces an issue: change the item to ❌ and add a note.
  • A new commit that fixes a previously flagged issue: change the item to ✅ and note the fix.
  • Items unaffected by the delta: leave unchanged.
• Post the amended summary as the updated sticky comment.

Otherwise (event is opened, reopened, ready_for_review, or no previous summary):

Evaluate the full diff and post a fresh summary.

Step 6 — Load review guidelines

Read the file docs/claude/PR_REVIEW_GUIDELINES.md from the repository root using the Read tool. Apply all sections relevant to the files changed in the PR. The file also contains the summary format to use when posting the sticky comment.