Perform a thorough 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

bash
1# If PR_NUMBER is not set and $ARGUMENTS is empty, detect from current branch:
2gh pr view --json number -q .number
3
4# If REPO is not set, detect:
5gh 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):

bash
1git fetch --depth=1 origin <BEFORE_SHA>
2git 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.

bash
1gh 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:

bash
1gh pr diff <PR_NUMBER>

Step 3 — Fetch existing inline review comments and sticky summary

Fetch all existing inline review comments (for deduplication):

bash
1gh api --paginate "repos/<REPO>/pulls/<PR_NUMBER>/comments" \
2  --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):

bash
1gh api "repos/<REPO>/issues/<PR_NUMBER>/comments" \
2  --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

Inline comments

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

Summary checklist

Only ever mention points that need attention in the summary checklist, not notes that things are fine.

If EVENT_ACTION is synchronize and a previous sticky summary exists:

• Evaluate only the delta diff against the guidelines.
• Read the previous summary checklist.
• Update individual checklist 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 checklist.

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 checklist format to use when posting the sticky comment.