How do I invoke the reviewer mid-PR?

From inside Claude Code: /review or explicitly Task tool with subagent_type: code-reviewer and the diff URL or branch name. From CI: a GitHub Action that runs claude code -p "review this diff: $DIFF" --agent code-reviewer and posts the output as a PR comment. The agent reads the diff, the changed files in full context, and your CLAUDE.md — it does not read the entire repo, which keeps the cost predictable. Typical run: 30–60 seconds for a small PR (1–5 files), 2–3 minutes for a large one (20+ files).