Code Review

Added March 13, 2026 Source: Garry Tan / Y Combinator

Catch common PR issues before landing: SQL safety, LLM trust boundaries, race conditions, and more. Analyzes your diff against main using a defined checklist, flagging both critical and informational issues with options to fix immediately.

Part of gstack — a set of 8 skills designed to work together. The npx command below installs the full stack. The browse and setup-browser-cookies skills require additional setup after install.

Installation

This skill is self-contained. Copy the SKILL.md below directly into your project to get started.

.claude/skills/review/SKILL.md    # Claude Code
.cursor/skills/review/SKILL.md    # Cursor

Or install as a personal skill (available across all your projects):

~/.claude/skills/review/SKILL.md

You can also install using the skills CLI:

npx skills add garrytan/gstack

Requires Node.js 18+.

SKILL.md

---
name: review
version: 1.0.0
description: |
  Pre-landing PR review. Analyzes diff against main for SQL safety, LLM trust
  boundary violations, conditional side effects, and other structural issues.
allowed-tools:
  - Bash
  - Read
  - Edit
  - Write
  - Grep
  - Glob
  - AskUserQuestion
---

# Pre-Landing PR Review

You are running the `/review` workflow. Analyze the current branch's diff against main for structural issues that tests don't catch.

---

## Step 1: Check branch

1. Run `git branch --show-current` to get the current branch.
2. If on `main`, output: **"Nothing to review — you're on main or have no changes against main."** and stop.
3. Run `git fetch origin main --quiet && git diff origin/main --stat` to check if there's a diff. If no diff, output the same message and stop.

---

## Step 2: Read the checklist

Read `.claude/skills/review/checklist.md`.

**If the file cannot be read, STOP and report the error.** Do not proceed without the checklist.

---

## Step 3: Get the diff

Fetch the latest main to avoid false positives from a stale local main:

```bash
git fetch origin main --quiet
```

Run `git diff origin/main` to get the full diff. This includes both committed and uncommitted changes against the latest main.

---

## Step 4: Two-pass review

Apply the checklist against the diff in two passes:

1. **Pass 1 (CRITICAL):** SQL & Data Safety, LLM Output Trust Boundary
2. **Pass 2 (INFORMATIONAL):** Conditional Side Effects, Magic Numbers & String Coupling, Dead Code & Consistency, LLM Prompt Issues, Test Gaps, View/Frontend

Follow the output format specified in the checklist. Respect the suppressions — do NOT flag items listed in the "DO NOT flag" section.

---

## Step 5: Output findings

**Always output ALL findings** — both critical and informational. The user must see every issue.

- If CRITICAL issues found: output all findings, then for EACH critical issue use a separate AskUserQuestion with the problem, your recommended fix, and options (A: Fix it now, B: Acknowledge, C: False positive — skip).
  After all critical questions are answered, output a summary of what the user chose for each issue. If the user chose A (fix) on any issue, apply the recommended fixes. If only B/C were chosen, no action needed.
- If only non-critical issues found: output findings. No further action needed.
- If no issues found: output `Pre-Landing Review: No issues found.`

---

## Important Rules

- **Read the FULL diff before commenting.** Do not flag issues already addressed in the diff.
- **Read-only by default.** Only modify files if the user explicitly chooses "Fix it now" on a critical issue. Never commit, push, or create PRs.
- **Be terse.** One line problem, one line fix. No preamble.
- **Only flag real problems.** Skip anything that's fine.

Originally by Garry Tan / Y Combinator, adapted here as an Agent Skills compatible SKILL.md.

This skill follows the Agent Skills open standard, supported by Claude Code, Cursor, Codex, Gemini CLI, and 20+ more editors.

Works with

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