code-review

A set of instructions for examining source code for security, correctness, performance, and maintainability problems. A code review is a structured check of code before or after changes are made.

In plain words
What is it for?
Use it to review a codebase, look for bugs and security weaknesses, and run dependency checks for JavaScript, Python, or Rust projects.
Why use it?
It provides a checklist for finding issues such as injection risks, missing error handling, race conditions, slow database access, and unsafe dependencies.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/jafini/learn-claude-code/code-review
Any agent
npx skills add jafini/learn-claude-code --skill code-review
Clone the repo
git clone --depth 1 https://github.com/jafini/learn-claude-code

Made for: Claude Code, Codex.

Per session 35 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,103 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00035 $0.01103
Opus 5 $0.00017 $0.00551
Sonnet 5 $0.00007 $0.00221
Haiku 4.5 $0.00003 $0.00110

Measured yesterday against content hash a64c8c43b496, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

code-review scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

os.system(f"ls {user_input}")
Origin

This is a copy

100% identical to code-review — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/code-review/SKILL.md · 158 lines

How it starts

The opening of the file, as written. The whole thing — 158 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Code Review Skill

You now have expertise in conducting comprehensive code reviews. Follow this structured approach:

Review Checklist

1. Security (Critical)

Check for:

  • Injection vulnerabilities: SQL, command, XSS, template injection
  • Authentication issues: Hardcoded credentials, weak auth
  • Authorization flaws: Missing access controls, IDOR
  • Data exposure: Sensitive data in logs, error messages
  • Cryptography: Weak algorithms, improper key management
  • Dependencies: Known vulnerabilities (check with npm audit, pip-audit)
# Quick security scans
npm audit                    # Node.js
pip-audit                    # Python
cargo audit                  # Rust
grep -r "password\|secret\|api_key" --include="*.py" --include="*.js"

2. Correctness

Check for:

  • Logic errors: Off-by-one, null handling, edge cases
  • Race conditions: Concurrent access without synchronization
  • Resource leaks: Unclosed files, connections, memory
  • Error handling: Swallowed exceptions, missing error paths
  • Type safety: Implicit conversions, any types

3. Performance

Check for:

  • N+1 queries: Database calls in loops
  • Memory issues: Large allocations, retained references
  • Blocking operations: Sync I/O in async code
  • Inefficient algorithms: O(n^2) when O(n) possible
  • Missing caching: Repeated expensive computations

4. Maintainability

Check for:

  • Naming: Clear, consistent, descriptive
  • Complexity: Functions > 50 lines, deep nesting > 3 levels
  • Duplication: Copy-pasted code blocks
  • Dead code: Unused imports, unreachable branches
  • Comments: Outdated, redundant, or missing where needed

5. Testing

Check for:

  • Coverage: Critical paths tested
  • Edge cases: Null, empty, boundary values
  • Mocking: External dependencies isolated
  • Assertions: Meaningful, specific checks

Read the full file on GitHub · 158 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 158 lines · 35 tokens per session scan A a64c8c43b496

Subscribe to this mod's changes

code-review is a skill published in the GitHub repository jafini/learn-claude-code (1 stars, last pushed 2d ago), licensed MIT. It adds 35 tokens to every session and 1,103 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (runs shell commands). It is 100% identical to code-review, differing in 0 lines, and is treated as a copy.