React Doctor Agent Skill
Diagnose and fix React codebase health issues. Use when reviewing React code, fixing performance problems, auditing security, or improving code quality.
Install
one command, takes just this skill from the repositorynpx skills add https://github.com/PostHog/posthog --skill react-doctorThe instruction itself
5 sections, as written by the authorReact Doctor
Scans your React codebase for security, performance, correctness, and architecture issues. Outputs a 0-100 score with actionable diagnostics.
Usage
npx -y react-doctor@latest . --verbose
Workflow
- Run the command above at the project root
- Read every diagnostic with file paths and line numbers
- Fix issues starting with errors (highest severity)
- Re-run to verify the score improved
Rules (47+)
- Security: hardcoded secrets in client bundle, eval()
- State & Effects: derived state in useEffect, missing cleanup, useState from props, cascading setState
- Architecture: components inside components, giant components, inline render functions
- Performance: layout property animations, transition-all, large blur values
- Correctness: array index as key, conditional rendering bugs
- Next.js: missing metadata, client-side fetching for server data, async client components
- Bundle Size: barrel imports, full lodash, moment.js, missing code splitting
- Server: missing auth in server actions, blocking without after()
- Accessibility: missing prefers-reduced-motion
- Dead Code: unused files, exports, types
Score
- 75+: Great
- 50-74: Needs work
- 0-49: Critical
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How to use it
Take posthog/react-doctor from the repository into ~/.claude/skills for personal
use, or into .claude/skills inside a project.
The agent identifies a skill by the name field in its header. Two skills with the
same name cannot sit side by side — one of them will be ignored.
The instructions reference npx.
Without those the skill loads but fails at the first command.