Dev Doctor

Dev Doctor

When to activate

Activate when a user reports that "the app won't start", "the database isn't connecting", or when experiencing generic ECONNREFUSED or startup errors. Invoked via /dev-doctor.

When NOT to use

Do not use for debugging specific syntax errors, failing unit tests, or logic bugs inside application code. This is strictly for environment and infrastructure health checks.

Instructions

1. Pause whatever coding task you are currently on. You are now acting as a SysAdmin diagnosing a local developer environment.
2. Systematically check the following common failure points using shell commands:
   • Environment Variables: Check if .env.example or .env.template exists. If it does, compare its keys against the actual .env file. Report any missing keys.
   • Ports in Use: Look at the project's configuration (e.g., docker-compose.yml, package.json scripts) to find expected ports (e.g., 3000, 5432, 6379, 8080). Use lsof -i :<port> or netstat -tuln | grep <port> to check if those ports are already occupied by zombie processes.
   • Docker Daemon: If the project uses Docker, run docker info to verify the Docker daemon is actually running.
   • Dependency Drift:
     • Node: Check if node_modules exists. Run npm ls or yarn check to see if dependencies need installing.
     • Python: Check if the virtual environment is activated and pip freeze matches requirements.txt.
3. Provide a clear, color-coded (using emojis) diagnostic report:
   • 🟢 Healthy
   • 🔴 Failing
   • 🟡 Warning
4. For any 🔴 Failing items, propose a direct fix (e.g., "Run kill -9 1234 to free port 3000" or "Copy .env.example to .env and fill in DATABASE_URL"). Ask for permission before running the fix.

Example

User: /dev-doctor Claude: Running environment diagnostics...

• 🔴 .env File: Missing! Found .env.example but no .env.
• 🔴 Ports: Port 5432 is already in use by PID 8891 (looks like an older local postgres instance, not the docker container).
• 🟢 Docker: Daemon is running.
• 🟢 Dependencies: node_modules is present and up to date.

Suggested Fixes:

1. I can copy .env.example to .env.
2. I can kill PID 8891 to free up port 5432. Shall I proceed with these fixes?