dev-server_skill

Overview

This skill starts local development servers with intelligent port management and environment detection. It handles port conflicts, cleans up stale processes when safe, picks the appropriate package manager, and opens the browser automatically. The goal is to get your app running with minimal fuss and safe defaults.

How this skill works

The skill first scans common dev ports to detect running processes and determines if they belong to the same project by comparing working directories. It then resolves conflicts by killing same-project processes automatically or prompting/choosing an alternate port for different projects. Next it detects the project environment (docker-compose, monorepo layout, framework) and selects the proper start command and package manager. Finally it launches the server with the correct port/open flags and falls back to opening the browser via a URL when needed.

When to use it

• When you want to "start the dev server", "run dev", or "launch the server" locally.
• When a port conflict prevents your app from starting and you need safe conflict resolution.
• When working in monorepos or projects with multiple package managers and you want automatic detection.
• When you prefer automatic browser opening after the dev server becomes available.
• When you need to spin up a Docker-based web service and get a recommendation for docker compose.

Best practices

• Run the skill from the project root to enable accurate ownership detection.
• Prefer --kill-if-same for non-interactive workflows to safely replace stale same-project processes.
• Use project-specific scripts (dev) in package.json to ensure consistent startup behavior in monorepos.
• Commit lockfiles so package manager detection (bun/pnpm/yarn/npm) is reliable.
• Choose an explicit port with --port when sharing machines to avoid surprises.

Example use cases

• You run "start the dev server" and the skill finds port 3000 in use by an old instance; it kills it and reboots the app.
• In a monorepo, it detects apps/web/package.json and runs the correct dev script for that subproject.
• On a Docker project with docker-compose.yml, it suggests using docker compose up instead of npm run.
• A colleague accidentally started a different project on your port; the skill prompts and selects an alternate port.
• Your framework doesn’t honor --open; the skill starts the server and opens http://localhost:PORT in your browser.