This PR adds a comprehensive .github/copilot-instructions.md file that provides detailed development guidance for GitHub Copilot coding agents working in the homebridge-camera-ffmpeg repository.

What's Included

The instructions cover all essential development workflows that have been thoroughly validated:

Setup and Dependencies

• Complete setup process from fresh clone to working development environment
• FFmpeg installation and integration requirements
• Critical importance of using npm ci (not npm install) to maintain version consistency
• Node.js v20+ or v22+ requirements

Build and Test Workflows

• All npm scripts with precise timing measurements (validated through testing)
• Build process: npm run build (~5 seconds)
• Test suite: npm run test (~1.3 seconds)
• Linting: npm run lint (~2.4 seconds)
• Coverage reporting and development watching modes

Plugin Architecture

• TypeScript compilation and ES2022 module structure
• Custom Homebridge UI components in src/homebridge-ui/
• Plugin registration and scoped package naming (@homebridge-plugins/homebridge-camera-ffmpeg)
• Configuration schema and unbridged accessory requirements

Functional Testing

• Complete camera configuration examples using FFmpeg synthetic test sources
• Plugin loading validation with Homebridge
• Manual testing scenarios for verifying changes work correctly

Common Development Pitfalls

• ESLint version conflicts when using npm install vs npm ci
• FFmpeg dependency requirements and installation
• TypeScript compilation workflow and custom UI file copying

Validation Process

Every command and workflow in these instructions has been thoroughly tested:

• Fresh repository clone scenarios
• Complete dependency installation and build processes
• Plugin linking and Homebridge integration testing
• FFmpeg synthetic video source validation
• End-to-end development workflow verification

The instructions are designed to save agents significant time by providing known-working commands and preventing common setup issues like ESLint configuration conflicts that occur when dependency versions are updated incorrectly.

Fixes #1507.

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.