Copilot Instructions

Core Requirements

Follow project eslint configuration
Ensure WCAG 2.2 Level AA compliance
Apply Shift-Left security practices

Code Style

JavaScript/TypeScript

For node.js, use features available to v20
For browsers, use features available to 90%+ browsers/users
No trailing semicolons
Single quotes for strings
Indent code blocks with 4 spaces
Use const by default, let when needed
Prefer arrow functions
Use optional chaining
Add JSDoc if missing
Add TypeScript types/interfaces

Documentation

Include JSDoc for functions and classes
Add @param and @returns tags
Document thrown errors
Include usage examples for complex functions

HTML/CSS

Use semantic HTML elements
Only use features available to 90%+ browsers/users
Include ARIA attributes where needed
Mobile-first responsive design
Use CSS custom properties
Follow BEM naming convention
Include print styles
Always use hsl colors
Indent code blocks with 4 spaces

Testing

Write unit tests using Vitest
Include accessibility tests
Maintain >80% code coverage
Test error scenarios

Performance

Lazy load components when possible
Optimize images and assets
Keep bundle size minimal
Use proper caching strategies

Security

Sanitize user inputs
Validate data on server-side
Follow OWASP guidelines
Use Content Security Policy