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UltraciteCursor CLI

Cursor CLI

Cursor's CLI, built to help you ship right from your terminal. Integrate with Ultracite to ship better code, faster.

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Configuration

Ultracite automatically creates and manages the configuration file for Cursor CLI.

This rules file teaches Cursor CLI your project's code standards covering type safety, modern JavaScript patterns, React best practices, accessibility, security, and performance.

.cursor/rules/ultracite.mdc

# Ultracite Code StandardsThis project uses **Ultracite**, a zero-config preset that enforces strict code quality standards through automated formatting and linting.## Quick Reference- **Format code**: `npm ultracite fix`- **Check for issues**: `npm ultracite check`- **Diagnose setup**: `npm ultracite doctor`biome (the underlying engine) provides robust linting and formatting. Most issues are automatically fixable.---## Core PrinciplesWrite code that is **accessible, performant, type-safe, and maintainable**. Focus on clarity and explicit intent over brevity.### Type Safety & Explicitness- Use explicit types for function parameters and return values when they enhance clarity- Prefer `unknown` over `any` when the type is genuinely unknown- Use const assertions (`as const`) for immutable values and literal types- Leverage TypeScript's type narrowing instead of type assertions- Use meaningful variable names instead of magic numbers - extract constants with descriptive names### Modern JavaScript/TypeScript- Use arrow functions for callbacks and short functions- Prefer `for...of` loops over `.forEach()` and indexed `for` loops- Use optional chaining (`?.`) and nullish coalescing (`??`) for safer property access- Prefer template literals over string concatenation- Use destructuring for object and array assignments- Use `const` by default, `let` only when reassignment is needed, never `var`### Async & Promises- Always `await` promises in async functions - don't forget to use the return value- Use `async/await` syntax instead of promise chains for better readability- Handle errors appropriately in async code with try-catch blocks- Don't use async functions as Promise executors### React & JSX- Use function components over class components- Call hooks at the top level only, never conditionally- Specify all dependencies in hook dependency arrays correctly- Use the `key` prop for elements in iterables (prefer unique IDs over array indices)- Nest children between opening and closing tags instead of passing as props- Don't define components inside other components- Use semantic HTML and ARIA attributes for accessibility:  - Provide meaningful alt text for images  - Use proper heading hierarchy  - Add labels for form inputs  - Include keyboard event handlers alongside mouse events  - Use semantic elements (`<button>`, `<nav>`, etc.) instead of divs with roles### Error Handling & Debugging- Remove `console.log`, `debugger`, and `alert` statements from production code- Throw `Error` objects with descriptive messages, not strings or other values- Use `try-catch` blocks meaningfully - don't catch errors just to rethrow them- Prefer early returns over nested conditionals for error cases### Code Organization- Keep functions focused and under reasonable cognitive complexity limits- Extract complex conditions into well-named boolean variables- Use early returns to reduce nesting- Prefer simple conditionals over nested ternary operators- Group related code together and separate concerns### Security- Add `rel="noopener"` when using `target="_blank"` on links- Avoid `dangerouslySetInnerHTML` unless absolutely necessary- Don't use `eval()` or assign directly to `document.cookie`- Validate and sanitize user input### Performance- Avoid spread syntax in accumulators within loops- Use top-level regex literals instead of creating them in loops- Prefer specific imports over namespace imports- Avoid barrel files (index files that re-export everything)- Use proper image components (e.g., Next.js `<Image>`) over `<img>` tags### Framework-Specific Guidance**Next.js:**- Use Next.js `<Image>` component for images- Use `next/head` or App Router metadata API for head elements- Use Server Components for async data fetching instead of async Client Components**React 19+:**- Use ref as a prop instead of `React.forwardRef`**Solid/Svelte/Vue/Qwik:**- Use `class` and `for` attributes (not `className` or `htmlFor`)---## Testing- Write assertions inside `it()` or `test()` blocks- Avoid done callbacks in async tests - use async/await instead- Don't use `.only` or `.skip` in committed code- Keep test suites reasonably flat - avoid excessive `describe` nesting## When biome Can't Helpbiome's linter will catch most issues automatically. Focus your attention on:1. **Business logic correctness** - biome can't validate your algorithms2. **Meaningful naming** - Use descriptive names for functions, variables, and types3. **Architecture decisions** - Component structure, data flow, and API design4. **Edge cases** - Handle boundary conditions and error states5. **User experience** - Accessibility, performance, and usability considerations6. **Documentation** - Add comments for complex logic, but prefer self-documenting code---Most formatting and common issues are automatically fixed by biome. Run `npm ultracite fix` before committing to ensure compliance.

Why use Ultracite with Cursor CLI?

AI coding assistants generate code faster, but without guidance they may not follow your project's conventions.

Consistent output

Generated code follows your linting rules from the start, reducing cleanup work.

Fewer iterations

The AI understands your standards upfront, producing acceptable code faster.

Team alignment

Everyone's AI assistant generates code that matches your team's style guide.

Zero configuration

Get started instantly with sensible defaults that work out of the box.

Type-safe code

Strict linting rules catch potential bugs and enforce type safety automatically.

AI-ready rules

Purpose-built rules that AI models understand and follow consistently.

Trusted by top companies

And used by thousands of open source projects.

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Alan Turing Institite
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