What is a .cursorrules file?
.cursorrules: A configuration file stored in the root of a repository that acts as the "Standard Operating Procedure" for AI assistants. It ensures that every AI-generated line of code follows the team's specific architectural patterns, styling rules, and security constraints.
Why It Matters for Clean Vibe
Without a .cursorrules (or similar tool-specific instructions), every AI interaction is a "Vibe Session." The AI guesses your patterns based on context, leading to Style Drift and Architectural Debt. A rules file turns "Vibes" into "Standards."
Anatomy of a Clean Vibe Rules File
A well-structured rules file (detailed in Chapter 4) includes:
- Architectural Guardrails: "We use Tailwind, not CSS-in-JS. We use Redux for state, not Context."
- Security Requirements: "Always use prepared statements. Never log PII."
- Agent Boundaries: "Forbidden:
/server/config/,.env. Stop at checkpoints for any database schema changes." - Style Preferences: "Use functional components. Prefer async/await over promises."
Example Rule
# Rule: Error Handling
- Never use empty catch blocks.
- All API errors must be logged to our internal logger.
- Surface a user-friendly message via the Toast component.
Statistics
Scaling with Teams
In Chapter 16: Clean Teams, we recommend version-controlling your .cursorrules. This ensures that every developer on the team—no matter which AI model they use—is working within the same engineering framework.
Related Terms
- Agent Boundaries: What rules enforce.
- Team Standards: What rules document.
- Context Flood: What rules prevent by providing high-signal instructions.
Book Reference
- Chapter 4: The Power of Rules — the pros and cons of instruction files.
- Chapter 14: Clean Agents — how to use rules to implement boundaries.
- Appendix C: Ready-to-use templates for
.cursorrules.