Enforces a tight set of TypeScript patterns that treat the type system as a proof assistant rather than documentation. Every rule here exists to close a gap where TypeScript would otherwise let you lie to yourself: discriminated unions over optional fields, branded primitives to prevent ID mixups, unknown for external data, and exhaustiveness checks that break the build when you add a variant. The narrowing hierarchy and type guard rules are especially useful if you're tired of as casts hiding bugs. Also pushes object parameters for readability and real tests over mocks, which is opinionated but defensible. If you want TypeScript to actually catch your mistakes instead of rubber stamping them, this is a solid foundation.

Install to Claude Code

npx -y skills add cursor/plugins --skill typescript-best-practices --agent claude-code