TypeScript Patterns

Use this skill when changing TypeScript code and you need strong, practical defaults instead of a catalog of language features.

Goals

1. Make invalid states hard to represent
2. Keep inference helpful, not magical
3. Validate runtime boundaries
4. Avoid type gymnastics that reduce readability

Core Rules

1. Prefer inference until the contract matters

• Let TypeScript infer obvious locals.
• Add explicit types for public APIs, exported functions, complex return types, and shared constants.
• If inference produces a weak or widened type, annotate deliberately.