TypeScript Advanced Types
Use this skill when generic inference, conditional/mapped types, template literals, or a reusable type utility is the actual problem. Ordinary typed API, form, and state work uses its domain guidance unless advanced type behavior needs attention.
| Concern being changed | Reference |
|---|---|
| Generics, conditional/mapped/template-literal and utility types | references/core-concepts.md |
| Reusable emitters, builders, clients, deep utilities, or discriminated models | references/advanced-patterns.md |
infer, narrowing, assertion functions, and type-contract tests | references/type-inference.md |
| Compiler configuration, type complexity, and maintainability | references/best-practices.md |
Prefer the simplest type that expresses the contract. Use unknown and real narrowing at untrusted boundaries; preserve discriminants and readonly intent. Let inference handle local values and follow repository conventions for public annotations, interface, and type.
Use the existing tsconfig; reference configurations are examples, not instructions to change it. Add compile-time tests only when type behavior is a product/library contract, using its owning suite. Avoid a new type framework or elaborate generic abstraction for a single ordinary call site. Run the repository's affected typecheck gate.