Implements advanced TypeScript type systems, creates custom type guards, utility types, and branded types, and configures tRPC for end-to-end type safety. Use when building TypeScript applications requiring advanced generics, conditional or mapped types, discriminated unions, monorepo setup, or full

TypeScript Pro Core Workflow 1. Analyze type architecture Review tsconfig, type coverage, build performance 2. Design type first APIs Create branded types, generics, utility types 3. Implement with type safety Write type guards, discriminated unions, conditional types; run tsc noEmit to catch type errors before proceeding 4. Optimize build Configure project references, incremental compilation, tree shaking; re run tsc noEmit to confirm zero errors after changes 5. Test types Confirm type coverage with a tool like type coverage ; validate that all public APIs have explicit return types; iterate on steps 3–4 until all checks pass Reference Guide Load detailed guidance based on context: Topic Reference Load When Advanced Types references/advanced types.md Generics, conditional types, mapped types, template literals Type Guards references/type guards.md Type narrowing, discriminated unions, assertion functions Utility Types references/utility types.md Partial, Pick, Omit, Record, custom utilities Configuration references/configuration.md tsconfig options, strict mode, project references Patterns references/patterns.md Builder pattern, factory pattern, type safe APIs Code Examples Branded Types Discriminated Unions & Type Guards Custom Utility Types Recommended tsconfig.json Constraints MUST DO Enable strict mode with all compiler flags Use type first API design Implement branded types for domain modeling Use satisfies operator for type validation Create discriminated unions for state machines Use Annotated pattern with type predicates Generate declaration files for libraries Optimize for type inference MUST NOT DO Use explicit any without justification Skip type coverage for public APIs Mix type only and value imports Disable strict null checks Use as assertions without necessity Ignore compiler performance warnings Skip declaration file generation Use enums (prefer const objects with as const ) Output Templates When implementing TypeScript features, provide: 1. Type definitions (interfaces, types, generics) 2. Implementation with type guards 3. tsconfig configuration if needed 4. Brief explanation of type design decisions Knowledge Reference TypeScript 5.0+, generics, conditional types, mapped types, template literal types, discriminated unions, type guards, branded types, tRPC, project references, incremental compilation, declaration files, const assertions, satisfies operator [Documentation](https://jeffallan.github.io/claude skills/skills/language/typescript pro/)

typescript-pro