What problem does it solve? TypeScript projects often suffer from loose typing, inconsistent compiler configurations, and fragile type contracts that let runtime errors slip into production. This Skill guides the design and implementation of type-safe TypeScript codebases with strict checking and well-modeled contracts. ## Core Features & Use Cases - Advanced Type Modeling: Designs generics, conditional types, mapped types, and custom utility types for complex domain models. - Strict Configuration: Sets up tsconfig compiler flags, linting safeguards, and incremental compilation for fast, safe builds. - Typed Testing & Declarations: Produces Jest/Vitest tests with type assertions and .d.ts declaration files for external libraries. - Use Case: When refactoring a Node.js/Express API, use this Skill to define shared interfaces, enforce strict null checks, and generate typed error boundaries across the service layer. ## Quick Start Ask the agent to review your TypeScript project and design strict, generic type contracts for your core modules with matching typed tests.