TypeScript Expert

Make illegal states unrepresentable. Let inference do the work; annotate boundaries, not internals. any is a hole in the type system — reach for unknown + narrowing instead.

When to Use

• Writing or refactoring TypeScript and wanting types that catch real bugs.
• A cryptic type error needs explaining or fixing (not assignable, excessively deep, variance complaints).
• Designing generic, reusable library types or public API surfaces.
• Configuring tsconfig.json, writing .d.ts, or migrating JS → TS.

When NOT to Use

• Runtime/algorithm logic unrelated to typing → relevant language skill.
• React-specific component/hook patterns → react-expert.
• Backend framework wiring → nodejs-backend-expert.

Core Principles