typescript-engineeringlisted

# TypeScript Engineering Write TypeScript that makes types, module boundaries, failure, and async ownership honest to the next maintainer. Prefer repository evidence and the type system over ambient strictness fashions, defensive `any`, or speculative abstraction. The compiler is a contract, not a lint to be silenced. ## Establish the Contract 1. Read scoped instructions, `tsconfig.json` (and any extended base or project references), `package.json`, lockfile, CI, lint and format policy, relevant ADRs, public entry points, nearby types, and representative call sites. Discover the compiler strictness, module and target settings, runtime (Node LTS, edge, worker, browser), module system (ESM/CJS), package manager, and repository-native commands. 2. State the changed behavior and boundaries: inputs, outputs, nullability, ownership of promises and resources, expected errors, cancellation, concurrency, and which values cross an untyped runtime boundary. Do not invent a stricter compiler flag set, a validation library, a bundler, or a runtime target the repository has not adopted. 3. Read [Types and boundaries](references/types-and-boundaries.md) for strictness contracts, honest narrowing and assertions, discriminated unions versus enums, generics restraint, the `any`/`unknown` policy, and where runtime validation replaces compile-time trust. 4. Read [Module and API design](references/module-and-api-design.md) for exports, barrel-file tradeof