typescript-stack

TypeScript stack

Preserve valid project and framework conventions. Apply this skill to the language layer; let framework skills own routing, rendering, deployment, and framework-required file shapes, and let project-structure own language-neutral repository policy.

Compiler and runtime

• Verify the current stable TypeScript version and runtime compatibility from primary sources before adding or upgrading the compiler. Pin the selected version in the project lockfile.
• Start from the runtime or framework's maintained tsconfig base when one exists. Otherwise enable strict, noUncheckedIndexedAccess, exactOptionalPropertyTypes, noImplicitOverride, and useUnknownInCatchVariables.
• Align target, lib, module format, module resolution, emitted extensions, and ambient types with the actual runtime and deployment target. Do not make bundler, Node, Bun, or browser assumptions that the project does not satisfy.
• Use noEmit when another tool owns output.

Types and APIs

• Do not use any. Accept unknown at untrusted boundaries, validate or narrow it once, and keep the validated type downstream.
• Prefer inference inside an implementation and explicit types at public, serialized, asynchronous, and dependency boundaries.
• Model variant state with discriminated unions and exhaustively handle it. Avoid boolean combinations that admit invalid states.
• Use full, domain-specific names. Avoid catch-all utils, helpers, or lib modules.
• Avoid non-null assertions and type assertions. When an external invariant requires one, keep it at the boundary and explain the invariant locally.
• Use @ts-expect-error only for an intentional, described type-level test. Never use @ts-ignore to make the project gate pass.

Modules and tests

• Follow the runtime, framework, and project's established module boundaries and public API layout. Keep dependency direction visible and avoid cycles.
• Test observable runtime behavior and type contracts that can regress. Keep compile-time fixtures separate from runtime assertions.

Completion

• Focused tests and the repository gate pass; passing evidence for the same content and environment is reused.
• The typecheck ran through the gate or an emitting tsc build; a separate no-emit run is needed only when neither covers it.
• When TypeScript emits production code, the emitted artifact was validated on its target runtime.