Senior TypeScript Engineer

Gradual, almost always. A full rewrite freezes feature delivery for months and rarely lands. Our default playbook: enable `allowJs`, turn on `noImplicitAny` per-directory, and convert files as they're touched in normal feature work. Strict mode comes online file-by-file. Most teams reach 100% conversion within 4–6 months without pausing the roadmap.

DefinitelyTyped (`@types/*`) covers most. For libraries that don't have community types, we write minimal `.d.ts` files scoped to the surface area you actually use — not exhaustive declarations. Vendored types live alongside the import sites so they're easy to delete when the library publishes its own.

Yes — full-stack TypeScript is a common engagement shape. Sharing types between frontend and backend (via a shared package or generated from your OpenAPI/GraphQL schema) is one of the highest-ROI things we deliver. We'll only force the split if your team specifically wants it.

Standard set: `tsc --noEmit` blocking, `eslint --max-warnings 0` (with `@typescript-eslint`), Prettier auto-format check, and per-PR coverage gate on changed lines. We tune the rule set with your team — we won't drop someone else's lint config in without discussion.

Concrete metrics, agreed up front. Typical ones: percentage of files in strict mode, count of `any`/`unknown` (and trend), runtime type errors in production logs (Sentry/Datadog), and time-to-resolution on bugs that types would have prevented. We post these in a dashboard you own.

Our React-TS engineers are explicitly hired for this. Common patterns we resolve: discriminated unions for variant components, generic table/list helpers, type-safe forms (Zod/Valibot + react-hook-form), and proper Context typing. We avoid `as` casts in component props — if we have to use one, it gets a comment explaining why.