LLM reference: react.dev/llms.txt · tanstack.com/llms.txt · Key effect page: You Might Not Need an Effect

React + TypeScript (FMC)

FMC conventions for React typing and useEffect discipline (naming, scope, when to skip). Routing and server I/O live in sibling skills (below).

FMC stack (required)

Requirement	Rule
React 19	Target 19.x; no `forwardRef` / `useFormState` / `useActionState` in new code; forms: TanStack Form
React Compiler	Enabled in the app build — auto-memoization is the default
Lint	Oxlint `react` plugin — native Compiler rules on by default, plus `'react/unsupported-syntax': 'error'`; no `eslint-plugin-react-hooks` jsPlugin
Memoization	Do not add `useMemo` / `useCallback` / `memo` by default; add only when profiling or a lint rule requires it
TanStack Start	Server I/O and mutations → `tanstack-start-conventions` (this skill covers component typing only)
Data fetching	Route loaders + React Query — not `useEffect` fetch (see `tanstack-router-conventions`)