TanStack Store framework-agnostic reactive state management with Store, Derived, Effect, and batch. Use when writing, reviewing, or refactoring code that involves: (1) Creating or managing state with TanStack Store or @tanstack/store, (2) Using useStore hook from @tanstack/react-store, @tanstack/vue-store, @tanstack/solid-store, @tanstack/angular-store, @tanstack/svelte-store, or @tanstack/preact-store, (3) Creating derived/computed state with Derived class, (4) Managing side effects with Effect class, (5) Batching state updates with batch(), (6) Choosing a lightweight state management solution for framework-agnostic libraries.