client-state-zustand

Zustand is for state that (a) is read by components that don't share a parent, or (b) changes frequently enough that Context would cause wide re-renders — e.g. a dialog's open/closed flag read by both the trigger and the dialog itself (src/lib/store.ts, useUiStore).
Plain React.useState/Context is still correct for state genuinely local to one component subtree, or for low-frequency global state (theme, locale) where Context's broader re-render is not a real cost — do not reach for Zustand by default.
One store per concern, not one giant app-wide store — useUiStore here only owns UI-only state (dialog visibility), never server data (that is TanStack Query's job, never duplicated into Zustand).
Select the narrowest slice a component needs (useUiStore((s) => s.isSubscribeDialogOpen)), never the whole store object — a whole-store selector re-renders on every field change.
Actions live on the store itself (openSubscribeDialog, closeSubscribeDialog), not as ad-hoc setState calls scattered across components — keeps the state's invariants in one place.

SKILL.md.claude/skills/client-state-zustand/SKILL.md