The props object returned by useCompositeRoot is consumed only by CompositeRoot, which passes it into useRenderElement → mergeProps — re-merged unconditionally every render, so the object's identity is never compared. The memo's ~15-entry dep array included highlightedIndex, so it invalidated on every arrow-key navigation anyway, and was pure maintenance burden with stale-closure risk.

• useCompositeRoot: the props object is now created per render. onKeyDown is wrapped in useStableCallback because its identity (as relayKeyboardEvent) does matter: it flows into the CompositeRootContext value memo and into useTriggerDataForwarding's effect deps via Object.values(stateUpdates). It's now fully stable, where previously it changed on every navigation.
• useCompositeRoot: the return-value memo is also removed — CompositeRoot is the only consumer and destructures it immediately.
• useCompositeItem: compositeProps memo removed — both consumers (CompositeItem, TabsTab) only pass it into useRenderElement props arrays.
• useCompositeListItem: return-value memo removed — all consumers only access .ref (already useCallback'd, identity unchanged) and .index; the wrapper object identity is never used.

Tests: Composite (jsdom + Chromium), Tabs and Menubar (jsdom) all pass; pnpm typescript and eslint clean.