fix(ui): toast auto-dismiss id derived inside the state updater (React 18 batching)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/ui/src/toast.tsx

@@ -1,4 +1,4 @@
-import { createContext, useCallback, useContext, useMemo, useRef, useState, type ReactNode } from 'react'
+import { createContext, useCallback, useContext, useMemo, useState, type ReactNode } from 'react'
 import { dismissToast, initialToasts, pushToast, type Toast, type ToastState } from './toast-store'
 
 const AUTO_DISMISS_MS = 4000
@@ -9,13 +9,14 @@ const Ctx = createContext<ToastApi | null>(null)
 /** Mount once at app root; renders the bottom-right stack. */
 export function ToastProvider(props: { children: ReactNode }) {
   const [state, setState] = useState<ToastState>(initialToasts)
-  const stateRef = useRef(state)
-  stateRef.current = state
 
   const push = useCallback((tone: Toast['tone'], message: string) => {
-    const id = stateRef.current.nextId
-    setState((s) => pushToast(s, tone, message))
-    window.setTimeout(() => setState((s) => dismissToast(s, id)), AUTO_DISMISS_MS)
+    setState((s) => {
+      const next = pushToast(s, tone, message)
+      const id = next.toasts[next.toasts.length - 1]!.id
+      window.setTimeout(() => setState((s2) => dismissToast(s2, id)), AUTO_DISMISS_MS)
+      return next
+    })
   }, [])
 
   const api = useMemo<ToastApi>(() => ({