Index: chapterx-frontend/src/store/uiStore.ts
===================================================================
--- chapterx-frontend/src/store/uiStore.ts	(revision b62cefc14094ca5ac7154f7d48797a1e6c444935)
+++ chapterx-frontend/src/store/uiStore.ts	(revision b62cefc14094ca5ac7154f7d48797a1e6c444935)
@@ -0,0 +1,29 @@
+import { create } from 'zustand'
+
+interface Toast {
+  id: number
+  message: string
+  type: 'success' | 'error' | 'warning' | 'info'
+}
+
+interface UIStore {
+  toasts: Toast[]
+  addToast: (message: string, type?: Toast['type']) => void
+  removeToast: (id: number) => void
+}
+
+export const useUIStore = create<UIStore>((set) => ({
+  toasts: [],
+
+  addToast: (message, type = 'success') => {
+    const id = Date.now()
+    set(state => ({ toasts: [...state.toasts, { id, message, type }] }))
+    setTimeout(
+      () => set(state => ({ toasts: state.toasts.filter(t => t.id !== id) })),
+      3500
+    )
+  },
+
+  removeToast: (id) =>
+    set(state => ({ toasts: state.toasts.filter(t => t.id !== id) })),
+}))