diff --git a/src/tests/wave16_toast_reducer.test.ts b/src/tests/wave16_toast_reducer.test.ts
new file mode 100644
index 0000000..55cc579
--- /dev/null
+++ b/src/tests/wave16_toast_reducer.test.ts
@@ -0,0 +1,57 @@
+describe('Wave 16 Zenith: Real-time Toast Notification State Reducer', () => {
+  interface Toast {
+    id: string;
+    type: 'success' | 'error' | 'info';
+    message: string;
+    timestamp: number;
+  }
+
+  interface ToastState {
+    toasts: Toast[];
+    maxToasts: number;
+  }
+
+  const toastReducer = (state: ToastState, action: { type: 'ADD_TOAST' | 'DISMISS_TOAST'; payload?: any }): ToastState => {
+    switch (action.type) {
+      case 'ADD_TOAST': {
+        const next = [action.payload, ...state.toasts].slice(0, state.maxToasts);
+        return { ...state, toasts: next };
+      }
+      case 'DISMISS_TOAST': {
+        return {
+          ...state,
+          toasts: state.toasts.filter(t => t.id !== action.payload.id)
+        };
+      }
+      default:
+        return state;
+    }
+  };
+
+  it('should add new payment toast and respect max toast limit', () => {
+    const initialState: ToastState = { toasts: [], maxToasts: 3 };
+    let state = toastReducer(initialState, {
+      type: 'ADD_TOAST',
+      payload: { id: 't1', type: 'success', message: 'Payment settled', timestamp: 1000 }
+    });
+    state = toastReducer(state, {
+      type: 'ADD_TOAST',
+      payload: { id: 't2', type: 'info', message: 'Processing intent', timestamp: 2000 }
+    });
+    expect(state.toasts.length).toBe(2);
+    expect(state.toasts[0].id).toBe('t2');
+  });
+
+  it('should dismiss toast by unique identifier', () => {
+    const initialState: ToastState = {
+      toasts: [
+        { id: 't1', type: 'success', message: 'Tx 1', timestamp: 1000 },
+        { id: 't2', type: 'error', message: 'Tx 2', timestamp: 2000 }
+      ],
+      maxToasts: 5
+    };
+    const nextState = toastReducer(initialState, { type: 'DISMISS_TOAST', payload: { id: 't1' } });
+    expect(nextState.toasts.length).toBe(1);
+    expect(nextState.toasts[0].id).toBe('t2');
+  });
+});