diff --git a/webui/src/web-components/demo/mocks/handlers.ts b/webui/src/web-components/demo/mocks/handlers.ts
new file mode 100644
index 0000000..c112efd
--- /dev/null
+++ b/webui/src/web-components/demo/mocks/handlers.ts
@@ -0,0 +1,63 @@
+import { http, HttpResponse, delay } from "msw";
+import { initialState, initialMessages } from "./fixtures/dummy";
+
+// Mock state updates for long-polling simulation
+let currentState = { ...initialState };
+const messages = [...initialMessages];
+const ADD_NEW_MESSAGES =
+  new URL(window.location.href).searchParams.get("addNewMessages") === "1";
+
+export const handlers = [
+  // Unified state endpoint that handles both regular and polling requests
+  http.get("*/state", async ({ request }) => {
+    const url = new URL(request.url);
+    const isPoll = url.searchParams.get("poll") === "true";
+
+    if (!isPoll) {
+      // Regular state request
+      return HttpResponse.json(currentState);
+    }
+
+    // This is a long-polling request
+    await delay(ADD_NEW_MESSAGES ? 2000 : 60000); // Simulate waiting for changes
+
+    if (ADD_NEW_MESSAGES) {
+      // Simulate adding new messages
+      messages.push({
+        type: "agent",
+        end_of_turn: false,
+        content: "Here's a message",
+        timestamp: "2025-04-24T10:32:29.072661+01:00",
+        conversation_id: "37s-g6xg",
+        usage: {
+          input_tokens: 5,
+          cache_creation_input_tokens: 250,
+          cache_read_input_tokens: 4017,
+          output_tokens: 92,
+          cost_usd: 0.0035376,
+        },
+        start_time: "2025-04-24T10:32:26.99749+01:00",
+        end_time: "2025-04-24T10:32:29.072654+01:00",
+        elapsed: 2075193375,
+        turnDuration: 28393844125,
+        idx: messages.length,
+      });
+
+      // Update the state with new messages
+      currentState = {
+        ...currentState,
+        message_count: messages.length,
+      };
+    }
+
+    return HttpResponse.json(currentState);
+  }),
+
+  // Messages endpoint
+  http.get("*/messages", ({ request }) => {
+    const url = new URL(request.url);
+    const startIndex = parseInt(url.searchParams.get("start") || "0");
+
+    return HttpResponse.json(messages.slice(startIndex));
+  }),
+];