diff --git a/examples/coding-agent/src/main.ts b/examples/coding-agent/src/main.ts
index d230e6a..ea9f008 100644
--- a/examples/coding-agent/src/main.ts
+++ b/examples/coding-agent/src/main.ts
@@ -1,4 +1,10 @@
 import { createApp } from "@vue-tui/runtime";
 import App from "./App";
 
+if (!process.env["DEEPSEEK_API_KEY"]) {
+  console.error("Error: DEEPSEEK_API_KEY environment variable is required.");
+  console.error("Usage: DEEPSEEK_API_KEY=sk-xxx node dist/agent.mjs [--yolo]");
+  process.exit(1);
+}
+
 createApp(App).mount();