feat(sdk): initial package bootstrap for SDK (#18861)

packages/sdk/examples/simple.ts

@@ -0,0 +1,38 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { GeminiCliAgent, tool, z } from '../src/index.js';
+
+async function main() {
+  const myTool = tool(
+    {
+      name: 'add',
+      description: 'Add two numbers.',
+      inputSchema: z.object({
+        a: z.number().describe('the first number'),
+        b: z.number().describe('the second number'),
+      }),
+    },
+    async ({ a, b }) => {
+      console.log(`Tool 'add' called with a=${a}, b=${b}`);
+      return { result: a + b };
+    },
+  );
+
+  const agent = new GeminiCliAgent({
+    instructions: 'Make sure to always talk like a pirate.',
+    tools: [myTool],
+  });
+
+  console.log("Sending prompt: 'add 5 + 6'");
+  for await (const chunk of agent.sendStream(
+    'add 5 + 6 and tell me a story involving the result',
+  )) {
+    console.log(JSON.stringify(chunk, null, 2));
+  }
+}
+
+main().catch(console.error);