feat(cli): implement send command for one-shot agent messages

src/cli/send.test.ts

@@ -0,0 +1,25 @@
+import { describe, it, expect, vi } from 'vitest';
+import { createSendAgent } from './send.js';
+import type { ChatRequest, ChatResponse } from '../models/types.js';
+
+describe('send command', () => {
+  it('createSendAgent creates an agent that can process a message', async () => {
+    // Mock model client that returns a canned response
+    const mockModelClient = {
+      chat: vi.fn().mockImplementation(async (_request: ChatRequest): Promise<ChatResponse> => ({
+        content: 'Hello from Flynn!',
+        stopReason: 'end_turn',
+        usage: { inputTokens: 10, outputTokens: 5 },
+      })),
+    };
+
+    const agent = createSendAgent({
+      modelClient: mockModelClient,
+      systemPrompt: 'You are Flynn.',
+    });
+
+    const response = await agent.process('Hi there');
+    expect(response).toBe('Hello from Flynn!');
+    expect(mockModelClient.chat).toHaveBeenCalledOnce();
+  });
+});