feat: add e2e tests with Letta Cloud (#149)

E2E testing infrastructure that tests the full message flow against a real Letta Cloud agent.

Changes:
- Add MockChannelAdapter for simulating inbound/outbound messages
- Add e2e/bot.e2e.test.ts with 4 e2e tests:
  - Simple message/response
  - /status command
  - /help command
  - Conversation context retention
- Add 'mock' to ChannelId type
- Update CI workflow with separate e2e job (uses secrets)
- Add npm run test:e2e script

E2E tests require:
- LETTA_API_KEY (already in repo secrets)
- LETTA_E2E_AGENT_ID (needs to be added)

E2E tests are skipped locally without these env vars.

Written by Cameron ◯ Letta Code

"Trust, but verify." - Ronald Reagan (on e2e testing)

e2e/bot.e2e.test.ts

@@ -0,0 +1,92 @@
+/**
+ * E2E Tests for LettaBot
+ * 
+ * These tests use a real Letta Cloud agent to verify the full message flow.
+ * Requires LETTA_API_KEY and LETTA_E2E_AGENT_ID environment variables.
+ * 
+ * Run with: npm run test:e2e
+ */
+
+import { describe, it, expect, beforeAll, afterAll } from 'vitest';
+import { LettaBot } from '../src/core/bot.js';
+import { MockChannelAdapter } from '../src/test/mock-channel.js';
+import { mkdtempSync, rmSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+
+// Skip if no API key (local dev without secrets)
+const SKIP_E2E = !process.env.LETTA_API_KEY || !process.env.LETTA_E2E_AGENT_ID;
+
+describe.skipIf(SKIP_E2E)('e2e: LettaBot with Letta Cloud', () => {
+  let bot: LettaBot;
+  let mockAdapter: MockChannelAdapter;
+  let tempDir: string;
+
+  beforeAll(async () => {
+    // Create temp directory for test data
+    tempDir = mkdtempSync(join(tmpdir(), 'lettabot-e2e-'));
+    
+    // Set agent ID from secrets
+    process.env.LETTA_AGENT_ID = process.env.LETTA_E2E_AGENT_ID;
+    
+    // Initialize bot with test config
+    bot = new LettaBot({
+      model: 'claude-sonnet-4-20250514', // Good balance of speed/quality
+      workingDir: tempDir,
+      agentName: 'e2e-test',
+    });
+    
+    // Register mock channel
+    mockAdapter = new MockChannelAdapter();
+    bot.registerChannel(mockAdapter);
+    
+    console.log('[E2E] Bot initialized with agent:', process.env.LETTA_E2E_AGENT_ID);
+  }, 30000); // 30s timeout for setup
+
+  afterAll(async () => {
+    // Cleanup temp directory
+    try {
+      rmSync(tempDir, { recursive: true, force: true });
+    } catch {
+      // Ignore cleanup errors
+    }
+  });
+
+  it('responds to a simple message', async () => {
+    const response = await mockAdapter.simulateMessage('Say "E2E TEST OK" and nothing else.');
+    
+    expect(response).toBeTruthy();
+    expect(response.length).toBeGreaterThan(0);
+    // The agent should respond with something containing our test phrase
+    expect(response.toUpperCase()).toContain('E2E TEST OK');
+  }, 60000); // 60s timeout
+
+  it('handles /status command', async () => {
+    const response = await mockAdapter.simulateMessage('/status');
+    
+    expect(response).toBeTruthy();
+    // Status should contain agent info
+    expect(response).toMatch(/agent|status/i);
+  }, 30000);
+
+  it('handles /help command', async () => {
+    const response = await mockAdapter.simulateMessage('/help');
+    
+    expect(response).toBeTruthy();
+    expect(response).toContain('LettaBot');
+    expect(response).toContain('/status');
+  }, 10000);
+
+  it('maintains conversation context', async () => {
+    // First message - set context
+    await mockAdapter.simulateMessage('Remember this number: 42424242');
+    
+    // Clear messages but keep session
+    mockAdapter.clearMessages();
+    
+    // Second message - recall context
+    const response = await mockAdapter.simulateMessage('What number did I just tell you to remember?');
+    
+    expect(response).toContain('42424242');
+  }, 120000); // 2 min timeout for multi-turn
+});