feat: add SQLite session persistence

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/session/store.test.ts

@@ -0,0 +1,65 @@
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { SessionStore } from './store.js';
+import { unlinkSync, existsSync } from 'fs';
+import { join } from 'path';
+import { tmpdir } from 'os';
+
+describe('SessionStore', () => {
+  const dbPath = join(tmpdir(), 'flynn-test-sessions.db');
+  let store: SessionStore;
+
+  beforeEach(() => {
+    store = new SessionStore(dbPath);
+  });
+
+  afterEach(() => {
+    store.close();
+    if (existsSync(dbPath)) {
+      unlinkSync(dbPath);
+    }
+  });
+
+  it('saves and retrieves messages', () => {
+    const sessionId = 'test-session';
+
+    store.addMessage(sessionId, { role: 'user', content: 'Hello' });
+    store.addMessage(sessionId, { role: 'assistant', content: 'Hi there!' });
+
+    const messages = store.getMessages(sessionId);
+
+    expect(messages).toHaveLength(2);
+    expect(messages[0].role).toBe('user');
+    expect(messages[0].content).toBe('Hello');
+    expect(messages[1].role).toBe('assistant');
+    expect(messages[1].content).toBe('Hi there!');
+  });
+
+  it('clears session messages', () => {
+    const sessionId = 'test-session';
+
+    store.addMessage(sessionId, { role: 'user', content: 'Hello' });
+    store.clearSession(sessionId);
+
+    const messages = store.getMessages(sessionId);
+    expect(messages).toHaveLength(0);
+  });
+
+  it('handles multiple sessions independently', () => {
+    store.addMessage('session-1', { role: 'user', content: 'Session 1' });
+    store.addMessage('session-2', { role: 'user', content: 'Session 2' });
+
+    expect(store.getMessages('session-1')).toHaveLength(1);
+    expect(store.getMessages('session-2')).toHaveLength(1);
+    expect(store.getMessages('session-1')[0].content).toBe('Session 1');
+  });
+
+  it('lists all sessions', () => {
+    store.addMessage('session-a', { role: 'user', content: 'A' });
+    store.addMessage('session-b', { role: 'user', content: 'B' });
+
+    const sessions = store.listSessions();
+
+    expect(sessions).toContain('session-a');
+    expect(sessions).toContain('session-b');
+  });
+});