feat: db pool + migration runner with idempotency

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/db/migrate.test.js

@@ -0,0 +1,28 @@
+import { describe, it, expect, beforeAll } from 'vitest';
+import { resetDb, withClient } from '../helpers/db.js';
+import { migrateUp } from '../../lib/db/migrate.js';
+
+describe('migrate', () => {
+  beforeAll(async () => { await resetDb(); });
+
+  it('creates schema_migrations table on first run', async () => {
+    await migrateUp();
+    await withClient(async (c) => {
+      const { rows } = await c.query(
+        `SELECT to_regclass('public.schema_migrations') AS t;`
+      );
+      expect(rows[0].t).toBe('schema_migrations');
+    });
+  });
+
+  it('is idempotent — second run is a no-op', async () => {
+    await migrateUp();
+    await migrateUp();
+    await withClient(async (c) => {
+      const { rows } = await c.query(
+        `SELECT count(*)::int AS n FROM schema_migrations;`
+      );
+      expect(rows[0].n).toBeGreaterThanOrEqual(0);
+    });
+  });
+});

tests/helpers/db.js

@@ -0,0 +1,16 @@
+import { pool } from '../../lib/db/pool.js';
+
+export async function resetDb() {
+  await pool.query(`
+    DROP SCHEMA IF EXISTS public CASCADE;
+    CREATE SCHEMA public;
+    CREATE EXTENSION IF NOT EXISTS pgcrypto;
+    CREATE EXTENSION IF NOT EXISTS vector;
+  `);
+}
+
+export async function withClient(fn) {
+  const client = await pool.connect();
+  try { await fn(client); }
+  finally { client.release(); }
+}

tests/helpers/setup.js

@@ -0,0 +1 @@
+import 'dotenv/config';