chore: import upstream snapshot with attribution

__tests__/sqlite-backend.test.ts

@@ -0,0 +1,44 @@
+/**
+ * SQLite backend reporting.
+ *
+ * node:sqlite (Node's built-in real SQLite) is the sole backend. Pin that
+ * DatabaseConnection / CodeGraph report it and come up in WAL.
+ */
+
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import * as fs from 'fs';
+import * as path from 'path';
+import * as os from 'os';
+import { DatabaseConnection } from '../src/db';
+import { CodeGraph } from '../src';
+
+describe('DatabaseConnection — backend reporting', () => {
+  let dir: string;
+
+  beforeEach(() => {
+    dir = fs.mkdtempSync(path.join(os.tmpdir(), 'codegraph-backend-'));
+  });
+
+  afterEach(() => {
+    if (fs.existsSync(dir)) {
+      fs.rmSync(dir, { recursive: true, force: true });
+    }
+  });
+
+  it('reports the node-sqlite backend in WAL for an initialized DB', () => {
+    const conn = DatabaseConnection.initialize(path.join(dir, 'test.db'));
+    expect(conn.getBackend()).toBe('node-sqlite');
+    expect(conn.getJournalMode()).toBe('wal');
+    conn.close();
+  });
+
+  it('CodeGraph.getBackend() delegates to the underlying DatabaseConnection', async () => {
+    fs.writeFileSync(path.join(dir, 'x.ts'), `export function x(): void {}\n`);
+    const cg = await CodeGraph.init(dir, { index: true });
+    try {
+      expect(cg.getBackend()).toBe('node-sqlite');
+    } finally {
+      cg.destroy();
+    }
+  });
+});