※アイズ・イヤー・ハンド・フォー・アイ・アシスト・モバイル開発。**

Quern は、AI コーディングエージェント、Claude コード、Cursor、Windsurf などのローカル デバッグ サーバーで、実際にアプリが何をしているか確認します。 ログ、ネットワークトラフィック、クラッシュレポート、スクリーンショット、UIの状態:スタックトレースとストールエラーメッセージから推測する代わりに、エージェントはライブで、デバイスで起こっているすべてのものへのアクセスを構造化します。

雲無し。 テレメトリー無し。 「ビルド成功」と「実際に動作する」の間のギャップを埋めるあなたのMac上でデーモンだけ。

iOSシミュレータ、物理的なiOSデバイス(WebDriverAgent経由)、Androidエミュレータ、および物理的なAndroidデバイスをサポートしています。

なぜ

筆記コードではAIエージェントが得意です。 特にモバイルデバイスで働いたかどうかを知ることは悪いことです。 ビルドのエラーがキャッチされます。サイレント API の失敗、間違った画面、または起動時のクラッシュは通常、ログをチャットに貼り付けない限り、使用しません。

Quern はそのループを閉じます.

Quern

Eyes, ears, and hands for AI-assisted mobile development.

Quern is a local debug server that lets AI coding agents — Claude Code, Cursor, Windsurf, and others — actually see what your app is doing. Logs, network traffic, crash reports, screenshots, UI state: instead of guessing from stack traces and stale error messages, your agent gets live, structured access to everything happening on the device.

No cloud. No telemetry. Just a daemon on your Mac that bridges the gap between “build succeeded” and “it actually works.”

Supports iOS simulators, physical iOS devices (via WebDriverAgent), Android emulators, and physical Android devices.

Simulator / Device
    │
Quern (localhost:9110)
    ├── Log capture (device, simulator, crash reports, build output)
    ├── Network proxy (intercept, mock, replay HTTP traffic)
    ├── Device control (boot, screenshot, tap, swipe, type)
    │
    ├── HTTP API ──→ Any tool or script
    └── MCP tools ──→ Claude Code, Cursor, etc.

Why

AI agents are good at writing code. They’re bad at knowing whether it worked – especially on mobile devices. A build error gets caught; a silent API failure, a wrong screen, or a crash on launch usually doesn’t — unless you paste logs back into the chat yourself.

Quern closes that loop. It gives agents direct, token-efficient access to everything they need to diagnose and fix problems autonomously: structured logs, network request/response pairs, parsed crash reports, screenshots, and the ability to interact with the running appon a simulator or real device.

Quern isn’t a cloud testing platform. It’s local infrastructure that makes the AI tools you already use actually effective at debugging and testing mobile apps.

• Local-first — No cloud, no accounts, no third-party API keys. Your code and logs never leave your machine, unless you point quern at another Mac you’ve paired with.
• Works with your existing AI — Not a replacement for Claude, Cursor, or Codex. It makes them better by giving them live access to what your app is actually doing.
• Built for your editor and CLI — Designed for agents already in your workflow, not a separate QA portal.
• Great for QA and SDET workflows — Pair with an agent during manual testing. Let it intercept network calls, mock error responses, or verify analytics payloads while you drive the app — no more juggling Charles Proxy and a terminal.
• Free and open source — Apache 2.0 licensed. Run it free, forever, on your own hardware.

Podcast

https://github.com/user-attachments/assets/885cda62-9355-41d9-a4fd-b989f7b90940

A 20-minute deep dive generated by Google NotebookLM from the Quern repository. Good overview of the architecture and use cases. This is definitely ‘AI slop’, and may be either useful, entertaining, or horrifying for you to listen to. You have been warned; choose wisely.

How to Use Quern