QRA · qjins

Background

I wanted to manage scattered computers from the web and control their screens with nothing but a browser. Existing remote desktop tools are built around 1:1 device connections. There is no operator’s view: groups, roles (RBAC), session history, audit logs. I needed a platform that operates machines, not a tool that attaches to one.

Design

Separate the control plane from the media plane. A NestJS server handles only auth, permissions, the session state machine and signalling; screen and input travel browser-to-agent over WebRTC, so video never passes through the server. Lighter server, lower latency. The console is Next.js; the agent is Rust (a Windows service with a separate user-session helper). The wire protocol and session transition table live in a shared package as Zod schemas and data, so the contract is code. Development runs without Docker on embedded PostgreSQL, and a simulator registering 30+ mock devices exercises the server logic.

Security defaults to the safe side. Remote-control approval treats no-response, errors and a missing helper all as denial, and switches that cannot be enforced were never built; a UI that promises protection it cannot deliver is the most dangerous kind. Agent auto-update verifies Ed25519 signatures against a key baked in at build time, so even the server is not trusted.

Trial and error

Reconnection passed all 43 e2e tests and then did not work at all against a real machine. The tests verified the server’s state transitions and token rules; what was broken was the transport layer between them. Hands-on verification became a habit after that. Only by attaching real devices did I find 3 server bugs, 3 silently failing defects, and a regression where enabling audio killed the video.

There was a misdiagnosis too. An intermittently hanging e2e suite got blamed on keep-alive sockets; the next run passed and I thought it was fixed. It was just intermittent. Only after reading the failure output to the end did the real cause surface: a dynamic-import deadlock, solved by splitting test processes. An intermittent failure is never refuted by one green run.

File transfer worked perfectly, uploads and downloads alike, while writing zero audit log entries. “Does it work” and “does it leave a record” are different questions, and the second one never surfaces unless you go look. As a bonus detour, Docker Desktop would not even start on this machine, so the verification environment moved into WSL2.

Outcome

Live at qra.qjins.com. Real Windows screens viewed and controlled from the browser, with adaptive quality, audio, clipboard and file transfer all verified against real hardware. The console covers the full admin path: login, dashboard, device groups, sessions, audit event log, agent installation. It is the first service card on this site.