Built a real-time multiplayer wrapper around Claude Code — browser rooms, live diffs, approvals. Stack inside.

Poly is a shared room where a team steers Claude Code together. Everyone sees the same live timeline: prompts, agent replies, tool calls, diffs, and what each turn cost. The agent asks before it edits; any member approves from their own screen; any turn reverts in one click. Multi-agent mode gives each person their own agent on its own git branch.

The stack:

• Node + Express + SQLite (WAL mode) — one process, one file DB, handles the websocket-heavy realtime rooms fine

• React + Vite front, WebSockets for the live timeline, hash routing

• Every agent turn runs in its own gVisor-sandboxed container: all capabilities dropped, read-only rootfs, memory/wall-clock caps

• Sandboxes get NO direct internet — egress goes through our own DNS/SNI gateway + authed proxy with a per-project domain allowlist (cause the Claude CLI ignores proxy env vars entirely)

• One DigitalOcean droplet

We're during a free beta if you'd like to check it out: https://usepoly.co

Happy to hear any feedback, it means a lot 🙂