foxsync — approve agent steps from your phone av Pooria

foxsync pairs a browser add-on with a phone, or with a second browser. The two ends talk over a WebRTC data channel. This add-on shows the foxsync library working, so developers can see it before they let a browser agent ask for approvals on a phone.

Who it is for: developers who want a person to approve an AI agent's step from a phone, without a cloud service in the middle.

What it does

• Pair a phone: the add-on shows a QR code, a short code and an offer. The phone page answers, and you paste the answer back (or a relay that you run passes it).
• Send a sample approval request. The phone shows it with Approve and Deny, and the add-on shows the answer.
• List paired devices, reconnect and unpair.

Use it in the sidebar: a popup closes when it loses focus, and the link closes with it.

Requirements: the phone needs the foxsync phone page, which you host yourself (pnpm build:phone in the project). With no relay and no STUN server, both ends must be on the same network.

What leaves the browser, and when

• Only after you pair: messages go straight to the device that you paired, over WebRTC. Each message is encrypted and authenticated with keys from the pairing, on top of the WebRTC encryption.
• Only if you type a relay URL: the pairing answer and reconnect offers go through that relay as sealed text. The relay sees box ids, IP addresses, times and sizes. It cannot read the texts. foxsync does not run a relay.
• foxsync has no server and sends nothing to its authors.

Permissions: none beyond the popup and the sidebar. Pair records and keys stay in this browser.

The source code is MIT licensed.