AgentLink gets a desktop application. An Electron window over the local broker shows the link, the peer identity with its key fingerprint and verification state, pending requests, and a metadata-only activity ring, and it creates or joins named rooms without a terminal. Invites are single-use codes with a required validity window, redeemed by the issuing side against the joining peer's public key, and a room binds to the first peer identity that proves membership, so a leaked room code cannot admit anyone else afterwards. Broker frontends now negotiate protocol version, client range, and method list, and replace an incompatible broker through authenticated graceful takeover instead of signalling a pid. Local state files are written atomically and merged under a cross-process lock, and trust state is scoped per room. Verified with clean installs on Windows and Ubuntu Node.js 20/22 plus Docker.