Relay lets Claude Code sessions message each other without alt-tabbing

A developer built a plugin called Relay that lets parallel Claude Code sessions message each other, eliminating the alt-tab/copy-paste dance when switching between backend and frontend contexts.

How it works

Relay piggybacks on Claude Code's channels capability (MCP server push messages between turns). Each session runs a tiny MCP server; a single hub daemon routes messages over a Unix socket. When you ask Claude in one session to query another, the message lands as a channel notification in the target session, which replies naturally on its next turn.

Key details

• Usage: In a frontend session, just say: "ask the backend session what the user object looks like". The backend session sees the question between turns, answers it, and the reply appears as a notification in the frontend session.
• Broadcasts: Works for asking all sessions what they're working on — replies trickle in one at a time.
• Architecture: First session started spawns the hub daemon. It self-exits ~5 minutes after the last session disconnects. Same machine only, no auth, nothing leaves your box.
• Open source: MIT license, day-one release so rough edges are expected. Repo with install steps at https://github.com/innestic/claude-relay.

Who it's for

Developers running multiple Claude Code sessions simultaneously (e.g., one per microservice or repo) who are tired of context-switching.