postino

Cross-boundary messaging for Claude Code

Claude Code agents in the same team can already talk via SendMessage.
Postino (mailman in Italian) connects everything outside that bubble:
different tabs, different teams, different sessions, CI pipelines, external scripts, and humans via a web GUI.

Why  ·  Quick Start  ·  Examples  ·  Tools  ·  GUI  ·  How It Works  ·  Config

Quick Start

As a Claude Code plugin (recommended)

claude plugin marketplace add manuelfedele/postino
claude plugin install postino

Or from within Claude Code: /plugin marketplace add manuelfedele/postino then /plugin install postino.

Via npx

npx @manuelfedele/postino install

Restart Claude Code after either method. Your agent is online.

Prerequisite: Valkey or Redis running on localhost:6379

git clone https://github.com/manuelfedele/postino.git
cd postino
npm install && npm run build
claude mcp add postino -s user -- node $(pwd)/dist/index.js

claude mcp add postino -s user -e POSTINO_AGENT_NAME=researcher -- npx @manuelfedele/postino

npx @manuelfedele/postino uninstall

Why Postino

Claude Code teams have built-in SendMessage. It works great inside a single team. Postino exists for everything else:

If all your agents are in one team, you don't need postino. If you work across tabs, sessions, or want external systems to reach your agents, you do.

MCP Tools

Web GUI

The GUI runs as a standalone daemon on port 3333, independent of any Claude Code session. It auto-starts on the first session and persists after all sessions close.

Open http://localhost:3333 in your browser.

Updates in real-time via Server-Sent Events. When an agent sends a message from the CLI, the GUI reflects it instantly.

Standalone mode

The GUI daemon starts automatically via the SessionStart hook. You can also run it manually:

npx @manuelfedele/postino serve    # or: node dist/cli.js serve

This starts the web server and Valkey connection without MCP/stdio, so it stays alive regardless of Claude Code sessions. If the daemon is already running, new sessions detect it and skip the spawn.