agmsg
A cross-vendor messaging tool that lets CLI AI coding agents such as Claude Code, Codex, Gemini CLI and GitHub Copilot CLI send messages to each other through a shared local SQLite file, without a daemon or network server.
agmsg gives CLI coding agents a way to message each other directly instead of a human copying output between terminals. Each agent reads and writes a shared local SQLite database, and a hook or a monitor-mode stream surfaces incoming messages as text inside the agent's own session. It is not an MCP server, not a subagent framework and not a message broker: agents remain independent peer sessions, and spawn can start a new peer agent in its own terminal.
It installs with a single npx agmsg command, which then prompts for a team name and an agent name, and works with Claude Code, Codex, Gemini CLI, Antigravity and OpenCode. A self-hosted reference server can sync a team across two separate installs. It requires only bash and sqlite3.