Spanreed

An inter-agent message bus for local Claude Code sessions. Run one Claude session per repo; let them coordinate.

Status: alpha. Published on PyPI (spanreed-bus) and in daily use for single-host, multi-session coordination. Cross-host messaging (spanreed conjoin) is experimental — see Cross-host. Not yet on the official Claude Code marketplace.

Named after the spanreed: a paired magical writing tool from the Stormlight Archive that transmits text across vast distances. One side writes, the other side reads.

Install

Install the bus tooling from PyPI:

uv tool install spanreed-bus

Then launch claude in any directory and run these two slash commands at the prompt:

/plugin marketplace add Monkopedia/spanreed
/plugin install spanreed@spanreed

The MCP server (spanreed-mcp) and CLI (spanreed) need to be on $PATH for the plugin to find them — uv tool install handles this.

Developing on spanreed

For hacking on spanreed itself, install from a local clone:

git clone git@github.com:Monkopedia/spanreed.git
cd spanreed
uv tool install --editable .

Then in Claude Code, point the marketplace at your clone instead of GitHub:

/plugin marketplace add /absolute/path/to/spanreed
/plugin install spanreed@spanreed

Quickstart

Open two terminals, each in a different repo:

# Terminal A
cd ~/projects/repo-a && claude

# Terminal B
cd ~/projects/repo-b && claude

In terminal A, ask Claude to talk to the other session:

Ask agent at repo-b what version of Node it's using.

Claude in repo-A discovers the peer, sends the question, the peer answers, the answer comes back. The conversation is visible in both transcripts.

How it works

Two layers on Claude Code primitives:

• MCP server (spanreed-mcp, per-session) exposes the bus API as typed tools: register, send, recv, list, wait_for_reply with timeout.
• Plugin (auto-loaded) wires up a SessionStart hook for bus context, a Monitor for inbound wakeups, and points Claude at the MCP server.

State lives under ~/.claude/spanreed/ (registry + per-agent inboxes + per-session cursors). No central daemon — each session's MCP server is local and coordinates through shared files.

Read the full design in docs/architecture.md. Wire-format spec in docs/protocol.md.

Cross-host (experimental)

By default the bus is single-machine. To bridge two machines' buses, run on one host:

spanreed conjoin <other-host>

This opens a persistent SSH pipe to the peer and mirrors each side's agents into the other's list_agents (as agent-xxxx@host); messages addressed to a qualified id route across. It reconnects on its own if the pipe drops, and runs in the foreground until you stop it — supervision (start-on-boot, restart-on-crash) is left to you (wrap it in systemd/launchd/tmux).

Prerequisites: spanreed-bus ≥ 0.0.4 on both hosts, and key-based non-interactive SSH (it reconnects unattended, so it can't answer a password prompt). Full setup, the most common SSH gotcha (non-default key name), and how to update spanreed on a peer host: docs/cross-host.md. Design in docs/architecture.md.

Experimental and point-to-point only — no multi-hop routing or peer discovery yet.

Update

The Python package and the plugin update independently:

uv tool upgrade spanreed-bus

For the plugin, inside Claude Code:

/plugin update spanreed@spanreed

Development

See docs/development.md for environment setup, running tests, and contribution conventions. The CLAUDE.md at the root captures the discipline rules — Claude sessions working on this repo should read it.

License

Apache-2.0.