Mycelium

Inter-session communication MCP server for Claude Code.

Multiple Claude Code sessions on the same machine can discover each other, exchange messages, broadcast via topics, and delegate tasks — like a fungal mycelium network connecting organisms underground.

Features

• Peer Discovery — Find other active Claude Code sessions (machine-wide or same git repo)
• Direct Messaging — Send signals between specific sessions
• Topic Broadcast — Publish/subscribe messaging via named topics
• Task Delegation — Structured request/response workflow between sessions
• Auto Summary — Sessions auto-identify from git branch and recent commits
• Channel Push (experimental) — Real-time message delivery without polling

Architecture

┌─────────────────┐     ┌─────────────────┐
│ Claude Code (A)  │     │ Claude Code (B)  │
│                  │     │                  │
│  ┌────────────┐  │     │  ┌────────────┐  │
│  │ MCP Server │  │     │  │ MCP Server │  │
│  │ (stdio)    │  │     │  │ (stdio)    │  │
│  └─────┬──────┘  │     │  └─────┬──────┘  │
└────────┼─────────┘     └────────┼─────────┘
         │ HTTP                   │ HTTP
         ▼                       ▼
   ┌─────────────────────────────────┐
   │         Broker Daemon           │
   │      localhost:7890             │
   │   (in-memory, auto-started)    │
   └─────────────────────────────────┘

Single Go binary. The broker starts automatically when the first session connects.

Installation

go install github.com/closer/mycelium/cmd/mycelium@latest

Or build from source:

git clone https://github.com/closer/mycelium.git
cd mycelium
go build -o mycelium ./cmd/mycelium

Setup

Register with Claude Code:

claude mcp add --scope user --transport stdio mycelium -- /path/to/mycelium serve

For channel push (experimental, real-time message delivery):

claude --dangerously-load-development-channels server:mycelium

MCP Tools

All tool names follow a biological metaphor inspired by mycelium networks.

Tool	Description
discover	Explore the network to find other active sessions
signal	Send a direct message to a specific peer
sporulate	Broadcast a message to all peers or topic subscribers
sense	Check for incoming messages
identify	Set a summary of your current work
attach	Subscribe to a topic
detach	Unsubscribe from a topic
nurture	Delegate a task to another peer
fruit	Report the result of a delegated task
survey	List all delegated and received tasks

Usage Examples

Session Discovery

You: discover で他のセッションを探して
Claude: [calls discover] → 2 peers found:
  - backend (feat/api) — latest: "feat: add /users endpoint"
  - frontend (main) — latest: "fix: button style"

Cross-Session Messaging

You: backend セッションに「API スキーマ更新したよ」と伝えて
Claude: [calls signal] → Message sent

With channel push enabled, the message arrives instantly in the other session without any action needed.

Task Delegation

You: frontend セッションに CORS ミドルウェアの追加を依頼して
Claude: [calls nurture] → Task delegated (id: abc-123)

# Later, in the frontend session:
Claude: [calls fruit] → Task completed

# Back in this session (auto-delivered via channel push):
<channel source="mycelium">
[From: frontend] Task "Add CORS middleware" completed: Done with tests
</channel>

Topic Broadcast

You: deploy トピックに「v2.0 をステージングにデプロイ中」とブロードキャストして
Claude: [calls sporulate] → Spores released

# All sessions subscribed to "deploy" receive the message

CLI Commands

Command	Description
mycelium broker	Start the broker daemon (usually auto-started)
mycelium serve	Start the MCP server (called by Claude Code)
mycelium status	Show broker status and active peer list
mycelium send <id> <msg>	Send a message from the command line (debug)

Configuration

Environment Variable	Default	Description
MYCELIUM_PORT	7890	Broker port
MYCELIUM_HOST	localhost	Broker host

Project Structure

mycelium/
├── cmd/mycelium/       CLI entry point (cobra)
├── internal/
│   ├── types/          Shared types (Peer, Message, Task)
│   ├── broker/         HTTP broker daemon + in-memory store
│   ├── client/         Broker HTTP client
│   └── mcp/            MCP server (stdio) + tool definitions
├── integration_test.go End-to-end test
└── CLAUDE.md           AI assistant context

License

MIT