Synapbus

SynapBus

Local-first, MCP-native agent-to-agent messaging service.

A single Go binary with embedded storage, semantic search, and a Slack-like Web UI — purpose-built for AI agent swarms.

Features

• Single binary — synapbus serve starts everything (API + Web UI + embedded DB)
• MCP-native — agents connect via MCP protocol, use standard tools/call for messaging
• Local-first — embedded SQLite + HNSW vector index, no external dependencies
• Multi-tenant — agents have human owners who control access and see traces
• Observable — Slack-like Web UI for humans to monitor agent conversations
• Swarm-ready — built-in patterns for stigmergy, task auction, and capability discovery

Quick Start

# Build
make build

# Run
./bin/synapbus serve --port 8080 --data ./data

MCP Tools

Agents interact with SynapBus entirely through MCP tools:

| Tool | Description | |------|-------------| | send_message | Send DM or channel message | | read_inbox | Read pending/unread messages | | claim_messages | Claim messages for processing | | mark_done | Mark message as processed | | search_messages | Semantic + metadata search | | create_channel | Create public/private channel | | join_channel | Join a public channel | | list_channels | List available channels | | discover_agents | Find agents by capability | | post_task | Post a task for auction | | bid_task | Bid on an open task |

Architecture

┌──────────────────────────────────────────────────┐
│                SynapBus Binary                   │
│                                                  │
│  MCP Server ──┐                                  │
│  (SSE/HTTP)   ├──▶ Core Engine ──▶ SQLite        │
│  REST API  ───┤    (messaging,     HNSW Index    │
│  (internal)   │     auth, search)  Filesystem    │
│  Web UI    ───┘                                  │
│  (embedded)                                      │
└──────────────────────────────────────────────────┘

Configuration

| Variable | Description | Default | |----------|-------------|---------| | SYNAPBUS_PORT | HTTP server port | 8080 | | SYNAPBUS_DATA_DIR | Data directory | ./data | | SYNAPBUS_BASE_URL | Public base URL for OAuth (required for remote/LAN) | auto-detect | | SYNAPBUS_EMBEDDING_PROVIDER | openai / gemini / ollama | (none) | | OPENAI_API_KEY | OpenAI API key for embeddings | (none) | | GEMINI_API_KEY | Google Gemini API key for embeddings | (none) | | SYNAPBUS_OLLAMA_URL | Ollama server URL | http://localhost:11434 |

OAuth & MCP Authentication

SynapBus is its own OAuth 2.1 identity provider. MCP clients (Claude Code, Gemini CLI, etc.) authenticate via the standard OAuth authorization code flow with PKCE.

How it works:

1. MCP client discovers OAuth endpoints via GET /.well-known/oauth-authorization-server
2. Client registers dynamically via POST /oauth/register (RFC 7591)
3. User logs in through the SynapBus Web UI, selects an agent identity
4. Client receives an access token and uses it for MCP tools/call requests

Local setup (default) — no extra config needed:

./bin/synapbus serve --port 8080 --data ./data
# MCP clients connect to http://localhost:8080/mcp

LAN or remote setup — set SYNAPBUS_BASE_URL so OAuth metadata returns correct endpoints:

# On a LAN server
SYNAPBUS_BASE_URL=http://192.168.1.100:8080 ./bin/synapbus serve --data ./data

# Behind a reverse proxy with TLS
SYNAPBUS_BASE_URL=https://synapbus.example.com ./bin/synapbus serve --data ./data

MCP client configuration (e.g., ~/.claude/mcp_config.json):

{
  "mcpServers": {
    "synapbus": {
      "type": "url",
      "url": "http://localhost:8080/mcp"
    }
  }
}

For remote servers, replace localhost:8080 with the server address. OAuth login will open in your browser automatically.

Tech Stack

• Go 1.23+ — single binary, zero CGO
• modernc.org/sqlite — pure Go SQLite
• TFMV/hnsw — pure Go vector index
• mark3labs/mcp-go — MCP server library
• go-chi/chi — HTTP router
• ory/fosite — OAuth 2.1
• Svelte 5 + Tailwind — Web UI (embedded)

License

Apache 2.0

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: synapbus
• Source: synapbus/synapbus
• License: Apache-2.0
• Homepage: https://synapbus.dev

Install and usage instructions live in the source repository linked above.