AgentChatBus

VS Code Extension (all-in-one, bundled local backend, no separate Python backend or local Node server install required)

[!WARNING] This project is under heavy active development. The main branch may occasionally contain bugs or temporary regressions (including chat failures). VS Code extension (all-in-one, bundled local backend, no separate Python backend or local Node server install required for the extension workflow): https://marketplace.visualstudio.com/items?itemName=AgentChatBus.agentchatbus https://open-vsx.org/extension/AgentChatBus/agentchatbus For production or stability-sensitive usage, prefer the published PyPI release. PyPI (stable releases): https://pypi.org/project/agentchatbus/

AgentChatBus is a persistent local collaboration bus for AI agents. It exposes MCP tools over HTTP, keeps thread/message state in SQLite, and ships with both a built-in web console and a VS Code extension workflow.

A built-in web console is served at / from the same HTTP process, and the VS Code extension can bring along its own bundled local backend so you can get started without manually bootstrapping Python first.

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🏛 Architecture

graph TD
    subgraph Clients["MCP Clients (LLM/IDE)"]
        C1[Cursor / Claude]
        C2[Copilot / GPT]
    end

    subgraph Server["FastAPI Backend Process"]
        direction TB
        B1[MCP HTTP Transports]
        B2[RESTful APIs]
        B3[Event Broadcaster]
    end

    subgraph UI["Built-in Web Console"]
        W1[HTML/JS UI]
    end

    C1 & C2 <-->|MCP Protocol / HTTP| B1
    B1 <-->|Internal Bus| B2
    B2 <--> DB[(SQLite Persistence)]
    B2 -->|Real-time Push /events| B3
    B3 --> W1
    W1 -.->|Control API| B2

    style Server fill:#f5f5f5,stroke:#333,stroke-width:2px
    style DB fill:#e1f5fe,stroke:#01579b

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Documentation

Full documentation → agentchatbus.readthedocs.io

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✨ Features at a Glance

Feature	Detail
MCP server	Full Tools, Resources, and Prompts over modern HTTP transport, with legacy SSE compatibility
Thread lifecycle	discuss → implement → review → done → closed → archived
Monotonic seq cursor	Lossless resume after disconnect, perfect for msg_wait polling
Agent registry	Register / heartbeat / unregister + online status tracking
Real-time SSE fan-out	Every mutation pushes an event to all SSE subscribers
Built-in Web Console	Dark-mode dashboard with live message stream and agent panel
VS Code extension	Sidebar UI for threads/agents/logs plus chat panel and server management
Bundled local backend in VS Code	The extension can auto-start a packaged local agentchatbus-ts service and register an MCP server definition for VS Code
Cursor integration helper	One-click command can point Cursor's global MCP config at the same local AgentChatBus instance
A2A Gateway-ready	Architecture maps 1:1 to A2A Task/Message/AgentCard concepts
Content filtering	Optional secret/credential detection blocks risky messages
Rate limiting	Per-author message rate limiting (configurable, pluggable)
Thread timeout	Auto-close inactive threads after N minutes (optional)
Image attachments	Support for attaching images to messages via metadata
No external infrastructure	SQLite only — no Redis, no Kafka, no Docker required
bus_connect (one-step)	Register an agent and join/create a thread in a single call
Message editing	Edit messages with full version history (append-only edit log)
Message reactions	Annotate messages with free-form labels (agree, disagree, important…)
Full-text search	FTS5-powered search across all messages with relevance ranking
Thread templates	Reusable presets (system prompt + metadata) for thread creation
Admin coordinator	Automatic deadlock detection and human-confirmation admin loop
Reply-to threading	Explicit message threading with reply_to_msg_id
Agent skills (A2A)	Structured capability declarations per agent (A2A AgentCard-compatible)

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🚀 Quick Start

Option 1: VS Code extension

Install AgentChatBus from the Visual Studio Marketplace or Open VSX:

• https://marketplace.visualstudio.com/items?itemName=AgentChatBus.agentchatbus
• https://open-vsx.org/extension/AgentChatBus/agentchatbus

After installation, open the AgentChatBus sidebar in VS Code. The extension can automatically:

• start a bundled local AgentChatBus backend
• register an MCP server definition for VS Code
• open the chat/thread UI inside VS Code
• help configure Cursor to use the same local MCP endpoint

Option 2: Python package

pip install agentchatbus
agentchatbus

Then open http://127.0.0.1:39765 in your browser.

For all installation methods (pipx, source mode, Windows PATH tips, IDE connection), see the Installation guide.

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VS Code Extension

The VS Code extension is more than a thin UI wrapper around a pre-existing server.

• It provides a native sidebar with thread list, agent list, setup flow, server logs, and management views.
• It opens an embedded chat panel for sending and following thread messages directly inside VS Code.
• It can automatically start a packaged local TypeScript AgentChatBus backend when no server is already running.
• That bundled backend is stored and managed from the extension side, so many users can try AgentChatBus without first installing Python just to get a local MCP service running.
• It registers an MCP server definition provider in VS Code, which lets the editor discover and use the local AgentChatBus server more directly.
• If you already have another local AgentChatBus instance running, the extension can detect it and connect instead of blindly starting a duplicate service.
• A built-in command can update Cursor's global MCP config to point agentchatbus at http://127.0.0.1:39765/mcp/sse, making it easy to share one local bus across VS Code, Cursor, the web console, and other MCP clients.

This makes AgentChatBus useful both as:

• a standalone local server you run yourself
• a VS Code-first experience that carries its own local MCP/backend runtime

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Screenshots

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🎬 Video Introduction

Click the thumbnail above to watch the introduction video on YouTube.

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Support

If AgentChatBus is useful to you, here are a few simple ways to support the project (it genuinely helps):

• ⭐ Star the repo on GitHub (it improves the project's visibility and helps more developers discover it)
• 🔁 Share it with your team or friends (Reddit, Slack/Discord, forums, group chats—anything works)
• 🧩 Share your use case: open an issue/discussion, or post a small demo/integration you built

Reddit (create a post) https://www.reddit.com/submit?url=https%3A%2F%2Fgithub.com%2FKillea%2FAgentChatBus&title=AgentChatBus%20%E2%80%94%20An%20open-source%20message%20bus%20for%20agent%20chat%20workflows

Hacker News (submit) https://news.ycombinator.com/submitlink?u=https%3A%2F%2Fgithub.com%2FKillea%2FAgentChatBus&t=AgentChatBus%20%E2%80%94%20Open-source%20message%20bus%20for%20agent%20chat%20workflows

📈 Star History

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🤝 A2A Compatibility

AgentChatBus is designed to be fully compatible with the A2A (Agent-to-Agent) protocol as a peer alongside MCP:

• MCP — how agents connect to tools and data (Agent ↔ System)
• A2A — how agents delegate tasks to each other (Agent ↔ Agent)

The same HTTP + SSE transport, JSON-RPC model, and Thread/Message data model used here maps directly to A2A's Task, Message, and AgentCard concepts. Future versions will expose a standards-compliant A2A gateway layer on top of the existing bus.

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👥 Contributors

A huge thank you to everyone who has helped to make AgentChatBus better!

Detailed email registry is available in CONTRIBUTORS.md.

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📄 License

AgentChatBus is licensed under the MIT License. See LICENSE for details.

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AgentChatBus — Making AI collaboration persistent, observable, and standardized.