Stdiobus MCP Server
stdio Bus: agentic process supervisor and message router, handling NDJSON-framed JSON-RPC messages with session-based routing while remaining completely agnostic to protocol semantics.
Stdiobus is an open-source mcp server by stdiobus, written mainly in Shell, with 20 GitHub stars and the Apache-2.0 license. Its code was last updated Sep 4, 2026.
stdio Bus kernel acts as a process supervisor and message router between external clients (IDEs, CLIs, services) and worker processes. It handles NDJSON-framed JSON-RPC messages with session-based routing, while remaining completely agnostic to protocol semantics.
Key Features
- Single-threaded: One event loop using epoll (Linux) or kqueue (macOS)
- No external dependencies: Only libc and POSIX APIs
- Protocol agnostic: Forwards messages unchanged, parsing only routing fields
- Session affinity: Messages with the same
sessionIdroute to the same worker - Backpressure management: Configurable limits prevent memory exhaustion
Prerequisites
- C11-compliant compiler (GCC 4.9+ or Clang 3.4+)
- Make or CMake 3.10+
- Node.js 18+ (for running example workers)
Binary Releases
Pre-compiled binaries for multiple platforms are available in the /releases directory. Each version contains ready-to-use stdio_bus binaries for different architectures:
Version 2.0.3
Available platforms:
- macOS:
darwin-amd64|darwin-arm64 - Linux:
linux-amd64|linux-arm64|linux-armv7 - Linux (musl):
linux-musl-amd64|linux-musl-arm64
Verification: SHA256 checksums available at checksums.sha256
Download the appropriate binary for your platform and make it executable:
# Example for Linux AMD64
curl -L -o stdio_bus https://github.com/stdiobus/stdiobus/releases/v2.0.3/linux-amd64/stdio_bus
chmod +x stdio_bus
Docker
Pre-built multi-architecture images available on Docker Hub:
docker pull stdiobus/stdiobus:latest
Supported platforms: linux/amd64, linux/arm64, linux/arm/v7
Available tags: latest, v2.0.3, main, develop
See Docker Hub for complete usage examples and configuration.
Implementations
Embedded stdio_bus runtime for your application process — no external daemon, no Docker, no TCP hop.
| Language | Package | Status |
|---|---|---|
| Rust | stdiobus | 🟩 Available |
| Node.js | @stdiobus/node | 🟩 Available |
| C++ | stdiobus | 🟩 Available |
| Python | stdiobus | 🟩 Available |
| Go | — | Planned |
MCP Orchestration
MCP server that connects IDE clients to ACP-compatible agents through stdio Bus: @stdiobus/mcp-agentic
Exposes 8 MCP tools covering agent discovery, session lifecycle, one-shot delegation, and health checks. Supports in-process agents and external worker processes. Includes a Provider Factory API for OpenAI, Anthropic, and Google Gemini with a unified interface, runtime parameter control per session and per prompt, and a defineProvider() contract for custom or private LLM integrations.
See mcp-agentic for provider setup, tool reference, and IDE integration.
MCP Module Launcher
Manifest-driven CLI launcher for MCP server modules in the stdio Bus ecosystem: @stdiobus/mcpx
Replaces hardcoded shell commands in mcp.json with a single portable entrypoint — mcpx run <module>. Each module is described by a module.json manifest that defines runtime, entry point, environment defaults, and arguments. Supports Node.js, Python, Go, Rust, Shell, and Docker runtimes. Works with any MCP client: Kiro, Cursor, Claude Desktop, Windsurf.
See mcpx for manifest reference and environment management.
Agent Skills
Structured, validated, machine-readable skills for AI agents delivered over MCP via stdio Bus: @stdiobus/skills
An MCP server that exposes agent skills as a machine-parseable knowledge base — not documentation for humans. Skills are organized in a 5-layer hierarchy (Concepts → API → Patterns → Guardrails → Diagnostics), CI-validated against real framework types, and served through five MCP tools: list_skills, read_skill, list_references, read_reference, search_skills. Ships with two skill collections: Runtime Web (12 skills for @worktif/runtime) and stdio Bus SDKs (C++, Node.js, Rust).
See skills for the skill catalog and agent consumption protocol.
Workers
Protocol workers for stdio Bus kernel: @stdiobus/workers-registry
Includes ACP Registry launcher for routing to any registered agent (Claude, Goose, Cline, GitHub Copilot and others), OpenAI-compatible endpoint bridge, MCP-to-ACP proxy for IDE integration, standalone ACP agent for protocol testing, and echo workers for protocol validation. Workers run as child processes of the kernel, communicating via NDJSON over stdin/stdout. Authentication supports API keys and OAuth 2.1 with PKCE (GitHub, Google, Azure AD, AWS Cognito, OIDC).
See workers-registry for the full worker catalog, configuration, and authentication setup.
License
Apache License, Version 2.0
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