Transport-level routing for MCP/ACP protocols
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Access the stdio Bus specification and reference implementation. This page provides source repository links, versioning information, and release history.
Source Repository
The stdio Bus specification and reference implementation are developed in the open. The source repository contains the normative specification documents, the C reference implementation, example workers, and test suites.
| Directory | Contents |
|---|---|
spec/ | Normative protocol specification documents |
include/ | C header files (public API) |
src/ | C implementation source code |
examples/ | Example workers and configurations |
tests/ | Test suite |
Current Version
Specification Version
v0.1.0
This is the current stable version of the stdio Bus specification. The specification and reference implementation are versioned together to ensure compatibility.
Versioning Policy
stdio Bus follows Semantic Versioning (SemVer) for both the protocol specification and reference implementation. Version numbers follow the format MAJOR.MINOR.PATCH.
MAJOR
Incremented for breaking changes to the protocol specification that require client or worker modifications.
Examples
- Changing message format
- Removing required fields
- Altering routing semantics
MINOR
Incremented for backwards-compatible additions to the specification.
Examples
- New optional fields
- Additional operating modes
- Extended configuration options
PATCH
Incremented for backwards-compatible clarifications and documentation fixes.
Examples
- Typo corrections
- Clarified requirements
- Additional examples
Stability Guarantee
Once stdio Bus reaches version 1.0.0, the protocol specification will maintain backwards compatibility within major versions. Clients and workers written for version 1.x will continue to work with any 1.y release where y ≥ x.
Pre-built Binaries
Pre-built binaries are not currently available. The reference implementation is designed to be built from source to ensure compatibility with your specific platform and configuration.
Building from Source
See the Getting Started page for build instructions. The build process requires only a C11 compiler and Make or CMake—no external dependencies.
| Platform | Status | Notes |
|---|---|---|
| Linux (x86_64) | Build from source | Uses epoll for I/O multiplexing |
| macOS (arm64/x86_64) | Build from source | Uses kqueue for I/O multiplexing |
| Windows | Not supported | WSL2 recommended for Windows users |
License
Apache-2.0 License
The stdio Bus specification and reference implementation are released under the Apache-2.0 License. You are free to use, modify, and distribute the software for any purpose, including commercial use, with minimal restrictions.
Release History
The following releases document the evolution of the stdio Bus specification and reference implementation.
v0.1.0
2026-02-23
Initial Release
- Initial protocol specification
- Reference C implementation
- Support for stdio, Unix socket, and TCP modes
- Session-based routing
- Backpressure management