Code Relay

Code Relay

English · Chinese

Build. Prove. Relay.

Code Relay lets your coding agent develop on one machine and prove the result on another.

Relay is an MCP-based coding-agent integration for cross-machine development and verification. AI on the Dev Host implements the request; the Target Host runs the real validation; a structured receipt comes back to guide the next repair iteration. It works with Codex, Claude Code, Cursor, VS Code, and other MCP-capable coding agents.

When Relay is useful

• Different environments — develop on Windows or macOS, verify on Linux, a private network, or a production-like host.
• Special hardware — send model code to a CUDA/GPU machine, or verify a camera, serial device, or sensor where it is connected.
• Real integrations — exercise payment callbacks, queues, databases, browsers, or internal services that cannot be reproduced locally.
• AI-driven iteration — return concrete expected/actual results so the coding agent can repair, republish, and retry.

What Relay provides

• Branch-scoped project binding and short-lived join links.
• Exact source-commit verification in an isolated worktree.
• Checkpoint execution through a code-relay-checkpoint GitHub Actions self-hosted runner.
• Safe, allowlisted validation commands with bounded output and timeouts.
• Structured receipt.json and human-readable receipts for passed, failed, and blocked runs.

Quick start

AI client installation

Let your coding agent read and follow the instructions:

https://raw.githubusercontent.com/zarcherlot/code-relay/main/install.md

npm fallback

npx -y code-relay-mcp@latest install --client codex

Replace codex with claude-code, cursor, vscode, or generic as needed.

MCP server details

Code Relay is a local MCP server that communicates over stdio. The npm package starts the server with:

npx -y code-relay-mcp@3.1.0

The server implements the MCP JSON-RPC surface directly in Go (without a third-party MCP SDK). It supports initialize, ping, tools/list, and tools/call, and exposes these tools:

Tool	Purpose
bind_project	Bind a repository and branch to a relay role.
create_checkpoint_invite	Create a short-lived checkpoint join link.
join_checkpoint	Join a branch-scoped checkpoint subscription.
watcher_status	Read local watcher state.
stop_watcher	Stop the local watcher.
doctor	Run non-mutating local health checks.
publish_runbook	Validate and publish a runbook.
status	Read runbook and receipt status.
fetch_receipt	Load and validate a runbook receipt.
analyze	Analyze a receipt and determine the next state.

The implementation and transport loop are in internal/relay/mcp.go.

How it works

the Dev Host sends a repository- and branch-bound runbook through Relay; the Target Host checks the exact source commit in its real environment and returns a Receipt recording the Checkpoint result.

Every runbook is bound to a repository, branch, and source commit. The Target Host acts as the Checkpoint, and the resulting receipt records passed, failed, or blocked verification for the next iteration.

Documentation

• Chinese README
• User guide
• AI-client installation guide
• Local desktop install runbook
• Deployment and runbook
• Security
• Contributing

License

Code Relay is released under the MIT License.