Mergetrain MCP server

mergetrain

<!-- mcp-name: io.github.yongjip/mergetrain -->

Safely integrate committed branches from parallel coding agents.

mergetrain is a local-first deploy train for coding-agent worktrees. Agents commit and enqueue their branches; one runner assembles them in order, tests the combined tree, and atomically updates your Git refs only after explicit approval. It is intentionally optimized as an owner-operated local utility, not a hosted team platform.

There is no mergetrain account, hosted control plane, OAuth app, or product telemetry. Queue and runner state stay on your machine; only your configured Git remote and trusted gate or verification commands may contact external services.

The problem

Worktrees let several agents edit one repository without sharing a checkout. They do not decide landing order, test the combined result, prevent push races, or tell you what happened if a laptop dies mid-push.

Without an integration boundary, the human becomes that boundary: rebase every finished branch, rerun gates after each merge, resolve cross-branch failures, and decide which session may push. The parallel coding gain disappears at the last mile.

mergetrain makes that last mile a durable protocol:

agent branches → FIFO queue → isolated integration worktree → combined gates
               → explicit approval → one atomic push → post-push verification

Who should use it?

Use mergetrain when:

day;

• multiple coding agents finish branches in the same repository throughout the

• agents work in Git worktrees and should enqueue rather than push deploy refs;
• the combined result must pass local tests before it lands;
• you want unattended processing only for explicitly pre-approved jobs; or
• one local hub should show queues and runners across several repositories.

It is harness-agnostic: Codex, Claude Code, agy, scripts, and humans all use the same CLI and JSON contract.

Who should not use it?

You probably do not need mergetrain when:

runner service; or

• one person or agent lands one branch at a time;
• every change already goes through a PR and your forge-native merge queue;
• you need a hosted review UI, organization-wide permission system, or remote

• you are looking for a general job queue, CI provider, or deployment platform.

For PR-first teams, use GitHub Merge Queue or GitLab Merge Trains. mergetrain is for local-agent, worktree-first integration, with or before a PR.

Enforcement boundary

Lease tokens fence concurrent and stale mergetrain runners. They do not intercept an arbitrary git push from a task agent that has shell access and an integration-branch credential. To make “one runner owns the push” an enforced property rather than a protocol assumption, use this topology:

task agents: commit + exact-SHA enqueue; no integration push credential
runner:      separate deploy identity
remote:      protected integration branch; runner or reviewed PR path only

Shortened. The full README is on GitHub.