Serialize parallel Claude Code agent merges with local queue

Claude Code Merge Queue 🚦

The local, zero-cost merge queue for parallel Claude Code agents. Several
agents land, build, and test at the same time - this serializes it so push
races, redundant heavy builds, and shared-resource test flakiness can't happen.

⚡ Quickstart

npm install --save-dev claude-code-merge-queue   # or: pnpm add -D / yarn add -D / bun add -d
npx claude-code-merge-queue init

Contents

• ⚙️ Configuration
• 🆚 vs. GitHub's Merge Queue
• 🧰 What's in the box
• 🚨 The emergency hatch
• 🔍 Know the limits
• 📄 License

⚙️ Configuration

Everything lives in one file - see
examples/claude-code-merge-queue.config.mjs for every
field with comments. The short version:

export default {
  branchPrefix: "lane/",               // lane/1, lane/2, ...
  worktreeSuffix: "-lane-",            // ../your-repo-lane-1
  portBase: 3000,                      // lane n gets portBase + n
  integrationBranch: "main",           // where agents land — see below
  productionBranch: null,              // set this for a two-stage model — see below
  protectedBranches: [],               // extra branches beyond the two above; most repos need none
  regenerableFiles: [],                // files a build tool rewrites — never block a rebase on these
  symlinks: [".env", ".env.local", "node_modules"],
  buildOutputDirs: ["dist", "build", ".next"], // preview never copies these onto your checkout
  checkCommand: "npm run check",       // what actually gates a landing — see below
  checksRequired: true,                // false = deliberately run with none; see below
};

A malformed config (empty branch names, a negative port, productionBranch
equal to integrationBranch, ...) fails loud with every problem listed,
the moment any command loads it - not a mysterious failure three steps
later.

🆚 vs. GitHub's Merge Queue

Same idea - serialize landings, test before merge, keep history clean - run
locally instead of in someone else's billed cloud.

🧰 What's in the box

A pre-push hook makes land non-optional: a direct git push straight to
the integration branch is rejected, with the actual command to run
instead, and the same hook runs checkCommand before allowing a landing
through - no checkCommand configured means every push fails by default.
There's a way out for every block (see 🚨 The emergency hatch), but it
takes naming the specific branch, not a generic flag.

📝 What init writes

• claude-code-merge-queue.config.mjs - integrationBranch and checkCommand auto-detected.
• CLAUDE.md (or appends to yours) - tells Claude Code to land its own
  work once green, without being asked.
• .claude/settings.json - the WorktreeCreate hook wired in, without
  touching anything else already there.
• .husky/pre-push - created or appended to, if you already have
  Husky. If you don't, init tells you rather than silently writing to
  the untracked .git/hooks/pre-push.
• package.json scripts - land, sync, promote, preview,
  preview:restore, skipping any you've already defined yourself.
• claude-code-merge-queue-preflight.mjs - a self-contained safety net
  that runs before land/sync, so a stale branch fails with a real
  diagnosis instead of a bare command not found.

🚨 The emergency hatch

Every blocked push - the integration branch, productionBranch, anything
in protectedBranches - has a real way through it. One env var, no
prompts, no second factor to remember:

CLAUDE_CODE_MERGE_QUEUE_EMERGENCY_PUSH=1 git push origin HEAD:main

This is a convention, not a hard guarantee: it stops mistakes and stray
pushes, not an adversarial agent that sets the var itself.

🔍 Know the limits

• No human reviews any of this before it lands. checkCommand passing
  is the only gate - a real test suite and echo ok look identical to this
  tool. Want a human on every change? This is missing that step on purpose.
• Locks are crash-safe by PID liveness, not a timeout. kill -9
  anything mid-claim and the next process notices the PID is dead and
  reclaims it - no stale locks, no timeout to tune.
• One machine, not a fleet. The FIFO queue lives in local temp storage -
  two machines landing at once just get git's ordinary non-fast-forward
  rejection.
• Not a security boundary. Every guardrail here stops mistakes and
  convention drift, not an adversarial agent - shell access always means
  git push --no-verify or editing the config on purpose.
• A slow checkCommand is a real throughput ceiling. The FIFO lock
  holds for its entire duration - a 3-4 minute suite caps you well under
  20 landings/hour.
• Rebase conflicts abort, they never guess. git rebase --abort on any
  conflict, working tree left clean - CLAUDE.md tells the agent to resolve
  it and re-run land.

📄 License

MIT. Fork it, rename it, argue with the config shape - that's the point.