Setup

1. Install the Mergify CLI, see the CLI installation guide for instructions.

2. GitHub authentication: Stacks needs access to create PRs. Either:

   • Set the GITHUB_TOKEN environment variable, or
   • Install the GitHub CLI and run gh auth login

3. Enable “Automatically delete head branches” in your GitHub repository settings (Settings > General > Pull Requests). When a stacked PR merges, this cleans up its remote branch automatically so the next PR in the chain can rebase onto main cleanly.

Run the setup command in your Git repository:

mergify stack setup

This installs:

• A commit-msg Git hook that automatically generates a Change-Id for every new commit. The Change-Id is how Stacks tracks the relationship between your local commits and their GitHub pull requests.

• A pre-push hook that warns you if you accidentally use git push instead of mergify stack push.

• A Claude Code skill that teaches the AI coding agent how to work with Mergify Stacks, so it automatically uses mergify stack push instead of git push.

Create a test commit to confirm the hook is active:

echo "test" >> test.txt
git add test.txt
git commit -m "test: verify stack setup"

Check the commit message:

git log -1

You should see a Change-Id trailer at the bottom of the message:

test: verify stack setup

Change-Id: Ia1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2

Clean up the test commit if you don’t need it:

git reset HEAD~1

These optional Git config settings let you customize Stacks behavior:

Example:

git config mergify-cli.stack-create-as-draft true

Head to Creating Stacks to push your first stack.