PR Mirror

PR Mirror is a CLI tool to mirror an existing pull request from a public GitHub repository by:

1. Cloning the repo (via SSH),
2. Fetching the pull request as a local branch,
3. Creating a new branch based on it with an empty signed commit (to distinguish the mirror),
4. Pushing the branch to the same repo,
5. Opening a new pull request (via the GitHub CLI) from the mirrored branch into a specified base branch.

This is useful in scenarios like:

• Creating a filtered or internal mirror of external PRs
• Testing PRs against a different base branch (e.g., staging instead of main)

Prerequisites

Node.js (see package engines)

git (must be in PATH)

GitHub CLI (gh) installed and authenticated (via gh auth login)

Git commit signing configured (required). This tool uses git commit -S for the tracking commits.

SSH access to GitHub ([email protected] must be reachable)

Usage

prmirror [-b <base-branch>] -n <pr-number> -o <org> -r <repo> [-d] [-s] [-v]

# Clean up mirror-repo directory and exit
prmirror -c

Installation

npm install -g @pandaswhocode/pr-mirror

Or run without installing:

npx @pandaswhocode/pr-mirror -n <pr-number> -b <base-branch> -o <org> -r <repo>

Arguments

Flag	Description
-b, --base	Base branch to target for the new PR (defaults to DEFAULT_BASE or main)
-c, --clean	Delete the mirror-repo directory and exit (no other arguments are needed)
-o, --org	GitHub organization (can use DEFAULT_ORG env var)
-r, --repo	GitHub repository name (can use DEFAULT_REPO env var)
-s, --sync	Sync the mirror-pr branch and update the mirror PR
-d, --deleteAfterAction	Delete the mirror-repo directory after a successful create/sync run (cleanup errors are logged but do not fail the run)
-h, --help	Show help
-n, --number	(Required) Pull request number to mirror
-v, --verify	Show resolved inputs and ask for confirmation before proceeding

Environment variables

You can set defaults in a .env file in your working directory:

• DEFAULT_ORG
• DEFAULT_REPO
• DEFAULT_BASE
• DEBUG (set to true for verbose logging)

Note: if DEFAULT_BASE is not set and --base is not provided, the base branch defaults to main.

Example (Create new mirror)

prmirror -n 42 -b main -o PandasWhoCode -r pr-mirror

To verify the resolved inputs before making any changes:

prmirror -n 42 -b main -o PandasWhoCode -r pr-mirror -v

This will:

• Clone [email protected]:PandasWhoCode/pr-mirror.git into a temporary mirror-repo directory
• Fetch pull request #42 into a temporary branch
• Create a new branch mirror/pr-42 from it
• Add an empty signed commit for traceability
• Push mirror/pr-42 to origin
• Open a new pull request targeting main, authored by your GitHub CLI user

Output

The new PR will be titled:

chore:Mirror PR-42

And will include all commits from the original PR, along with an empty commit to mark it as mirrored.

Example (Sync existing mirror)

prmirror -n 42 -b main -o PandasWhoCode -r pr-mirror -s

This will:

• Clone [email protected]:PandasWhoCode/pr-mirror.git into a temporary mirror-repo directory
• Fetch pull request #42 into a temporary branch
• Sync the branch mirror/pr-42 from with the temporary branch
• Add an empty signed commit for traceability
• Push mirror/pr-42 to origin

Output

The existing mirror PR will be titled:

chore: Mirror PR-42 (sync)

The PR will include all commits from the original PR, along with an empty commit to mark it as mirrored.

Example (Delete mirror-repo after success)

prmirror -n 42 -b main -o PandasWhoCode -r pr-mirror -d

Example (Clean mode)

This deletes the local mirror-repo directory and exits without doing any other work:

prmirror -c

Notes

The tool exports GITHUB_TOKEN and GITHUB_UNAME using the GitHub CLI so that gh pr create can assign the author correctly.

The mirror-repo directory is created in the current working directory.

License

Apache 2.0