pr-stack

A GitHub App that auto-rebases stacked PRs when a PR they depend on gets merged. Also exposes a /ci-check endpoint for skipping CI when no actual code changed.

How it works

Auto-rebase

• Listens for pull_request.closed (merged) webhook events
• Finds all open PRs whose base branch is the merged PR's head branch
• Clones the repo, rebases each dependent PR onto the new base, and force-pushes
• Attempts to auto-resolve conflicts by checking git blame — if a conflict was introduced by the merged PR itself, it keeps the incoming change; otherwise it aborts

CI check

• Accepts a POST /ci-check request with before/after commit SHAs and PR metadata
• Compares the tree SHA at each commit tip; if they match and no new commits were added, returns { skipCI: true }
• Intended for use in CI pipelines to skip redundant runs after a rebase-only push

Setup

Prerequisites

• bun v1+
• A GitHub App with pull_requests: read/write and contents: read/write permissions, subscribed to pull_request webhook events

Environment variables

Variable	Description
APP_ID	GitHub App ID
PRIVATE_KEY	GitHub App private key (PEM)
WEBHOOK_SECRET	Webhook secret configured on the GitHub App

Install and run

bun install
bun run dev:api

API

POST /webhook — receives GitHub webhook events and triggers the rebase flow

POST /ci-check — takes a GitHub push event payload and returns { skipCI: true/false, message: "..." } indicating whether CI can be skipped