---
title: Merge PR Chain
tags: pull-request, stacked-pr, merge, squash, cherry-pick, github
---

# Skill: Merge PR Chain

Merge a chain of stacked GitHub PRs into main as individual squash commits. Use when user has multiple PRs where each targets the previous one's branch (e.g., PR #2 -> PR #1's branch -> main) and wants to squash merge them all to main while preserving separate commits per PR.

## Workflow

### 1. Identify the chain

Fetch PR details to map the chain structure:
```
main
  └── #1 (base: main, branch: feat-a)
        └── #2 (base: feat-a, branch: feat-b)
              └── #3 (base: feat-b, branch: feat-c)
```

### 2. Merge and rebase sequentially

**First PR** (targets main):
```bash
# Squash merge via GitHub CLI
gh pr merge <N> --squash --title "<PR title> (#N)"
git pull origin main
```

**Subsequent PRs** — rebase onto main, update base, then merge:
```bash
# 1. Checkout the branch for the next PR
git checkout <next-branch>

# 2. Rebase onto main, excluding commits from the old base branch
#    This replays only this PR's commits onto main
git rebase --onto origin/main <old-base-branch> <next-branch>

# 3. Force push the rebased branch
git push --force-with-lease origin <next-branch>

# 4. Update the PR's base branch to main via GitHub CLI
gh pr edit <N> --base main

# 5. Squash merge the PR
gh pr merge <N> --squash --title "<PR title> (#N)"

# 6. Update local main
git fetch origin main
git checkout main
git pull origin main
```

Repeat step 2 for each subsequent PR in the chain.

## Key details

- **Always use PR title as commit title** — GitHub may default to branch name or first commit otherwise. Pass `--title` explicitly.
- **Use `--force-with-lease`** — Safer than `--force`, fails if remote has unexpected changes.
- **Update PR base before merging** — After rebasing, change the PR's base branch to `main` so it merges correctly and shows "merged into main" in GitHub UI.

## Handling conflicts

When `git rebase --onto` encounters conflicts:

1. Git will pause and show which files have conflicts
2. **Stop and ask the user** to resolve conflicts manually
3. After user resolves: `git add <resolved-files> && git rebase --continue`
4. If user wants to abort: `git rebase --abort`

**Never auto-resolve conflicts** — always ask the user to review and resolve manually.

## Why this works

`git rebase --onto <new-base> <old-base> <branch>` takes commits that are in `<branch>` but not in `<old-base>` and replays them onto `<new-base>`. This effectively strips the already-merged commits and moves only the PR's unique changes onto main.

## Benefits over cherry-pick

- PRs show as "merged into main" in GitHub UI
- Clean linear history on main
- No duplicate commits or confusing merge states
- Each PR's diff remains reviewable until merged