Backmerge

Backmerge

Automate the backmerge chain after a hotfix or production merge. Optional argument: $ARGUMENTS (starting branch, defaults to prod).

Branch Strategy Reference

prod ──PR──> test ──PR──> main

After a hotfix lands on prod, it must be backmerged through test into main to keep all branches in sync.

Step 0: Validate State

git fetch origin

Check that the starting branch exists and has commits ahead of the target:

# Check prod -> test delta
git log --oneline origin/test..origin/prod | head -20

# Check test -> main delta (may be empty if prod hasn't merged to test yet)
git log --oneline origin/main..origin/test | head -20

If origin/test..origin/prod is empty, there's nothing to backmerge. Inform the user and stop.

Step 1: Create PR from prod -> test

Check if a backmerge PR already exists:

gh pr list --base test --head prod --state open --json number,title,url

If a PR already exists: show it and ask if the user wants to proceed to the next step.

If no PR exists: create one:

gh pr create 
  --base test 
  --head prod 
  --title "chore(release): backmerge prod -> test" 
  --body "$(cat <<'EOF'
# Description

Automated backmerge of production changes into test branch.

### Commits included
$(git log --oneline origin/test..origin/prod)

## Type of change

- [x] Chore (non-breaking change which does not modify src or test files)

# How Has This Been Tested?

- [ ] Review for merge conflicts
- [ ] CI passes after merge

### Action required
- Review for conflicts
- Merge when ready
- Then backmerge test -> main (use `/backmerge` again)

EOF
)"

Step 2: Wait for merge or prompt user

Ask the user:

• "PR #{number} created for prod -> test. Should I also create the test -> main PR now, or wait until the first one is merged?"

If user says wait: stop here, print the PR URL. If user says continue: proceed to step 3.

Step 3: Create PR from test -> main

Check if a backmerge PR already exists:

gh pr list --base main --head test --state open --json number,title,url

If a PR already exists: show it and stop.

If no PR exists: create one:

gh pr create 
  --base main 
  --head test 
  --title "chore(release): backmerge test -> main" 
  --body "$(cat <<'EOF'
# Description

Automated backmerge of test changes into main branch.

### Commits included
$(git log --oneline origin/main..origin/test)

## Type of change

- [x] Chore (non-breaking change which does not modify src or test files)

# How Has This Been Tested?

- [ ] Review for merge conflicts
- [ ] CI passes after merge

### Action required
- Review for conflicts
- Merge when ready

EOF
)"

Step 4: Output Summary

Backmerge Status:
  1. prod -> test: PR #{number} ({state}) — {url}
  2. test -> main: PR #{number} ({state}) — {url}

Next steps:
  - Review and merge PRs in order (test first, then main)
  - Resolve any conflicts in the PRs