GitHub Actions Orphan Branch Accumulation

The Problem: workflow_dispatch Can't Push to Protected Branches

My blog-publish.yml workflow auto-posts articles to Qiita and dev.to, then needs to flip published: false → true in the draft file and commit it back to main.

But GitHub's branch protection rules block direct pushes from workflow_dispatch:

error: GH006 Protected branch update failed for refs/heads/main.

The Fix: Route Through a PR Branch

workflow_dispatch can't push to main directly, but creating a temporary branch and merging it works:

# blog-publish.yml — update published status
- name: Update published status
  run: |
    BRANCH="blog-publish/${{ github.run_id }}-$(date +%Y%m%d-%H%M%S)"
    git checkout -b "$BRANCH"
    sed -i 's/^published: false/published: true/' "$DRAFT_PATH"
    git add "$DRAFT_PATH"
    git commit -m "docs: $DRAFT_PATH published:true"
    git push origin "$BRANCH"
    gh pr create --title "Blog published: $TITLE" \
      --body "Auto-merge" --base main --head "$BRANCH"
    gh pr merge --auto --squash

This creates a blog-publish/<run_id>-YYYYMMDD-HHMMSS branch and auto-merges it.

The New Problem: Orphan Branches Never Get Cleaned Up

When auto-merge fails (or the merge step is skipped), the branch sticks around. After enough runs, you accumulate dozens of stale branches:

git branch -r | grep "blog-publish/"
# origin/blog-publish/24613652356-20260419-055202
# origin/blog-publish/24614707550-20260419-065252
# origin/blog-publish/24619748692-20260419-070413
# ... (30 more)

This slows down git ls-remote, pollutes CI logs, and makes branch management confusing.

Cleanup Command

# Check accumulation per category
for pattern in "blog-publish/*" "cs-check-*" "ai-university-update/*" "daily-report-*"; do
  count=$(git ls-remote --heads origin "$pattern" | wc -l)
  echo "$count  $pattern"
done

# Merge and delete all blog-publish orphans
git fetch origin
for branch in $(git branch -r | grep "origin/blog-publish/" | sed 's|.*origin/||'); do
  git merge "origin/$branch" --no-edit 2>&1
  git push origin --delete "$branch" 2>&1
done
git pull --rebase origin main && git push origin HEAD:main

Note: Always merge before deleting. The branch may contain published:true updates that haven't reached main yet.

Other Patterns That Accumulate the Same Way

All follow the same pattern: workflow_dispatch → can't push to main → PR branch → merge succeeds but branch cleanup is forgotten.

Prevention: Prune in Your WF Health Check

I run a Rule17 WF health check at the start of each session. Adding orphan branch detection there means they never accumulate past a handful:

for pattern in "blog-publish/*" "cs-check-*" "ai-university-update/*"; do
  count=$(git ls-remote --heads origin "$pattern" | wc -l)
  if [ "$count" -gt 5 ]; then
    echo "⚠️ $pattern: $count branches — cleaning up"
    # ... cleanup commands
  fi
done

5+ orphans = cleanup trigger. At the session cadence I run (daily), this stays manageable.

Key Lessons

1. workflow_dispatch + branch protection → always use PR branch strategy
2. PR branch auto-merge → always check if merge actually succeeded
3. Orphan branches → add periodic cleanup to your health check routine, not to each individual workflow

The PR-branch pattern is the right architecture. The cleanup discipline is what makes it not turn into a mess.

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