Drill — Detached-HEAD Rescue

The brief

On-call engineer checks out a release tag to reproduce a stakeholder's number, makes a "quick fix" commit while detached, then git switch main — the fix vanishes from all branches the night before a reporting deadline.

Starter state (seed script)

mkdir rescue-drill && cd rescue-drill
git init && git switch -c main
for i in 1 2 3 4 5; do echo "v$i" >> report.py; git add . && git commit -m "report v$i"; done
git tag v1.2
git checkout v1.2            # DETACHED HEAD
echo "fix off-by-one in totals" >> report.py
git add . && git commit -m "fix off-by-one in totals"   # orphan commit
git switch main              # the fix "vanishes"

Your task

1. Confirm the fix is gone from every branch: git log --all --oneline shows no fix off-by-one.
2. Find the orphan commit: git reflog → locate the commit: fix off-by-one in totals entry → note its SHA.
3. Recreate the branch at that SHA: git switch -c fix/off-by-one <sha>.
4. Verify the content: git log --oneline --graph shows the rescued commit on a named branch; cat report.py contains the fix.
5. Write RESCUE.md: what detached HEAD means, how reflog located the orphan, the prevention rule (never commit detached; use git switch -c).

Deliverables

• Repo URL (submission notes).
• RESCUE.md file upload.

Submission contract: paste the repo URL into submission notes and upload RESCUE.md. Reviewer checks the rescued branch exists with the fix content, and the graph shows a clean topology.

100-pt rubric

• Reproduce detachment + locate orphan via reflog (25)
• Recreate branch at orphan SHA, verify content (25)
• Explain detached-HEAD semantics correctly in RESCUE.md (20)
• Graph shows clean topology (15)
• Prevention rule stated (15)