validate-git-safety

# Validate Git Safety Skill

**Purpose**: Validate git history-rewriting operations won't affect protected branches or cause unintended data loss.

## When to Use

- Before `git filter-branch`
- Before `git rebase` with `--all` or `--branches`
- Before any history-rewriting operation
- Before deleting branches

## Protected Branch Patterns

### Version Branches (NEVER modify)
- Pattern: `v[0-9]+` (e.g., v1, v13, v21)
- Protection: NEVER delete, rewrite history, or force push

### Main/Master (careful modifications only)
- Only fast-forward merges
- No history rewriting

### Task Branches
- Treat as immutable after completion

## Dangerous Commands

```bash
# NEVER use --all with history rewriting
git filter-branch --all
git rebase --all

# NEVER force push without explicit request
git push --force
git push -f

# NEVER delete version branches
git branch -D v21

# NEVER rebase shared branches
git checkout main
git rebase feature  # Rewrites main!
```

## Safe Alternatives

```bash
# Target specific branch (not --all)
git filter-branch main

# Rebase feature onto main (not main onto feature)
git checkout feature
git rebase main

# Use --force-with-lease instead of --force
git push --force-with-lease

# Move version branch pointer forward (not rewrite)
git branch -f v21 <new-commit>
```

## Worktree Verification (M101)

**During CAT task execution, NEVER operate on the main `/workspace` worktree.**

```bash
# Before ANY git operation in a CAT task, verify location:
CURRENT_DIR=$(pwd)
if [[ "$CURRENT_DIR" == "/workspace" ]] && [[ -d "/workspace/.worktrees" ]]; then
  echo "BLOCKED: Currently in main worktree while task worktrees exist"
  echo "Expected: /workspace/.worktrees/<task-name>"
  echo "Current:  $CURRENT_DIR"
  exit 1
fi
```

**Check for active task worktrees:**
```bash
# If any worktrees exist, you should be in one of them (not main)
if ls -d /workspace/.worktrees/*/ 2>/dev/null | head -1 | grep -q .; then
  # Worktrees exist - verify we're in one
  if [[ "$(p