implementlisted

# /implement ## Preflight: worktree guard Task-scoped mutating skill — must run from a worktree, not the main checkout. Contract: `skills/_shared/worktree-guard.md`. ```bash TOPLEVEL="$(git rev-parse --show-toplevel 2>/dev/null || echo '')" if [ -z "$TOPLEVEL" ]; then echo "✗ worktree-guard: not inside a git repository" >&2 exit 1 fi BRANCH="$(git branch --show-current 2>/dev/null || echo '')" DEFAULT_BRANCH="$(git symbolic-ref --short refs/remotes/origin/HEAD 2>/dev/null | sed 's@^origin/@@' || echo 'main')" if [ -f "$TOPLEVEL/.forge/worktree-task.json" ]; then echo "✓ worktree-guard: $TOPLEVEL ($BRANCH)" elif [ "$BRANCH" = "${DEFAULT_BRANCH:-main}" ]; then echo "✗ worktree-guard: refusing to run on default branch '$BRANCH' from $TOPLEVEL" >&2 echo " Parallel Claude Code sessions on the main checkout clobber each other's HEAD." >&2 echo " → cd into an existing worktree, or run /pickup-task to create one." >&2 exit 1 else echo "⚠ worktree-guard: no .forge/worktree-task.json at $TOPLEVEL (branch: $BRANCH)" >&2 echo " Proceeding, but this worktree may be manually-created or stale." >&2 fi ``` ## Preconditions - `plans/tasks/{LINEAR-ID}.plan.md` exists and was committed - OR `--quickfix` flag with justification ## Execution 1. Read plan 2. Execute step-by-step, committing after each logical unit 3. Use conventional commit messages 4. **Mid-implementation forks:** If a decision surfaces that wasn't in the plan, apply the fork severity filter from `/pla