using-git-worktrees

# Using Git Worktrees ## Overview Ensure work happens in an isolated workspace. Prefer your platform's native worktree tools. Fall back to manual git worktrees only when no native tool is available. **Core principle:** Detect existing isolation first. Then use native tools. Then fall back to git. Never fight the harness. **Announce at start:** "I'm using the using-git-worktrees skill to set up an isolated workspace." ## Step 0: Detect Existing Isolation **Before creating anything, check if you are already in an isolated workspace.** ```bash GIT_DIR=$(cd "$(git rev-parse --git-dir)" 2>/dev/null && pwd -P) GIT_COMMON=$(cd "$(git rev-parse --git-common-dir)" 2>/dev/null && pwd -P) BRANCH=$(git branch --show-current) ``` **Submodule guard:** `GIT_DIR != GIT_COMMON` is also true inside git submodules. Before concluding "already in a worktree," verify you are not in a submodule: ```bash # If this returns a path, you're in a submodule, not a worktree — treat as normal repo git rev-parse --show-superproject-working-tree 2>/dev/null ``` **If `GIT_DIR != GIT_COMMON` (and not a submodule):** You are already in a linked worktree. Skip to Step 3 (Project Setup). Do NOT create another worktree. Report with branch state: - On a branch: "Already in isolated workspace at `<path>` on branch `<name>`." - Detached HEAD: "Already in isolated workspace at `<path>` (detached HEAD, externally managed). Branch creation needed at finish time." **If `GIT_DIR == GIT_COMMON` (or in a submodul...