git-cow-worktree

name	git-cow-worktree
description	Create a git worktree, using copy-on-write reflinks when the volume supports it. Use whenever adding a git worktree.
user-invocable	true

git-cow-worktree

Create a git worktree via a bundled file-based C# app. It behaves like git worktree add, but on a copy-on-write volume (Windows ReFS/Dev Drive, Linux Btrfs/XFS/ZFS, macOS APFS) it seeds the new worktree with reflink clones of an existing worktree so unchanged files share on-disk blocks. Off a CoW volume it does a regular checkout. The result is identical either way.

Running It

Pass app args after --:

dotnet run "<skill-dir>\app\git-cow-worktree.cs" -- <path> [<commit-ish>] [options]

<skill-dir> is this folder. Run with --help for all options; the common ones are -b <branch> (new branch), --source <dir> (worktree to reflink from, defaults to the current worktree), and -v. Only the handful of git worktree add flags listed in --help are accepted; for anything else use git worktree add directly.

The app pins itself to net10.0; that runtime plus git must be installed.

Workflow

1. Resolve the repo (default cwd), worktree path, and branch/commit (use -b for a new branch).
2. Run the app.
3. Report where the worktree landed, the branch, and whether files were reflinked or it was a regular checkout.

Guardrails

• Let git worktree add reject an existing path; never delete to make room.
• Never modify the source worktree; a dirty source is fine (git checkout -f HEAD fixes any mismatch).
• A regular (non-CoW) checkout is a correct result, not a failure.