Worktree Cwd

ExitWorktree cwd-override: merge from inside the worktree with git -C

Problem

You called EnterWorktree(name="my-feature") to set up an isolated branch. The harness moved your session's working directory into .claude/worktrees/my-feature on branch worktree-my-feature. You dispatched a subagent, the work landed, you ran reviews, and now you want to ExitWorktree(action="keep") to return to main so you can fast-forward main to the new commits.

ExitWorktree refuses:

ExitWorktree cannot be called from a subagent with a cwd override
(isolation: "worktree" or explicit cwd) — it would mutate the parent
session's process-wide working directory.

You're stuck: you can't exit; you can't change directory from inside the tool calls; the merge command appears to require being on the target branch.

Root cause

ExitWorktree's job is to revert the session's working directory. In some harness configurations (notably when the session itself was launched with a cwd override, or after EnterWorktree has nested-overridden the cwd), the tool can't safely mutate the process-wide cwd back. It refuses rather than corrupt parent state.

But the BLOCKER assumed by the error message — "I need to be on main to merge into main" — is wrong for git merge. Git operates on branch REFS, not on working directory state. You can merge into main from anywhere as long as you tell git which repo to operate on.

Fix

Use git -C "<path-to-main-repo>" to invoke git as if you were in the main repo directory. The merge runs against main's HEAD ref, brings in the worktree branch's commits, and updates main's pointer — all without your shell ever cd'ing.

# You're currently in C:/...repo/.claude/worktrees/my-feature
# Main repo is at C:/...repo
git -C "C:/.../repo" merge --ff-only worktree-my-feature
# Or for a non-ff merge:
git -C "C:/.../repo" merge --no-ff worktree-my-feature -m "Merge worktree-my-feature"

This works because:

• git -C <path> is equivalent to cd <path> && git ... but doesn't change YOUR shell's cwd
• The merge target (main) is checked out in the main repo's working directory
• The merge source (worktree-my-feature) is a branch ref in the shared .git/ directory
• No two checkouts of the same branch are needed; main stays checked out in main's working dir, the feature branch stays checked out in the worktree

Verification

After the merge, verify main advanced and the worktree branch is preserved:

git -C "<main-path>" log --oneline -3            # main now contains the merged commits
git -C "<main-path>" branch -v                   # both 'main' and 'worktree-my-feature' present
git -C "<main-path>" status                      # clean

If you want to push immediately:

git -C "<main-path>" push origin main

When NOT to use this

• If ExitWorktree DOES work, just use it. This workaround is for when the cwd-override refusal happens.
• If your merge has conflicts, you'll want to be ON the merging branch (main) interactively — the git -C approach still works, but you can't navigate to fix conflicts from inside the same shell. Resolve them by editing files (Edit tool works fine regardless of shell cwd).
• If you're doing a rebase rather than a merge, the same git -C works.

Notes

• Don't try to use EnterWorktree(path=<existing-worktree>) to "switch" to the main worktree as a workaround — the main worktree typically isn't a linked worktree and isn't in the worktree registry the tool checks.
• Don't try to cd "<main>" in a Bash tool call and then run plain git merge — Bash tool calls don't persist cwd between invocations on most platforms, and even when they do, the harness's process-wide cwd may not be what the next tool call sees.
• The same git -C pattern works for git log, git diff, git status, etc. — any time you need to ask git about a repo other than the one your shell is currently in.

Example (from skill-harness 2026-06-09)

1. EnterWorktree(name="w2-cli-engineering") — session moves to .claude/worktrees/w2-cli-engineering
2. Implementer subagent commits a9bdacc, then f6201a8, on branch worktree-w2-cli-engineering
3. Reviews pass.
4. Try ExitWorktree(action="keep") — REFUSED ("cwd override").
5. Workaround:
   git -C "/path/to/your/repo" merge --ff-only worktree-w2-cli-engineering
   → Fast-forward; main advanced f13b3fd → f6201a8 (2 commits, +521 insertions).
6. git -C "/path/to/your/repo" push origin main

The merge succeeded without ever exiting the worktree session.

References

• git -C documentation: https://git-scm.com/docs/git#Documentation/git.txt--Cltpathgt
• Git worktree documentation: https://git-scm.com/docs/git-worktree