Desktop + WSL: composer branch chip shows '—' and worktree toggle silently creates no worktree (session runs in main checkout)

Summary

On the Windows desktop app with a WSL (Ubuntu) environment, the new-session composer's branch/worktree chip renders a dash (—) instead of the branch name for a healthy repo on the WSL filesystem. Additionally, with the worktree toggle enabled, the session starts directly in the main checkout — no worktree is ever created (git worktree list shows only the main checkout).

The same composer shows the branch correctly (main) for a repo in a cloud environment, so the chip UI itself works — the failure is specific to the WSL path.

Environment

• Desktop app: Windows (Microsoft Store install, Claude_pzs8sxrjxfjjc), WSL environment = Ubuntu
• WSL: WSL 2, kernel 6.18.35.2-microsoft-standard-WSL2, systemd enabled
• Bundled remote CLI: ~/.claude/remote/ccd-cli/2.1.209 (standalone CLI in distro: 2.1.211, native install)
• Repo: a private repo under /home/<user>/... (Linux filesystem, not /mnt/c), branch master, clean, owned by the session user (no safe.directory issue)
• git inside distro: 2.53.0 at /usr/bin/git only (no Windows git on PATH)

What I verified (it's not the WSL setup)

• git branch --show-current inside the distro instantly returns master; git rev-parse --is-inside-work-tree → true.
• The desktop's WSL bridge (~/.claude/remote/srv/.../server --serve/--bridge) is running and spawning sessions fine.
• The bridge log (~/.claude/remote/run/<id>/remote-server.log) shows the app polling git in this repo every ~20s–3min, and every git process exits with code 0 — no errors in current or rotated logs. So the branch data is being fetched successfully but not rendered.

Repro

1. Windows desktop app → new session → environment: WSL Ubuntu → folder: a git repo under /home/... (branch master).
2. Composer branch/worktree chip shows — instead of master. (A cloud-environment repo in the same composer shows its branch correctly.)
3. Enable the worktree toggle and start the session.
4. In the session: pwd = the main checkout path (not a worktree); git worktree list = main checkout only. No worktree was created, despite the toggle.

Expected

• The chip shows the current branch for WSL repos (docs state branch status "works, backed by the git inside the distribution" — https://code.claude.com/docs/en/desktop-wsl.md).
• With the worktree toggle on, the session runs in a freshly created worktree, or surfaces an error if creation fails — rather than silently running in the main checkout while the UI implies isolation.

Impact

Sessions the user believes are isolated in a worktree are actually mutating the primary checkout.