Desktop app 1.1.15: cannot create a second Local (branch) session while one is running — "This project already has an active Local workspace"

首先，使用一個正在執行的 Local 工作階段透過 create_branch_workspace 重現失敗，然後檢查 1.1.15 的記錄以及回報的主動分支預熱字串。完成的標準是可以再次並行建立多個 Local 工作階段，或是將任何刻意設定的限制與可採取行動的錯誤訊息一併記錄。

Describe the bug

After the desktop app auto-updated to 1.1.15, creating a new Local (branch-type) session in a project fails whenever another Local session in that same project has a live CLI process:

Session creation failed: Failed to create session: invalid argument: This project already has an active Local workspace.

This is a behavior change. Before 1.1.15 I routinely ran several Local sessions side by side in the same project, and had done so for ~3 months.

The blocking condition appears to be a running session, not the number of workspaces: at the moment of failure the project had 74 non-archived workspace_type='branch' workspaces, and exactly one session row with is_running = 1 — the session I was actively chatting in. So the app effectively enforces "one live Local session per project", and the currently-focused session is the thing that blocks creating the next one.

Affected version

Desktop app 1.1.15 (macOS). Bundled CLI: 1.0.83-5.

Steps to reproduce the behavior

1. Open a project backed by a local checkout using Local / branch workspaces (not worktrees).
2. Start a session in it and keep it active (live CLI process).
3. Try to create another session in the same project.
4. Creation fails with invalid argument: This project already has an active Local workspace.

Expected behavior

Multiple Local sessions in the same project should be creatable concurrently, as they were in 1.1.13 / 1.1.14. If concurrent Local sessions must now be limited, the restriction should be documented and the error should say what to do about it (e.g. "stop session X first") rather than surfacing a raw invalid argument.

Additional context

Evidence that this is new in 1.1.15

Possibly related new strings in the 1.1.15 binary, which suggest this comes from a new proactive branch-warmup mechanism:

• This project already has an active Local workspace.
• Local workspace creation is still waiting for proactive warmup cleanup.
• Proactive branch warmup stopped because the shared checkout changed before the session started.
• internal error: entered unreachable code: branch workspace wait loop always returns

Why worktrees aren't a workaround here

The project in question is a personal Obsidian vault. The notes must live at one fixed path so the Obsidian app and the sessions see the same files, so Local/in-place is the only viable workspace type — a worktree would create a detached copy and break the vault. That makes "use worktrees instead" not an option, and "stop the session you're currently talking in before you can start another" a significant workflow regression for anyone using several topic-scoped sessions against one local checkout.

Environment

• macOS, Apple Silicon
• Desktop app 1.1.15, CLI 1.0.83-5