6d16c19a04
Workspace setup/teardown (git clone/fetch, worktree add/remove, chown) ran synchronously on the asyncio dispatcher loop, so one stalled subprocess froze the entire process. - Offload every ensure_workspace/remove_workspace call to a worker thread via a new _run_workspace_op helper that drains the thread to completion on cancellation, so a cancelled event cannot reap/release a slot the setup thread still owns. - Serialize same-repo setup with a per-repo threading.RLock while letting distinct repos run concurrently. - Bound the direct git/chown subprocesses with a 120s timeout (returncode 124); treat a timed-out branch probe as an error rather than "branch absent" to avoid silently rebasing a follow-up onto the default branch and losing the PR's commits. - When a timed-out worktree remove leaves the checkout behind, rmtree it and run `git worktree prune` so the pool's dangling registration cannot trip a later worktree add for the same path. Adds regression tests for event-loop liveness, cancellation-safe offload, per-repo lock serialization, subprocess timeout mapping, the branch-probe timeout guard, and worktree-prune after a failed remove. Op: correct Restores: spec:dispatcher-event-loop-never-blocks-on-workspace-io