Worktree handoff on a Hermes ACP thread kills the run and leaves the continuation and cwd behind #63

Observed (2026-11-01, thread "i wanna add continuous voice mode…")

t3_worktree_handoff created the worktree and rebound the thread, but then:

• the outgoing ACP run ended with "The provider event stream closed unexpectedly";
• the continuation was preserved as queued run [muse] fix(server): reject checkpoint revert while a turn is active #6 but never started on its own;
• the agent's tool shell stayed in the old checkout until it was corrected by hand.

The owner had to send "troubleshoot issue w/ handoff".

Upstream

Upstream 22971 (open, 9 comments) reports the same failure for Claude: the handoff fails the turn and its continuationPrompt never starts. 16520 and 22863 (closed) are earlier Claude variants. This adds the ACP/Hermes case. Contribute the repro there, not as a new issue.

Acceptance

• After a handoff on an ACP provider, the continuation starts in the new worktree with no manual step.
• The provider process cwd matches the new binding.