[cdalar]

Fixes two cmd/mux.go bugs found in the review that went with #1275.

1. --mux moved the box to another multiplexer while sessions still ran there

useBoxMux checked only whether the session being started was running in the box's other multiplexer. Every start overwrites the box's mux marker, though, so the box's other sessions were then looked for in the wrong multiplexer:

1. On a herdr box, claude-auth is running and the main session is stopped.
2. onctl claude --mux tmux passes the check, and the marker becomes tmux.
3. claude ls now shows auth as stopped.
4. onctl claude --task auth sees nothing running in tmux, so it starts a second Claude in the same worktree.

Fix: with --mux, the run lists the other multiplexer's sessions and refuses while any Claude session (claude, claude-<task>) is running there. The error names the sessions. Sessions in that multiplexer that aren't Claude's don't count.

2. An ephemeral herdr pane stopped the server after the box was kept

An ephemeral run's pane ran herdr server stop after Claude exited, so the attached client would return and the box could be deleted. That command was fixed at start, so it still ran after the user detached and the run kept the box. If the user then started --box X --task foo there, the main Claude exiting stopped the server and killed foo's Claude.

Fix: the pane stops the server only while /run/boxctl/<session>.stop exists. The run creates that file at start and removes it when it decides to keep the box.

Tests

• TestHerdrStartEphemeral runs the pane's actual command against the fake herdr. With the stop file present, the server is stopped; once the file is removed (kept box), it isn't. A detached start makes no stop file.
• TestClaudeSessions checks that Claude sessions are counted, other sessions aren't, and no herdr server means none.
• Each test fails when its original bug is put back.
• go test ./cmd/ passes, golangci-lint reports 0 issues.

Not tested end to end on a real box. useBoxMux itself needs ssh, so only its decision (claudeSessions) is unit-tested.

🤖 Generated with Claude Code

https://claude.ai/code/session_01Ba6Vc66D5hH1xSTvJcCbVz

[codecov]

Codecov Report

❌ Patch coverage is 63.63636% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 50.67%. Comparing base (5b1c68f) to head (a489bc2).

Files with missing lines	Patch %	Lines
cmd/claude.go	42.85%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1276      +/-   ##
==========================================
+ Coverage   50.64%   50.67%   +0.02%     
==========================================
  Files          83       83              
  Lines        9822     9840      +18     
==========================================
+ Hits         4974     4986      +12     
- Misses       4848     4854       +6     

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