[hhff]

What

• test/kit.test.mjs:
  • A tmux shim first on PATH runs the real tmux only while TMUX_TMPDIR is an existing private dt-tmux-* directory, and refuses (exit 1) otherwise.
  • The run's private directory is removed in a process exit handler, after its kill-server, instead of in the "devteam kit" test's t.after.
  • The fleet fixtures' done() kills their own server before removing their directory.

Why

tmux silently falls back to the default server when TMUX_TMPDIR points at a deleted directory. I verified it: TMUX_TMPDIR=<deleted> tmux ls lists the live fleet's session.

The "devteam kit" test's cleanup deleted the private directory, and about 80 later top-level tests call tmux, including kill-server. So running the full suite on a machine with live devteam fleets killed them: stacksbot's fleet was wiped twice today, at 20:40Z and 23:47Z. Thanks to the stacksbot supervisor for the report, and to the test-speed session for finding the mechanism. CI was never affected, since nothing else runs tmux there.

Checked by hand:

• with a live private directory, the shim passes through to tmux;
• with a deleted directory, or with TMUX_TMPDIR unset, it refuses;
• nothing in the kit or the tests calls tmux by an absolute path.

Migration

None. Tests only.

🤖 Generated with Claude Code

[hhff]

Merging (upstream loop): a test-only safety fix, and CI 18/20/22/24 is green. The shim was checked by hand (it passes with a live private dir, and refuses with a deleted one or none), and nothing calls tmux by an absolute path. The full local suite runs next as part of the v0.20.1 candidate, with this in it.