Server(fix[new_session]): Harden error handling and TMUX env restoration #628
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why: new_session() deletes os.environ["TMUX"] before calling tmux but only restores it on the success path — any exception permanently leaks the deletion. Additionally, proc.stdout[0] raises an unhelpful IndexError if tmux produces no output. what: - Wrap all code after del os.environ["TMUX"] in try/finally to ensure restoration on any exception (including setup-phase errors) - Guard against empty proc.stdout with descriptive LibTmuxException - Add tests for empty stdout, TMUX env restoration on cmd errors, and TMUX env restoration on setup-phase errors - Document monkeypatch usage in test docstrings per CLAUDE.md
Codecov Report❌ Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## master #628 +/- ##
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+ Coverage 45.39% 45.76% +0.36%
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Files 22 22
Lines 2249 2253 +4
Branches 360 361 +1
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+ Hits 1021 1031 +10
+ Misses 1082 1077 -5
+ Partials 146 145 -1 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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Summary
new_session()deletesos.environ["TMUX"]before calling tmux but only restores it on the success path — any exception permanently leaks the deletion. This wraps all post-deletion code intry/finally.proc.stdout[0]raises an unhelpfulIndexErrorif tmux produces no output. This adds an explicit guard with a descriptiveLibTmuxException.Split out from #576 — hardening that's independent of the race condition fix itself.
Changes
src/libtmux/server.py:del os.environ["TMUX"]intry/finallyto ensure restoration on any exception (including setup-phase errors likepathlib.Path.expanduser())proc.stdoutwith descriptiveLibTmuxExceptiontests/test_server.py:test_new_session_empty_stdout— verifies error on empty stdouttest_new_session_restores_tmux_env_on_error— verifies TMUX restored after cmd errortest_new_session_restores_tmux_env_on_setup_error— verifies TMUX restored after setup-phase errorTest plan
uv run pytest— 875 passed, 1 skippeduv run ruff check .— all checks passeduv run mypy src tests— no issues