Re-add hang protection after the user's run showed pytest hanging in interpreter shutdown (ThreadPoolExecutor.__del__ / live_gui teardown) after Batch 1 completed successfully. The previous naive watchdog (e1c8730f, 30s os._exit(0)) cut off batches mid-test; the immediate removal (4103c08e) let real hangs wait 1000s for the runner's subprocess timeout.
This SMART watchdog only fires when pytest is ACTUALLY hanging:
- pytest_unconfigure hook sets _pytest_finished_event when the
test session is done (BEFORE interpreter finalization).
- Watchdog waits for the event with 120s timeout:
* If not set in 120s: pytest is hung in test execution -> os._exit(2).
* If set: pytest finished cleanly; give 30s for normal
interpreter shutdown (ThreadPoolExecutor.__del__, etc.).
* If still alive after grace: io_pool / live_gui teardown
is hung -> os._exit(2).
- Exit code 2 (not 0) so run_tests_batched.py correctly reports
a failed batch (CalledProcessError). The 0 in the previous
version masked hangs and hid test failures.
Contract:
- Normal batch (35s execution, 2s shutdown): pytest_unconfigure
fires at 35s, watchdog's first wait returns immediately, 30s
grace elapses without fire, pytest exits with 0. Runner: passed.
- Hung batch: pytest_unconfigure never fires, watchdog fires
os._exit(2) at 120s. Runner: failed.
- Hung shutdown (io_pool.__del__ blocks): pytest_unconfigure
fires, 30s grace elapses, watchdog fires os._exit(2). Runner: failed.
5 new tests in tests/test_conftest_smart_watchdog.py:
- test_watchdog_thread_registered: daemon thread named conftest-smart-watchdog
- test_watchdog_thread_is_daemon: doesn't block pytest exit
- test_pytest_unconfigure_sets_finished_flag: hook exists in conftest
- test_watchdog_uses_non_zero_exit_code: os._exit(2) is used
- test_watchdog_timeouts_documented: 120s and 30s are present
