The docker suite's wall time was max(whale files): four files each
serialized 2-3 ~110s container boots internally while 21 fast files
finished in seconds (P50 9.9s vs max 341s on the ARC runners). The
per-file parallel runner can only overlap what lives in separate files.
- test_dashboard.py -> 3 files (one boot each); shared _http_probe
helper moves to conftest
- test_container_restart.py -> 2 files (restart_container fixture
travels via the shared header; per-file container isolation is the
point of the split)
- test_docker_exec_privilege_drop.py -> boot-heavy e2e login test split
out; the two fast tests stay together
- test_config_migration.py: single test, unchanged
53 tests before and after, zero assertions changed — pure file
reorganization. Local (-j4, same cap as CI): 374.6s -> 58.0s wall,
slowest file 341.7s -> 18.6s.
