nightly.yml runs every harness from scratch on main at 03:00 Paris time on the Mac mini's runner, after
preparing the resources again if the preparer changed. tools/ci/parity_issues.py compares the results with
the previous audit: a harness that passed and now fails gets one issue labelled parity-regression (an open
one is commented on), and an issue closes when its harness passes again. The bugs session picks them up.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>