findPreviousRun excluded only the file being written, by name, so every
suite compared against _partial-e2e.json — the current run's own
accumulator, relabelled with the current tier just before each flush.
That is why every block read '+$0.00, +0s, Stable run, no regressions.'
This harness has never been able to detect a regression, and reassuring
output that cannot fail is worse than none. In-progress runs are now
excluded by role, and a run with nothing to compare against says NO
BASELINE instead of claiming stability.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
(cherry picked from commit f3140b5245221fff7fb9411c7ec07c2ca11587b5)