run-visual verified only that the captured PNG was non-empty AS A FILE. A
blank screen is a perfectly valid ~19 KB PNG, so it passed — and once a blank
capture had been recorded as a golden, every later blank capture matched it at
0.0% and the scenario PASSED. atlas_GJ338Bd_Block and atlas_GJ445c-m1_Chunk
sat green against blank goldens while the suite's other 30 scenarios failed.
That is the worst kind of test result: indistinguishable from success, and
load-bearing for exactly the work it fails to cover. e024cfb3f recorded this
same failure once already ("the Atlas Global goldens have been measuring
nothing"); it recurred because nothing checked the property, only the file.
tooling/visual-blank-check measures the share of the frame taken by its single
most common colour. On this project's real captures the classes are far apart:
Global (real world map) 38.7% modal
Region (flat colour wash) 7.2% modal <- dither; least uniform of all
District 45.4% modal
Block / Chunk / Quarter 92.9-94.6% modal <- nothing drawn
Nothing falls between 45% and 93%, so the 0.85 default sits in open space
rather than being tuned against a boundary case. Deliberately NOT an aesthetic
judgement: the Region wash is a real product gap (T-1213) and scores 7.2%,
comfortably "content". The question is only whether a world reached the
screen.
Wired into both paths, and the update path is the one that matters — refusing
to RECORD a blank golden is what stops the trap being re-armed. Ad-hoc
--screenshot only warns, since capturing a rung that renders nothing is a
legitimate thing to want to do; that is how the empty deep rungs were found.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
jpmschweitzerandClaude Opus 5
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