design-dev's test read 'the originals shown small (no generated thumbnail)',
which was true when written and is precisely what the operator rejected: four
images per booth on the page he opens first was the heaviest surface in the
service.
Declared rather than quietly edited, per the rule that an existing assertion is
not changed to make a change pass. The behaviour genuinely changed, on his own
instruction to swap all four small surfaces in one commit.
Worth recording in the docstring: the URL carries ?thumb=1 from the EXTENSION
alone, with no disk read, so a tiny stub fixture still gets the parameter and
the route serves the original when there is nothing worth generating. The URL
never depends on what is on disk.
39/39 falsifiers proved across both mutation tables.