The initial fit-to-width in the pdf viewer measures container.clientWidth
immediately after showViewer() flips display:flex. Under CI load the reflow
can lag a tick, leaving widthFit >= 1.0 and zoom at 100% when first read,
which intermittently fails the toBeLessThan(100) assertion (~6 failures in
the 30 runs since #583).
Swap the single-shot read for expect.poll, matching the pattern already used
for the post-fullscreen assertion below, then capture inlineZoom for the
subsequent comparison.
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