Loads each overlay's real URL in a live iframe (using its own ?test=1/?preview=
harness where one exists) and checks the rendered DOM for broken images, empty or placeholder
(undefined/NaN) text, and layout overflow — a PASS here means the graphic actually looks right for
that club, not just that the data resolved. Heavier per-club checks are opt-in (click Run) so the page
doesn't hammer the worker/esportsdesk on every load.
Static assets
Standings PNGs, DVD Bounce loops, UP-NEXT graphics — checked directly (no iframe needed), auto-runs on load.
Same worker/CDN endpoints the overlays themselves use. Nothing here writes to the live control
channel except the explicit L3/Starting-Lineup ?preview= checks, which render locally
in the test iframe only — they never touch another producer's live state.
Docs: repo README.