The card render endpoint's file-on-disk cache short-circuit returned
FileResponse immediately when the cached PNG existed, bypassing the
backfill BackgroundTask that populates battingcard.image_url /
pitchingcard.image_url. If a variant row was later recreated with
image_url=NULL while the PNG was still cached, the DB column stayed
NULL forever, breaking every downstream consumer that reads image_url for
display.
Extract the backfill-scheduling logic into a _schedule_variant_image_backfill
helper and call it on both the cache-hit and full-render paths. The
helper's internal guards (variant > 0, tier is None, row exists with
NULL image_url) keep the happy-path cache hit a no-op.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
