-- Long-term cache for page → image URL mappings extracted via og:image,
-- JSON-LD, or first content <img>. Fetching every recipe page on every
-- search is expensive; store the mapping with a 30-day default TTL.
CREATE TABLE thumbnail_cache (
  url        TEXT PRIMARY KEY,
  image      TEXT,          -- NULL = page has no image (cache the negative too)
  expires_at TEXT NOT NULL  -- ISO-8601 UTC
);

CREATE INDEX idx_thumbnail_cache_expires ON thumbnail_cache(expires_at);