-- Track when we last successfully scraped a wsid's "Required Items" section.
-- Without this, we can't distinguish "successfully scraped, zero required
-- items" (a stable empty []) from "never scraped" (also empty {} per schema
-- default). Backfill jobs and the missing-dep auto-resolver use it to skip
-- already-known-empty pages.
ALTER TABLE workshop_meta
    ADD COLUMN IF NOT EXISTS required_scraped_at TIMESTAMPTZ;