Dry run for a batch of video ids: resolves which campaigns each id actually appears in and returns the summary — matched, unknown, and skipped-because-ended — WITHOUT writing anything.

scope defaults to campaign (act only on this campaign, what a brand expects from a button on one campaign's Content tab). scope: shop is the opt-in that also resolves every OTHER campaign the video appears in — far more destructive, so it is never implied. Always preview a shop-scoped batch before applying it.

Read-only, but gated on read_write scope: it is the first step of the bulk-exclusion write flow and reveals exactly what that flow would change. No Idempotency-Key needed (nothing is written).