Distinct counts of the entities that share a transaction with each requested entity inside the window — cards, fingerprints, emails, phones, IP addresses, customers, merchants — plus the transaction count and black-list membership. Renders the RELATIONS list of the investigation screen; asking for the whole batch costs the same as asking for one entity. Counts are exact, so they always match the number of members the list endpoint returns. A same-type relation is omitted: one transaction row carries one value per type, so linking two values of the same type is a two-hop question for graph-links/get. The window is required and its span is capped server-side