<b>Reading sellers.json as a graph, not a list</b>

<b>Reading sellers.json as a graph, not a list</b>

sellers.json (a public file where an exchange declares every seller account and whether it's a publisher or an intermediary) and the supply chain object in the bid request together let you reconstruct the full path of an impression. The skill is reading them as a connected graph.

1. Each hop in the supply chain object names a selling entity and its seller ID in that exchange's sellers.json.
2. Walk the chain: publisher to SSP to reseller to your DSP. Each node should be declared, and each declared 'PUBLISHER' node should appear only where a publisher legitimately sits.
3. A reseller declared as PUBLISHER, or a chain that names a domain whose ads.txt never authorized that seller, is a break in the graph — a sign of misrepresented or laundered inventory.

The graph view catches things a flat path list hides: the same impression sold through two chains that converge on an undeclared intermediary, or a 'direct' relationship that ads.txt contradicts.

<b>Why it matters:</b> validating supply chain objects against sellers.json and ads.txt is the cheapest fraud filter you have, and it runs on data already in your log-level feed. Inventory whose graph doesn't close is inventory you should stop buying before you optimize anything else.