The Margin Ceiling on Resold Intelligence: Why AI Infrastructure Is Now an Agency Cost-Architecture Decision

Every AI-inclusive retainer an agency signs is a bet on third-party compute pricing it does not control. As frontier model access commoditizes, the agencies that win are the ones that treat model routing, caching, and self-hosted inference as delivery infrastructure rather than as line items on a client invoice. The strategic question is no longer which model to use; it is how much of the inference stack you own before a provider repricing event eats your margin.