ECO.5:1 - Problem frame
Use this pattern when an exchange depends on quality, circumstances or future action that one party knows or controls and another cannot cheaply observe or verify. Begin with the consequential choice each party can make under the proposed terms. Compare terms that make the desired contribution worthwhile while leaving participation attainable.
The useful result is a proposed exchange with a stated incentive mechanism and its limits, or a reason the exchange cannot be made acceptable. An ordinary purchase with adequate known quality and established terms needs no new contract model.