Scheme: exact

Summary

exact is a scheme that transfers a specific amount of funds from a client to a resource server. The resource server must know in advance the exact amount of funds they need to be transferred.

Example Use Cases

• Paying to view an article
• Purchasing digital credits
• An LLM paying to use a tool

Appendix

Critical Validation Requirements

While implementation details vary by network, facilitators MUST enforce security constraints that prevent sponsorship abuse. Examples include:

SVM

• Fee payer safety: the fee payer MUST NOT appear as an account in sensitive instructions or be the transfer authority/source.
• Destination correctness: the receiver MUST match the payTo derived destination for the specified asset.
• Amount exactness: the transferred amount MUST equal maxAmountRequired.

Network-specific rules and exact instruction layouts are defined in the per-network scheme documents. For Solana (SVM), see scheme_exact_svm.md.