TSAPS v1.0: Transaction-Scoped Authenticated Proof System with Deterministic Channel Binding and Multi-Region Idempotency

We introduce TSAPS v1.0, a transaction-scoped authentication and integrity protocol designed for high-integrity API ecosystems. TSAPS binds application-layer transactions to TLS sessions and enforces multi-region replay resistance through deterministic transaction identifiers and short-lived identity tokens. We formalize the protocol in a computational model and provide security arguments for authenticity, replay resistance, channel binding integrity, and bounded idempotency. The protocol was designed through an iterative AI-assisted cryptographic engineering process under human-directed threat modeling.