O4DB Protocol: A Sovereign Agentic Commerce Architecture for Cryptographic Buyer Sovereignty

Current e-commerce architectures impose a structural asymmetry: demand signals are captured by platform intermediaries before reaching supply, enabling price discrimination, ranking manipulation, and systematic extraction of buyer surplus. O4DB™ (Only For Determined Buyers) is a decentralized protocol that inverts this model through three architectural mechanisms: (1) Hybrid Public Key Encryption (HPKE, RFC 9180) for price ceiling confidentiality, making buyer valuation cryptographically inaccessible to any relay or seller node; (2) a local-only Automated Ranking Algorithm (ARA) that executes ranking exclusively on the buyer device; and (3) a deterministic four-state settlement machine with Ed25519-signed fingerprints for post-transaction auditability. The paper also introduces UODI (Universal Omnimodal Demand Identifier, U.S. Provisional App. No. 63/993,355), a 91-character fixed-width structured identifier achieving a 10× reduction in demand payload size compared to standard JSON schemas, with native support for progressive location disclosure in security-sensitive logistics scenarios. Stress tests at 100 concurrent buyer/seller nodes yield p50 = 2.0s end-to-end latency with p95 = 5.0s on commodity hardware, with a 95% transaction completion rate. The protocol is analyzed against Sybil, replay, and man-in-the-middle attack vectors. The reference implementation is available at github.com/dannythecountok/O4DB-Protocol. U.S. Provisional Patent App. No. 63/993,946 (O4DB) and 63/993,355 (UODI). Filed March 1, 2026.