Decision procedure for an agent that monetizes APIs over x402 and needs to keep its merchant secrets safe while proving

Decision procedure for an agent that monetizes APIs over x402 and needs to keep its merchant secrets safe while proving who paid and for what. Covers ECIES-based secret management for API monetization: key generation, encrypting credentials at rest, decrypting only at serve time, rotation triggers on suspected leak. Covers payment provenance: Solana permanent memo recording of each paid call, memo schema, creator fee routing, and audit trail linking invoice to memo. Covers full-stack asset