# Key diagrams System Overview Architecture Diagram * Three layers: User (App / Live / Tasks) → PayFi (Card / Clearing & Settlement / Risk) → On-chain (Contract Suite / Anchors). * Highlight the event bus, ledger, KYC/AML, and merchant portal placement. Sequence Diagram: Top-up to Spend * Top-up → FX → Ledger Posting → Auth → Capture → Anchoring → Rebates Swimlane Diagram: Merchant Quest → Issuance → Settlement * Five lanes: Merchant, User, Risk Control, Contracts, Clearing & Settlement. DID/NFT Social Card & Rights Linkage Diagram * DID → Reputation → Social Card → Rights (Membership / Fee Discounts / Limits / Allowlist). Anti-Fraud / Risk Signal Stack Diagram * Pre / During / Post controls with signal sources: device, behavior, MCC, geography, history. Public KPI Dashboard Examples * MAPU, Card Activation Rate, Merchant GMV, Repurchase Rate, Net Demand Curve. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://metya.gitbook.io/metya/product-and-architecture/key-diagrams.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.