System architecture

flowchart TB
    Customer["Customer"] --> Wallet["SAGIO Wallet"]
    Merchant["Merchant"] --> Terminal["SAGIO Terminal"]
    Merchant --> Dashboard["SAGIO Merchant"]
    Wallet --> API["SAGIO API"]
    Terminal --> API
    Dashboard --> API
    API --> DB[("PostgreSQL / Neon")]
    API --> Privy["Privy identity + wallets"]
    API --> Base["Base network"]
    Terminal --> Worldline["Worldline / Fasstap"]
    API -. integration .-> Facilitator["x402 facilitator<br/>separate repository"]

Source boundaries

Product	Path	Production shape
API	apps/api	Cloudflare Worker
Merchant	apps/dashboard	Cloudflare Pages
Wallet	apps/wallet	Web + Capacitor app
Terminal	apps/terminal	Android application
Landing	apps/landing	Cloudflare Pages
x402 facilitator	separate repository	Independent service

Architectural invariants

1. Frontends never authorize themselves; server-side tenant and role checks remain authoritative.
2. Monetary values cross contracts as exact integer minor units or exact token quantities—not floating-point approximations.
3. A payment success claim must point to authoritative rail evidence.
4. Retried requests must not duplicate money movement or external side effects.
5. Uncertain external outcomes are reconciled before retrying.
6. Secrets never enter client bundles, logs, documentation, or repository history.