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Bill8:Checkout — Flutter App

The hosted payment surface: payment pages and links rendered for the customer.

1. Summary​

Bill8:Checkout is the customer-facing Flutter app that renders hosted payment pages. It serves the page definitions supplied by the checkout service and completes sessions through the BFF proxy.

2. Motivation​

Card-handling UI lives in one place — this app — so merchants never build payment pages. Hosted pages keep card data in one surface and simplify compliance.

3. Architecture & High-Level Design​

4. Key Traits and Data Structures​

  • Bff8ApiClient — shared BFF client.
  • Page renderer driven by session definitions.

5. Rationale, Trade-offs, and Alternatives​

  • Hosted over embedded SDK: one card-handling surface.

6. Internal Implementation & Invariants​

  • All calls route through Bff8ApiClient.

7. Unresolved Questions / Future Designs​

  • See the vertical backlog.md.

Design attribution: bill8:checkout and its underlying concepts were designed by Hamid Jahanzad Hamid@Jahanzad.com.