Summary of Changes

Hello @yashbhutwala, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request integrates Cashu payment support into the x402 A2A library. It introduces enhanced functionality for defining Cashu payment requirements, including pre-configured mint URLs, and refines the payment processing workflow to explicitly manage Cashu payloads. These changes aim to provide a clear and robust mechanism for handling Cashu-based transactions within the system.

Highlights

• Cashu Payment Requirements: Added support for creating Cashu payment requirements, including default mint URLs for Bitcoin testnet and mainnet, and validation for numeric price inputs.
• Explicit Cashu Payload Handling: Modified wallet helper functions to explicitly process Cashu payment payloads, requiring direct submission of Cashu proofs and preventing implicit handling of Cashu tokens in general payment processing.
• Unit Test Coverage: New unit tests have been added to validate the correct creation of Cashu payment requirements and the proper processing of Cashu payments.

Code Review

This pull request introduces support for Bitcoin Cashu payments by updating the core merchant and wallet logic. The changes are well-structured, adding a new 'cashu-token' payment scheme and handling its specific requirements, such as mint URLs and proofs. The inclusion of unit tests for the new functionality is a great practice. My review includes a couple of suggestions to improve code clarity and provide more helpful error messages, but overall, this is a solid implementation.

Code Review

This pull request introduces support for Bitcoin Cashu payments. The changes include updating create_payment_requirements in merchant.py to handle the cashu-token scheme and modifying process_payment in wallet.py to process Cashu payloads. New unit tests have been added to cover the basic flow. My review focuses on improving code structure, enhancing error reporting for better debugging, and expanding test coverage to ensure the new functionality is robust. Overall, the implementation is solid, and the suggested changes are aimed at improving maintainability and reliability.

Code Review

This pull request introduces support for Cashu payments by extending create_payment_requirements and process_payment to handle the cashu-token scheme. The changes include logic for creating payment requirements with Cashu-specific details like mint URLs and processing payments with provided Cashu proofs. Unit tests for the new happy path flows are also included.

My review focuses on improving the robustness and maintainability of the new logic. I've suggested improvements to price validation to prevent silent data loss, refactoring opportunities to reduce code duplication, performance enhancements for payload validation, and an expansion of the test suite to cover important failure scenarios. Overall, the changes are well-structured, and addressing these points will further strengthen the implementation.

Thanks for this PR. We're glad to see you're using the extra field for the Cashu-specific data—that's the right approach.

We have an architectural concern about adding this logic directly into the core create_payment_requirements function. Adding Cashu-specific arguments and if...then logic there will bloat the core library and make it hard to maintain as we add more payment methods.

We'd like to propose a more scalable "plugin" approach. We're thinking the new file structure would look like this:

python/
  x402_a2a/
    ...
    core/
      (our existing core files)
    partners/
      __init__.py
      cashu/
        __init__.py
        helpers.py   <-- Your new code would go here
        README.md

In this new partners/cashu/helpers.py, you would add your new functions (like create_cashu_payment_requirements and process_cashu_payment). The core functions would remain untouched.

This keeps our core library clean, stable, and scalable. It correctly separates the "partner implementation" from the "core logic" and lets each partner's code live in one isolated place.

Let us know your thoughts and if you would you be open to refactoring this PR to follow this structure? Thanks again for your contribution!