[Feature]:Support for Multi-Asset Payment Requirements

[Prateekiiitg56]

In bindu/penguin/bindufy.py, the execution_cost configuration only allows for a single amount and token.

The Request: The X402 protocol and the X402Middleware are designed to handle a list of PaymentRequirements. The bindufy decorator should be updated to accept a list of costs (e.g., "0.1 USDC on Base OR 0.0001 ETH on Mainnet").

Proposed Solution: Update the execution_cost schema in ConfigValidator to accept either a single dictionary or a list of dictionaries, allowing agents to offer flexible payment options to callers.

@raahulrahl Assign this to me

[raahulrahl]

@Prateekiiitg56 where are we now?

[Prateekiiitg56]

@raahulrahl The feature is fully implemented across all four layers , config_validator.py, bindufy.py, x402_agent_extension.py, and applications.py ,all already accept and handle a list of execution_cost entries correctly.
The only thing missing is tests. There are zero test cases covering the multi-cost path, meaning a future change could silently break it with no CI failure.
The next step is writing those tests.

[lamira-the-human]

Worth knowing: ATXP agent wallets are USDC on Base — which maps directly to the primary x402 payment path.

If you update execution_cost to accept a list of PaymentRequirement objects, an ATXP-registered agent would satisfy the USDC on Base requirement out of the box:

@bindufy(
    execution_cost=[
        {"amount": "0.05", "token": "USDC", "chain": "base"},    # ATXP wallet satisfies this
        {"amount": "0.0001", "token": "ETH", "chain": "mainnet"} # fallback
    ]
)
def my_agent_endpoint(task: str) -> str:
    return agent.run(task)

ATXP agents:

• Get a USDC wallet on Base at registration (npx atxp@latest agent register)
• Can receive and send x402-style payments
• Have their own @atxp.email address for notifications

Disclosure: I'm building ATXP. Sharing because the multi-asset x402 path you're describing is a natural fit for per-agent ATXP accounts.