4mica-x402 1.0.0

Python integration for x402 Payment Protocol with 4mica credit flow

4mica-x402

Python integration for the x402 Payment Protocol with 4mica credit flow support.

Install

pip install 4mica-x402

Optional extras:

• fastapi (FastAPI middleware)
• flask (Flask middleware)
• httpx (async HTTP client wrapper)
• requests (sync HTTP client wrapper)
• all (everything)

Quick Start (Server)

from fastapi import FastAPI
from fourmica_x402.http import fastapi_payment_middleware_from_config

app = FastAPI()

routes = {
    "GET /premium": {
        "accepts": {
            "scheme": "4mica-credit",
            "price": "$0.01",
            "network": "eip155:11155111",
            "payTo": "0xRecipient",
        }
    }
}

middleware = fastapi_payment_middleware_from_config(
    routes,
    tab_endpoint="https://api.example.com/payment/tab",
)

@app.middleware("http")
async def x402_mw(request, call_next):
    return await middleware(request, call_next)

Quick Start (Client)

from x402 import x402ClientSync
from x402.http.clients import x402_requests
from fourmica_x402.client_scheme import FourMicaEvmScheme

client = x402ClientSync()
client.register("eip155:11155111", FourMicaEvmScheme("0xYourPrivateKey"))

session = x402_requests(client)
resp = session.get("https://api.example.com/premium")
print(resp.status_code, resp.text)

V2 Validation Policy Notes

For x402 V2 requests, include validation policy metadata in paymentRequirements.extra:

• validationRegistryAddress
• validatorAddress
• validatorAgentId
• minValidationScore
• optional requiredValidationTag

validationChainId is optional. When omitted, the underlying 4mica SDK derives validation_chain_id from the CAIP-2 network value (for example, eip155:1). If provided, it must match that network chain id.

Development

python -m build
python -m pytest

Install dev tools:

pip install -e .[dev]