sangria-core 0.3.3

Python Merchant SDK for Sangria payment preflight and settlement

sangria-core

Python SDK for accepting x402 payments. Supports FastAPI.

Install

pip install sangria-core

Quick Start

FastAPI

from fastapi import FastAPI, Request
from sangria_sdk import SangriaMerchantClient
from sangria_sdk.adapters.fastapi import require_sangria_payment

app = FastAPI()
client = SangriaMerchantClient(
    base_url="https://api.sangria.net",
    api_key="sg_live_...",
)

@app.get("/premium")
@require_sangria_payment(client, amount=0.01, description="Premium content")
async def premium(request: Request):
    # request.state.sangria_payment.transaction == "0x..."
    return {"data": "premium content"}

Bypass Payments

Skip payment for certain requests. This is useful if you want to let API key users access your endpoints for free while charging anonymous or agent-based callers via x402:

@app.get("/premium")
@require_sangria_payment(
    client,
    amount=0.01,
    bypass_if=lambda req: req.headers.get("x-api-key") is not None,
)
async def premium(request: Request):
    return {"data": "premium content"}

If your bypass_if callback raises, the SDK logs the exception (via logging.getLogger("sangria_sdk"), prefixed [sangria-sdk]) and falls through to the normal payment-required flow — the request is not bypassed. This is intentional: the SDK fails closed so a crashing callback cannot silently leak free access to paid endpoints. Write callbacks defensively against missing headers, unavailable stores, etc.

How It Works

The @require_sangria_payment decorator handles the x402 negotiation loop:

1. First request (no PAYMENT-SIGNATURE header): calls Sangria's /v1/generate-payment endpoint, returns 402 Payment Required with payment terms and a base64-encoded PAYMENT-REQUIRED response header.
2. Retry (with PAYMENT-SIGNATURE header): forwards the signed payload to Sangria's /v1/settle-payment endpoint. On success, stores the result in request.state.sangria_payment and calls your handler.

Errors

The SDK raises a SangriaError (or subclass) when the Sangria backend is unreachable, times out, or returns a non-2xx status. Business-level payment failures (bad signature, insufficient funds) are not errors — they flow through as normal 402 responses.

SangriaError                   # base — catch-all
├── SangriaConnectionError     # DNS, refused, socket error
│   └── SangriaTimeoutError    # client-side timeout
└── SangriaAPIStatusError      # backend returned non-2xx (has .status_code, .response)

Every error carries .operation ("generate" or "settle") so you know which call failed.

from fastapi import Request
from fastapi.responses import JSONResponse
from sangria_sdk import SangriaError

@app.exception_handler(SangriaError)
async def sangria_error_handler(_request: Request, exc: SangriaError):
    return JSONResponse(
        status_code=503,
        content={"error": "Payment provider unavailable"},
    )

API Contract

POST /v1/generate-payment

Request:

{ "amount": 10000, "resource": "/premium", "description": "Premium content" }

Response (402):

{
  "x402Version": 2,
  "accepts": [{
    "scheme": "exact",
    "network": "eip155:84532",
    "amount": "10000",
    "asset": "0x036CbD53842c5426634e7929541eC2318f3dCF7e",
    "payTo": "0xWalletAddress",
    "maxTimeoutSeconds": 60
  }],
  "resource": { "url": "/premium", "description": "Premium content" }
}

POST /v1/settle-payment

Request:

{ "payment_payload": "<base64 EIP-712 signed authorization>" }

Response:

{ "success": true, "transaction": "0x...", "network": "base", "payer": "0x..." }

Requirements

• Python >= 3.10
• FastAPI >= 0.135.1
• httpx >= 0.28.1