Python Client Manual Flow

import requests

url = "http://localhost:4021/weather"
response = requests.get(url, timeout=10, allow_redirects=False)

import base64
import json

if response.status_code != 402:
    raise RuntimeError(f"Not a payment challenge ({response.status_code}); stop this walkthrough")

payment_required_b64 = response.headers.get("PAYMENT-REQUIRED")
if not payment_required_b64:
    raise ValueError("402 without PAYMENT-REQUIRED header")

payment_required = json.loads(
    base64.b64decode(payment_required_b64, validate=True).decode("utf-8")
)
# payment_required has: x402Version, error, resource, accepts, extensions
# accepts is a list of payment options (scheme, network, amount, asset, payTo, etc.)

import re

accepts = payment_required["accepts"]
# EVM path:
accepted = next((a for a in accepts
    if a["scheme"] == "exact" and a["network"] == approved_network
    and a["asset"] == approved_asset and a["payTo"] == approved_recipient
    and re.fullmatch(r"[1-9][0-9]*", a["amount"])
    and int(a["amount"]) <= max_amount_atomic), None)
if not accepted:
    raise ValueError("No payment option approved by local policy")

import os
import time

# You need: payer private key, accepted requirement, token contract (asset),
# valid_after, valid_before, nonce, and EIP-712 signing.
payload = {
    "x402Version": 2,
    "resource": payment_required["resource"],
    "accepted": accepted,
    "payload": {
        "signature": "0x...",  # EIP-712 signature
        "authorization": {
            "from": payer_address,  # Replace with your wallet address
            "to": accepted["payTo"],
            "value": accepted["amount"],
            "validAfter": "0",
            "validBefore": str(int(time.time()) + min(60, accepted["maxTimeoutSeconds"])),
            "nonce": "0x" + os.urandom(32).hex(),
        },
    },
    "extensions": payment_required.get("extensions", {}),
}
payment_signature_b64 = base64.b64encode(json.dumps(payload).encode()).decode()

# Alternative to the EVM block: use an exact Solana requirement approved
# by the same explicit resource/network/asset/recipient/budget policy.

# 4. Build Solana transaction (pseudocode — use solders/solana-py in practice)
# - Configure compute-budget instructions within the facilitator's current policy
# - Add TransferChecked: amount=accepted["amount"], mint=accepted["asset"],
#   decimals from token metadata, source=payer_token_account, destination=payee_token_account
# - Finalize all instructions, then partially sign with the payer keypair
# - Serialize transaction to bytes, then base64

# transaction_bytes = serialized_signed_tx  # from your Solana library
transaction_b64 = base64.b64encode(transaction_bytes).decode()

payload = {
    "x402Version": 2,
    "resource": payment_required["resource"],
    "accepted": accepted,
    "payload": {
        "transaction": transaction_b64,
    },
    "extensions": payment_required.get("extensions", {}),
}
payment_signature_b64 = base64.b64encode(json.dumps(payload).encode()).decode()

retry_response = requests.get(
    url,
    headers={"PAYMENT-SIGNATURE": payment_signature_b64},
    timeout=10,
    allow_redirects=False,
)

payment_response_b64 = retry_response.headers.get("PAYMENT-RESPONSE")
if payment_response_b64:
    payment_response = json.loads(
        base64.b64decode(payment_response_b64, validate=True).decode("utf-8")
    )
    print("Reported settlement (validate before use):", payment_response)
    if payment_response.get("success") is not True:
        raise RuntimeError("Settlement not confirmed; retain the response and reconcile before paying again")
else:
    print("Settlement details unavailable; do not infer settlement from HTTP status")

if not 200 <= retry_response.status_code < 300:
    raise RuntimeError(f"Request failed: {retry_response.status_code}; reconcile before paying again")
print(retry_response.json())

{
  "success": true,
  "transaction": "0x1111111111111111111111111111111111111111111111111111111111111111",
  "network": "eip155:84532",
  "payer": "0x857b06519E91e3A54538791bDbb0E22373e36b66"
}

{
  "success": true,
  "transaction": "AXGcLa7sqSjt7pXV4mpVRP5a77tVjokZbgx8gkQ16X8Wgg3vDkWKMh9BrPTr1f2KrDuf9nSX7FrZEAQTkJ3y5UN",
  "network": "solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1",
  "payer": "6KPYDyuRnpuKcm1TerUmwLd2BcaihvhF4Ccrr8beruu2"
}

{
  "success": false,
  "errorReason": "insufficient_funds",
  "transaction": "",
  "network": "eip155:84532"
}