Cogito

class PaymentHandler:
    """HTTP 402 Payment Required protocol handler."""

    def __init__(self, wallet: SolanaWallet, settings: Settings):
        self.wallet = wallet
        self.budget_limit = settings.autonomy.budget_limit_usd
        self._spent_usd = 0.0

    async def handle_402(self, response: httpx.Response) -> dict:
        """Parse 402 invoice and execute payment."""
        invoice = response.json()
        recipient = invoice["recipient"]
        amount_sol = invoice["amount_sol"]
        memo = invoice.get("memo", "cogito-payment")

        if self._spent_usd + (amount_sol * self._sol_price) > self.budget_limit:
            raise BudgetExceededError(f"Would exceed limit: {self.budget_limit}")

        tx_sig = await self.wallet.send_sol(recipient, amount_sol, memo)
        self._spent_usd += amount_sol * self._sol_price

        return {
            "tx_signature": tx_sig,
            "headers": {
                "X-Payment-Tx": tx_sig,
                "X-Payment-Chain": "solana",
            }
        }