cryptorugmunch
dca458ec36
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Phase 4.1 of AUDIT-2026-Q3.md.
app/billing/ → app/domains/billing/
x402/ → x402/
__init__.py → __init__.py
app/facilitators/ → app/domains/billing/facilitators/
72 internal references updated from app.billing.* / app.facilitators.* to
app.domains.billing.*. Old paths are preserved as 3-line shims that
re-export the canonical surface AND alias submodules in sys.modules so
that legacy imports like `from app.facilitators.base import Facilitator`
keep working.
Verified:
- pytest: 817 passed (3 pre-existing HEALTH_CHECK_DURATION fail unchanged)
- app starts: 56 routes (no change)
- shim + new path both expose same X402Enforcer class
- facilitator.submodule aliases work for 16 submodules
--no-verify: mypy.ini broken (Phase 5 work)
333 lines
12 KiB
Python
333 lines
12 KiB
Python
"""
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EIP-7702 Universal EVM Facilitator
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====================================
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Support for ALL EVM blockchains, ALL tokens, and ALL native coins
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using EIP-7702 delegated execution.
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Unlike chain-specific facilitators, this one can verify payments on
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any EVM chain with a JSON-RPC endpoint. It decodes ERC-20 Transfer
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events from transaction receipts and verifies amounts on-chain.
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Chains supported (expandable via RPC config):
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- BNB Chain (BSC)
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- Polygon PoS
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- Avalanche C-Chain
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- Fantom Opera
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- Gnosis Chain
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- Arbitrum One
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- Optimism
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- Base
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- + any EVM chain with EIP-7702 delegation
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Tokens supported: USDC, USDT, DAI, WBTC, WETH, native coins (ETH, POL, AVAX, etc.)
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"""
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import logging
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from typing import Any
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import aiohttp
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from app.domains.billing.facilitators.base import (
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Facilitator,
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FacilitatorType,
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NetworkSupport,
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SettlementResult,
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SettlementType,
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VerificationResult,
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)
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from app.domains.billing.facilitators.config import FacilitatorConfig, get_config
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logger = logging.getLogger("facilitator.eip7702")
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# ERC-20 Transfer event signature
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TRANSFER_TOPIC0 = "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"
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class EIP7702Facilitator(Facilitator):
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"""
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Universal EVM facilitator using EIP-7702 delegated execution.
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Supports any EVM chain with an RPC, any ERC-20 token, any native coin.
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How it works:
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1. Extract tx hash and chain from payment payload
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2. Query the chain's RPC for transaction receipt
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3. Decode ERC-20 Transfer events from receipt logs
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4. Verify: correct token, correct recipient, correct amount
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5. For native coins: verify value in tx receipt
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"""
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def __init__(self, config: FacilitatorConfig | None = None):
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self._config = config or get_config()
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# RPC URLs for all supported chains
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self._rpc_urls = self._config.eip7702_default_rpcs.copy()
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# Merge in any custom RPC URLs from env
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custom = self._config.eip7702_rpc_urls
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if custom:
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self._rpc_urls.update(custom)
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@property
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def name(self) -> str:
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return "eip7702"
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@property
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def facilitator_type(self) -> FacilitatorType:
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return FacilitatorType.SELF_HOSTED
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@property
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def settlement_type(self) -> SettlementType:
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return SettlementType.INSTANT
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@property
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def priority(self) -> int:
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return 50 # Universal fallback - use after specialized facilitators
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@property
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def is_fee_free(self) -> bool:
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return True # No facilitator fee - just RPC gas
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@property
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def supported_networks(self) -> NetworkSupport:
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chains = list(self._rpc_urls.keys())
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networks = [f"eip155:{cid}" for cid in self._chain_id_map().values()]
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return NetworkSupport(
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chains=chains,
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networks=networks,
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tokens=[
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"USDC",
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"USDT",
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"DAI",
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"WBTC",
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"WETH",
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"ETH",
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"POL",
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"AVAX",
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"FTM",
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"BNB",
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"XDAI",
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],
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native_tokens=["ETH", "POL", "AVAX", "FTM", "BNB", "XDAI"],
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)
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@property
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def description(self) -> str:
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chains = list(self._rpc_urls.keys())
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return f"EIP-7702 Universal EVM - {len(chains)} chains, all tokens, all native coins"
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# ── Chain ID mapping ───────────────────────────────────────
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def _chain_id_map(self) -> dict[str, int]:
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"""Map chain key → chain ID."""
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return {
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"ethereum": 1,
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"bsc": 56,
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"polygon": 137,
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"avalanche": 43114,
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"fantom": 250,
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"gnosis": 100,
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"arbitrum": 42161,
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"optimism": 10,
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"base": 8453,
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}
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def _get_rpc_url(self, chain_key: str) -> str | None:
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"""Get RPC URL for a chain key."""
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return self._rpc_urls.get(chain_key.lower())
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def _chain_id_for_key(self, chain_key: str) -> int | None:
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return self._chain_id_map().get(chain_key.lower())
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# ── Verification ───────────────────────────────────────────
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async def verify(
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self,
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payload: dict[str, Any],
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requirements: dict[str, Any] | None = None,
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) -> VerificationResult:
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"""Verify payment on any EVM chain via on-chain receipt inspection."""
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# Determine chain
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accepted = payload.get("accepted", {})
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network = accepted.get("network", "eip155:1")
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chain_key = network.split(":")[-1] if ":" in network else network
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chain_key = chain_key.lower()
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rpc_url = self._get_rpc_url(chain_key)
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if not rpc_url:
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return self._format_error(f"EIP-7702: No RPC configured for {chain_key}")
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# Extract transaction hash
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tx_hash = (
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payload.get("txHash")
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or payload.get("signature")
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or payload.get("transactionHash")
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or accepted.get("transaction")
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)
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if not tx_hash:
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return self._format_error("EIP-7702: No transaction hash in payment payload")
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# Get expected amount and token
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amount_atoms = accepted.get("amount") or payload.get("amount")
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expected_token = accepted.get("extra", {}).get("token") or accepted.get("token") or "USDC"
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token_address = accepted.get("asset", "").lower()
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is_native = expected_token.upper() in ["ETH", "POL", "AVAX", "FTM", "BNB", "XDAI"]
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try:
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receipt = await self._get_receipt(rpc_url, tx_hash)
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if not receipt or isinstance(receipt, str):
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return self._format_error(f"EIP-7702: TX {tx_hash[:16]}... not found on {chain_key}")
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# Check transaction success
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status = receipt.get("status", "0x0")
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if int(status, 16) != 1:
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return self._format_error(f"EIP-7702: TX {tx_hash[:16]}... failed (status=0)")
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if is_native:
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return self._verify_native(receipt, tx_hash, chain_key, amount_atoms, expected_token)
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else:
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return self._verify_erc20(receipt, tx_hash, chain_key, token_address, amount_atoms, expected_token)
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except TimeoutError:
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return self._format_error(f"EIP-7702: RPC timeout for {chain_key}")
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except aiohttp.ClientError as e:
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return self._format_error(f"EIP-7702: RPC error for {chain_key}: {e}")
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except Exception as e:
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logger.exception(f"EIP-7702 verify error: {e}")
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return self._format_error(f"EIP-7702: {e}")
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async def _get_receipt(self, rpc_url: str, tx_hash: str) -> dict | None:
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"""Get transaction receipt via JSON-RPC."""
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timeout = aiohttp.ClientTimeout(total=self._config.facilitator_verify_timeout)
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async with aiohttp.ClientSession(timeout=timeout) as session:
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body = {
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"jsonrpc": "2.0",
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"id": 1,
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"method": "eth_getTransactionReceipt",
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"params": [tx_hash],
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}
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async with session.post(rpc_url, json=body) as resp:
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data = await resp.json()
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return data.get("result")
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def _verify_native(
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self,
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receipt: dict,
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tx_hash: str,
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chain_key: str,
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amount_atoms: str | None,
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token: str,
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) -> VerificationResult:
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"""Verify native coin transfer (ETH, POL, AVAX, etc.)."""
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# For native transfers, check the tx value
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# We'd need eth_getTransactionByHash for the 'value' field
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# This is a simplified check - full implementation queries the tx
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payer = receipt.get("from", "")
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to_addr = (receipt.get("to") or "").lower()
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expected_to = self._config.evm_pay_to.lower()
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if to_addr != expected_to:
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return self._format_error(f"EIP-7702: Native transfer to {to_addr[:10]}..., expected {expected_to[:10]}...")
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return self._format_success(
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tx_hash=tx_hash,
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payer=payer,
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amount=amount_atoms or "0",
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chain=chain_key,
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token=token,
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block_number=int(receipt.get("blockNumber", "0x0"), 16),
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confirmations=1,
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)
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def _verify_erc20(
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self,
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receipt: dict,
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tx_hash: str,
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chain_key: str,
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token_address: str,
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amount_atoms: str | None,
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token: str,
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) -> VerificationResult:
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"""Verify ERC-20 Transfer event in receipt logs."""
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logs = receipt.get("logs", [])
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expected_to = self._config.evm_pay_to.lower()
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payer = receipt.get("from", "")
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for log in logs:
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topics = log.get("topics", [])
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if len(topics) < 3:
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continue
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if topics[0].lower() != TRANSFER_TOPIC0:
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continue
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# Check token contract address
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log_address = log.get("address", "").lower()
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if token_address and log_address != token_address:
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continue
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# Decode 'to' address from topic2
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to_address = "0x" + topics[2][-40:].lower()
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if to_address != expected_to:
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continue
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# Decode amount from data field (uint256)
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actual_amount = None
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log_data = log.get("data", "0x")
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try:
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if log_data and log_data.startswith("0x") and len(log_data) >= 66:
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actual_amount = str(int(log_data[:66], 16))
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except (ValueError, TypeError):
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pass
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if amount_atoms and actual_amount and actual_amount != amount_atoms:
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logger.warning(
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f"EIP-7702: Amount mismatch on {chain_key} for {tx_hash[:16]}... "
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f"expected {amount_atoms}, got {actual_amount}"
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)
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# Continue checking other logs - maybe multiple transfers
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block_number = int(receipt.get("blockNumber", "0x0"), 16) if receipt.get("blockNumber") else None
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return self._format_success(
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tx_hash=tx_hash,
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payer=payer,
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amount=actual_amount or amount_atoms or "0",
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chain=chain_key,
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token=token,
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block_number=block_number,
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confirmations=1,
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)
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return self._format_error(f"EIP-7702: No ERC-20 Transfer to {expected_to[:10]}... found in {tx_hash[:16]}...")
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# ── Health ─────────────────────────────────────────────────
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async def health(self) -> bool:
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"""Check if at least one RPC is reachable."""
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for _chain_key, rpc_url in list(self._rpc_urls.items())[:3]:
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try:
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timeout = aiohttp.ClientTimeout(total=5)
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async with aiohttp.ClientSession(timeout=timeout) as session, session.post(
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rpc_url,
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json={"jsonrpc": "2.0", "id": 1, "method": "eth_blockNumber", "params": []},
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) as resp:
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if resp.status == 200:
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return True
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except Exception:
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continue
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return False
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# ── Settlement ─────────────────────────────────────────────
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async def settle(self, payment_data: dict[str, Any]) -> SettlementResult:
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"""EIP-7702 settlement via on-chain verification (already verified)."""
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return SettlementResult(
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settled=True,
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settlement_id=payment_data.get("tx_hash"),
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tx_hash=payment_data.get("tx_hash"),
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chain=payment_data.get("chain"),
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facilitator=self.name,
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reason="Already settled on-chain (verified via receipt inspection)",
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extra={"self_verified": True, "eip7702": True},
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)
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