[Alicepoltora]

Summary

Fixes #15

prepareUserOperation used a hardcoded 3 gwei maxFeePerGas floor when neither the caller-supplied partialUserOp fields nor a custom estimateFeesPerGas callback provided fees. On L2s where base fees sit well below 1 gwei (Base, Arbitrum, Optimism regularly see 0.001–0.1 gwei) this inflates the worst-case spend (gasLimit × maxFeePerGas) that Gas Station policies check by 100–500×, rejecting otherwise-trivial UserOperations with a typical ~0.01 USDC budget.

Changes

• Add defaultMaxFeePerGasFor(chainId): 0.05 gwei floor on L2s with routine sub-gwei base fees (Base / Base Sepolia, Arbitrum One / Sepolia, Optimism / OP Sepolia, Polygon / Amoy); keep the 3 gwei L1-tuned default for Ethereum mainnet and unknown chains
• The existing max(estimated × 2) clamp is unchanged — when the node estimates non-trivial fees they still win
• Custom estimateFeesPerGas override path untouched

Notes

0.05 gwei is chosen as a floor that clears current L2 minimum base fees while being ~60× smaller than the old 3 gwei constant; on these chains a typical UserOp uses < 300k gas, so the checked worst-case spend drops from ~0.0009 ETH to ~0.000015 ETH — comfortably inside Gas Station budgets.

internal fun defaultMaxFeePerGasFor(chainId: Long): BigInteger = when (chainId) {
    8453L, 84532L,      // Base, Base Sepolia
    42161L, 421614L,    // Arbitrum One, Arbitrum Sepolia
    10L, 11155420L,     // Optimism, OP Sepolia
    137L, 80002L,       // Polygon, Polygon Amoy
        -> parseGwei("0.05")
    else -> parseGwei("3")
}