@codeswithroh/reckon-core

The pre-flight engine behind Reckon — a transaction seatbelt for Monad.

On Monad you pay for the gas limit you declare, not the gas you use, even when your transaction reverts. preflight() simulates a transaction before you send it, refuses to let you broadcast a doomed one, computes the tightest safe gas limit, and flags approval/permission- escalation risk (unlimited ERC-20 allowances, NFT operator grants, EIP-2612 permits) that a naive revert check would miss.

Install

npm install @codeswithroh/reckon-core viem

Usage

import { createPublicClient, http } from "viem";
import { monadTestnet, preflight } from "@codeswithroh/reckon-core";

const client = createPublicClient({ chain: monadTestnet, transport: http() });

const verdict = await preflight(client, {
  from: "0xYourAddress",
  to: "0xTargetContract",
  data: "0x...",
});

if (verdict.willRevert) {
  console.log("Would fail:", verdict.revertReason);
} else if (verdict.riskFlags.some((f) => f.severity === "critical")) {
  console.log("Critical risk:", verdict.riskSummary);
} else {
  console.log("Safe to send with gas limit", verdict.recommendedGasLimit);
}

What it does

• preflight(client, tx, options?) — simulates via eth_estimateGas, decodes revert reasons, computes the tightest safe gas limit (static or adaptive), and flags approval risk. Never broadcasts.
• safeSend(clients, tx, options?) — pre-flights, then broadcasts only if safe.
• detectRiskFlags(tx) — pure, synchronous decoding of approve/increaseAllowance/ setApprovalForAll/permit calldata into severity-ranked risk flags.
• fetchHistoricalGasUsage / computeAdaptiveBuffer / recommendAdaptiveGasLimit — an opt-in adaptive gas buffer learned from a contract's real historical execution variance, instead of a flat percentage.

Why this exists

Verified empirically, not assumed: a reverted transaction on Monad testnet paid its full declared gas limit, exact to the wei. See the verification writeup and the full project README.

License

MIT