The one fact no Ethereum receipt carries: which transaction ran first
You got sandwiched. Your swap landed between a searcher's buy and their sell, you paid for it, and every receipt you can pull agrees that you were robbed. None of them can prove the order it happened in. That is the strange gap this post is about. A transaction receipt carries the block number, the gas used, the logs, the status. It does not carry the transaction's position inside the block. The…
Most Ethereum receipts do not indicate the position of a transaction inside a block. The transactionIndex field returned by an RPC node is the node's estimation, not a fact that can be verified by a contract on another chain. This creates a gap: it is known which transaction was sandwiched, but nobody can prove the exact position it took within the block.
A contract called index41 on Creditcoin addresses this issue. It uses the Attestcoin Protocol to verify that a specific transaction was included in a specific block, and if so, pays the sandwiched victim. The position of the transaction is derived from a merkle authentication path, which also reveals whether the leaf was the left or right child at each level.
This bit string is then converted into an integer representing the transaction's position in the block. Creditcoin's verifier precompile exposes this calculation as calculateTxIndex, costing minimal gas. The key is that this position only becomes meaningful after the transaction has been verified, and the contract must enforce the correct order.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
