The four V4 swap actions are read only as the parameter structs deployed on mainnet and Sepolia. ethers decoded the newer v4-periphery structs, which add minHopPriceX36, as the deployed ones without an error, and the newer multi-hop exact-in struct showed the offset of its hop-price array as the swap amount. A decode now counts only when encoding it again gives back the same bytes. When a swap action fails that, its step is listed as "V4 Swap (could not be decoded)", and a token line left without a currency reads "Unknown (could not be decoded)" rather than "not named in the calldata". The README records both. Model: opus-5-5