tokenInfo(null) yielded "ETH (native)", so a swap whose input token the calldata never named was asserted to the user as ETH. The determination established for the output side in #353 applies unchanged: Currency is a value type over address, so native ETH arrives as the truthy zero-address string and WRAP_ETH sets it explicitly -- null can only mean undetermined.
The rule now lives in tokenInfo() itself rather than at each call site, so the redundant output-side guard added by #356 is removed; both sides read one UNNAMED_CURRENCY constant and cannot drift. Verified by execution that a genuine native-ETH input still renders as ETH, including via WRAP_ETH and a V4 zero-address PoolKey, and that the real mainnet output-side fixture is unchanged.
