A war story about hand-managing the EVM stack, two words of litter left behind a CALL, and the debug trace that finally made the drift visible.
I had a contract that worked. Then I rewrote it in a second language so it would behave the same way, faster — and it didn't. The bug wasn't a crash. It was worse: the contract ran to completion, returned status 1, and the value it produced was quietly wrong.
This is the story of that bug, the tool that caught it, and what porting an opcode dispatcher from Yul to Huff taught me about the one thing Yul had been doing for me the whole time without ever saying so.
Two implementations of the same thing
The contract is an opcode dispatcher — it reads a packed byte-stream of commands and routes funds through multi-hop swap paths across seven DEX families. The whole thing is open source (adaptive-mev-router on GitHub), so every snippet below can be read in full context. The detail that matters for this story is that it ships twice: once in Yul as the reference implementation (MEV_V2.yul), and once in Huff as a hand-optimised port (MEV_V2.huff) with an O(1) jump-table dispatch.
