Tried a million different mega-prompts, tried all the models, they couldn't solve the bug until..

... until I realized that there were 2 functions with similar names. Somehow Claude probably renamed a function that made it basically the same as another one, and it was throwing off all the models.

If you're going back and forth repeatedly on a bug with the AI, check the function names.. I was pulling my hair out until I realized what was happening.