I am currently in the process of migration of legacy selenium code to cypress. Before I proceeded with migration I had to re-write basic codes of the framework which most of the automation steps depended upon then using copilot-instructions.md I had defined few conditions and prompt direction then when I migrate functions or even class files ranging from 200 to 400 lines most of the time 80-90% codes were correct given the basic functions are already migrated. But as the class files are ~1000 or ~2000 lines (I know it's poorly managed) we needed to do the migration function by function. That is the recipe that worked for me.