I use something similar to this decorator (more or less a thin wrapper around instructor) and have looked a little bit at the codegen + cache route. It gets more interesting with the addition of tool calls, but I've found JSON outputs create quality degradation and reliability issues. My next experiment on that thread is to either use guidance (https://github.com/guidance-ai/guidance) or reimplement some of their heuristics to try to get tool calling without 100% reliance on JSON.