Library/API conflicts are the biggest pain point for me usually. Especially breaking changes. RLlib (currently 2.41.0) and Gymnasium (currently 0.29.0+) have ended in circles many times for me because they tend to be out of sync (for multi-agent environments).
My go to test now is a simple hello world type card game like war, competitive multi-agent with rllib and gymnasium (pettingzoo tends to cause even more issues).
Claude Sonnet 4.5 was able to figure out a way to resolve it eventually (around 7 fixes) and I let it create an rllib.md with all the fixes and pitfalls and am curious if feeding this file to the next experiment will lead to a one-shot. GPT-5 struggled more but haven't tried Codex on this yet so it's not exactly fair.
All done with Copilot in agent mode, just prompting, no specs or anything.
Claude Sonnet 4.5 was able to figure out a way to resolve it eventually (around 7 fixes) and I let it create an rllib.md with all the fixes and pitfalls and am curious if feeding this file to the next experiment will lead to a one-shot. GPT-5 struggled more but haven't tried Codex on this yet so it's not exactly fair.
All done with Copilot in agent mode, just prompting, no specs or anything.