I guarantee you the weights are already versioned like you're describing. Each training run results in a static bundle of outputs and these are very much pinned (OpenAI has confirmed multiple times that they don't change the model weights once they issue a public release).
> Not quantized. Weights are the same. If we did change the model, we’d release it as a new model with a new name in the API.”
- [Ted Sanders](https://news.ycombinator.com/item?id=44242198) (OpenAI)
The problem here is that most issues stem from broader infrastructure issues like numerical instability at inference time. Since this affects their whole service pipeline, the logic here can't really be encapsulated in a frozen environment like a Docker container. I suppose _technically_ they could maintain a separate inference cluster for each of their point releases, but that also means that previous models don't benefit from common infrastructure improvements / load balancing would be more difficult to shard across GPUs / might be logistically so hard to coordinate to effectively make it impossible.
https://www.anthropic.com/engineering/a-postmortem-of-three-...
https://thinkingmachines.ai/blog/defeating-nondeterminism-in...