I’ve done long conversations with ChatGPT and it really does start losing context fast. You have to keep correcting it and refeeding instructions.

It seems to degenerate into the same patterns. It’s like context blurs and it begins to value training data more than context.

Yes, and with very long chats, you'll see it even forget how to do things like make tool calls - or even respond at all! I've had ChatGPT reply with raw JSON, regurgitate an earlier prompt, reply with a single newline, regurgitate information from a completely different chat, reply in a foreign language, and more.

Things get really wacky as it approaches decoherence.

I’ve seen the raw json before. I didn’t realize that was an actual failure mode.

I’ve also had it fail to respond in long chats but I thought it was a network error despite having no error messages.

Yeah, the raw JSON (in my case) is the result of a failed tool call, it was trying to generate an image. With thinking models, you can observe the degeneration of its understanding of image tool calls over the lifetime of a chat. It eventually puzzles over where images are supposed to be emitted, how it's supposed to write text, if it's allowed to provide commentary - and eventually, it gets all of it wrong. This also happens with file cites (in projects) and web search calls.