I've had great luck with asking the current session to "summarize our goals, conversation, and other relevant details like git commits to this point in a compact but technically precise way that lets a new LLM pick up where we're leaving off".
The new session throws away whatever behind-the-scenes context was causing problems, but the prepared prompt gets the new session up and running more quickly especially if picking up in the middle of a piece of work that's already in progress.
Wow, I had useless results asking “please summarize important points of the discussion” from ChatGPT. It just doesn’t understand what’s important, and instead of highlighting pivoting moments of the conversation it produce a high level introduction for a non-practitioner.
Honestly, I just type out something by hand that is roughly like what I quoted above - I'm not big on keeping prompt libraries.
I think the important part is to give it (in my case, these days "it" is gpt-5-codex) a target persona, just like giving it a specific problem instead of asking it to be clever or creative. I've never asked it for a summary of a long conversation without the context of why I want the summary and who the intended audience is, but I have to imagine that helps it frame its output.
The new session throws away whatever behind-the-scenes context was causing problems, but the prepared prompt gets the new session up and running more quickly especially if picking up in the middle of a piece of work that's already in progress.