What does your AI assistant keep forgetting, even after you have explained it three times?

I am building a memory for AI assistants and I would rather collect real cases than assumptions before I go further.

For me it is three kinds that keep coming back. Decisions first: why we took a detour two months ago that every newcomer immediately wants to straighten out again. Then preferences: how I want things written, explained from scratch every time. And the expensive ones, hard-won fixes where I know I have had this problem before but no longer how I solved it.

What I am actually curious about: have you built a habit against it? I mostly see three approaches. Some keep a rules file in the project and stop maintaining it after a while. Some paste a block of context at the start of every session. Some have made their peace with it and just explain again.

And the question behind it: where would you want that memory to live? On your machine, in files you can read, or with a service that takes the work off your hands and keeps the data? I went with the first, but I am genuinely curious how many of you see it differently.