teaching a model to remember: RAG vs fine-tuning

My use case is to have the llm query my personal conversations & other digital activity with questions like:

My understanding is there are at least these ways to solve this problem:

RAG

Very standard RAG - which I have yet to do still.

Chunk the messages. For example each chunk is a message [chat name, time stamp, author, message] Embed all these chunks, finally ask the question, embed the question, get relevant chunks, add them to the prompt, get the answer.

fine tuning

If the goal for the fine tuned model to reply as I would, or be able to simulate my contacts, then simply feeding all conversations as linear text makes sense. Also actually never did this, so a good idea to try.

Fine-tuning algorithm ideas:

My hypothesis is that its not aligned with the goal. The goal is to remember facts. So the fine tuning should be done by feeding the model very limited information about prior conversation so it could not simply emulate the style of the person we are predicting a response for, but rather remember the actual message they sent.

Algorithm ideas:

Thoughts: