I vibe coded a Signal Messenger LLM bot a few months ago. I used a sqlite database to remember chat history (and respect dissapearing messages), and a vector database for searching the chat history. Basically a RAG bot for chat history. It's quite good how it is, but could use some work. It can also recognise images that users post and comment on them. It is used by me and my friends in our chat groups and ads a comedic element. It's also handy for summarizing chat history if you missed out on discussions.
I was going to clean up the code before I open source it, but I think I'm just going to put it out there. Stay tuned.