I can highly recommend gp.nvim, it has a few features but by default it's just a chat window with a yank-to-chat function. It also supports a context file that gets pasted into every chat automatically (for telling the AI about the tools you use etc)

Last time I used it, Avante was pretty much nailing what you are describing.

https://github.com/yetone/avante.nvim

Have you seen CodeCompanion (https://github.com/olimorris/codecompanion.nvim)?

That is the dream! Would love someone to create a vim plugin for this, if not I'll do it myself if there is enough demand.