Isn't this similar to https://aider.chat/docs/usage/copypaste.html

Just checked to see how it works. It seems that it does all that you are describing. The difference is in the way that it provides the files - it doesn't use xml format.

If you wish you could /add * to add all your files.

Also deducing from this mode it seems that any file that you add to aider chat with /add has its full contents added to the chat context.

But hey I might be wrong. Did a limited test with 3 files in project.

that’s correct. aider doesn’t RAG on files which is good. I don’t use it because 1) UI is so slow and clunky 2) using gemini 2.5 via api in this way (huge context window) is expensive but also heavily rate limited at this point. No such issue when used via aistudio ui.