I assume you're aware but there are some open source assistants that can get you this (at least to some extent).

E.g. Codename Goose https://block.github.io/goose/docs/quickstart/

Which I think supports Gemini among with all the other major AI providers, plus MCP. I have heard anecdotally that it doesn't work as well as Claude Code, so maybe there are additional smarts required to make a top notch agent.

I've also heard that Claude is just the best LLM at tool use at the moment, so YMMV with other models.

Not a desktop app, but Gemini has “Jules” which is their autonomous coding agent

You hook up your GitHub repo and it’ll clone it, setup the env and then work on the task you give it

Cursor + Gemini is rather good.