Not the GP, but I've been working on an open platform [0] for integrating OpenAI APIs with other tools (VSCode, JupyterLab, bash, chrome, etc) that you might find interesting, the VSCode integration supports editing specific files / sections etc.

Also worth taking a look at Github Copilot Chat[1], it's a bit limited but in certain cases it works well for editing specific parts of files.

[0] https://github.com/lightrail-ai/lightrail

[1] https://marketplace.visualstudio.com/items?itemName=GitHub.c...