CLI input should have a vi/vim input mode

[RyanHecht]

Describe the feature or problem you'd like to solve

The core problem is the lack of efficient, keyboard-driven navigation and editing for users familiar with modal editors (like Vim/Vi) within the interactive portions of the GitHub Copilot CLI. The feature requested is the implementation of a Vim mode to enable users to navigate, select, and edit text (e.g., suggested commands, explanations, or input prompts) using standard Vim keybindings (h, j, k, l, w, d, y, etc.) in addition to the default keybindings.

Proposed solution

We need to introduce Normal, Insert, and Visual modes to allow power users to edit and manipulate text with high speed and precision, mirroring the functionality found in other modern, interactive CLIs.

Example prompts or workflows

No response

Additional context

No response

[Gelio]

Perhaps a simpler alternative would be to use open the prompt using $EDITOR and then after it is closed, replace the current prompt with whatever the user typed in that editor?

Gemini CLI does that and I liked that. See CTRL+X in https://github.com/google-gemini/gemini-cli/blob/main/docs/cli/keyboard-shortcuts.md

IMO that would achieve full Vim compatibility, since users would be able to edit the prompt in a real vim/nvim (or even use VSCode if they want to).

[hackel]

Basic keybindings for prompt editing would be more than sufficient, but it might be worthwhile to integrate with Neovim (like vscode-neovim), using its API to do most of the work for you. That would be rather epic!