[FEATURE] Gemini-CLI support

[PieterPel]

Problem Statement

Google recently released Gemini-CLI, which provides similar functionality to Claude Code but with access to Gemini 2.5 Pro and with a free tier. As a developer who uses multiple AI tools, I want to be able to switch between different AI assistants without leaving my Neovim environment.

Proposed Solution

Add support for Gemini-CLI alongside the existing Claude Code integration. This would include:

• Detection and integration of the Gemini-CLI tool (gemini command or @google/gemini-cli npm package)
• Unified interface that allows users to choose between Claude Code and Gemini-CLI as their AI backend
• Configuration options to specify which AI tool to use (similar to how LSP servers can be configured)
• Authentication handling for both Google account authentication and API key methods
• Command mapping to translate the plugin's existing functionality to work with Gemini-CLI's interface
• Status indicators to show which AI tool is currently active

Alternative Solutions

• Separate plugin: Create a completely separate Neovim plugin for Gemini-CLI, but this would fragment the ecosystem and require users to learn different interfaces
• Fork approach: Fork this plugin specifically for Gemini-CLI support, but this would duplicate maintenance effort

Use Case

This feature would benefit:

• Multi-tool developers who want to compare responses from different AI models for the same coding task
• Open source contributors who want to leverage the free tier of Gemini 2.5 Pro (60 requests/minute, 1000/day)

Additional Context

• Gemini-CLI is installed via npm: npm install -g @google/gemini-cli
• Authentication: Google account sign-in or GEMINI_API_KEY environment variable
• Repository: https://github.com/google-gemini/gemini-cli

[greggh]

Sorry for the long wait. I like the idea of supporting Gemini-cli and possibly OpenAI's codex cli too. I wonder how that will feel with the plugin being named claude-code.nvim. Your alternative ideas might have some merit though. Now that I can pay attention to things again, let me think on this one.