copilot-cli.nvim

A Neovim plugin that connects Neovim with a running GitHub Copilot CLI instance. Send context-rich prompts from your editor directly to Copilot CLI running in another tmux pane.

Features

• 🔍 Smart process detection — Finds running copilot instances via process tree traversal (not limited to current tmux window)
• 💬 Floating prompt editor near the cursor with multiline editing and placeholder support
• 📄 @file — Current file path (relative)
• 📁 @buffers — All open buffer paths
• 📍 @here — Cursor position info
• ✂️ @selection — Visual selection content
• 🔍 @diagnostics — LSP diagnostics for current line
• 🖥️ Reliable tmux sending — Uses load-buffer + paste-buffer (handles long text and special characters)
• ⚡ Multi-instance support — Detects multiple Copilot CLI instances and lets you choose

Requirements

• Neovim >= 0.8.0
• tmux — Required for sending messages to Copilot CLI
• copilot CLI running in a tmux pane (any session/window)

Installation

lazy.nvim

{
  "copilot-cli.nvim",
  dev = true,
  keys = {
    { "<C-l>", "<cmd>CopilotSend<cr>", desc = "Send prompt to Copilot CLI" },
    { "<C-l>", "<cmd>CopilotSend<cr>", mode = "v", desc = "Send selection to Copilot CLI" },
    { "<leader>cs", "<cmd>CopilotSelect<cr>", desc = "Select Copilot CLI instance" },
  },
  cmd = {
    "CopilotSend",
    "CopilotSelect",
  },
  config = function()
    require("copilot-cli").setup()
  end,
}

vim-plug

Plug 'dustier/copilot-cli.nvim'

Then in your Lua config:

require('copilot-cli').setup()

vim.keymap.set({ "n", "v" }, "<C-l>", "<cmd>CopilotSend<cr>", { desc = "Send prompt to Copilot CLI" })
vim.keymap.set("n", "<leader>cf", "<cmd>CopilotFocus<cr>", { desc = "Focus Copilot CLI pane" })

packer.nvim

use {
  'copilot-cli.nvim',
  config = function()
    require('copilot-cli').setup()
  end
}

Usage

Commands

Command	Description
:CopilotSend	Open the floating prompt editor with placeholder support
:CopilotSelect	Re-detect and select Copilot CLI instance

Placeholders

Use these in your prompts to include context:

Placeholder	Description
@file	Current file path (relative to cwd)
@buffers	All open buffer file paths
@here	Cursor position (file:line)
@selection	Visual selection content
@diagnostics	LSP diagnostics for the current line

Example Prompts

• "Fix this error: @diagnostics"
• "Explain this code: @selection" (select text first)
• "What does @file do?"
• "Add tests for @file"
• "Help me at @here in @file"

Prompt Editor Controls

• Insert mode <CR> — Insert a newline
• Normal mode <CR> — Send the prompt to Copilot CLI
• <C-s> — Send the prompt to Copilot CLI
• <C-c> — Cancel and close the prompt editor
• q — Close the prompt editor in normal mode

Workflow

1. Start tmux and split your terminal
2. Run copilot in one pane
3. Open Neovim in another pane (can be any tmux session/window)
4. Press <C-l> to open the prompt editor near the cursor
5. The editor starts as a single line and expands as your prompt grows
6. Press <C-s> to send
7. The prompt is sent to the Copilot CLI pane automatically

Configuration

No configuration required — the plugin works out of the box.

Call require("copilot-cli").setup() to initialize (needed for plugin managers that require it).

How It Works

Detection Strategy

Unlike simpler approaches that only scan the current tmux window, this plugin uses process tree detection:

1. Runs ps to find all processes matching copilot (excluding language-server)
2. Builds a process tree from all running processes
3. Lists all tmux panes and their root PIDs
4. Maps each copilot process to its containing tmux pane via tree traversal
5. Caches the result until the target process exits

This means the Copilot CLI can be running in any tmux session or window — it doesn't need to be in the same window as Neovim.

Multi-Instance Handling

When multiple Copilot CLI instances are running:

1. First prompt triggers a selection dialog to choose which instance to send to
2. The selected instance is cached — subsequent prompts go to the same instance automatically
3. If the cached instance exits, the next prompt re-detects and prompts again if needed
4. Use :CopilotSelect to manually switch to a different instance at any time

Sending Strategy

Uses tmux load-buffer + tmux paste-buffer instead of tmux send-keys. This is more reliable for:

• Long prompts with multiple lines
• Special characters and escape sequences
• Unicode content

Troubleshooting

"No Copilot CLI instance found"

• Make sure copilot is running in a tmux pane
• Check that the process is visible: ps aux | grep copilot
• Try manual target: set tmux_target = "%42" (find pane id with tmux list-panes -a -F "#{pane_id} #{pane_current_command}")

"Failed to send to Copilot CLI pane"

• Verify the tmux pane still exists
• Check tmux buffer permissions

Debug Tips

# List all tmux panes with their commands
tmux list-panes -a -F '#{pane_id} #{pane_pid} #{pane_current_command}'

# Find copilot processes
ps -u $USER -ww -o pid,ppid,args | grep copilot

# Test manual send
tmux load-buffer -b test - <<< "hello"
tmux paste-buffer -b test -d -r -t %42

Acknowledgments

This plugin was inspired by and builds upon ideas from:

• opencode-context.nvim — Placeholder system and tmux sending approach
• sidekick.nvim — Process tree detection strategy and copilot CLI process matching

License

MIT License