Trouble connecting to gemini_cli

[akashb95]

Hello. Firstly, thanks for making CodeCompanion. Without it, I'd have had to change editors.

Symptoms
I am trying to connect to gemini_cli, but it seems the initialisation step is timing out. The logs:

[DEBUG] 2025-12-07 12:47:57
Starting ACP process: { "gemini", "--experimental-acp" }
[DEBUG] 2025-12-07 12:47:57
[acp::start_agent_process] ACP process started
[DEBUG] 2025-12-07 12:47:57
[acp::write_message] Sending data:
{"jsonrpc":"2.0","method":"initialize","id":1,"params":{"clientInfo":{"version":"1.0.0","name":"CodeCompanion.nvim"},"protocolVersion":1,"clientCapabilities":{"fs":{"readTextFile":true,"writeTextFile":true}}}}

[ERROR] 2025-12-07 12:48:17
[acp::wait_for_rpc_response] Request timeout ID 1
[ERROR] 2025-12-07 12:48:17
[acp::connect_and_initialize] Failed to initialize

Steps to reproduce

1. Open CodeCompanionChat
2. Use ga to change adapters
3. Use gemini_cli adapter

Context
My config is:

return {
	"olimorris/codecompanion.nvim",
	version = "v17.33.0",
	lazy = false,
	dependencies = {
		"nvim-lua/plenary.nvim",
		"nvim-treesitter/nvim-treesitter",
	},
	config = function()
		local codecompanion = require("codecompanion")

		codecompanion.setup({
			strategies = {
				chat = {
					adapter = "gemini_cli",
					opts = {
						completion_provider = "blink",
					},
				},
				inline = {
					adapter = "gemini_cli",
					keymaps = {
						accept_change = {
							modes = { n = "ga" },
							description = "Accept the suggested change",
						},
						reject_change = {
							modes = { n = "gr" },
							opts = { nowait = true },
							description = "Reject the suggested change",
						},
						stop = {
							modes = { n = "q" },
							index = 4,
							callback = "keymaps.stop",
							description = "Stop (abort) request",
						},
					},
				},
			},
			adapters = {
				http = {
					gemini = function()
						return require("codecompanion.adapters").extend("gemini", {
							schema = {
								model = {
									default = "gemini-3-pro-preview",
								},
							},
							env = {
								api_key = "cmd:op read op://Employee/ukafu5czkq37oo7thictjenh4e/credential --no-newline",
							},
						})
					end,
				},

				-- ACP allows agentic mode, including inline edits.
				acp = {
					gemini_cli = function()
						return require("codecompanion.adapters").extend("gemini_cli", {
							defaults = {
								auth_method = "gemini-api-key", -- "oauth-personal"|"gemini-api-key"|"vertex-ai"
							},
							env = {
								GEMINI_API_KEY = "cmd:op read op://Employee/ukafu5czkq37oo7thictjenh4e/credential --no-newline",
							},
						})
					end,
				},
			},
			opts = {
				log_level = "DEBUG",
			},
		})
	end,
}

I have installed Gemini-CLI using npm install -g @google/gemini-cli per the instructions at https://github.com/google-gemini/gemini-cli. I can use the HTTP adapter, so I can rule out issues with API keys. I can also talk to Gemini from the terminal using the gemini application I installed using npm, so I suppose we can rule out issues with the application?

Things I've tried:

1. Using a commands block to specify how to use the gemini app. I got the same symptoms. Logs:

[DEBUG] 2025-12-07 12:46:37
Starting ACP process: { "gemini", "--experimental-acp" }
[DEBUG] 2025-12-07 12:46:37
[acp::start_agent_process] ACP process started
[DEBUG] 2025-12-07 12:46:37
[acp::write_message] Sending data:
{"params":{"clientCapabilities":{"fs":{"writeTextFile":true,"readTextFile":true}},"clientInfo":{"version":"1.0.0","name":"CodeCompanion.nvim"},"protocolVersion":1},"jsonrpc":"2.0","method":"initialize","id":1}

[ERROR] 2025-12-07 12:47:24
[acp::wait_for_rpc_response] Request timeout ID 1
[ERROR] 2025-12-07 12:47:24
[acp::connect_and_initialize] Failed to initialize

1. Use the --output-format json opt for gemini
2. Use the --output-format stream-json opt for gemini

No joy.

Any clues what might be going on here? 😬 Any help would be greatly appreciated.

[olimorris]

Thanks for your kind words.

Your setup looks good. Couple of things to try:

1. Run gemini and confirm that it loads
2. Run gemini --experimental-acp - you should see the command hang with no output.
3. If you run op read op://Employee/ukafu5czkq37oo7thictjenh4e/credential --no-newline you should be prompted to authorize and see the credential output
4. You can remove the schema.model.default it doesn't do anything for ACP adapters

[akashb95]

Your setup looks good. Couple of things to try:

1. Run gemini and confirm that it loads
2. Run gemini --experimental-acp - you should see the command hang with no output.
3. If you run op read op://Employee/ukafu5czkq37oo7thictjenh4e/credential --no-newline you should be prompted to authorize and see the credential output
4. You can remove the schema.model.default it doesn't do anything for ACP adapters

Thanks for the quick response!

1. Confirmed.
2. Confirmed. Even didn't work!
3. Yes.
4. Removed. Updating OP with updated config.

[jovulic]

I ran into this same issue and updating gemini-cli to v0.20.0 resolved it.

It looks like it was caused by a change that violated the ACP protocol definition.
google-gemini/gemini-cli#13646