💡 Get Claude Code + ChatGPT (Codex) + Gemini all running in one terminal in ~5 minutes. Each model has hard limits — combine all three and every limit disappears.
Last verified · April 27, 2026
What you’re installing
Claude Code
The driver. Builds, edits, runs the terminal. Already installed.
Codex (GPT-5.5)
The reviewer. Different brain catches what Claude misses.
Gemini 2.5 Pro
The senses. Sees video, hears audio, reads massive PDFs — for free.
✅ Prerequisites
Node.js 20+ — run node --version to check
Claude Code installed and working
A ChatGPT account — Free tier works, Plus/Pro is fine, or an OpenAI API key
A Google account — free Gemini tier auto-enabled
Part A · Install the two CLIs
Run these in your normal terminal (not Claude Code):
npm install -g @openai/codex
npm install -g @google/gemini-cli
Verify both installed:
codex --version # should print: codex-cli 0.125+
gemini --version # should print: 0.39+
Part B · Log in
⚠️ Important correction: the command gemini auth does not exist. Use plain gemini instead. Notes corrected below.
Codex login
codex login
Opens a browser. Sign in with your ChatGPT account (Free works) or paste an OpenAI API key.
Gemini login
gemini
Just run gemini on its own. It launches interactive mode and prompts you to pick auth (Google OAuth is the default). Browser opens. Pick your Google account. Once it says you’re authenticated, type /quit to exit.
Part C · Install the two plugins
These are slash commands you paste inside Claude Code — not in your terminal.
⚠️ Critical: paste them ONE at a time, hitting enter after each, and waiting for each to finish. Pasting all five at once causes Claude Code to glue them into a malformed command and the install fails.
Step 1 — Add OpenAI’s plugin marketplace
/plugin marketplace add openai/codex-plugin-cc
↑ Press enter. Wait until it confirms before doing the next one.
Step 2 — Install the Codex plugin
/plugin install codex@openai-codex
↑ Press enter. Wait.
Step 3 — Add Pushkar’s Gemini marketplace
/plugin marketplace add thepushkarp/cc-gemini-plugin
↑ Press enter. Wait.
Step 4 — Install the Gemini plugin
/plugin install cc-gemini-plugin@cc-gemini-plugin
↑ Press enter. Wait.
Step 5 — Reload
/reload-plugins
↑ Press enter. Done.
Part D · Smoke test
Inside Claude Code:
/codex:setup
Should print ready: true.
In your terminal:
gemini -p “say hello”
Should print a greeting.
If both pass — you’re fully wired up. 🎉
How the slash commands work (one-line summary)
/plugin marketplace add owner/repo → tells Claude Code to trust a GitHub repo as a plugin source. Like adding a new App Store.
/plugin install pluginname@marketplacename → installs a specific plugin from that source. Like tapping the install button.
The names (codex@openai-codex, cc-gemini-plugin@cc-gemini-plugin) are declared by each plugin author in their repo’s marketplace.json. You just copy them from the README.
What you can do once it’s installed
Drop in the three-brain auto-router skill at ~/.claude/skills/three-brain/SKILL.md. After that, talk to Claude normally — the skill silently routes:
You say
Skill silently fires
“check over your work”
Codex review
“tear this apart”
Codex adversarial review
“I’m stuck, you’ve tried 3 times”
Codex rescue
“watch this clip” • a video file or YouTube URL
Gemini multimodal
“transcribe” • an audio file
Gemini transcription
“scan the whole repo”
Gemini 1M-context scan
Any edit on src/auth/**, **/migrations/**, **/billing/**
Forced Codex adversarial review
Anything else (write, edit, refactor, explain) → Claude direct, skill stays asleep.
Updating + uninstalling
Update plugins (inside Claude Code):
/plugin marketplace update cc-gemini-plugin
/plugin marketplace update openai-codex
/reload-plugins
Uninstall plugins:
/plugin uninstall codex@openai-codex
/plugin uninstall cc-gemini-plugin@cc-gemini-plugin
Uninstall CLIs (in terminal):
npm uninstall -g @openai/codex @google/gemini-cli
The bottom line: Claude builds. Codex reviews. Gemini sees + hears the things Claude can’t. You ship.