Multi-Backend Setup

Overview

Jean supports three AI backends:

Claude CLI - Official Anthropic Claude desktop CLI
Codex CLI - OpenAI’s Codex CLI for GPT models
OpenCode - Open-source AI coding assistant

You can install all three and switch between them per-project or per-session.

Backend Comparison

Feature	Claude CLI	Codex CLI	OpenCode
Provider	Anthropic	OpenAI	Open Source
Models	Opus, Sonnet, Haiku	GPT-5.x series	Multiple providers
Thinking Levels	Yes (off/think/mega/ultra)	No	No
Reasoning Effort	Yes (Opus 4.6 adaptive)	Yes (low/medium/high/xhigh)	No
MCP Support	Yes (.claude.json)	Yes (config.toml)	Yes (opencode.json)
Installation	via Jean UI	via Jean UI	via Jean UI
Authentication	`claude auth`	`codex auth`	`opencode auth`

Installing Backends

Via Jean UI

Open Preferences (Cmd/Ctrl + ,)
Navigate to Backends tab
For each backend:
- View installation status
- Click Install if not installed
- Click Authenticate after install
- Verify status shows “Authenticated”

Manual Installation

Claude CLI

# macOS
brew install anthropics/claude/claude-cli

# Authenticate
claude auth

Codex CLI

# Install (varies by platform)
# See: https://openai.com/codex

# Authenticate
codex auth

OpenCode

# Install via npm
npm install -g opencode

# Or download binary from releases
# See: https://github.com/opencode/opencode

# Authenticate (varies by provider)
opencode auth

Configuration Files

Claude CLI

Global settings: ~/.claude/settings.json

{
  "env": {
    "ANTHROPIC_API_KEY": "sk-ant-..."
  }
}

Project settings: .claude/settings.json in project root MCP servers: .claude.json (global) or .mcp.json (project)

Codex CLI

Global config: ~/.codex/config.toml

[auth]
api_key = "sk-..."

[[mcp_servers]]
name = "filesystem"
command = "npx"
args = ["-y", "@modelcontextprotocol/server-filesystem", "/path"]

Project config: .codex/config.toml in project root

OpenCode

Global config: ~/.config/opencode/opencode.json

{
  "apiKey": "...",
  "mcpServers": {...}
}

Project config: opencode.json in project root

Default Backend

Set the default backend for new sessions: Global default:

Preferences > General
Default Backend dropdown
Select: Claude, Codex, or OpenCode

Per-project override:

Right-click project > Project Settings
Navigate to General tab
Default Backend dropdown
Select backend or “Use Global Default”

Switching Backends

In Active Session

You cannot change backend mid-session. Backend is locked when session starts. To switch:

Create new session (Cmd/Ctrl + T)
Select different backend from toolbar
Start chatting

For Existing Session

Backend is stored with session metadata and persists across restarts.

Backend-Specific Features

Claude CLI

Thinking Levels:

off - No extended thinking
think - 4K thinking tokens
megathink - 10K thinking tokens
ultrathink - 32K thinking tokens

Adaptive Effort (Opus 4.6):

low - Minimal reasoning
medium - Moderate reasoning
high - Deep reasoning
max - No limits

CLI flags:

claude --model opus --thinking ultrathink --effort high

Codex CLI

Models:

gpt-5.3-codex - Latest flagship
gpt-5.2-codex - Previous flagship
gpt-5.1-codex-max - Maximum capability
gpt-5.2 - General purpose
gpt-5.1-codex-mini - Fast, lightweight

Reasoning Effort:

codex --model gpt-5.3-codex --reasoning-effort high

Multi-Agent Mode (experimental):

Enable: Preferences > Codex > Multi-Agent Enabled
Max threads: 1-8 concurrent agents

OpenCode

Provider Support:

Anthropic
OpenAI
OpenRouter
Local models (Ollama, LM Studio)
Custom API endpoints

Model Format: opencode/[provider]/[model] Example:

opencode/anthropic/claude-opus-4
opencode/openai/gpt-5
opencode/openrouter/anthropic/claude-opus

Custom CLI Profiles

For Claude CLI, you can configure custom provider profiles:

Predefined Profiles

OpenRouter:

{
  "name": "OpenRouter",
  "settings_json": {
    "env": {
      "ANTHROPIC_BASE_URL": "https://openrouter.ai/api",
      "ANTHROPIC_AUTH_TOKEN": "<your_api_key>"
    }
  }
}

MiniMax:

{
  "name": "MiniMax",
  "supports_thinking": false,
  "settings_json": {
    "env": {
      "ANTHROPIC_BASE_URL": "https://api.minimax.io/anthropic",
      "ANTHROPIC_AUTH_TOKEN": "<your_api_key>",
      "ANTHROPIC_MODEL": "MiniMax-M2.5"
    }
  }
}

Z.ai:

{
  "name": "Z.ai",
  "supports_thinking": false,
  "settings_json": {
    "env": {
      "ANTHROPIC_BASE_URL": "https://api.z.ai/api/anthropic",
      "ANTHROPIC_AUTH_TOKEN": "<your_api_key>",
      "ANTHROPIC_DEFAULT_OPUS_MODEL": "glm-4.7"
    }
  }
}

Moonshot:

{
  "name": "Moonshot",
  "supports_thinking": false,
  "settings_json": {
    "env": {
      "ANTHROPIC_BASE_URL": "https://api.moonshot.ai/anthropic",
      "ANTHROPIC_AUTH_TOKEN": "<your_api_key>",
      "ANTHROPIC_MODEL": "kimi-k2.5"
    }
  }
}

Creating Custom Profiles

Preferences > Advanced > CLI Profiles
Click Add Profile
Enter profile name
Paste settings JSON
Check Supports Thinking if provider supports it
Save profile

Using Custom Profiles

Select custom provider from toolbar dropdown
Profile’s settings override global Claude CLI config
Environment variables are merged with defaults

Per-Prompt Backend Overrides

You can force specific backends for magic prompts: Example: Always use Claude for code reviews, Codex for commit messages:

{
  code_review_backend: 'claude',
  commit_message_backend: 'codex',
  investigate_issue_backend: null  // Use session default
}

Configure in: Preferences > Magic Prompts > [prompt] > Backend Override

Version Management

Checking Versions

Via Jean UI:

Preferences > Backends
View installed version for each backend

Via CLI:

claude --version
codex --version
opencode --version

Updating Backends

Via Jean UI:

Preferences > Backends
Click Check for Updates
If update available, click Update

Manual update:

# Claude CLI
brew upgrade claude-cli

# Codex CLI
codex update

# OpenCode
npm update -g opencode

Backend Health Checks

Jean monitors backend health: Checks:

CLI binary exists and is executable
Version can be queried
Authentication is valid
MCP servers are accessible (if configured)

View status:

Preferences > Backends > [Backend] > Health Status

Manual check:

claude auth status
codex auth status
opencode auth status

Troubleshooting

Backend Not Found

Error: claude: command not found

Solution:

Install backend via Jean UI or manually
Add to PATH: export PATH="$PATH:/path/to/cli"
Restart Jean

Authentication Failed

Error: Not authenticated. Run 'claude auth' first.

Solution:

Open terminal
Run: claude auth (or codex auth, opencode auth)
Follow authentication flow
Restart Jean

Wrong Backend Version

Error: This version of Jean requires Claude CLI >= 1.2.0

Solution: Update CLI to required version

MCP Servers Not Loading

Ensure MCP config uses correct format for backend:

Claude: .claude.json / .mcp.json
Codex: config.toml
OpenCode: opencode.json

Backends don’t share MCP configs.

Session Crashes After Backend Switch

Backend cannot be changed mid-session. Create new session instead.

Best Practices

Install all backends: Maximum flexibility per-project
Set project defaults: Match backend to project needs
- Claude: Complex reasoning, long context
- Codex: Fast iteration, code-heavy tasks
- OpenCode: Custom providers, local models
Test authentication: Verify all backends before heavy use
Keep updated: Update CLIs regularly for new features
Separate configs: Use project configs to isolate backend settings
Profile per project: Create custom profiles for different API keys/endpoints

Advanced: Backend Detection

Jean detects installed backends at startup: Detection logic:

pub async fn get_installed_backends() -> Vec<CliBackend> {
    let mut backends = vec![];
    
    if is_claude_cli_installed().await { backends.push("claude"); }
    if is_codex_cli_installed().await { backends.push("codex"); }
    if is_opencode_cli_installed().await { backends.push("opencode"); }
    
    backends
}

Checked paths:

System PATH
Common installation directories
Platform-specific locations

Cache duration: 5 minutes (refreshed on manual check)

Get Started

Core Concepts

Features

Guides

Advanced

Reference

​Overview

​Backend Comparison

​Installing Backends

​Via Jean UI

​Manual Installation

​Claude CLI

​Codex CLI

​OpenCode

​Configuration Files

​Claude CLI

​Codex CLI

​OpenCode

​Default Backend

​Switching Backends

​In Active Session

​For Existing Session

​Backend-Specific Features

​Claude CLI

​Codex CLI

​OpenCode

​Custom CLI Profiles

​Predefined Profiles

​Creating Custom Profiles

​Using Custom Profiles

​Per-Prompt Backend Overrides

​Version Management

​Checking Versions

​Updating Backends

​Backend Health Checks

​Troubleshooting

​Backend Not Found

​Authentication Failed

​Wrong Backend Version

​MCP Servers Not Loading

​Session Crashes After Backend Switch

​Best Practices

​Advanced: Backend Detection

Build docs developers (and LLMs) love

Overview

Backend Comparison

Installing Backends

Via Jean UI

Manual Installation

Claude CLI

Codex CLI

OpenCode

Configuration Files

Claude CLI

Codex CLI

OpenCode

Default Backend

Switching Backends

In Active Session

For Existing Session

Backend-Specific Features

Claude CLI

Codex CLI

OpenCode

Custom CLI Profiles

Predefined Profiles

Creating Custom Profiles

Using Custom Profiles

Per-Prompt Backend Overrides

Version Management

Checking Versions

Updating Backends

Backend Health Checks

Troubleshooting

Backend Not Found

Authentication Failed

Wrong Backend Version

MCP Servers Not Loading

Session Crashes After Backend Switch

Best Practices

Advanced: Backend Detection