Getting Started with CodeMantis

Prerequisites

Before installing CodeMantis, make sure you have:

• macOS 12 (Monterey) or later — CodeMantis is a native macOS application.
• At least one coding agent CLI installed — either Claude Code (see Installing Claude Code) or OpenAI Codex (see Installing Codex). Having both is recommended — it unlocks per-task routing — but either alone is enough to use CodeMantis.
• An active subscription for the agent(s) you install — Claude Pro ($20/mo) or Max ($100-200/mo) for Claude Code, or ChatGPT Plus/Pro/Business for OpenAI Codex.

Not sure which agent to pick? See Choosing Your Coding Agent.

Download and Install

1. Visit the CodeMantis GitHub Releases page.
2. Download the latest .dmg file for your Mac (Apple Silicon or Intel).
3. Open the .dmg and drag CodeMantis into your Applications folder.
4. Launch CodeMantis from Applications. On first launch, macOS may ask you to confirm you want to open the app — click Open.

Opening a Project

When CodeMantis launches, you can start working in two ways:

• Open an existing folder — Click Open Project and select any folder on your Mac. CodeMantis will detect its structure and initialize a new session. When both Claude Code and Codex are installed, an Agent Picker appears so you can choose which agent powers the session.
• Create from a template — Choose from built-in project templates (Next.js, Tauri, Python, and more) to scaffold a new project with sensible defaults.

Sending Your First Message

Once a project is open, the chat panel is front and center. Type a message describing what you want to build or change — for example:

Add a login page with email and password fields

Your active agent will analyze your project, propose changes, and ask for approval before modifying any files.

Session Modes at a Glance

Claude Code sessions use the Mode Selector:

• Normal — You approve each action before it runs. Best for learning and sensitive work.
• Auto-Accept — The agent works without pausing for approval. Best for fast iteration.
• Plan — Reasoning only, no code changes. Best for architecture discussions.

You can switch modes at any time with Command + . or by using the mode selector in the chat panel.

Codex sessions use the Codex Policy Pill instead — two independent dials for sandbox (read-only / workspace-write / danger) and approval policy (untrusted / on-request / on-failure / never). Same goal, different model.

Learn more in Session Modes Explained.

Next Steps

• Understanding the Three-Panel Layout — Learn how the workspace is organized.
• Choosing Your Coding Agent — Claude Code vs. Codex, plus per-task routing.
• Session Modes Explained — Decide how much control to give your agent.
• Installing Claude Code / Installing Codex — Troubleshoot CLI setup issues.
• Per-Task Agent Routing — Route different task categories to different agents (v1.5.0).
• Setting Up AI API Keys — Configure API keys for changelogs, assistants, and SpecWriter.