FAQ
Frequently asked questions about ChatML.
General
What is ChatML?
ChatML is a native macOS desktop application that gives Claude direct access to your codebase through isolated git worktrees. It's an AI-native IDE for software development.
What models does ChatML support?
ChatML works with Claude models from Anthropic: Claude Opus, Claude Sonnet, and Claude Haiku. You need an Anthropic API key.
Is ChatML free?
ChatML itself is free. You pay for Claude API usage through your Anthropic account based on token consumption.
What operating systems are supported?
ChatML currently supports macOS 13 (Ventura) and later. Windows and Linux support is planned.
Sessions & Worktrees
Can I have multiple sessions working at the same time?
Yes. Each session has its own git worktree and branch, so multiple AI agents can work on different tasks simultaneously without interfering with each other.
How much disk space do sessions use?
Session worktrees share git objects with the main repository, so they use significantly less space than full clones. However, each worktree contains a full copy of the working files. Delete or archive sessions you no longer need.
Can I use an existing branch for a session?
Yes. You can create a session from an existing pull request or branch. ChatML checks out the branch into a new worktree.
AI & Usage
How do I control costs?
Use budget controls to set cost limits, turn limits, and thinking token budgets per conversation.
What is Extended Thinking?
Extended Thinking lets Claude reason through complex problems before responding. It shows Claude's internal thought process in a collapsible section. Enable it in Settings > AI > Extended Thinking.
What is Plan Mode?
Plan Mode puts Claude in a read-only state where it researches and designs an approach before making any changes. You review and approve the plan before Claude executes it.
Integrations
Do I need GitHub connected to use ChatML?
No. GitHub integration is optional. You can use ChatML for AI-assisted coding without it. GitHub is needed for PR creation, CI monitoring, and issue tracking features.
Can I use custom MCP servers?
Yes. ChatML supports custom MCP servers with stdio, SSE, or HTTP transport. Configure them in Settings or via a .mcp.json file in your repository.
Features
What is Mission Control?
Mission Control is a dashboard that gives you visibility across all your sessions — an Attention Queue for items needing action, a Live Activity feed, and a Spend Tracker for cost monitoring.
What are Sub-Agents?
When Claude encounters tasks that can be parallelized, it can spawn sub-agents — independent AI processes that work on separate subtasks simultaneously. This is automatic and cost-aware.
Can I use voice dictation?
Yes. ChatML supports macOS speech-to-text via the microphone icon in the chat input. All processing happens on-device using macOS's built-in speech recognition. See Voice Dictation.
What is CLAUDE.md?
CLAUDE.md is a special file you can place in your repository root to give Claude persistent, project-level instructions about coding conventions, architecture, and standards.
How do @ mentions work?
Type @ in the chat input to search and reference files from your session's worktree. The file content is included in your message as context. See File @ Mentions.
Does ChatML support deep links?
Yes. ChatML registers the chatml:// protocol, used for OAuth callbacks (GitHub, Linear, Sentry) and for opening specific sessions or workspaces from external links.