Quick start
A Markdown editor where you, your team, and your agents write in the same document. Local by default, on your own agent subscription.
Install
Download Sundial for macOS (13.5 or later), drag it to Applications, and open it. No account is needed: your files stay on your disk and agents run on your machine until you choose to share something.
If Claude Code or Codex is installed, Sundial finds it and uses it as the default agent, on the plan you already pay for. Nothing to configure and no API key.
Open a folder
On first launch, pick Open folder to work in any folder of Markdown you already have, Clone from GitHub to start from a repository, or Blank project for a fresh one. A blank project comes with a short welcome document that walks through the editor.
Everything in the folder opens in place: Markdown renders as a rich editor with a raw toggle, code files get a code editor, images and PDFs preview inline. Edits are written back to the same plain files, so any other tool keeps working.
Ask for an edit
Press Cmd+Shift+J for a new chat, or select some text and press Cmd+J to add it to the chat, then describe what you want.
The agent's edits land in the document as suggestions: insertions and deletions you accept or reject one by one, or all at once. Suggest is the default for every chat, so nothing becomes final text without you. Switch a chat to Edit when you want changes applied directly.
Delegate from a comment
Select a sentence, press Cmd+Option+M, and write a comment that starts with @Agent. The agent answers in the thread and its fix arrives as a suggestion on exactly that selection. Comments without a mention are just comments, for you and your collaborators.
Share when you are ready
Sign in and share a file, a folder, or the whole project. What you share syncs live through Sundial's cloud: collaborators see your cursor and you see theirs, comments and suggestions flow both ways, and everything else in the project stays on your machine. Stop sharing and you are fully local again.