File Tree and Lightweight Editor Tab

[BadTechBandit]

Summary

It would be great if cmux could include a simple built-in file tree and text editor that can be opened as a tab, just like a terminal or browser. This would allow users to quickly browse project files, open them in an editor, and view markdown previews without leaving cmux or switching to a full IDE.

Motivation

Many workflows need a lightweight way to inspect and edit files alongside terminals:

• Quick edits: fixing configs, scripts, and small code changes should not require opening a full editor.
• Project navigation: a file tree makes it easier to understand and jump around a codebase or repo.
• Markdown notes: documentation, runbooks, and scratch notes are often markdown, so being able to preview them in place is very useful.
• Agent workflows: AI coding agents working in cmux could use the built-in editor for small edits and inline previews instead of spawning external tools.

Proposed Behavior

1. File tree tab

   • A new tab type (for example, “Files”) that shows a file tree for the current workspace root.
   • By default, the tree is rooted at the workspace directory, but you can change the root to any directory on the machine.
   • Clicking a file opens it in an editor pane within that tab.
   • Basic actions: rename, delete, create file or folder.

2. Inline editor

   • Minimal text editor for plain text, code, and config files.
   • Standard keybindings for navigation, save, and search.
   • Optional basic syntax highlighting for common languages as an add-on feature, so the core stays fast and simple.

3. Markdown preview

   • A “Preview” toggle or button for .md files that renders markdown in a split view or separate pane.
   • Supports headings, lists, links, and code blocks at minimum.
   • The markdown preview follows the existing cmux color scheme for a consistent look.

4. Integration with existing tabs

   • The file editor lives in its own tab, like the browser or terminal model already in cmux.
   • Opening a file from the tree can optionally open it in a new tab or reuse the current editor tab.
   • The default workspace root for the file tree follows the workspace configuration directory, with the option to switch to other directories.

Open Questions

1. Should syntax highlighting be configurable per workspace, or as a global setting?
2. Should the editor support multiple open files via tabs within the editor, or just a single active file per file tab?
3. Should there be simple keybindings to jump between file tree, editor, and preview without using the mouse?

[oanguenot]

Yes good idea. I need the same on my side to bring more context to a workspace