cmux

open-source programmable terminal built for coding agents

[Benۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗۗ☁️ @benswerd]

Interesting GPT 5.6 behavior:

"I can't use apple Terminal for safety reasons", oh well I'll just use @cmuxdev

This model does not like sandboxes.

It does like cmux.

I like 50% of its taste.

[Lawrence Chen @lawrencecchen]

We made cmux's sidebar fast

Previously, the sidebar would lag because of issues in our SwiftUI <> AppKit sidebar virtualization

We completely refactored the sidebar from SwiftUI to AppKit, and now it's pretty fast!

Out in v0.64.20

[Lawrence Chen @lawrencecchen]

It’s genuinely insane to see cmux growing via word of mouth

I go to events in SF and people are using software that I built!? I 100% need to be doing more marketing, but even so, cmux is still growing

cmux is almost at 100k DAUs!

This is just nuts

brew install --cask cmux

[Lawrence Chen @lawrencecchen]

A sneak peak at cmux's design mode

One cool part is you can add multiple elements as tags/badges/pills into the rich text element.

You can also backspace on the element pills to remove them and reference multiple elements at the same time (annotating single elements at a time often isn't expressive enough to describe the change.

So there's a pretty direct 1-to-1 mapping of rich text editor content <> LLM prompt.

AFAIK Cursor's browser is the only other app that does this today, more people should copy it!

[WILL NESS @WillNessAI]

I built a variant of @mattpocockuk's grilling skill dedicated to frontend and it has improved how I build new apps and components.

The general idea:
1. Use /grilling and /prototype as a base
2. Tell Claude to build 5 WILDLY different prototypes
3. Tell Claude to include a picker that lets you switch between each variant live
4. Each round you select your favorite(s) + leave feedback, and Claude will walk down each branch of the design tree, helping you zoom in on your desired design

And THEN, I went and added it to /wayfinder, so whenever I make a new map and there's novel frontend work, a ticket is created specifically referencing that /grilling-frontend-prototyping needs to be invoked.

This will not be the last time I build a cool skill and add it to Wayfinder; this is a very powerful pattern for planning work.

You can find my skill here: https://t.co/4M4QPlfnp1

[Lawrence Chen @lawrencecchen]

Introducing cmux: the open-source terminal built for coding agents.

- Vertical tabs
- Blue rings around panes that need attention
- Built-in browser
- Based on Ghostty

When Claude Code needs you, the pane glows blue and the sidebar tells you why.

No Electron/Tauri. Just Swift/Appkit.

[Lawrence Chen @lawrencecchen]

Introducing cmux Fork

cmux Fork Conversation lets you branch Codex/Claude Code/OpenCode/Pi/Hermes... threads to new tabs, new splits, and new workspaces

It's pretty useful for exploring multiple directions in parallel, or if you want to have multiple Claudes with the same context work in the same directory (works surprisingly well)

Right click anywhere in the tab/terminal or Cmd+Shift+P -> "Fork Conversation to..."

Out in v0.64.19

[cmux @cmuxdev]

@gabimoncha @markstachowski @theo @thsottiaux this one is ghostty actually