Nice work! I have actually been working on something similar.

Main differentiators: - Based on tmux, so you can connect to a persistent session from multiple devices - Responsive, resizes sidebar based on mobile/desktop client connecting - Status indicator icons for major LLM CLIs (needs input/thinking) - Completely built into tmux, emulator-agnostic - Supports grouping of windows - Supports color and emoji-coding windows / panes / window groups - It's higly configurable using yaml

https://github.com/brendandebeasi/tabby

Hey, this looks seriously awesome. Love the ideas here, specifically: the programmability (I haven't tried it yet, but had been considering learning tmux partly for this), layered UI, browser w/ api. Looking forward to giving this a spin. Also want to add that I really appreciate Mitchell Hashimoto creating libghostty; it feels like an exciting time to be a terminal user.

Some feedback (since you were asking for it elsewhere in the thread!). Happy to go into more detail about any of these if it's helpful:

- It's not obvious/easy to open browser dev tools (cmd-alt-i didn't work), and when I did find it (right click page -> inspect element) none of the controls were visible but I could see stuff happening when I moved my mouse over the panel

- Would be cool to borrow more of ghostty's behavior:

  - hotkey overrides - I have some things explicitly unmapped / remapped in my ghostty config that conflict with some cmux keybindings and weren't respected

  - command palette (cmd-shift-p) for less-often-used actions + discoverability

  - cmd-z to "zoom in" to a pane is enormously useful imo

Thanks for the feedback! Mitchell Hashimoto is awesome. Have a PR for fixing devtools here: https://github.com/manaflow-ai/cmux/pull/117

> hotkey overrides - I have some things explicitly unmapped / remapped in my ghostty config that conflict with some cmux keybindings and weren't respected

We need to be better about this; right now you can modify keyboard shorcuts with cmd+, in the GUI. Planning on making it a config file in the spirit of ghostty though, not sure if we want to reuse ghostty's config file though since it might become a maintenance burden for them...

> command palette (cmd-shift-p) for less-often-used actions + discoverability

yes

> cmd-z to "zoom in" to a pane is enormously useful imo

Thinking of the right way to design this. Like hypothetically we can expand it, but what happens if you make a vertical/horizontal split, or cmd+t to make a new tab? I guess we could just "merge" it back into the original space which would be pretty cool.

I've been running this for about a week and the workspace switching is genuinely faster than tmux sessions for my workflow. One thing that caught me off guard: the API server binds to localhost by default, so I had to adjust my dotfiles to hook into it properly. The layered UI actually makes more sense once you have 4-5 terminals open compared to traditional tiling.

IMO (re zoom behavior): if you make a new tab, it should add a new tab as normal and stay zoomed in. the tab bar (of the currently zoomed in panel) would still be at the top while zoomed in, and workspaces still appear to the side

if you make a new split (or navigate splits), it would zoom you back out (contract the panel) and just split/navigate the way it normally would

I had sort of the same idea. https://wingthing.ai/ This idea started at “sandbox” and worked its way toward “remote access”. But same thoughts about muxing sessions. Love being able to leave and reattach while an agent is working. I’ll give yours a shot!

Would love your feedback and suggestions!

I like what you did here and with your direction with the stack. We have some common overlap. Last week I started clauding up something to manage my Claude sessions. It is built on Tauri 2 using xterm.js. It has is project-based and each project has resumable sessions. I borrowed inspiration from Happy coder and clauded an Expo app so I can claude remotely on-the-go. It has been a force multiplier in my clauding with developing new features and addressing bugs and defects. It was a pretty amazing feeling when I started using it to further its own development. There's a slew of other features as I adapt it to my development style.

Mobile interface is definitely nice. Planning on adding iOS app since libghostty works there too! And I imagine that having your main terminal app be synced directly to your phone must be nice, though it doesn't solve the problem of closing my laptop.

Would love to hear what other features have been particularly beneficial to your dev style too. Some directions I'm interested in is having everything be programmable; so my coding agent can set up workspaces for me, click through browsers to test things, etc. And having a main Claude Code manage subagents that have their own easily visible terminal windows.

Wow! That would be incredible! I don't have the agents control the browsers like you are doing. I'm watching to see what you do though because that is incredible. The performance hit is real though -- I may look at libghostty.

I went the similar path of going vertical tabs after having worked that way in iTerm2 for months. Here's what I currently have:

Project-based organization -- Group sessions by working directory with a visual icon strip sidebar.

Multiple session types -- Claude Code sessions, standalone terminal shells, and embedded browser tabs.

Session persistence -- Terminal output is logged and replayed on relaunch so you never lose context.

Session resume -- Claude Code sessions detect their session ID automatically and resume where you left off.

Planning mode -- Draft and refine plans in a built-in text editor, then send them to Claude with one click.

Planning templates -- Start plans from structured templates for bug reports, feature requests, code reviews, refactors, and more.

Auto-titling -- Generic session names are replaced with descriptive titles generated by Claude after the first exchange.

Theming -- Light and dark themes with full CSS variable control.

Native menus and keyboard shortcuts -- macOS-native menu bar with comprehensive shortcut coverage.

Resizable layout -- Adjustable sessions sidebar width with state persistence across restarts.

Dock badge -- macOS dock icon shows the number of actively working Claude sessions.

Pin and archive -- Pin important sessions to the top or archive completed ones to keep the list clean.

Session card view -- See all sessions in a sortable grid with activity stats, token counts, and quick actions.

File tracker -- See which files Claude creates, modifies, and deletes in a live sidebar panel.

Macros -- One-click buttons for frequently used commands like /clear or commit this work.

Remote mode -- Monitor and control sessions from your phone via an encrypted WebSocket relay.

It has become my development hub where I can iterate very quickly.

Just a quick correction: libghostty isn't actually what you want for reducing memory overhead here. It's a library wrapper around Ghostty's GPU renderer, not a lighter-weight alternative to running multiple terminal sessions. Each Claude Code session would still consume full resources regardless of the terminal renderer you use.

Very cool stuff! Would be curious if the stuff you've built is open sourced? Having a bunch of Claude Codes will definitely eat a ton of CPU/RAM. libghostty should help to a certain extent, but at some scale, you'll probably a custom optimized agent loop or remote VMs.

I really like having ~8-12 active Ghostty windows tiled so I can keep an eye on everyone's progress, and then I'll expand one or two for deeper work. Would love to see some sort of auto-expand/contract so I can keep an eye on everything but then when I foreground a pane it grows, or something like that.

Ah, like a way to maximize the current pane you're focused on?

We rebuilt this same stack in '08 with tmux and a Rails backend for session resumption. Tauri seems like overkill for what's essentially a wrapper around a terminal multiplexer, but the mobile angle is interesting if you can keep the latency under control.

Hm... any idea how I might script `git worktree` into the new-pane action?

Currently experimenting with agent-of-empires for tmux+worktrees to parallelize code changes.

No built in way to override new-pane actions right now, but `cmux --help` can automate all parts of cmux.

So you can make your own script that can make new panels/workspaces and just invoke it from the terminal:

  git worktree add -b my-branch ../repo-my-branch
  ws=$(cmux new-workspace 2>&1 | awk '{print $2}')
  cmux send --workspace "$ws" "cd ../repo-my-branch && claude"
  cmux send-key --workspace "$ws" Enter

I think we should make this easier though, open to suggestions!

Vertical tabs for a terminal emulator seems killer, I'll be trying this out for sure.

We shipped vertical tabs in our internal terminal fork last year and it completely changed how our team works. The extra pixels for long branch names and the quick visual scan actually matter when you're juggling 10+ sessions. Funny how a simple UI change can have outsized impact on workflow.

Yes it's cool. I wonder if other terminal emulator apps like WezTerm, iTerm etc also has this feature?

iTerm2 has vertical tabs too

https://iterm2.com/3.0/documentation-preferences.html#:~:tex...

I've been looking for something like this. It was just two weeks ago I had Claude modify Wezterm to add tree-style vertical reorderable tabs. It works OK but your solution is nicer.

So I've been using cmux for a few hours this morning, and I like it. One thing I'd like to disable is the reordering of tab groups. Currently it shows the most recent notifications on top. This also makes the keyboard shortcut for a given conversation change all the time, which is a cognitive burden for me.

Makes sense, added as issue: https://github.com/manaflow-ai/cmux/issues/205

Looks like this could be really cool, but it's a buggy mess. Can't switch top tabs, can't close tabs. Once I lose focus in a tab, I can't ever type again in that terminal tab. Can't switch between the different sidebar tabs, either.

Sorry you likely encountered this issue: https://github.com/manaflow-ai/cmux/issues/103

The latest release (0.57.0) should fix it.

Have you looked into zmx? [0]

It doesn't have built-in notifications and there's no panel to see all the open sessions, but I wonder how hard that would be to add.

I've used zmx since I ran into it a few weeks ago. Uses libghostty as well. It's great because it allows me to replace tmux completely in all my ssh sessions, and can keep one session per assistant.

[0]: https://github.com/neurosnap/zmx

zmx solves persistence well, and I like their minimalism (not supporting windows, tabs, or splits). I think it's possible to make a CLI wrapper for zmx that adds notifications though, so you can have some niceties of cmux without switching to a new terminal. Lowkey we might explore this direction as well.

ive been working on glue for zmx+kitty (would do ghostty if it had proper ipc/scripting support). just changed the repo visibility on on gh cwelsys/kmux.

Nice. I should add notifications to https://github.com/rcarmo/webterm - I already have sparklines as a CPU usage indicator and live thumbnails, but a visual highlight should be easy to add.

If I were you, I'd just start always in what you call "dashboard mode". Its underwhelming to start it up and not see the "boxes" :)

That’s what I do, via docker compose.

Cool project! How are you liking ghostty-web so far?

I use it every day multiple hours a day and I forget it’s a web terminal until I hit Ctrl+W on Firefox :)

I've been curious whether ghostty-web's rendering performance stays consistent under heavy load (large scrollback, rapid updates). The original ghostty implementation uses GPU acceleration pretty aggressively, but I'm not sure how much of that translates to the browser environment given WebGL constraints.

Just took it for a spin, thought it was pretty nice. Some quirks with the tab dragging, you never really know what it's going to do on mouseup, a drop-target indicator would help.

Would love to be able to color the sidebar tab.

Nice work!

Thanks! Will add drop target and sidebar coloring.

Should be in latest release!

Looks really useful! Does this support the new Claude Code agent teams feature, so it will open all the team members in their own pane?

We're working on a tmux/it2 compatibility layer to make this happen!

This is pretty slick, man. The only thing is that the Ctrl-Cmd-] is too hard to press but I'll just use the number thing.

Thank! I personally have caps lock mapped ctrl... but open to suggestions! Since it's hard to handle both horizontal and vertical tabs.

Ah, I regret training myself into Caps Lock to Escape. Well, a personal problem then. It doesn't seem to have copy-paste support that I have in my Ghostty but I bet that's a config somewhere.

Get the best of both worlds by having it be Ctrl when held down + pressed with another key and Esc when you press and release it by itself.

> copy-paste support that I have in my Ghostty

Want to fix this, how do I reproduce? Select with mouse and cmd+c seems to work for me.

Awesome work, keen to try it out tomorrow. Can I make the notifications work with Gemini CLI and Kiro CLI too?

Thanks! Yup, notifications can be triggered via cli:

  cmux notify --title "Claude Code" --subtitle "Waiting" --body "Agent needs input"

And afaik, both Gemini/Kiro should have stop hooks. If they send OSC notifications, then notifications will "just work" as well.

Docs: https://www.cmux.dev/docs/notifications

Got a bunch of errors when starting Claude.

Could you file an issue with more details: https://github.com/manaflow-ai/cmux/issues

Would greatly appreciate it!

Gave this a run and it was pretty intuitive. Good work!

Thanks!

vertical tabs are a great idea for ghostty!

This looks cool. I honestly haven’t ever thought about using vertical tabs in a terminal window but that seems nice.

One question though, have you thought about trying to upstream any of this into Ghostty instead of making an entirely different app?

Upstreaming into Ghostty would be very difficult as it's not actually a fork, I just used libghostty under the hood.

VSCode has vertical tabs for it's terminals like this, but on the right side.

Good idea, but I don't want to move to another terminal now, will stick with Ghossty

It's an open discussion. I also have a PR ready, but they are working on stability before a release, which means a pause on new features right now. https://github.com/ghostty-org/ghostty/discussions/2549

Fair enough! I like Ghostty a lot too, and the only reason I built this was because I wanted vertical tabs and nicer notifications.

18 (!) releases in two days. This is some really fast coding.

Lots of stuff to iron out pre-launch!

With this one, small tweak it is perfect:

osascript << 'EOF' use framework "Foundation" use framework "AppKit"

set ghosttyIconPath to "/Applications/Ghostty.app/Contents/Resources/Ghostty.icns" set cmuxAppPath to "/Applications/cmux.app"

-- Read the icon file set iconImage to current application's NSImage's alloc()'s initWithContentsOfFile:ghosttyIconPath

-- Set it as the custom icon for cmux.app current application's NSWorkspace's sharedWorkspace()'s setIcon:iconImage forFile:cmuxAppPath options:0 EOF

((The ghost pairs well with Kiro, what can I say?))

:ghost:

I disagree that multiplexing is the right abstraction here. We've had screen and tmux for decades—wrapping them in Electron doesn't solve the actual problem, which is that terminal UIs are fundamentally constrained. You're just adding layers of complexity when what people really need is better native shell integration and composability at the OS level.

> If two agents are working on the same local dev server, do they share the browser context or get isolated profiles

Currently they share browser context. Adding isolated profiles is a good idea. Do you often use multiple agents in a single project and have them both work on different pages? I personally use multiple checkouts, and the problem for me is that agents working in the same project want to spin up the same dev server. And the dev servers will conflict unless I make different instances of the same project listen in their own port ranges (perhaps via a PORT env var).

We want to solve the latter by bringing better SSH support where the WebView will proxy directly to a remote machine or Docker container, so different workspaces in the vertical tabs can talk to their corresponding dev servers. But I want to hear more about your use case.

Can’t wait for better SSH support. We have a warm container host that spawns a fresh container so we get nice sandboxing and isolation, but the UX has left us with basically the same challenges you solved here for one box.

> a cron or hook that runs tmux capture-pane on each agent pane and checks for the idle prompt is enough to know when one needs attention.

Curious why you aren't using Claude Code's stop/notification hook

> Separate Chrome profiles per agent is the brute-force fix, but it's expensive. The better pattern is treating browser access as a serialized resource — one agent gets it at a time, with the others queued.

Ports could also be another serialized resource. Another direction we're exploring is to give agents VMs that have Chrome + VNC preinstalled [1]. Prompting Claude to use Docker also goes a long way there.

[1] https://cloudrouter.dev/

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