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Show HN: Ghostty-based terminal with vertical tabs and notifications
I run a lot of Claude Code and Codex sessions in parallel. I was using Ghostty with a bunch of split panes, and relying on native macOS notifications to know when an agent needed me. But Claude Code's notification body is always just "Claude is waiting for your input" with no context, and with enough tabs open, I couldn't even read the titles anymore.
I tried a few coding orchestrators but most of them were Electron/Tauri apps and the performance bugged me. I also just prefer the terminal since GUI orchestrators lock you into their workflow. So I built cmux as a native macOS app in Swift/AppKit. It uses libghostty for terminal rendering and reads your existing Ghostty config for themes, fonts, colors, and more.
The main additions are the sidebar and notification system. The sidebar has vertical tabs that show git branch, working directory, listening ports, and the latest notification text for each workspace. The notification system picks up terminal sequences (OSC 9/99/777) and has a CLI (cmux notify) you can wire into agent hooks for Claude Code, OpenCode, etc. When an agent is waiting, its pane gets a blue ring and the tab lights up in the sidebar, so I can tell which one needs me across splits and tabs. Cmd+Shift+U jumps to the most recent unread.
The in-app browser has a scriptable API ported from agent-browser [1]. Agents can snapshot the accessibility tree, get element refs, click, fill forms, evaluate JS, and read console logs. You can split a browser pane next to your terminal and have Claude Code interact with your dev server directly.
Everything is scriptable through the CLI and socket API – create workspaces/tabs, split panes, send keystrokes, open URLs in the browser.
Demo video: https://www.youtube.com/watch?v=i-WxO5YUTOs
Repo (AGPL): https://github.com/manaflow-ai/cmux
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:
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 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.
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.
It isn't open sourced, just a private repo on GitHub. I built it as a pet project just throwing things at the wall seeing how far I could go in a short time as a means to an end. Currently, I cannot commit time to maintaining an open source project and it would be negligent of me to put something out there that would stagnate. As quickly as my app shaped up, I bet I could claude something from scratch and implement the features that have worked out for me. There are many rough edges that I just work around that you have a better grasp on, like notifications.
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?
Yep! Also a simple text editor pane would be sweet too.
Haha, it's like we're moving towards an IDE but starting from the opposite direction.
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!
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.
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!
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:
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:
I think we should make this easier though, open to suggestions!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 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.
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.
Cool project! How are you liking ghostty-web so far?
Gave this a run and it was pretty intuitive. Good work!
Thanks!
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.
Well, there's a fantastic idea. Apparently so many people are already in this better world: https://gist.github.com/tanyuan/55bca522bf50363ae4573d4bdcf0...
I have Karabiner Elements so I added it and it's amazing!
> 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.
Oh thank you. Perhaps it's something in my Ghostty. Here's a gist to work with:
https://gist.github.com/roshan/b2a073e2377f370ce83cf7c4ea6d8...
I'm on MacOS 15.7.4 on an M4 Max Macbook
Thanks for repro, taking a look!
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:
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
vertical tabs are a great idea for ghostty!
Good idea, but I don't want to move to another terminal now, will stick with Ghossty
Fair enough! I like Ghostty a lot too, and the only reason I built this was because I wanted vertical tabs and nicer notifications.
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.
Ah! Thanks for explaining that. I totally keep forgetting, to my own detriment, libghostty exists. It’s mighty cool to see it being used more and more to build cool new terminals (like yours and the mobile terminal that showed up here the other day).
I missed the mobile terminal and I've been hunting for a good one, did a search for past week but found nothing, if you had a link handy that would be great - thank you.
VSCode has vertical tabs for it's terminals like this, but on the right side.
18 (!) releases in two days. This is some really fast coding.
Lots of stuff to iron out pre-launch!
[flagged]
> 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.
Excited that someone besides me wants this! I want to hear more about your warm container host, is that shared between multiple people, or just yourself?
Also want some feedback on how we should implement it. Could make it a CLI command that opens a new vertical tab/workspace:
Or maybe a configurable dropdown next to the plus button.[flagged]
> 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/
@dang another bot