What is sophonz?

sophonz is an agentic development environment built on a terminal multiplexer. It brings the coding agents on your machines into one orchestration you watch and steer from the desktop, a browser or your phone.

sophonz is an agentic development environment (ADE) built on a terminal multiplexer. Your coding agents (Claude Code, Codex, Gemini CLI) run in tmux sessions on your own machines, and sophonz lets you watch them, hand work between them and step in, from the desktop app, a browser or your phone.

On each machine runs st, one binary. It shares that machine's tmux sessions. The desktop app and the iPhone and Android apps are the main way in; a browser works too, on a desktop or a phone. Whatever you open it with, it is the same session: type on the phone and the computer's terminal changes with it.

In the desktop app, a coordinator starts three workers; st ui steps into one; the workers report and the history and documents are read; the run is archived from a phone and brought back; an agent from another machine joins the run; st ui lists four machines.

Core model


Machine	A computer that runs `st`. Your laptop, a desktop, a Mac you keep for builds, a Linux box.
Session	A tmux session on that machine, with its windows and panes. It belongs to tmux, not to the connection, so it keeps running when every screen has gone.
Agent	Claude Code, Codex or Gemini CLI running in a pane. With hooks it tells `st` whether it is working, waiting for you or done.
Coordinator and workers	One agent that hands parts of a task to other agents, each in a window of its own, and the agents doing them. A worker can be on another machine of the account.
Account	Optional. Signed in, each machine keeps one link that does not change, and the apps list all your machines.

How st works goes into each of these.

What makes it an ADE

Built on the multiplexer, so nothing locks you in. The sessions are ordinary tmux sessions (psmux on Windows). Open any terminal on the machine, attach to the session and carry on where the agents are; stop using sophonz and the sessions and the agents are still yours. From any terminal (iTerm, Warp, any), st attach <machine>/<session> joins a session on another of your machines. The agents are the ones you already use, with their own logins and settings. See Sessions, windows and panes.
One orchestration across your machines. One agent, the coordinator, hands parts of a task to workers, each in a window of its own, on this machine or on another machine of the account. The whole run is one tree you can watch and change. See Orchestration.
It comes back after a restart. st keeps a snapshot of the sessions every 10 seconds. When the computer has restarted, it sets them up again once you say so, and Claude Code and Codex continue their conversations. See Restoring after a tmux crash.
Handoffs on record, an audit log of the orchestration. A brief one agent hands another is kept as a Markdown file that says when it was sent and to whom. The run's history records every handoff, each worker's result and every change to the tree (adopted, released, renamed) with who asked for it. The History tab beside the agent graph, in the desktop app and the web terminal, lists it, and a line opens the handoff document itself. See Handoffs are kept.
A whole orchestration in one file. st project save keeps a run as one .sophonz file: the tree of agents, the history, the handoff documents, the last summaries and which conversations they had. st project open brings it back, on this machine or another, with each agent in its own window again and its conversation resumed where it is there. In the desktop app it is File → Open / Save / Archive Project…. See A run as one file.
Watch and step in from anywhere. The desktop app, a browser and the iPhone and Android apps open the same sessions. Each window has a status dot, an agent that asks a question or finishes sends a notification with its options as buttons, and the iPhone has a Live Activity for the whole account. See Agents and their state.
A terminal a phone can use. A key bar with Ctrl, Esc, Tab and arrows, a sheet for writing a long prompt, dictation in the apps, the agent's conversation as chat, and a phone on another window gets its own size instead of squashing the desktop's.

Compared with a plain web terminal

The session survives. ttyd kills the shell the moment the websocket closes. The session belongs to a multiplexer instead, so a locked screen, an app switch or a changed network all come back to the same shell.
One link, whatever the address. A free tunnel address is different after every restart. Sign in and one link that does not change reaches the machine. The token that opens the terminal never leaves it.
Nothing to install first. No bun, no ttyd, no multiplexer to install: st carries them. tmux is preferred, your own when you have one — it is the only backend where two browsers can be on different windows of one session at once. On Windows it is psmux.

How it fits together

Your machine. st starts an agent and joins a multiplexer session to ttyd, which is bound to loopback and nothing else.
The tunnel. On Free, a Cloudflare quick tunnel gives it a public address that changes each run; on Pro, the sophonz relay gives it a fixed one. The machine's tailnet can stand in instead (st route). st's share token sits in front of the shell, and Cloudflare Access can stand there too.
The browser. The proxy serves everything you see: the touch key bar, the session list, and a cached Nerd Font. The machine dials out, so nothing waits for an inbound connection and there is no SSH client in the way.

Audience

People who leave coding agents running on their own machines and want to keep an eye on them away from the desk: answer a permission prompt from the phone, see which agent is done, pick up a session started at work on the laptop at home. And anyone who wants a terminal on their machine from a phone, with or without an agent in it.

Out of scope

Not a model or an agent. st runs the agents you already have, with their own logins and settings. It watches them and types into them; it does not think for them.
Not a hosted machine. No computer is rented to you. The sessions, the agents and your code stay on your machines, and the apps are clients. The account keeps where each machine can be reached and sends the notifications.
Not an SSH client. There is no port to open and no SSH server to run. The machine reaches out through a tunnel, and the apps come in through it. See Ways to run.
Not a replacement for git. Workers can each have a git worktree, but moving code between machines is still your shared remote's job.

Installation

One binary on each machine. It carries ttyd, tmux, zellij and its own web page, and uses the machine's own tmux when there is one.

curl -fsSL https://dl.sophonz.io/install.sh | sh

Next steps

Install st on a machine.
Share a terminal: run st and open what it prints.
Your first multi-agent session: one agent, two workers, one report.
Get the desktop app or the iPhone and Android apps.