Technical design

How the product is built.

flowchart LR
    subgraph APPS["Apps · one shared client library"]
        DESKTOP["muxy-app<br/>desktop · Rust + GPUI"]
        TUI["muxy<br/>CLI and terminal UI · Ratatui"]
        PHONE["Phone apps<br/>muxy-mobile SDK"]
    end
    SERVER["muxy-server<br/>Ghostty terminals · history · projects"]
    REMOTE["muxy-server<br/>on another computer"]
    DESKTOP <-->|"Unix socket"| SERVER
    TUI <-->|"Unix socket"| SERVER
    DESKTOP <-->|"SSH · muxy stdio"| REMOTE
    TUI <-->|"SSH · muxy stdio"| REMOTE
    PHONE <-->|"TLS"| SERVER
    PHONE <-->|"SSH · muxy stdio"| REMOTE

The big ideas:

1. The server owns the terminals. Each session is a Ghostty terminal on the server, with its history. Apps never parse terminal output. They receive rows of styled text and draw them.
2. Only changes are sent. About 60 times a second the server sends the rows that changed. A slow app gets one merged update, never a backlog.
3. One client library. The desktop app, the terminal UI, and the phone apps all use the same Rust client and protocol.
4. The protocol only grows. New fields and messages don't break older builds.

Read next

1. Architecture: processes, crates, and how a keystroke travels.
2. Protocol: how apps and the server talk, and the compatibility rules.
3. Mobile: how phones pair and connect.
4. Decisions: the key choices and why they were made.
5. Constraints: supported platforms and hard-won lessons.