---
title: Terminal
description: The MixOS terminal, with tabs, split panes and a GPU-drawn grid, driven by the session settings and fully scriptable over the Bus.
---

# Terminal

`term` is the MixOS terminal (app id `dev.mixos.term`): tabs, split panes,
and a grid drawn on the GPU. It is an egui shell (see
[AGENTS.md](https://github.com/markc/mixos/blob/main/AGENTS.md) §4.1) around
two private crates:

- `crates/term-core`: the engine. PTYs, the VT grid, tabs and panes,
  selection, mouse reporting, configuration, the native session and the
  `term.*` Bus verbs.
- `crates/term-render`: the grid on the GPU. A glyph atlas and instanced
  cells drawn by an egui-wgpu paint callback per pane. The CPU raster in
  term-core is its test oracle.

The shell adds the window: the toolkit title bar and menus, the tab strip,
pane borders on whole physical pixels, the keyboard and input method, the
pointer (selection, mouse reporting, middle-click paste of the primary
selection), the clipboard, and font zoom. Every action is a command on the
toolkit registry, published on `term.command.executed`.

The source is [`apps/term`](https://github.com/markc/mixos/tree/main/apps/term).

## Bus

The window registers `term` (or `term-<pid>` when another instance holds
it) and answers:

- the terminal's verbs, served by term-core (`HELP` lists them):
  `term.session`, `term.tabs`, `term.tab.*`, `term.panes`, `term.pane.*`,
  `term.snapshot`, `term.scroll`, `term.type`, `term.props.watch`;
- the window's own: `term.commands`, `term.execute`, `app.describe`, and the
  toolkit drive verbs (`term.ui.*`, `term.window`, `term.window.state`).

`term --headless` serves the terminal's verbs with no window.

## Configuration

The desktop profile's `terminal.*` settings, held by
[settingsd](../settingsd/README.md) and edited in [Prefs](../prefs/README.md):
font family, size and weight, padding, border width, history lines, scroll
speed, cursor shape and blink, the focus ring, copy on select, and `TERM`.
The window follows them as they change; Ctrl+plus and minus write
`terminal.font.size` back 400 ms after the last zoom key. Ctrl+0 returns to
the profile size without writing, except to correct a write already in
flight. An unsaved zoom stays pending in memory until another zoom key or a
successful settings read; a validation refusal discards it. Failures
schedule no retry timers. History lines and `TERM` apply to tabs and panes
opened afterwards. Without settingsd the defaults stand, and zoom stays the
window's own. `TERM_FONT_PX` sets the size until settingsd answers, and
`TERM_SPIKE_FONT` overrides the font file; `term --print-config` prints the
startup values.

## Keys

`term --help` lists them. Tabs: Ctrl+Shift+T/W, Ctrl+PageUp/PageDown.
Panes: Ctrl+Shift+E/O split, Ctrl+Shift+X close, Ctrl+Shift+arrows,
Tab/Shift+Tab or Ctrl+Tab between split panes. Clipboard: Ctrl+Shift+C/V,
Shift+Insert. Font: Ctrl+plus/minus/0 and Ctrl+wheel. History:
Shift+PageUp/PageDown/Home/End. Alt is Meta (ESC before the key; Alt+cursor
keys send xterm's CSI 1;3 sequences). Right-hand modifier chords are the
person's own on MixOS and are not bound.

## Building and testing

On an authorised build worker at a pushed commit:

```
cargo test --locked -p term-core -p term-render -p term
cargo build --locked --profile release-fast -p term
```

`tests/window.rs` takes an offscreen snapshot of the window with two tabs
and a split; regenerate it with `UPDATE_SNAPSHOTS=1` and look at it. The
PTY tests need the Mix binary at `/opt/mixos/bin/mix`.