termi

A modal terminal code editor written in Rust, built on ratatui and crossterm. Inspired by Helix and Kilo: modal like the first, small enough to read end to end like the second.

Install

Linux and macOS:

curl -fsSL https://github.com/tuna4ll/termi/releases/latest/download/install.sh | sh

Windows PowerShell:

irm https://github.com/tuna4ll/termi/releases/latest/download/install.ps1 | iex

The installers select the right prebuilt binary and verify its SHA-256 checksum. Linux and macOS install to ~/.local/bin; Windows installs under Local AppData and adds that directory to the user PATH.

Alternatively, install from crates.io or download an archive from the releases page:

cargo install termi

Building from source needs Rust 1.88 or newer:

cargo run --release -- src/main.rs

What it does

Text — UTF-8 throughout, a ropey rope underneath, so editing a large file costs the same as editing a small one. Tabs, wide glyphs and mixed line endings are handled at the edges: everything in between works in plain character indices.

Modal editing — normal, insert, visual, visual-line, command and search modes. hjkl and word motions, dd/yy/p, undo and redo with typing merged into sensible steps, and multiple cursors (Alt+↑ / Alt+↓) as a first-class part of the editing core rather than a bolted-on mode.

Selecting — v and the motions, or the ways a modeless editor does it: hold Shift and press an arrow, click and drag, or Ctrl+A for all of it. Those leave the mode alone — you stay in normal or insert mode, the status bar counts what is selected, and Backspace, Delete, Ctrl+C, Ctrl+X, Ctrl+V or simply typing act on the selection. A plain motion drops it again.

The two conventions differ where they have to: a selection dragged out with Shift or the mouse is exclusive, so one press covers one character, while visual mode stays inclusive of the character under the caret. Each behaves the way the people who reach for it expect.

Word-wise keys — Ctrl+← and Ctrl+→ jump a word at a time, Ctrl+Backspace and Ctrl+Delete remove one. A run of spaces or tabs counts as a word of its own, so a single press clears the gap between two words, or a line's indentation, without swallowing the word beside it.

Typing — indentation carried onto new lines, } pulled back to line up with its opener, and brackets and quotes closed as you type them. Typing the closing half steps over it instead of doubling it, backspace between the halves takes both, and Enter between { and } opens the block out over three lines. :set autopairs off if you would rather type them yourself.

Search — incremental, literal or regex, smart case, with matches highlighted as you type and :%s/a/b/g for replacement.

Syntax highlighting — regex based, for Rust, C, C++, Zig, Python, Markdown, and diffs. Block-comment state is cached per line, so scrolling deep into a file does not rescan it. A .diff, .patch or .rej file is coloured the way a diff wants to be read: added lines green, removed lines red, hunk headers and file headers apart from both.

Files — multiple buffers with a tab strip, a lazily expanded file tree (Ctrl+B) that can create files and directories, atomic saves, and a watcher that reloads clean buffers when they change on disk and warns rather than clobbers when they do not. The same watcher keeps the tree current, so a file another program adds or removes appears and disappears without a restart, and Ctrl+B re-reads the directory as it opens the panel. :w name.c names an unnamed buffer and highlights it as C from that moment on.

Windows — split the screen as many ways as you like (Ctrl+W s / Ctrl+W v). A buffer holds the text, the undo history and the highlighting; a window holds a viewport and its cursors. The same file can therefore be open in two windows at once, scrolled to different places, with an edit in one appearing immediately in the other and a single undo stack behind both.

Looks — dark and light themes built in, plus TOML themes that override only the slots you care about.

Keys

Press :help inside the editor for the same list.

Commands: :w [path] :q[!] :wq :e[!] path :touch path :mkdir path :bn :bp :<line> :sp :vs :clo :on :set <option> [value] :theme <name> :%s/pattern/replacement/g

Configuration

See config.example.toml. Themes go in <config-dir>/termi/themes/<name>.toml and layer over a built-in base:

name = "midnight"
base = "dark"

[comment]
fg = "#4a5058"
italic = true

[selection]
bg = "bright-blue"

Architecture

Layers depend downwards only:

app/         event loop, state, action dispatch, ex commands
├── ui/      layout and widgets; renderer/ owns the terminal
├── input/   keys → actions
└── editor/  text, with no knowledge of terminals
    ├── document/   rope, file, dirty state, indentation
    ├── cursor/     positions, motions, word boundaries
    ├── selection/  character ranges
    ├── buffer/     a file: document + history + highlighting
    ├── window/     a view: viewport + cursors, and the split tree
    ├── edit/       changes a buffer's text through a window
    └── command/    ex-command parsing

config/  theme/  syntax/  search/  undo/  clipboard/  filesystem/

The editor core is UI-free and the UI layer is read-only, so a render pass is a pure function of the state plus the terminal size. Every module's header documents its purpose, its responsibility and its public API.

unsafe_code is forbidden crate-wide.

Development

cargo test
cargo clippy --all-targets -- -D warnings
cargo fmt --all

CI runs these plus the test suite on Linux, macOS and Windows and a build against the minimum supported Rust version. See CONTRIBUTING.md for what the code expects of a change.

Roadmap

Syntax highlighting is deliberately regex based for now. The next step is tree-sitter behind the same Highlight span interface, which the renderer and themes already consume — no changes above the syntax module.

License

MIT