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.

cargo install termi

Or grab a prebuilt binary from the releases page — Linux (glibc and static musl), macOS (Intel and Apple silicon) and Windows.

Building from source needs Rust 1.88 or newer:

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

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.

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 and Markdown. Block-comment state is cached per line, so scrolling deep into a file does not rescan it.

Files — multiple buffers with a tab strip, a lazily expanded file tree (Ctrl+B), atomic saves, and a watcher that reloads clean buffers when they change on disk and warns rather than clobbers when they do not.

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.

Press :help inside the editor for the same list.

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

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"

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.

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.

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. Mouse support is also intentionally deferred.

MIT