ratatata

A tiny terminal text editor built with ratatui.

Just like bat is a modern replacement for cat, rat(atata) aims to be a modern replacement for nano.

• Simple and intuitive to use
• Syntax highlighting
• Nothing to learn or remember
• Full optional mouse control
• No AI features

In short, a simple editor you can use to quickly edit configuration or code files without worrying if your .env secrets are sent to AI or having to remember how vim/emacs works when editing a remote file over ssh.

Installation

cargo install ratatata

Or from source:

cargo install --path .

Or run in place:

cargo run -- [path]

Installs as the rat command (the binary name is set explicitly in Cargo.toml, separate from the ratatata package name). Requires Rust 1.90 or later. Edition 2024 landed in 1.85, but the current dependency tree (ratatui 0.30, image 0.25, …) needs a newer compiler; Cargo.toml also avoids TOML 1.1 multi-line inline tables so an older Cargo is not what blocks the build. Works in any terminal that supports crossterm's event and drawing APIs — including tmux/screen when mouse reporting is enabled.

Features

• Sidebar + editor split — browse directories on the left, edit files on the right
• Clickable shortcut bar — the keyboard shortcuts are shown as buttons in a bar at the top; click one to run it, hover it for a longer description in the status bar. The keys and the buttons are the same actions, so they always behave identically
• Catppuccin Mocha UI theme — semantic application colors supplied by ratatui-themes, including themed panels, selections, search matches, caret, status bar and shortcut buttons. Truecolor terminals (COLORTERM=truecolor / 24bit, a recognized terminal name, or a *-direct terminal name) keep the RGB theme unchanged. Dedicated terminal names for Ghostty (xterm-ghostty), Kitty (xterm-kitty), Alacritty (alacritty), foot (foot / foot-extra), and WezTerm (wezterm) are recognized even over SSH when COLORTERM is not forwarded. WezTerm defaults to xterm-256color; its dedicated name must be configured to benefit from that recognition. Otherwise, terminal names advertising 256color (such as xterm-256color, screen-256color, and tmux-256color) use the extended color cube and grayscale ramp to approximate the theme. Other terminals use ANSI 16 with deliberate syntax colors, white-on-blue selections, and contrasting text for search matches, hovered shortcuts and the caret. Selected hidden files remain readable instead of dimmed. There is no theme toggle, and NO_COLOR / FORCE_COLOR are ignored so a sandbox cannot grayscale Ghostty.
• Syntax highlighting — Sublime Text grammars via syntect, detected by extension and first-line heuristics; re-highlights incrementally as you type, only re-parsing lines from the edit point onward
• Parinfer Smart Mode — for .clj, .cljs, .cljc, and .edn files, indentation and parentheses stay in sync as you type (a user edit and the automatic adjustment undo together). Cursor-only movement updates the remembered caret without re-running the engine. Other file types are unchanged; incomplete forms (for example an unclosed string) are left as typed.
• Clipboard integration — copy/cut/paste through the system clipboard (arboard), with bracketed-paste support for terminals that send it
• Full mouse support — click to place the cursor, drag or Shift+click to select, double-click to select a word, triple-click to select a line, Ctrl/Cmd+click a web link to open it in the default browser, scroll wheel to move through text without moving the editor cursor (with a scrollbar) and directories
• macOS-friendly keys — on terminals supporting the kitty keyboard protocol, Cmd+key works like Ctrl (unsupported terminals just ignore the request)
• Incremental search — Ctrl+F opens a search bar: matches are highlighted as you type, Enter / Shift+Enter step to the next / previous match, Esc closes
• Find and replace — Ctrl+Shift+H (or the replace shortcut button) extends search: type the find text, Tab or Enter to type the replacement, Enter replaces the current match and steps to the next, Shift+Enter replaces all, Esc closes. Ctrl+H is still hide-dotfiles.
• Go to line — Ctrl+G (or the line shortcut button) prompts for a 1-based line number and jumps there, keeping the cursor visible. Invalid input is a status message.
• Toggle sidebar — Ctrl+B (or the files shortcut button) hides or shows the file tree so the editor can use the full width. Directory and selection survive. Ctrl+O while the sidebar is hidden shows it and focuses it.
• Word wrap — Ctrl+W wraps long lines at word boundaries (a single unbreakable word still hard-breaks) instead of scrolling horizontally; navigation (arrows, Home/End, PgUp/PgDn, mouse) follows the visual rows, and wrapping re-flows automatically on resize
• Image previews — opening an image file (png, jpg, gif, webp, bmp, …) renders it in the editor pane via the terminal's graphics protocol: kitty graphics where supported (kitty, Ghostty, WezTerm, iTerm2, …), unicode half-blocks elsewhere. Half-block pixels use the detected color depth (RGB, 256 colors, or ANSI 16), independently of the syntax palette; native graphics retain their original colors. Images are contained within the pane without clipping; small images remain at native size, while larger images are scaled using logical cell dimensions. Esc closes the preview and restores the previously open text buffer (including word wrap); closing a preview that was the first thing opened lands on empty untitled
• Hide dotfiles — the sidebar hides names starting with . by default (.. is always listed). Ctrl+H (or the hidden shortcut button) toggles them. Hidden entries are dimmed when shown.
• Safe saves — writes are staged beside the destination and published after a complete, synced write. Existing symlinks are retained and their targets updated; existing permissions and Unix ownership are preserved. Save-as asks before replacing an existing file and keeps failed filenames editable.
• Line endings — CRLF files remain CRLF when edited, with carriage returns kept out of the editable text. Unedited files round-trip exactly; editing files with mixed LF/CRLF endings normalizes their separators to CRLF.
• Safe file handling — a dirty buffer blocks opening another file or starting a new one (Ctrl+N), and Ctrl+Q asks for confirmation before discarding unsaved changes
• Reload from disk — Ctrl+R re-reads the open file (or the image preview) so external changes show up, and refreshes the sidebar listing in the same go; refused while the buffer has unsaved edits
• Undo / redo — Ctrl+Z undoes, Ctrl+Shift+Z redoes; continuous typing, backspacing, deleting and pastes each collapse into a single undo step, and undoing restores the cursor, selection and modified state
• Unicode-aware editing — the cursor tracks characters, not bytes, so wide characters and non-ASCII text render and edit correctly

Usage

rat [path]
rat -h | --help
rat -V | --version

Argument	Behavior
(none)	Browse the current directory
file.txt	Open the file
image.png	Preview the image in the editor pane (kitty graphics protocol, unicode half-blocks as fallback; contained and scaled to the pane)
dir/	Browse the directory
new.txt (doesn't exist)	Start an untitled buffer bound to that path (created on first save)
-h / --help	Print usage and exit
-V / --version	Print the version and exit

Keys

Keys	Action
Ctrl+N	Start a new untitled buffer
Ctrl+O	Switch between sidebar and editor (shows the sidebar first if it was hidden)
Ctrl+B	Show or hide the file sidebar
Ctrl+S	Save (asks for a name if untitled)
Ctrl+R	Reload the current file from disk (and refresh the sidebar)
Ctrl+C / Ctrl+X / Ctrl+V	Copy / cut / paste
Ctrl+A	Select all
Ctrl+F	Search (type to filter, Enter / Shift+Enter next / previous match, Esc closes)
Ctrl+Shift+H	Find and replace (Tab / Enter to the replacement field, Enter replace current, Shift+Enter replace all, Esc closes). Does not steal Ctrl+H.
Ctrl+G	Go to line (1-based; invalid input is a status message)
Ctrl+W	Toggle word wrapping of long lines (visual rows instead of horizontal scrolling)
Ctrl+H	Show or hide dotfiles in the sidebar (.. is never hidden; hidden by default)
Ctrl+Z / Ctrl+Shift+Z	Undo / redo
Ctrl+Q	Quit (press twice when there are unsaved changes)
Esc	Close an image preview (restores the previous file) / cancel the save-as prompt

Sidebar: ↑/↓ select, Enter/→ open (directory = enter, file = open), Backspace/← go up, Home/End, PgUp/PgDn page.

Editor: type to insert, ←/→/↑/↓ move (hold Shift to extend the selection), Home/End, PgUp/PgDn, Backspace, Delete, Enter auto-indents (the new line keeps the current indentation), Tab indents (four spaces, or every selected line), Shift+Tab dedents. With wrapping on (Ctrl+W), ↑/↓/Home/End/PgUp/PgDn move by visual rows (a wrapped line spans several).

Mouse: click the editor to move the cursor, drag or Shift+click to select, double-click selects the word under the cursor, triple-click selects the whole line, Ctrl/Cmd+click an http://, https://, or www. link to open it in the default web browser, scroll to move the viewport without moving the cursor; the editor shows a vertical scrollbar when the content is longer than the viewport. Single-click the sidebar to select, double-click to open, scroll to browse. The shortcut buttons in the bar at the top are clickable too — hover one for a description in the status bar, click it to run the action (the buttons wrap onto a second row on narrow terminals).

Testing

cargo test

The test suite covers buffer editing, undo/redo coalescing, save/save-as flows, dirty-buffer guards, sidebar navigation and hide/show, mouse interactions, image-preview opening/closing/restoring, unwrapped-line clipping, truecolor/256-color/ANSI-16 palettes, selection and highlight contrast, image color depth across cached frames and resizing, hide-dotfiles listing, find and replace, go-to-line, Parinfer Smart Mode on Clojure-family files, and headless rendering (including syntax-highlight colors) via ratatui's TestBackend.

How it works

src/
├── main.rs       entry point: arg resolution, terminal setup (mouse,
│                 bracketed paste, kitty keyboard protocol, image-protocol
│                 detection), event loop
├── app.rs        shared application state and initialization
├── app/          input and mouse handling, file/search actions, links,
│                 shortcut layout, editor/status rendering and text clipping
│   └── tests/    existing app regressions grouped by behavior;
│                 shared fixtures live in app/tests.rs
├── buffer.rs     buffer state and common text helpers
├── buffer/       editing, selection, history, navigation, wrapping,
│                 viewport calculations, atomic storage and Parinfer integration
│   └── tests/    existing buffer regressions grouped by behavior;
│                 shared fixtures live in buffer/tests.rs
├── sidebar.rs    scrollable directory listing (dirs first, ".." entry,
│                 optional hide-dotfiles)
├── theme.rs      color-depth detection, UI/syntax palettes and image quantization
├── image_view.rs image previews: decode via the `image` crate, render
│                 through the kitty/sixel/iTerm2 protocols (or half-blocks)
│                 via ratatui-image
├── highlight.rs  incremental syntect highlighting with per-line cached
│                 parse states and scope stacks
├── parinfer.rs   Parinfer Smart Mode for Clojure-family files (path
│                 detection, grapheme/display-column cursor mapping)
├── parinfer_engine/  vendored parinfer-rust algorithm (ISC;
│                 eraserhd/parinfer-rust@0d334950099cd30a8e1ca520026f8da9ea1382fa)
├── search.rs     case-insensitive incremental search (matches, navigation)
└── clipboard.rs  system clipboard behind a small trait (tests use a fake)

Highlighting follows the pattern recommended in syntect's HighlightState docs: the parse state and scope stack after each line are cached, so an edit invalidates only the lines from the edit point onward, and they're re-parsed only when they become visible. The syntax definitions and Catppuccin Mocha theme (embedded by two-face) are loaded once into process-wide statics.