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<a href="https://dylancobb.github.io/sev">Website</a> | <a href="https://discord.gg/u9tvBmTMwx">Chat</a>

</h1>

Sev

Sev is an Emacs-like, Vim-like graphical text editor, built from scratch using SDL3 and Clay, with Chibi Scheme as its scripting layer. It runs natively on Linux and macOS (Windows soon!), and in the browser via WebAssembly.

Screenshots

<figure> <img width="3778" height="2047" alt="image" src="https://github.com/user-attachments/assets/5b595e0d-571f-4b2d-9ecd-ce4916cd9e6a" /> <figcaption>Panes, tabs and syntax highlighting.</figcaption> </figure> <figure> <img width="3778" height="2047" alt="image" src="https://github.com/user-attachments/assets/84412c21-f423-4884-9566-360ca90f9b32" /> <figcaption>Welcome screen and command palette.</figcaption> </figure> <figure> <img width="3778" height="2047" alt="image" src="https://github.com/user-attachments/assets/87ed1065-f070-4aa8-b271-566000c7153c" /> <figcaption>Theme picker with theme previews.</figcaption> </figure>

Features

• Full Vim-style modal editing — normal, insert, visual, replace, and operator-pending modes; motions, operators, text objects, registers, macros and marks
• Modern VSCode/Zed-style command palette — ctrl-shift-p or : to search and run any command by name
• Which-key overlay — press a prefix key and see all available continuations
• Scheme scripting — every command, keybinding, and mode is defined in Scheme and can be overridden; no recompile needed
• Themes — Catppuccin and Solarized themes are included, with many more planned; define your own in a few lines
• Split panes — horizontal and vertical splits, navigate and resize with the keyboard or mouse
• Runs in the browser — build with Emscripten for a zero-install WebAssembly version
• Undo tree, jump list, buffer-local variables, tab bar, and so much more

Quick Start

Prerequisites

• CMake 3.20+
• A C compiler (GCC or Clang)
• SDL3 system dependencies (on Debian/Ubuntu: libgl-dev libgles-dev)

Dependencies (SDL3, SDL_ttf, Chibi Scheme) are vendored as git submodules.

git clone --recursive https://github.com/your-username/sev
cd sev

Desktop

cmake -S . -B build-desktop
cmake --build build-desktop
./build-desktop/app

WebAssembly

Requires Emscripten.

emcmake cmake -S . -B build-wasm
cmake --build build-wasm
python3 -m http.server   # then open http://localhost:8000

Scriptable with Scheme

All commands, keybindings, modes, and themes are defined in Scheme. Drop your configuration in scheme/init.scm or load it from there.

Define and bind a custom command:

(defcommand (greet)
  "editor: greet\nShow a personalised message in the echo area."
  (interactive)
  (minibuffer-read "Your name: "
    (lambda (name)
      (message (string-append "Hello, " name "!")))))

(set-key! global-keymap "ctrl-shift-g" 'greet)

Define a custom theme:

(define-theme
  'my-theme
  "My Theme Display Name"
  'palette
  '((bg-0    . "#1a1b26")
    (bg-1    . "#16161e")
    (bg-2    . "#13131a")
    (fg-0    . "#2a2b3d")
    (fg-1    . "#3b3c52")
    (fg-2    . "#414868")
    (accent-0 . "#565f89")
    (accent-1 . "#6b7394")
    (accent-2 . "#828bb8")
    (text-0  . "#c0caf5")
    (text-1  . "#a9b1d6")
    (text-2  . "#9aa5ce")
    (select  . (alpha accent-2 0.25))
    (blue    . "#7aa2f7")
    (cyan    . "#7dcfff")
    (green   . "#9ece6a")
    (yellow  . "#e0af68")
    (orange  . "#ff9e64")
    (red     . "#f7768e")
    (purple  . "#bb9af7")
    (pink    . "#ff007c"))
  'canonical-map
  '((fg-text      . text-0)
    (fg-text-dim  . text-2)
    (fg-warm      . text-1)
    (selection-bg . select))
  'overrides
  '((mode.normal . blue)))   ; omit to keep *default-roles* value

(activate-theme 'my-theme)

The full Vim modal editing system — motions, operators, text objects, macros — is implemented in scheme/editor/evil/. It's a good reference for what's possible without touching C.

Project Organisation

├── resources/    fonts and SVG icons
├── scheme/       all Scheme scripts (commands, modes, keybindings, themes)
│   └── editor/   R7RS modules: command, mode, evil, theme, minibuffer, …
├── src/          C source (~12k LOC)
│   ├── command/  input handling, keymaps, command dispatch, Scheme bridge
│   ├── text/     buffers, marks, lines, registers, undo
│   └── display/  layout, panes, tabs, status bar, Clay components
└── vendored/     SDL3, SDL_ttf, Chibi Scheme (git submodules)

Roadmap

Beyond standard text editing, the longer-term vision includes:

• Collaborative editing — real-time sessions using the Eg-walker algorithm
• Declarative UI-builder DSL — enable users to create custom UIs for their plugins directly via the Scheme layer
• Alternative text display — better use of modern monitors and typography (see this paper)
• Wiki / hypermedia — Org Mode-style directives and wiki links, inspired by Obsidian and the original hypertext vision
• Embeddable core — Sev is designed to be usable as a foundation for non-text-editor apps (smart notes software, data tools, etc.) where rich text editing is a first-class feature

Project Status

Sev is early / experimental. Core editing works and it is usable, but there are a few specific features that will make it more viable as a daily driver. Namely:

• Text search and replace
• A file picker / file tree
• LSP integration
• In-app documentation

Expect rough edges, missing features, and breaking changes. Feedback and contributions are very welcome.

Contributing

See CONTRIBUTING.md for how to get started. The Scheme layer (scheme/) is a great place to contribute without needing to touch C — new commands, themes, motions, and modes can all be written in pure Scheme.

Community

Discord — join the conversation as the community gets off the ground.

License

MIT © 2026 Dylan Cobb