Cortex

A small macOS-only terminal code editor written in Rust.

Cortex is currently in v0.3 development. The current goal is one fast editing loop: open files or a directory, edit and switch buffers, search, save, and quit cleanly.

Platform

Cortex is currently macOS-only. Other platforms are not a current or v1 goal.

Install

Install the latest stable release with the shell installer:

curl -fsSL https://raw.githubusercontent.com/owainlewis/cortex/main/install.sh | bash

The installer downloads the latest GitHub Release for macOS arm64, verifies the checksum, and installs cortex to ~/.local/bin by default. Set CORTEX_INSTALL_DIR to choose another install directory.

curl -fsSL https://raw.githubusercontent.com/owainlewis/cortex/main/install.sh | CORTEX_INSTALL_DIR="$HOME/bin" bash

To install a specific stable release, pass its tag:

curl -fsSL https://raw.githubusercontent.com/owainlewis/cortex/main/install.sh | bash -s -- --version v0.2.0

You can also download the release tarball and .sha256 file directly from GitHub Releases. Verify the checksum before running the binary.

Update

Run the installer again to update to the latest stable release:

curl -fsSL https://raw.githubusercontent.com/owainlewis/cortex/main/install.sh | bash

Check the installed binary version with:

cortex --version

Check whether GitHub has a newer stable release with:

cortex --check-update

cortex --check-update never updates the binary by itself. It only reports release status.

Developer Run

Install Rust, then run Cortex. Pass a file path to open that file directly:

cargo run -- path/to/file.txt

Pass a directory path to open the directory picker:

cargo run -- .

Run Cortex with no path to open the current directory in the picker:

cargo run

For a temporary smoke test file:

cargo run -- /tmp/cortex-smoke.txt

You can also install from the current Git repository as a developer fallback:

cargo install --git https://github.com/owainlewis/cortex.git

Existing files open with their current contents. Missing files open as empty clean buffers attached to the requested path. Saving can create the target file when its parent directory already exists. Saving does not create missing parent directories. Inside Cortex, C-x C-f accepts an existing or missing file path. Enter a missing path, edit the empty buffer, and save to create the file. Enter a directory path to browse it in the directory picker. Directories open a picker that lists non-hidden entries. The picker can open regular files. The picker can expand and collapse directories.

Current Scope

The current editor supports multiple file buffers in the terminal alternate screen. It uses raw terminal mode while running and should restore the shell after exit. It shows file text, cursor position, dirty state, save errors, and short status messages in a modeline. It includes shared prompts for commands and buffer navigation, a directory picker, forward search, mark and cut/yank editing, undo and redo, visual polish, and syntax highlighting for supported file types.

Editor Keybindings

Key	Action
Printable character	Insert character
Enter	Insert newline
Backspace	Delete backward
Delete or C-d	Delete forward
Left or C-b	Move backward one character
Right or C-f	Move forward one character
Up or C-p	Move to previous line
Down or C-n	Move to next line
C-a	Move to start of line
C-e	Move to end of line
C-s	Repeat the previous search
C-Space	Set the mark
C-w	Cut the active region
C-k	Cut to the end of the line
C-y	Yank the last cut text
C-/ or C-_	Undo the last edit
C-x u	Undo the last edit
Command-z	Undo the last edit
C-x C-f	Enter a path to find or create a file buffer
C-x b	Switch to an open buffer by path or unique file name
C-x C-r	Reload a clean buffer from disk
C-x C-s	Save the file
C-x C-c	Quit
M-x	Open the slash command line

If any open buffer is dirty, C-x C-c asks whether to quit without saving. Press y to confirm. Press n or Escape to cancel.

Slash Commands

Command	Action
/save	Save the current file
/reload	Reload a clean buffer from disk
/search <text>	Search forward for text
/next	Repeat the previous search
/undo	Undo the last edit
/redo	Redo the last undone edit
/quit	Quit, using the same dirty-buffer prompt as C-x C-c
/quit!	Quit without saving
/open <path>	Open another file buffer
/help	Show the available slash commands
/commands	Show the available slash commands (alias for /help)

Escape cancels the command line. Unknown slash commands leave the editor open and show an error message. /open <path> rejects directories and opens another buffer without discarding unsaved changes.

Directory Picker Keybindings

Key	Action
Down or C-n	Move to next entry
Up or C-p	Move to previous entry
Enter	Open the selected regular file or expand the selected directory
Left	Collapse the selected directory or move to its parent row
Backspace	Browse to the parent directory
Escape	Quit the picker
C-x C-c	Quit the picker

Syntax Highlighting

Cortex highlights Rust, Markdown, JSON, TOML, Python, JavaScript, JSX, TypeScript, TSX, Ruby, and OCaml files. Other file types render as plain text.

Releases And Nightlies

Stable releases are built from tags like v0.2.0. The release workflow publishes an arm64 macOS tarball and matching .sha256 checksum.

Nightly builds are unstable test artifacts from main. They are downloadable from the Nightly workflow run artifacts and are not used by the stable installer.

See docs/release.md for the release checklist.

Known Limitations

Redo is available from the slash command line, but does not have a dedicated keybinding yet. Cortex shows one active buffer at a time. The switch-buffer prompt requires an exact path or a unique file name and does not offer completion yet. Search is forward-only through /search <text>, with C-s or /next repeating the last search. Incremental and reverse search are not implemented yet. Cut and yank retain only the latest cut text, with no kill ring or yank-pop yet. Slash commands are entered through M-x; the leading slash remains part of the command syntax until the command registry lands. The directory picker can expand directories, but it is still a minimal picker. The slash command /open <path> opens files only, not directories. There are no splits, tabs, command registry, config, plugins, LSP, AI integration, or embedded terminal pane yet. Long lines are clipped to the terminal width instead of wrapped. External file changes are not watched automatically. The modeline marks detected disk changes, and C-x C-r or /reload reloads the file. Reload refuses to replace a buffer with unsaved edits.

License

MIT.