dunders

We ship the underscores. You write what goes between them.

An open-source terminal platform built on Textual, where everything is a panel. At its core it's a Norton Commander–style dual-pane manager with an embedded text editor and an LLM-agent CLI — but the bigger idea is the blank between the underscores: the core ships __, and you fill in the rest.

Two panels aren't really about files. They're about any two sets of objects you can copy between — folders, archives, remote/cloud filesystems, containers, databases, API responses. dunders brings back the dual-pane workflow of mc / Far Manager — with a real windowing layer (Turbo Vision–inspired), code folding, recordable macros, a command palette, and an embedded LLM/agent CLI mode — and makes that surface extensible.

The CLI command is __ or dunders ; the __ is the platform's blank, waiting to be filled.

Status: alpha. Core file-manager and editor are usable; agent/CLI mode is a stub.

Quick install (any OS — one line)

Installs uv if you don't have it, then installs dunders (plus the __ / __w launchers and every opt-in dunder — sftp:, the db: database dunder, image and office/PDF viewers — via the [all] extra) into an isolated environment — no system Python needed.

Linux / macOS / WSL (bash/zsh) — editor and Claude Code integration:

curl -LsSf https://astral.sh/uv/install.sh | sh && export PATH="$HOME/.local/bin:$PATH" && uv tool install --force "dunders[all] @ git+https://github.com/tumikosha/dunders.git" && dunders --setup-claude

Then start a new claude session and press Ctrl+G: your prompt opens in __ with the session transcript below a sentinel line, and Ctrl+G again sends back only what you typed. (ctrl+x ctrl+e is the same action, and works at both ends too.) The setup step writes nothing outside ~/.claude — no shell profile, no plugin — and dunders --remove-claude undoes exactly what it wrote. Drop that last command if you only want the editor.

Windows (PowerShell) — editor only:

irm https://astral.sh/uv/install.ps1 | iex; $env:Path = "$env:USERPROFILE\.local\bin;$env:Path"; uv tool install --force "dunders[all] @ git+https://github.com/tumikosha/dunders.git"

Run __w on Windows (__ assumes a persistent relay subshell; __w suspends instead). The Claude Code integration is not available there yet — its wrappers are bash — and dunders --setup-claude says so instead of leaving a dead $EDITOR behind.

Already have uv? Just the last command: uv tool install "dunders[all] @ git+https://github.com/tumikosha/dunders.git".

Want a leaner install? Pick only the extras you need instead of [all] — e.g. dunders[db] (database only), dunders[sftp,db], or plain dunders for the base file manager + editor. Available extras: sftp, db, image, office, all.

Features

• Dual-pane file manager powered by AI with sort, multi-select, quick-search, and the classic NC F-key bar (F3 view, F4 edit, F5 copy, F6 move, F7 mkdir, F8 delete, F9 menu, F10 quit).
• Embedded text editor with split view, search & replace, fold-by-indent, and bracket/region folding rules.
• Recordable macros with persistent storage.
• Hex viewer for binary or large files (mmap-backed, switches in automatically above 4 MiB).
• Turbo Vision–style windowing layer (dunders.windowing) — reusable in other Textual apps. Tile, cascade, maximize, modal dialogs, command palette, themable via YAML.
• Mouse support everywhere, including the menu bar and status bar.
• LLM agent / CLI mode (in progress) — bring your own model.

Install

Zero-Python install via uv (recommended)

uv is a single static binary. It installs Python for you, then installs dunders into an isolated environment and puts the dunders command on your PATH. No system Python required.

# 1. Install uv (one-liner, no Python needed)
curl -LsSf https://astral.sh/uv/install.sh | sh        # macOS / Linux
# Windows PowerShell:
#   powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex"
# Or via package manager: brew install uv  /  pipx install uv  /  scoop install uv

# 2. Install dunders (uv fetches Python 3.12+ automatically if missing)
uv tool install dunders

# 3. Run
__ 
dunders

Try it once without installing:

uvx --from dunders dunders          # downloads, runs in a temp env, then forgets

Upgrade / uninstall:

uv tool upgrade dunders
uv tool uninstall dunders

If you already have Python 3.12+

pipx install dunders            # preferred — isolated, on $PATH
# or, inside an active venv:
pip install dunders

Requires Python 3.12+ in any path above.

Usage

__
dunders                  # two-panel file manager (default)
dunders path/to/dir      # file manager seeded at a directory
dunders path/to/file     # open a file in the editor
dunders --cli            # agent / CLI mode (stub)

A file argument opens the editor in Project View: the file on the right, a file tree on the left. The tree starts at the current working directory, so running __ src/deep/mod.py from a project root shows the project. --pd overrides that — --pd PATH roots the tree wherever you like, and a bare --pd (or --pd '') roots it at the edited file's own directory.

Short launchers

Two extra console scripts are installed alongside dunders, differing only in how embedded shell commands hand off the terminal:

Command	Terminal mode	Platform
__	relay — persistent relay subshell	Linux / macOS
__w	suspend — suspend + subprocess, no persistent session	cross-platform (use this on Windows)

Both take the same arguments (files open in cascaded editor windows; a lone directory or no args open the mc-style file manager) and accept --suspend explicitly; __w is just __ --suspend.

Inside the app:

Key	Action
F3	View file (hex if binary/large)
F4	Edit file
F5 / F6	Copy / Move selected items
F7 / F8	Mkdir / Delete
F9 / F10	Menu / Quit
Tab	Switch panel
Shift+Tab	Cycle desktop windows
Alt+L / Alt+R	Focus left / right panel
Ctrl+K	Command palette

Editor-scoped keys (Save, Find/Replace, Split, Fold, Record macro) appear in the status bar when an editor window has focus.

Claude Code integration

Ctrl+G — the whole loop, one key. In Claude Code it opens your prompt in __ with the session transcript below it; in __ it saves and exits, sending only what you typed.

Use __ as Claude Code's external editor, with the current session's transcript loaded alongside your prompt. Ctrl+X Ctrl+E is the same Claude Code action (chat:externalEditor) if you have remapped Ctrl+G in your own keybindings.json. The editor opens like this:

▌cursor here — write your prompt

════ HISTORY BELOW — everything from this line down is discarded ════

### user
...
### assistant
...

Write above the marker, save, exit. The history is cut away before Claude reads the file back, so only your text is sent — the transcript is there to read, not to resend.

Install — as a Claude Code plugin

Inside Claude Code:

/plugin marketplace add tumikosha/dunders
/plugin install dunders

Then restart claude. That is the whole installation — no script to run, no shell profile to edit. The plugin's SessionStart hook copies the wrapper to ~/.claude/dunders-cc/ and points env.EDITOR in ~/.claude/settings.json at it, which is the one thing a plugin manifest cannot declare on its own.

/plugin uninstall dunders

undoes it. The hook stops running; the next ctrl+x ctrl+e notices the plugin is gone, removes the settings.json entry, deletes the directories it created, and opens your file in a plain editor. Cleanup happens on that first use rather than at uninstall, because Claude Code has no plugin-removal hook — uninstall and never press the key again and one inert directory and one settings line stay behind.

An EDITOR you set yourself is never overwritten; the integration stays inert and logs why.

Install — from a clone

git clone https://github.com/tumikosha/dunders dunders
bash dunders/skills/setup/scripts/install.sh

To make the skill available to Claude without the plugin system, symlink it — edits in the clone then take effect without reinstalling:

mkdir -p ~/.claude/skills
ln -s "$PWD/dunders/skills/setup" ~/.claude/skills/

The installer fetches uv and dunders if __ is missing, drops two scripts into ~/.claude/dunders-cc/, registers a SessionStart hook in ~/.claude/settings.json, and adds a marked block to your shell profile. It backs up every file it touches (*.bak-dunders-cc) and is safe to rerun.

install.sh --editor nvim     # wire up a different editor instead of __
install.sh --skip-dunders    # wrapper only
install.sh --check           # report current state, change nothing
install.sh --uninstall       # remove everything it added
install.sh --purge           # the above plus the log and dunders itself

--uninstall leaves dunders in place — __ is useful outside Claude Code. --purge also removes it (from both uv and pipx) and deletes ~/.claude/cc-edit.log; it confirms first, or takes --yes for scripts.

Then: open a new terminal, restart claude (the hook fires at session start, so already-running sessions have no entry in the PID map), and press Ctrl+X Ctrl+E.

Configuration

Set in the managed block of your shell profile:

Variable	Default	Effect
CC_REAL_EDITOR	__	Editor to run. GUI editors need a wait flag: code --wait, subl -w
CC_HISTORY_LINES	200	How many recent messages to show
CC_EDIT_DEBUG	1	0 silences ~/.claude/cc-edit.log

Notes

• $EDITOR is global, so git commit without -m opens the wrapper too. It detects commit, merge, tag, rebase and diff buffers and passes them through untouched — no transcript ever lands in a commit message. To confine the change to Claude Code, move the exports into the env block of ~/.claude/settings.json instead.
• History is per session; a fresh session shows its own, nearly empty transcript.
• If something looks wrong, tail -20 ~/.claude/cc-edit.log — a healthy run logs resolved by : session-map/<pid>.json.
• macOS and Linux. The wrapper is bash; __w still covers Windows for normal editing, but this integration does not.

The directory also ships as a Claude Code skill — copy or symlink skills/setup into ~/.claude/skills/ and Claude can perform the setup and troubleshooting itself. skills/setup/references/design.md documents how the transcript is located and why the obvious approaches fail.

Development

git clone https://github.com/tumikosha/dunders dunders
cd dunders
uv sync --extra dev          # or: pip install -e '.[dev]'

pytest                       # full suite
pytest -k fold_engine        # by keyword
ruff check

The repository ships a standalone windowing demo to exercise the framework without the file-manager layer:

python -m dunders.windowing.demo

Project layout

The PyPI distribution is named dunders; the importable Python package and the CLI command are both dunders.

dunders/
├── app.py            # DundersApp shell — wires menus, panels, dispatcher
├── main.py           # entry point (argparse)
├── fm/               # file-manager domain (panels, dialogs, file ops)
├── windowing/        # Turbo Vision–style framework on Textual
│   ├── core/         # buffer, fold engine, macros, search
│   ├── editor/       # embeddable editor widget + content
│   ├── themes/       # palette loader + modern_dark default
│   └── demo/         # standalone framework demo
├── themes/           # dark.yaml / light.yaml palettes
└── config/defaults.py

Alongside the package, the repository root carries skills/ — Claude Code skills shipped with the project, currently setup (see Claude Code integration).

See CLAUDE.md for an architecture deep-dive aimed at contributors and AI coding assistants.

Terminal limitations on macOS

macOS Terminal.app does not report several modifier+key combinations to the application, so some editor shortcuts can't reach dunders there:

• Shift+↑ / Shift+↓ / Shift+Home / Shift+End — selection by line / to start/end of line. Terminal.app sends the same sequence as the unmodified key, so the selection variant never arrives.
• Cmd+C, Cmd+↑ / Cmd+↓ — the terminal intercepts Cmd shortcuts itself and never forwards them.

You can confirm what your terminal sends with cat -v (press the combo, then Ctrl+C to quit): if Shift+↑ prints ^[[A (same as plain ↑) the modifier is being dropped.

Two fixes:

1. Use a terminal that supports the kitty keyboard protocol — iTerm2, Ghostty, Kitty, WezTerm. These deliver Shift+arrows and Cmd+arrows/Cmd+C out of the box, no configuration needed. (Recommended.)

2. Remap the keys in Terminal.app — Settings → Profiles → your profile → Keyboard → +, with Action Send Text (\033 is the Esc character):

Key	Modifier	Send Text
↑	Shift	\033[1;2A
↓	Shift	\033[1;2B
Home	Shift	\033[1;2H
End	Shift	\033[1;2F

Cmd+C can't be remapped this way (Terminal.app keeps it for its own Copy). In the editor and command line use Ctrl+C to copy instead — in the command line Ctrl+C copies the current selection and otherwise cancels/clears, like a shell.

License

MIT — see LICENSE.