BunSCP

A cross-platform, dual-panel SFTP/local file manager — a small WinSCP-style commander built on Bun, Electrobun, and Angular.

Each of the two panels independently shows either the local filesystem or a remote server over SSH/SFTP, so you can move files local↔remote, remote↔remote, or local↔local through one symmetric engine.

Name & icon are placeholders. See Rebranding — it's a one-file change.

Features

• Dual-panel commander UI; either panel can be Local or any saved connection.
• Session tabs: each tab is an independent left/right workspace; remote sessions stay connected and transfers keep running in background tabs.
• Per-panel action toolbar with a direction-explicit copy button, plus a VSCode-style status bar showing live transfer progress (click to expand the transfer queue with per-file speed and ETA).
• Overwrite confirmation on name collisions, with a source-vs-destination comparison (size, modified date, which is newer) and batch replace-all / skip-all.
• Settings (gear, top-right): light / dark / system theme and speed units (MB/s or Mbps), persisted across restarts.
• On macOS the tab bar is fused with the window titlebar; other platforms keep a standard titlebar.
• Edit files (F4 / toolbar / File menu): a built-in editor works on local and remote files directly; or pick an external app (Options → Editor → Custom → Choose…). External edits of remote files download to a temp folder, are watched, and every save auto-uploads (visible in the transfer list) until the session disconnects. Leftover temp files from a crash are offered for cleanup at the next start.
• Browse, sort (name/size/modified, folders first), keyboard navigation.
• Create folder / file, rename, delete (recursive), change permissions (chmod).
• Upload, download, and remote→remote copy — files and whole folders — with a transfer queue, per-job progress, and cancel.
• Connection manager: saved connections organised into folders, password or private-key auth (with passphrase).

Stack

Layer	Choice
Runtime	Bun (main process, all SSH/SFTP + file IO)
Desktop	Electrobun 1.18 (native webview, typed RPC bridge)
Frontend	Angular 22 (standalone, signals, zoneless) in ui/
Styling	Tailwind CSS v4, shadcn-style tokens (no component library)
Icons	@ng-icons/mynaui
SSH/SFTP	ssh2 (pure-JS under Bun)

The repo is a Bun workspace: the Electrobun app at the root, the Angular app in ui/. Shared types and the RPC contract live in src/shared/ and are imported by both sides.

src/shared/     types.ts, rpc.ts (wire contract), branding.ts
src/bun/        Electrobun main process
  fs/           FileSystemProvider + LocalProvider + SftpProvider + registry
  transfers/    engine.ts (queue/stream copy) + walk.ts (recursive helpers)
  store/        connections.json persistence
ui/src/app/     Angular components + signal services

Prerequisites

• Bun ≥ 1.3 (bun --version).
• macOS: Xcode Command Line Tools (for the app build).
• No Node install required — a preload shim (scripts/node-version-shim.ts) satisfies the Angular CLI's Node version check while running under Bun.

Setup

bun install          # installs root + ui workspace deps

Develop

bun run dev

This starts the Angular dev server (hot reload for UI code) and launches the Electrobun app pointed at it. Edits under ui/ reload instantly; edits to the Bun main process (src/bun/**, RPC schema) trigger an app relaunch.

Build a packaged app

bun run build        # ng build (ui/dist) + electrobun build -> build/*/BunSCP*.app

The Angular bundle is copied into the app under views://app. The macOS icon is compiled from assets/icon.iconset into AppIcon.icns automatically.

For a distributable (optimized, with auto-update channel) build, use bunx electrobun build --env=stable (see the Electrobun docs for signing, notarization, and release hosting).

Rebranding

Everything user-facing reads from src/shared/branding.ts:

export const BRANDING = {
  appName: "BunSCP",           // window title, bundle name, app-data folder
  identifier: "es.teknes.bunscp",
  version: "0.1.0",
  icon: "assets/icon.iconset",
} as const;

To change the icon: replace assets/icon.png (1024×1024) and run ./scripts/gen-iconset.sh (regenerates the .iconset with sips), or point icon at your own .iconset. scripts/make-icon.py regenerates the current placeholder.

Renaming appName changes the app-data directory, so existing saved connections won't be found under the new name — copy connections.json across if you need them.

Where connections are stored

Saved connections live in a plain JSON file in the OS app-data directory (macOS: ~/Library/Application Support/BunSCP/connections.json), written with 0600 permissions.

⚠️ Passwords are stored in plaintext in this file (a deliberate v1 simplicity choice). Anyone who can read the file can read the passwords. If that isn't acceptable for your use, use key-based auth or don't save the password (connect ad-hoc). OS-keychain storage is a natural future addition.

Keyboard shortcuts

Tab switch panel · ↑/↓/PgUp/PgDn/Home/End move cursor · Space select · Enter open folder · Backspace parent · Ctrl/Cmd+A select all · F5 copy to other panel · F2 rename · F7 new folder · F8/Delete delete · Cmd/Ctrl+T new tab · Cmd/Ctrl+W close tab · Ctrl+Tab next tab.

(On Macs, function keys may need fn — every action also has a toolbar button.)

Same-file protection

Copying a file or folder onto itself would truncate it to zero bytes (the destination is opened for writing before the source is read). BunSCP blocks this at several layers:

• Same session / same host: every connection carries a filesystem identity (local, or resolvedIP:port — the hostname is DNS-resolved, so myserver.lan and its IP compare equal even across two panels/tabs holding separate SSH sessions to the same server). Equal identity + equal or nested paths ⇒ the transfer is refused before anything is opened.
• Hidden aliases (two different addresses that reach the same machine — NAT, split DNS): when identities differ but source and destination paths collide anyway, a probe file is written through one connection and looked up through the other; if it's visible on both, they're the same machine and the copy is refused. (SFTP offers no device/inode identity — the mechanism cp/rsync use locally — so probing is the only deterministic test.)
• The overwrite dialog never offers to "Replace" a file with itself — such items are auto-skipped with a notice.

Known residual limitation: the same filesystem mounted at different paths on two connections (bind mounts, NFS exported twice, shared container volumes) cannot be detected — the paths differ, so no guard or probe triggers. Be careful when two panels reach the same data through different mount points.

Portability notes

The codebase is platform-neutral except for two seams, both macOS-only today:

• External editor launch (launchEditor in src/bun/edits.ts): uses macOS open [-a app] file. A Windows port should use cmd /c start "" [app] file; Linux xdg-open file (or invoke the configured editor binary directly). The .app picker in the pickEditorApp handler needs the equivalent executable picker per platform.
• Application menu (src/bun/menu.ts): electrobun menus are macOS-only; the in-app UI covers every menu action.

Known issues

• Rare native crash under load. A long-running session (multiple remote connections, extended uptime) can hit a Bun panic — a segfault inside Bun 1.3.13's FFI thread-safe callbacks executing Electrobun's native→worker bridge (FFI_Callback_threadsafe_call → web_worker.spin in the decoded crash report). This is an upstream Bun × Electrobun bug, not app code; a restart recovers cleanly and in-flight work isn't corrupted. Expected to resolve when Electrobun bumps its pinned Bun (currently 1.3.13; 1.3.14+ available). Bun's own crash reporter link is printed to the console on panic.

Not in v1

Drag-and-drop, file preview/edit, transfer resume, symlink following (symlinks are listed but skipped by transfers), OS keychain, tab persistence across restarts, Windows/Linux packaging (the code is portable; only macOS packaging is wired up).