Anchor

A mobile-first Android app for monitoring and interacting with remote tmux sessions over SSH. Not a terminal emulator — a chat-like interface that views tmux pane content via tmux capture-pane and sends input via tmux send-keys.

Features

• Managed host list — save hosts with label, hostname, port, and username; persisted locally via Room database
• SSH key management — generate ECDSA keys and deploy them to saved hosts via password auth
• Host key verification — fingerprint checking with persistent known_hosts storage; warns on new or changed keys
• Tmux session browser — lists active tmux sessions on the connected host
• Session viewer — chat-style display of tmux pane content with a command input bar
• Adaptive pane sizing — resizes the tmux window to fit your phone screen based on font size and orientation
• Configurable font size — adjustable in-session with +/- controls; persists across sessions

Requirements

• Android 8.0+ (API 26)
• A remote server with tmux installed and SSH access

Building

The build environment runs in Docker:

docker compose up -d
docker compose exec build ./gradlew assembleDebug

Install to a connected device or emulator:

adb install -r app/build/outputs/apk/debug/app-debug.apk

Emulator setup (Linux with KVM)

The emulator runs on the host (not in Docker) for GPU/KVM support:

# Install emulator and system image
sdkmanager --install "emulator" "system-images;android-35;google_apis;x86_64"

# Create AVD
avdmanager create avd -n anchor_test -k "system-images;android-35;google_apis;x86_64" -d "pixel_9"

# Run (enable keyboard input)
emulator -avd anchor_test -gpu auto

To enable hardware keyboard in the emulator, add hw.keyboard = yes to ~/.android/avd/anchor_test.avd/config.ini.

Usage

1. Set up SSH key — tap the key icon in the top bar, generate a key, then deploy it to a saved host
2. Add a host — tap the + button, enter label/hostname/username
3. Connect — tap a saved host to connect and see its tmux sessions
4. View a session — tap a session to see its pane content; type commands in the input bar at the bottom

Known issues

Tmux window resizing

Anchor resizes the tmux window to match your phone's screen width so content fits without overflow. This means if you have the same tmux session open on a desktop terminal, it will appear narrow while the phone is actively viewing it.

To restore your desktop terminal size, detach and reattach:

Ctrl-b d
tmux attach -t <session>

Or from any shell with tmux attached at your desired size:

tmux resize-window -A -t <session>

Architecture

• Kotlin + Jetpack Compose — Material 3 UI
• JSch (mwiede fork) — SSH connections
• BouncyCastle — ECDSA key generation
• Room — local host database
• Stateless polling — captures pane content periodically via tmux capture-pane -p; no persistent terminal session or mosh required

License

MIT — see LICENSE.