Skeldri

Skeldri turns an iPad into a wireless finger-annotation surface and opt-in trackpad for a Mac. It mirrors one selected Mac display over the local network while sending normalized vector strokes or relative pointer gestures on a separate low-latency channel. It requires neither Apple Pencil nor a cloud service.

Note

Skeldri is prepared for local signing and App Store archival, but it has not been submitted or published. Final distribution signing, App Store Connect metadata, and review remain owner actions.

Features

• Automatic Mac discovery with Bonjour; no IP address configuration.
• Finger-first pen, highlighter, stroke eraser, color, thickness, undo, and clear.
• iPad-owned switching between attached Mac displays.
• Optional clearing of annotations when switching displays.
• Transparent, click-through Mac annotation overlay.
• Low-latency H.264 mirroring with stale-frame protection during display changes.
• Explicit Draw/Trackpad/Read selector, with pointer movement, tap, drag, two-finger scroll, and secondary click.
• Read mode: a strictly read-only reading viewport over a Mac-approved window or display, with local pinch zoom, pan, fit, and a precision navigation rail. The Mac's owner chooses the source; the iPad can never name one.
• Collapsible trackpad sensitivity, speed, and acceleration controls with persistent preferences.
• A top-left Back control that safely releases pointer state and returns to Mac discovery.
• Native Liquid Glass controls on current systems, with a material fallback on older supported iPadOS releases.
• Local-network-only operation with no accounts, telemetry, audio, or cloud backend.

Requirements

• macOS 15 or later.
• iPadOS 18 or later.
• Xcode 27 or later for the currently checked-in project (Swift 6 and the current Liquid Glass SDK APIs).
• Mac and iPad connected to the same local network.
• XcodeGen only when regenerating Skeldri.xcodeproj; it is not needed for normal builds.

Linux host (experimental)

A separate Rust host for Linux (Omarchy / Hyprland, Wayland wlr-layer-shell) lives in linux/, with an Omarchy QuickShell bar plugin in plugins/skeldri. See the Linux & Omarchy guide and the landing page.

Warning

The Linux host still speaks the earlier DrawPad protocol (version 2, _drawpad._tcp). Skeldri 1.0 for iPad uses protocol 7 and _skeldri._tcp, so it cannot discover or connect to the Linux host until the host is updated.

curl -fsSL https://onembyte.github.io/Skeldri/install.sh | bash

The reference development environment is recorded in docs/ENVIRONMENT.md.

Architecture

ScreenCaptureKit → VideoToolbox → video TCP → iPad video layer
Finger → normalized vectors → control TCP → transparent Mac overlay
Trackpad gesture → validated relative event → control TCP → permission-gated Mac pointer

Video and drawing state remain independent, preventing the Mac overlay from being recursively captured and keeping finger feedback responsive when video is delayed. See Architecture, Clean Architecture, and Wire Protocol.

Build and test

./scripts/doctor.sh
./scripts/build.sh
./scripts/test.sh

All DerivedData produced by these scripts stays in .build/DerivedData.

Run on a Mac

1. Open Skeldri.xcodeproj.
2. Select the SkeldriMac scheme and My Mac destination.
3. Run the app.
4. Grant Screen Recording access when prompted, then relaunch if macOS requests it.
5. To use Trackpad mode, grant Pointer Control access from the menu-bar popover and follow the macOS prompt.

Run on iPad Simulator

Select the SkeldriPad scheme, choose an installed iPad simulator, and run. Discovery and physical network behavior are best validated on a real iPad.

Run on a physical iPad

1. Enable Settings → Privacy & Security → Developer Mode on iPad and complete its requested restart.
2. Connect the iPad over USB and trust the Mac if prompted.
3. In SkeldriPad → Signing & Capabilities, enable automatic signing and choose your Apple Development Team. No Team ID is committed to this repository.
4. Select the connected iPad as the run destination and press Run.
5. Permit Local Network access when prompted.
6. If iPadOS blocks the first launch, trust the developer under Settings → General → VPN & Device Management.

Personal installation without opening Xcode

After signing in to Xcode with your paid Apple Developer Program account once, you can build, install, package, and launch both apps from Terminal. Use the paid team, not a free Personal Team: both apps use the App Store identifier com.onembyte.skeldri, and a free team could claim it.

./scripts/install-personal.sh --team YOUR_TEAM_ID --device "Your iPad Name"

The script remembers those two values only inside the ignored .build directory. Future refreshes are one command:

./scripts/install-personal.sh

To keep the Mac app permanently available, add --applications once:

./scripts/install-personal.sh --applications

That installs it to /Applications/Skeldri.app and refreshes it on every later run. The choice is remembered in the ignored .build directory, and --no-applications turns it off. Keeping it on matters: refreshing the iPad while a stale copy remains in /Applications leaves the two speaking different protocol versions, which surfaces only as a failed connection. This is the one thing Skeldri writes outside its repository, so it is opt-in.

The optimized Mac app and its ZIP archive are written to .build/PersonalInstall. The iPad app behaves like a normal installed app while its provisioning profile is valid. Development profiles from the paid team last a year. Xcode must remain installed for its compiler, signing, and device tools, but it does not need to be open during normal use or refreshes.

Privacy and security

Skeldri advertises only its modern and legacy-compatibility services on the LAN. It has no internet relay, analytics, telemetry, microphone access, or camera access. It does not transmit arbitrary keyboard input; trackpad magnification uses only the focused app's standard Command-plus/Command-minus shortcut. Each iPad session requires explicit approval from the Mac before screen content or input is allowed. Trackpad mode additionally uses macOS's permission-gated event-posting API. The transport is not end-to-end encrypted, so use it only on a trusted local network. See SECURITY.md.

Project generation

project.yml is the source of truth for project structure. When XcodeGen is already installed:

xcodegen generate

Commit both project.yml and the regenerated Skeldri.xcodeproj when project structure changes.

Documentation

• Linux / Omarchy Guide
• Manual acceptance testing
• Troubleshooting
• Implementation status
• App Store release checklist
• Privacy policy
• Security audit
• Contributing
• Changelog

License

No open-source license has been selected yet. Until the repository owner adds one, the source remains under default copyright terms.