Phosphene: reverse-engineered Apple's video wallpaper engine for macOS Tahoe

Phosphene is a new open-source project that reverse engineers Apple's video wallpaper system to let macOS Tahoe users play their own video files as desktop and lock-screen wallpaper. Built by an independent developer, it functions as a menu bar app plus a wallpaper extension that plugs directly into the system's native wallpaper picker. Videos appear alongside Apple's built-in Aerials in System Settings → Wallpaper. The app leverages Apple's private WallpaperExtensionKit framework via dlopen and runtime introspection, meaning playback runs out-of-process, survives app quits, and properly integrates with lock-screen, idle, and sleep lifecycles. However, because it uses a private framework, Apple could break compatibility with any major OS release.

Phosphene supports MP4, MOV, and any AVFoundation-readable file with frame-accurate gapless looping achieved by offsetting PTS/DTS across loop boundaries. It offers per-display wallpapers for multi-monitor setups, power-aware playback that scales down or pauses based on thermal state, battery level, AC vs battery, Game Mode, and presentation mode (active/locked/idle). Additional features include a smooth cubic-curve fade for lock-screen transitions, pausing when windows fully occlude the desktop, and adaptive lower-resolution variants that swap at loop boundaries to save power. The extension runs inside Apple's WallpaperAgent process, communicating via XPC. The project is built for macOS 26 (Tahoe) and Apple Silicon, using Swift 6 with strict concurrency.