Hydra vs Vivid Walls

Hydra is a continuous integration service for projects based on Nix. It checks out project source periodically or continuously, builds it, runs tests, and produces reports. Work is organized into jobsets whose inputs can trigger builds when they change; jobsets can also depend on one another. Flake jobsets are supported when their outputs expose a hydraJobs attribute set. Jobs can produce packages, ISO images, or tarballs, and jobset inputs can use Git checkout sources. Hydra also provides a JSON API. It is aimed at Nix and NixOS package developers, not people who only need to use NixOS. Hydra is open source under GPL-3.0 and listed at free. It is self-hosted, with no hosted option listed, and running it is currently supported only on NixOS; the repository recommends the NixOS module for production. Flake evaluation is restricted from accessing files outside the Nix store. Some state is stored in the database, so backups are needed, and the wiki reports that hydra-queue-runner can sometimes leave queued builds unscheduled.

Vivid Walls is a native macOS app for Wallpaper Engine scene files and video, web, GIF, and image wallpapers. It renders scenes on Apple Silicon with a Metal scene engine. Wallpapers can react to cursor movement, clicks, system audio, or focus modes. Users can span a scene across displays or set independent scenes, then schedule them by time of day or focus mode. The app pauses when the desktop is fully covered or another app is fullscreen, reduces its frame rate on battery, and respects Low Power Mode. Eight animated 1080p wallpapers are loaded into the library at first launch. A free Windows Companion transfers a Wallpaper Engine library to the Mac over local Wi-Fi using a four-character code. The free plan keeps the bundled wallpapers; the Full Library costs $9.99, paid once. The app requires macOS 14.0 or later and Apple Silicon M1 or later, and does not support Intel Macs. The maker says some scenes may render incorrectly because of their varied effects and content.