Syzygy is a Mac application that runs open large language models entirely on-device, requiring no cloud inference, API keys, or internet connection. It ships with Mach-1 Small, a compressed multimodal mixture-of-experts model optimized for Apple Silicon Macs with 16 GB or more of memory. The tool provides a full agent harness that gives the local model permissioned access to files, apps, browsers, and code, while intelligently managing context to maximize efficiency on personal hardware. Syzygy is currently in beta and targets users who want cloud-agent capabilities without sending data off their machine.