SDXL image generation now works on iPhone. The bug that blocked it for months was a missing file check

We've been building [Off Grid] - open-source app for on-device AI (text + image gen, no cloud). SDXL on iwas broken for months. Users kept reporting it, we couldn't reproduce it consistently. Turns out: SDXL models ship in two UNet layouts: - Monolithic: one big `Unet.mlmodelc` file - Chunked: `UnetChunk1.mlmodelc` + `UnetChunk2.mlmodelc` Our validation code only checked for the monolithic layout. If you downloaded a chunked SDXL model (which most are), the app said "model invalid" and refused to load it. Months of reports.