TL;DR: Meta launched Muse Spark on April 8, 2026. Most commentary split into two camps. Meta went closed because Meta won. Meta went closed because Meta lost. Both miss what Meta actually built. Muse Spark does frontier-class reasoning in less than half the output tokens Claude Opus 4.6 and GPT-5.4 spend on the same benchmark, and Meta AI, the product serving roughly three billion daily active use