Meta says Muse Spark 1.3 scored above GPT-5.6 and Opus 5 on the DeepSWE 1.1 coding benchmark, and the model is already rolling out on Meta's model APIs. The comparison comes from Meta's own announcement.
Two more releases are queued: a next big model upgrade codenamed "Watermelon" and an open-weight version of Muse Spark. Muse Spark 1.3 landed on September 2, 2026, under a month after 1.2, which shipped August 5, 2026 and sits on OpenRouter's contributor tier.