Meta's internal codename for its next frontier large language model after Muse Spark, Watermelon reportedly uses roughly 10× the compute of its predecessor while reaching parity with OpenAI's GPT-5.5 on unnamed internal benchmarks, according to July 2026 statements from Chief AI Officer Alexandr Wang. Internal documents cited in late-August reporting targeted an October 2026 public release to power upgraded Muse agents and broader Meta AI products, following a July pre-training pause that shifted timelines. Mark Zuckerberg teased the project with a watermelon emoji in early September, but the model did not appear at Meta Connect later that month. As of early October, no weights, API, benchmarks, or official launch have materialized, leaving trader consensus focused on the narrow October window amid Meta's aggressive infrastructure spending and competitive pressure from OpenAI and Anthropic. Key near-term catalysts include any developer conference updates or API certifications that could confirm or delay availability.