Meta's Muse appears to use an OpenAI model labeled muse-special

Meta's Muse, an AI website builder, appears to use an OpenAI model labeled "muse-special" in addition to its primary internal model, Avocado. Evidence from session logs shows one subagent session on September 21 routed to "azure/muse-special," distinct from the usual Avocado sessions. Further investigation revealed this model is linked to "GPT Responses model client via MAGI native Azure OpenAI lane," with signatures like "gpt_responses_v1" and encrypted "gAAAAA" payloads, consistent with OpenAI's Responses API. The broader model catalogue also lists GPT-5.5 and GPT-5.6 variants, Claude Opus, Sonnet, and Haiku.