Muse Spark 1.2 Contributor and Mistral Medium 3.5 are available through the OpenRouter API, so switching between them takes a model slug change rather than a new integration.
Muse Spark 1.2 Contributor, from Meta, has a 1,048,576-token context window and is priced at $0.10/M tokens input, $0.20/M tokens output on OpenRouter.
Mistral Medium 3.5, from Mistral AI, has a 262,144-token context window and is priced at $1.50/M tokens input, $7.50/M tokens output on OpenRouter.