Mistral Large 3 2512 and GPT-5.2 Pro are available through the OpenRouter API, so switching between them takes a model slug change rather than a new integration.
Mistral Large 3 2512, from Mistral AI, has a 262,144-token context window and is priced at $0.50/M tokens input, $1.50/M tokens output on OpenRouter.
GPT-5.2 Pro, from OpenAI, has a 400,000-token context window and is priced at $21/M tokens input, $168/M tokens output on OpenRouter.