GPT-5.6 Sol Pro and Claude Fable 5 are available through the OpenRouter API, so switching between them takes a model slug change rather than a new integration.
GPT-5.6 Sol Pro, from OpenAI, has a 1,050,000-token context window and is priced at $2/M tokens input, $10/M tokens output on OpenRouter.
Claude Fable 5, from Anthropic, has a 1,000,000-token context window and is priced at $10/M tokens input, $50/M tokens output on OpenRouter.