Seed 2.1 Turbo and GPT-5.6 Sol are available through the OpenRouter API, so switching between them takes a model slug change rather than a new integration.
Seed 2.1 Turbo, from bytedance-seed, has a 262,144-token context window and is priced at $0.50/M tokens input, $2.50/M tokens output on OpenRouter.
GPT-5.6 Sol, from OpenAI, has a 1,050,000-token context window and is priced at $5/M tokens input, $30/M tokens output on OpenRouter.