Claude Opus 4.6 (Fast) and Gemma 4 31B are available through the OpenRouter API, so switching between them takes a model slug change rather than a new integration.
Claude Opus 4.6 (Fast), from Anthropic, has a 1,000,000-token context window and is priced by the provider serving it on OpenRouter.
Gemma 4 31B, from Google, has a 262,144-token context window and is priced at $0.09/M tokens input, $0.34/M tokens output on OpenRouter.