[Bug]: Invalid model name: gemini/imagen-4.0-fast-generate-preview-06-06 not supported by Gemini API

[tjx666]

What happened?

The model imagen-4.0-fast-generate-preview-06-06 is configured in model_prices_and_context_window.json for the gemini provider, but this model does not exist in the Gemini API, causing 404 errors when attempting to use it.

Expected behavior: The model should work or be removed from the configuration if it's invalid.

Actual behavior: Getting a 404 NOT_FOUND error when trying to use this model with the Gemini provider.

Relevant log output

Google AI image generation error: Error [ApiError]: {"error":{"message":"{\n  \"error\": {\n    \"code\": 404,\n    \"message\": \"models/imagen-4.0-fast-generate-preview-06-06 is not found for API version v1beta, or is not supported for predict. Call ListModels to see the list of available models and their supported methods.\",\n    \"status\": \"NOT_FOUND\"\n  }\n}\n","type":"None","param":"None","code":"404"}

Additional Context

Current configuration in model_prices_and_context_window.json:

"gemini/imagen-4.0-fast-generate-preview-06-06": {
    "output_cost_per_image": 0.02,
    "litellm_provider": "gemini",
    "mode": "image_generation",
    "source": "https://cloud.google.com/vertex-ai/generative-ai/pricing"
}

The same model is also configured for Vertex AI:

"vertex_ai/imagen-4.0-fast-generate-preview-06-06": {
    "output_cost_per_image": 0.02,
    "litellm_provider": "vertex_ai-image-models",
    "mode": "image_generation",
    "source": "https://cloud.google.com/vertex-ai/generative-ai/pricing"
}

Suggested fix: Remove the gemini/imagen-4.0-fast-generate-preview-06-06 configuration since this model is not supported by the Gemini API, while keeping the Vertex AI configuration if that provider supports it.