Google Vertex AI provider.

This provider implements streaming for Google Cloud's Vertex AI API, which provides enterprise-grade access to Gemini models.

Authentication

Uses Application Default Credentials (ADC) or service account authentication. Project, location, and inline service account JSON should be resolved by the caller and passed in stream options.

Authentication is handled via:

• Application Default Credentials (gcloud auth)
• Inline service account JSON passed in stream options
• Service account key file (GOOGLE_APPLICATION_CREDENTIALS)

Features

• Streaming text generation
• Tool/function calling
• Thinking/reasoning mode (for supported models)
• Image input (for multimodal models)