Summary

• Adds support for Vercel AI Gateway's order and only routing filters
• Enables advanced provider routing strategies for cost optimization and compliance
• Closes Feature Request: Add Vercel AI Gateway Provider Routing Support (only and order filters) #2153

Changes

This PR implements the Vercel AI Gateway routing feature requested in #2153 by:

1. Adding GatewayOptions type - Defines the structure for order and only routing configuration
2. Creating extractGateway helper - DRY function to extract gateway options from provider or model config
3. Supporting dual-level configuration - Gateway options can be set at:
   • Provider level (global default for all models)
   • Model level (overrides provider defaults)
4. Integrating with existing flows - Gateway options are now passed to:
   • Initial title generation
   • Main conversation streaming
   • Session summarization

Configuration Example

Users can now configure advanced routing strategies:

{
  "provider": {
    "vercel": {
      "options": {
        "gateway": {
          "order": ["cerebras", "groq", "fireworks"],
          "only": ["cerebras", "groq", "fireworks"]
        }
      }
    }
  }
}

Or per-model overrides:

{
  "models": {
    "gpt-4o": {
      "options": {
        "gateway": {
          "only": ["openai"]
        }
      }
    }
  }
}

Benefits

• Cost optimization: Prioritize cheaper providers with order
• Performance: Route to fastest providers for better UX
• Compliance: Restrict to specific geographic regions with only
• Flexibility: Model-specific overrides for specialized use cases
• Backward compatible: No changes required for existing configurations

Test plan

• Gateway options extracted correctly from provider config
• Model-level config overrides provider defaults
• Options passed to all AI SDK calls (title, streaming, summary)
• No impact on non-Vercel providers
• Backward compatibility maintained