feat: Implement openai_embeddings method in GeminiInferenceAdapter

This method addresses the absence of usage statistics in Gemini's embedding API by providing default values.

llama_stack/providers/remote/inference/gemini/gemini.py

@@ -4,6 +4,14 @@
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
 
+from openai import NOT_GIVEN
+
+from llama_stack.apis.inference import (
+    OpenAIEmbeddingData,
+    OpenAIEmbeddingsRequestWithExtraBody,
+    OpenAIEmbeddingsResponse,
+    OpenAIEmbeddingUsage,
+)
 from llama_stack.providers.utils.inference.openai_mixin import OpenAIMixin
 
 from .config import GeminiConfig
@@ -20,3 +28,55 @@ class GeminiInferenceAdapter(OpenAIMixin):
 
     def get_base_url(self):
         return "https://generativelanguage.googleapis.com/v1beta/openai/"
+
+    async def openai_embeddings(
+        self,
+        params: OpenAIEmbeddingsRequestWithExtraBody,
+    ) -> OpenAIEmbeddingsResponse:
+        """
+        Override embeddings method to handle Gemini's missing usage statistics.
+        Gemini's embedding API doesn't return usage information, so we provide default values.
+        """
+        # Prepare request parameters
+        request_params = {
+            "model": await self._get_provider_model_id(params.model),
+            "input": params.input,
+            "encoding_format": params.encoding_format if params.encoding_format is not None else NOT_GIVEN,
+            "dimensions": params.dimensions if params.dimensions is not None else NOT_GIVEN,
+            "user": params.user if params.user is not None else NOT_GIVEN,
+        }
+
+        # Add extra_body if present
+        extra_body = params.model_extra
+        if extra_body:
+            request_params["extra_body"] = extra_body
+
+        # Call OpenAI embeddings API with properly typed parameters
+        response = await self.client.embeddings.create(**request_params)
+
+        data = []
+        for i, embedding_data in enumerate(response.data):
+            data.append(
+                OpenAIEmbeddingData(
+                    embedding=embedding_data.embedding,
+                    index=i,
+                )
+            )
+
+        # Gemini doesn't return usage statistics - use default values
+        if hasattr(response, "usage") and response.usage:
+            usage = OpenAIEmbeddingUsage(
+                prompt_tokens=response.usage.prompt_tokens,
+                total_tokens=response.usage.total_tokens,
+            )
+        else:
+            usage = OpenAIEmbeddingUsage(
+                prompt_tokens=0,
+                total_tokens=0,
+            )
+
+        return OpenAIEmbeddingsResponse(
+            data=data,
+            model=params.model,
+            usage=usage,
+        )