fix: parse service tier in usage metadata

Author: MukundaKatta

google/genai/tests/common/test_common.py

@@ -677,6 +677,18 @@ def test_repr_complex_object():
   assert repr(obj) == expected
 
 
+def test_generate_content_usage_metadata_service_tier():
+  response = types.GenerateContentResponse.model_validate({
+      'usageMetadata': {
+          'promptTokenCount': 1,
+          'totalTokenCount': 1,
+          'serviceTier': 'priority',
+      }
+  })
+
+  assert response.usage_metadata.service_tier == types.ServiceTier.PRIORITY
+
+
 def test_move_value_by_path():
   """Test move_value_by_path function with array wildcard notation."""
   data = {

google/genai/types.py

@@ -7809,6 +7809,10 @@ class GenerateContentResponseUsageMetadata(_common.BaseModel):
       default=None,
       description="""Output only. A detailed breakdown of the token count for each modality in the prompt.""",
   )
+  service_tier: Optional[ServiceTier] = Field(
+      default=None,
+      description="""Output only. The service tier used for this request.""",
+  )
   thoughts_token_count: Optional[int] = Field(
       default=None,
       description="""Output only. The number of tokens that were part of the model's generated "thoughts" output, if applicable.""",
@@ -7856,6 +7860,9 @@ class GenerateContentResponseUsageMetadataDict(TypedDict, total=False):
   prompt_tokens_details: Optional[list[ModalityTokenCountDict]]
   """Output only. A detailed breakdown of the token count for each modality in the prompt."""
 
+  service_tier: Optional[ServiceTier]
+  """Output only. The service tier used for this request."""
+
   thoughts_token_count: Optional[int]
   """Output only. The number of tokens that were part of the model's generated "thoughts" output, if applicable."""