Add operation.cost span attribute to model request spans, rename ModelResponse.price() to .cost() (#2767)

Author: alexmojaki

pydantic_ai_slim/pydantic_ai/messages.py

@@ -1024,8 +1024,12 @@ class ModelResponse:
     provider_response_id: str | None = None
     """request ID as specified by the model provider. This can be used to track the specific request to the model."""
 
-    def price(self) -> genai_types.PriceCalculation:
-        """Calculate the price of the usage.
+    @deprecated('`price` is deprecated, use `cost` instead')
+    def price(self) -> genai_types.PriceCalculation:  # pragma: no cover
+        return self.cost()
+
+    def cost(self) -> genai_types.PriceCalculation:
+        """Calculate the cost of the usage.
 
         Uses [`genai-prices`](https://github.com/pydantic/genai-prices).
         """

pydantic_ai_slim/pydantic_ai/models/instrumented.py

@@ -420,10 +420,15 @@ def _record_metrics():
                         return
 
                     self.instrumentation_settings.handle_messages(messages, response, system, span)
+                    try:
+                        cost_attributes = {'operation.cost': float(response.cost().total_price)}
+                    except LookupError:
+                        cost_attributes = {}
                     span.set_attributes(
                         {
                             **response.usage.opentelemetry_attributes(),
                             'gen_ai.response.model': response_model,
+                            **cost_attributes,
                         }
                     )
                     span.update_name(f'{operation} {request_model}')

tests/models/test_anthropic.py

@@ -252,7 +252,7 @@ async def test_async_request_prompt_caching(allow_model_requests: None):
     )
     last_message = result.all_messages()[-1]
     assert isinstance(last_message, ModelResponse)
-    assert last_message.price().total_price == snapshot(Decimal('0.00003488'))
+    assert last_message.cost().total_price == snapshot(Decimal('0.00003488'))
 
 
 async def test_async_request_text_response(allow_model_requests: None):