From 41afb13fc6c9fcb6705e807be5f59fd40e48929b Mon Sep 17 00:00:00 2001
From: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Date: Thu, 13 Aug 2026 22:34:56 +0000
Subject: [PATCH] fix(cost): resolve vertex location from global config and env
 for cost tracking

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
---
 litellm/litellm_core_utils/litellm_logging.py | 13 +++++---
 .../test_litellm_logging.py                   | 33 +++++++++++++++++++
 2 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/litellm/litellm_core_utils/litellm_logging.py b/litellm/litellm_core_utils/litellm_logging.py
index 5d33b5ff490..21e06077dde 100644
--- a/litellm/litellm_core_utils/litellm_logging.py
+++ b/litellm/litellm_core_utils/litellm_logging.py
@@ -1397,6 +1397,13 @@ class Logging(LiteLLMLoggingBaseClass):
         if margin_total_amount is not None:
             self.cost_breakdown["margin_total_amount"] = margin_total_amount
 
+    def _resolve_vertex_location(self) -> str | None:
+        from litellm.llms.vertex_ai.vertex_llm_base import VertexBase
+
+        if not (hasattr(self, "litellm_params") and self.litellm_params):
+            return None
+        return VertexBase.safe_get_vertex_ai_location(litellm_params=self.litellm_params)
+
     def _response_cost_calculator(
         self,
         result: Union[
@@ -1484,11 +1491,7 @@ class Logging(LiteLLMLoggingBaseClass):
                     if hasattr(self, "litellm_params") and self.litellm_params
                     else None
                 ),
-                "vertex_location": (
-                    self.litellm_params.get("vertex_location") or self.litellm_params.get("vertex_ai_location")
-                    if hasattr(self, "litellm_params") and self.litellm_params
-                    else None
-                ),
+                "vertex_location": self._resolve_vertex_location(),
             }
         except Exception as e:  # error creating kwargs for cost calculation
             debug_info = StandardLoggingModelCostFailureDebugInformation(
diff --git a/tests/test_litellm/litellm_core_utils/test_litellm_logging.py b/tests/test_litellm/litellm_core_utils/test_litellm_logging.py
index 498c3f04937..50d0018a91a 100644
--- a/tests/test_litellm/litellm_core_utils/test_litellm_logging.py
+++ b/tests/test_litellm/litellm_core_utils/test_litellm_logging.py
@@ -4575,3 +4575,36 @@ def test_response_cost_calculator_passes_vertex_location(monkeypatch, vertex_loc
     cost = logging_obj._response_cost_calculator(result=response)
 
     assert cost == pytest.approx((1000 * 3e-6 + 200 * 1.5e-5) * uplift, rel=1e-9)
+
+
+def test_response_cost_calculator_uses_env_vertex_location(monkeypatch):
+    """A deployment can leave vertex_location unset and let the region come from the environment, which
+    still routes to a regional endpoint, so cost has to pick the same fallback the request dispatch does."""
+    monkeypatch.setenv("LITELLM_LOCAL_MODEL_COST_MAP", "True")
+    monkeypatch.setattr(litellm, "model_cost", litellm.get_model_cost_map(url=""))
+    monkeypatch.setenv("VERTEXAI_LOCATION", "us-east5")
+
+    logging_obj = LitellmLogging(
+        model="vertex_ai/claude-sonnet-4-6",
+        messages=[{"role": "user", "content": "Hey"}],
+        stream=False,
+        call_type="completion",
+        start_time=time.time(),
+        litellm_call_id="vertex-location-env-123",
+        function_id="test-fn",
+    )
+    logging_obj.update_environment_variables(
+        model="vertex_ai/claude-sonnet-4-6",
+        user="",
+        optional_params={},
+        litellm_params={"vertex_project": "test-project"},
+    )
+    logging_obj.model_call_details["custom_llm_provider"] = "vertex_ai"
+
+    response = ModelResponse(
+        model="claude-sonnet-4-6",
+        usage=litellm.Usage(prompt_tokens=1000, completion_tokens=200, total_tokens=1200),
+    )
+    cost = logging_obj._response_cost_calculator(result=response)
+
+    assert cost == pytest.approx((1000 * 3e-6 + 200 * 1.5e-5) * 1.1, rel=1e-9)