fix(interactions): stop the unpollable-create path from firing a false cost-tracking alert

The tightened gate correctly stopped deferring the reservation release for
InteractionsAPIResponses the scheduler will not poll (terminal status, or
in_progress without an id), but the response then fell through into the
generic 'Cost tracking failed' raise and the failed_tracking_alert path.
A create returning failed, cancelled, requires_action, incomplete,
budget_exceeded, or an id-less in_progress without usage therefore released
its reservation as intended and, in the same breath, alerted operators for a
legitimate no-usage response, both creating noise and masking real
cost-tracking failures.

The two gates are now nested under a single 'unbilled interaction response'
outer check, so any InteractionsAPIResponse with no usage takes either the
defer path (pollable, polling on) or the release-and-return path, and none
of them fall through to the generic failure raise. The two regression tests
also now assert failed_tracking_alert is not called, closing the observation
gap the report flagged.

litellm/proxy/hooks/proxy_track_cost_callback.py

@@ -319,8 +319,10 @@ class _ProxyDBLogger(CustomLogger):
                 elif budget_reservation is not None:
                     await _release_budget_reservation(budget_reservation=budget_reservation)
             else:
-                if _is_unbilled_in_progress_interaction(completion_response):
-                    if BACKGROUND_INTERACTION_COST_POLLING_ENABLED:
+                if _is_unbilled_interaction_response(completion_response):
+                    if BACKGROUND_INTERACTION_COST_POLLING_ENABLED and _is_unbilled_in_progress_interaction(
+                        completion_response
+                    ):
                         verbose_proxy_logger.debug(
                             "Cost tracking deferred for in-progress background interaction; "
                             "the budget reservation stays open until the poll task logs the final usage"
@@ -328,8 +330,8 @@ class _ProxyDBLogger(CustomLogger):
                         return
                     await _release_budget_reservation(budget_reservation=budget_reservation)
                     verbose_proxy_logger.debug(
-                        "Background interaction cost polling is disabled; released the budget "
-                        "reservation for an in-progress interaction that will not be billed"
+                        "Released the budget reservation for an interaction create with no usage "
+                        "that no poll task will settle"
                     )
                     return
                 await _release_budget_reservation(budget_reservation=budget_reservation)
@@ -477,6 +479,12 @@ def _write_spend_metadata_to_kwargs(kwargs: dict, metadata: dict) -> None:
                     bucket[key] = value
 
 
+def _is_unbilled_interaction_response(completion_response: object) -> bool:
+    from litellm.types.interactions import InteractionsAPIResponse
+
+    return isinstance(completion_response, InteractionsAPIResponse) and completion_response.usage is None
+
+
 def _is_unbilled_in_progress_interaction(completion_response: object) -> bool:
     from litellm.interactions.background_cost_polling import is_pollable_background_interaction
     from litellm.types.interactions import InteractionsAPIResponse

tests/test_litellm/proxy/hooks/test_proxy_track_cost_callback.py

@@ -871,6 +871,10 @@ async def test_track_cost_callback_releases_reservation_for_unpollable_interacti
     callback must release it there and then, or the pre-call estimate stays
     added to the key, user, team and org spend counters and starts refusing
     traffic against budget that was never actually spent.
+
+    A no-usage terminal create is also not a cost-tracking failure, so the
+    callback must not fire ``failed_tracking_alert``: doing so would flood
+    operators with false alerts and mask real cost-tracking failures.
     """
     from litellm.types.interactions import InteractionsAPIResponse
 
@@ -897,6 +901,7 @@ async def test_track_cost_callback_releases_reservation_for_unpollable_interacti
         )
 
         assert reservation["finalized"] is True
+        mock_proxy_logging.failed_tracking_alert.assert_not_called()
 
 
 @pytest.mark.asyncio
@@ -904,7 +909,8 @@ async def test_track_cost_callback_releases_reservation_for_interaction_without_
     """
     The scheduler also refuses a response with no id, since it has nothing to
     poll for, so the callback must not defer to a poll task that will never
-    exist.
+    exist, and it must not fire ``failed_tracking_alert`` for what is a
+    legitimate no-usage response rather than a cost-tracking failure.
     """
     from litellm.types.interactions import InteractionsAPIResponse
 
@@ -931,6 +937,7 @@ async def test_track_cost_callback_releases_reservation_for_interaction_without_
         )
 
         assert reservation["finalized"] is True
+        mock_proxy_logging.failed_tracking_alert.assert_not_called()
 
 
 @pytest.mark.parametrize(