fix(proxy): reconcile budget reservations when no database logger

Without a prisma client, cost_tracking registered nothing while auth still
reserved spend and bound the reservation to success callbacks. Nothing
reconciled on success, so the in-memory reservation stuck until TTL and
later requests failed with BudgetExceededError under custom_auth_run_common_checks.

Register a success-only BudgetReservationReconcileLogger when prisma is
absent so reservations settle to response_cost (or release on reconcile
failure). Fixes #45895.

litellm/proxy/hooks/budget_reservation_reconcile_logger.py

@@ -0,0 +1,61 @@
+"""Reconcile in-memory budget reservations when no database logger is registered.
+
+See https://github.com/BerriAI/litellm/issues/45895.
+"""
+
+from collections.abc import Mapping
+from datetime import datetime
+from typing import Final
+
+from litellm._logging import verbose_proxy_logger
+from litellm.integrations.custom_logger import CustomLogger
+from litellm.litellm_core_utils.core_helpers import (
+    budget_reservation_from_metadata,
+    get_litellm_metadata_from_kwargs,
+)
+
+class BudgetReservationReconcileLogger(CustomLogger):
+    """Settle auth's spend-counter reservation on success when ProxyDBLogger is absent.
+
+    With ``custom_auth_run_common_checks`` and no ``database_url``, auth still reserves
+    spend in the in-memory counter and ``bind_budget_reservation_to_callbacks`` marks
+    ``callback_bound=True``. ``ProxyDBLogger`` (the only success path that reconciled)
+    is registered only when ``prisma_client is not None``, so the reservation stuck
+    until TTL and every later request on that key failed with ``BudgetExceededError``.
+    """
+
+    async def async_log_success_event(
+        self, kwargs: Mapping[str, object], response_obj: object, start_time: datetime, end_time: datetime
+    ) -> None:
+        del response_obj, start_time, end_time
+        metadata: Final = get_litellm_metadata_from_kwargs(kwargs=dict(kwargs))
+        if not isinstance(metadata, Mapping):
+            return
+        budget_reservation: Final = budget_reservation_from_metadata(metadata)
+        if not isinstance(budget_reservation, dict) or budget_reservation.get("finalized") is True:
+            return
+
+        sl_object = kwargs.get("standard_logging_object")
+        response_cost: object
+        if isinstance(sl_object, Mapping):
+            response_cost = sl_object.get("response_cost")
+        else:
+            response_cost = kwargs.get("response_cost")
+        actual_cost: Final = float(response_cost or 0.0)
+
+        from litellm.proxy.spend_tracking.budget_reservation import reconcile_budget_reservation
+
+        try:
+            await reconcile_budget_reservation(
+                budget_reservation=budget_reservation,
+                actual_cost=actual_cost,
+            )
+        except Exception:
+            verbose_proxy_logger.exception(
+                "Failed to reconcile budget reservation without a database logger; releasing instead"
+            )
+            from litellm.proxy.spend_tracking.budget_reservation import (
+                release_or_invalidate_budget_reservation,
+            )
+
+            await release_or_invalidate_budget_reservation(budget_reservation=budget_reservation)

litellm/proxy/proxy_server.py

@@ -3326,6 +3326,17 @@ def cost_tracking():
         litellm.logging_callback_manager.add_litellm_callback(db_logger)
         litellm.logging_callback_manager.add_litellm_async_success_callback(db_logger)
         litellm.logging_callback_manager.add_litellm_callback(ShadowEvalLogger())
+    else:
+        # No DB logger means nothing reconciled auth's in-memory reservation after
+        # success (callback_bound=True skipped the request-end release). Register a
+        # success-only reconciler so no-database custom_auth budgets do not stick. #45895
+        from litellm.proxy.hooks.budget_reservation_reconcile_logger import (
+            BudgetReservationReconcileLogger,
+        )
+
+        litellm.logging_callback_manager.add_litellm_async_success_callback(
+            BudgetReservationReconcileLogger()
+        )
 
 
 async def _drain_spend_event_producer_on_shutdown() -> None:

tests/unit/proxy/hooks/test_budget_reservation_reconcile_logger.py

@@ -0,0 +1,146 @@
+"""Unit tests for BudgetReservationReconcileLogger (#45895)."""
+
+from datetime import UTC, datetime
+from unittest.mock import AsyncMock
+
+import pytest
+
+from litellm.proxy.hooks.budget_reservation_reconcile_logger import (
+    BudgetReservationReconcileLogger,
+)
+
+
+def _reservation(callback_bound: bool = True) -> dict:
+    return {
+        "reserved_cost": 0.00255,
+        "entries": [{"counter_key": "spend:key:hashed", "reserved_cost": 0.00255}],
+        "finalized": False,
+        "callback_bound": callback_bound,
+        "input_cost": 0.0,
+        "input_tokens": None,
+    }
+
+
+@pytest.mark.asyncio
+async def test_success_reconciles_reservation_to_response_cost(monkeypatch: pytest.MonkeyPatch) -> None:
+    reservation = _reservation()
+    reconcile = AsyncMock(return_value=())
+    monkeypatch.setattr(
+        "litellm.proxy.spend_tracking.budget_reservation.reconcile_budget_reservation",
+        reconcile,
+    )
+    logger = BudgetReservationReconcileLogger()
+
+    await logger.async_log_success_event(
+        {
+            "litellm_params": {
+                "metadata": {"user_api_key_budget_reservation": reservation},
+            },
+            "response_cost": 0.0,
+        },
+        response_obj=object(),
+        start_time=datetime.now(UTC),
+        end_time=datetime.now(UTC),
+    )
+
+    reconcile.assert_awaited_once()
+    assert reconcile.await_args.kwargs["budget_reservation"] is reservation
+    assert reconcile.await_args.kwargs["actual_cost"] == 0.0
+
+
+@pytest.mark.asyncio
+async def test_success_uses_standard_logging_response_cost(monkeypatch: pytest.MonkeyPatch) -> None:
+    reservation = _reservation()
+    reconcile = AsyncMock(return_value=())
+    monkeypatch.setattr(
+        "litellm.proxy.spend_tracking.budget_reservation.reconcile_budget_reservation",
+        reconcile,
+    )
+    logger = BudgetReservationReconcileLogger()
+
+    await logger.async_log_success_event(
+        {
+            "litellm_params": {
+                "litellm_metadata": {"user_api_key_budget_reservation": reservation},
+            },
+            "standard_logging_object": {"response_cost": 0.001},
+            "response_cost": 9.9,  # ignored when SL payload present
+        },
+        response_obj=object(),
+        start_time=datetime.now(UTC),
+        end_time=datetime.now(UTC),
+    )
+
+    assert reconcile.await_args.kwargs["actual_cost"] == 0.001
+
+
+@pytest.mark.asyncio
+async def test_success_noop_when_no_reservation(monkeypatch: pytest.MonkeyPatch) -> None:
+    reconcile = AsyncMock(return_value=())
+    monkeypatch.setattr(
+        "litellm.proxy.spend_tracking.budget_reservation.reconcile_budget_reservation",
+        reconcile,
+    )
+    logger = BudgetReservationReconcileLogger()
+
+    await logger.async_log_success_event(
+        {"litellm_params": {"metadata": {}}},
+        response_obj=object(),
+        start_time=datetime.now(UTC),
+        end_time=datetime.now(UTC),
+    )
+
+    reconcile.assert_not_awaited()
+
+
+@pytest.mark.asyncio
+async def test_success_noop_when_already_finalized(monkeypatch: pytest.MonkeyPatch) -> None:
+    reservation = _reservation()
+    reservation["finalized"] = True
+    reconcile = AsyncMock(return_value=())
+    monkeypatch.setattr(
+        "litellm.proxy.spend_tracking.budget_reservation.reconcile_budget_reservation",
+        reconcile,
+    )
+    logger = BudgetReservationReconcileLogger()
+
+    await logger.async_log_success_event(
+        {
+            "litellm_params": {"metadata": {"user_api_key_budget_reservation": reservation}},
+            "response_cost": 0.0,
+        },
+        response_obj=object(),
+        start_time=datetime.now(UTC),
+        end_time=datetime.now(UTC),
+    )
+
+    reconcile.assert_not_awaited()
+
+
+@pytest.mark.asyncio
+async def test_success_falls_back_to_release_when_reconcile_fails(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    reservation = _reservation()
+    monkeypatch.setattr(
+        "litellm.proxy.spend_tracking.budget_reservation.reconcile_budget_reservation",
+        AsyncMock(side_effect=RuntimeError("counter down")),
+    )
+    release = AsyncMock()
+    monkeypatch.setattr(
+        "litellm.proxy.spend_tracking.budget_reservation.release_or_invalidate_budget_reservation",
+        release,
+    )
+    logger = BudgetReservationReconcileLogger()
+
+    await logger.async_log_success_event(
+        {
+            "litellm_params": {"metadata": {"user_api_key_budget_reservation": reservation}},
+            "response_cost": 0.0,
+        },
+        response_obj=object(),
+        start_time=datetime.now(UTC),
+        end_time=datetime.now(UTC),
+    )
+
+    release.assert_awaited_once_with(budget_reservation=reservation)

tests/unit/proxy/proxy_server/test_lifecycle.py

@@ -776,18 +776,23 @@ async def test_cost_tracking_adds_db_and_shadow_eval_callbacks_when_prisma_set(
     assert event.response_cost > 0
 
 
-def test_cost_tracking_no_op_when_prisma_missing(monkeypatch):
-    """Without a prisma_client cost_tracking is a no-op — not an error."""
+def test_cost_tracking_registers_budget_reconciler_when_prisma_missing(monkeypatch):
+    """Without a prisma_client, still register a success reconciler for in-memory reservations (#45895)."""
     import litellm
+    from litellm.proxy.hooks.budget_reservation_reconcile_logger import (
+        BudgetReservationReconcileLogger,
+    )
 
     monkeypatch.setattr(ps, "prisma_client", None, raising=False)
     monkeypatch.setattr(litellm, "callbacks", [], raising=False)
     monkeypatch.setattr(litellm, "_async_success_callback", [], raising=False)
 
     cost_tracking()
+    cost_tracking()  # dedupe by logger class key
 
     assert litellm.callbacks == []
-    assert litellm._async_success_callback == []
+    assert len(litellm._async_success_callback) == 1
+    assert isinstance(litellm._async_success_callback[0], BudgetReservationReconcileLogger)
 
 
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