fix(cost-optimization): preserve cache token helper coverage

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

litellm/proxy/db/db_spend_update_writer.py

@@ -73,6 +73,10 @@ else:
     ProxyLogging = Any
 
 
+def _extract_cache_read_tokens(usage_obj: dict) -> int:
+    return extract_cache_read_tokens({"usage_object": usage_obj})
+
+
 def _extract_cache_creation_tokens(usage_obj: dict) -> int:
     """
     Anthropic: top-level cache_creation_input_tokens field.

tests/test_litellm/proxy/management_endpoints/test_cost_optimization_endpoints.py

@@ -7,6 +7,7 @@ import pytest
 from litellm.proxy.management_endpoints.cost_optimization_endpoints import (
     build_optimized_request_log,
     cost_optimization_usage_logs,
+    _parse_date,
 )
 
 
@@ -48,6 +49,30 @@ def test_build_optimized_request_log_computes_both_savings():
 
 def test_build_optimized_request_log_ignores_unoptimized_row():
     assert build_optimized_request_log(_row({"usage_object": {"prompt_tokens": 10}})) is None
+    assert build_optimized_request_log(_row("{invalid-json")) is None
+
+
+def test_build_optimized_request_log_handles_cached_request_metadata_string():
+    result = build_optimized_request_log(
+        _row(
+            '{"usage_object": {"prompt_tokens_details": {"cached_tokens": 50}}}',
+            startTime="2026-07-13T12:00:00+00:00",
+            total_tokens="invalid",
+        )
+    )
+
+    assert result is not None
+    assert result.optimization_type == "caching"
+    assert result.cache_read_tokens == 50
+    assert result.timestamp == "2026-07-13T12:00:00+00:00"
+    assert result.total_tokens == 0
+
+
+def test_parse_date_supports_empty_and_end_of_day_values():
+    assert _parse_date(None) is None
+    assert _parse_date("2026-07-01") == datetime(2026, 7, 1, tzinfo=timezone.utc)
+    assert _parse_date("2026-07-01", end=True) == datetime(2026, 7, 2, tzinfo=timezone.utc)
+    assert _parse_date("2026-07-01 12:30:00") == datetime(2026, 7, 1, 12, 30, tzinfo=timezone.utc)
 
 
 @pytest.mark.asyncio
@@ -81,3 +106,15 @@ async def test_cost_optimization_usage_logs_returns_paginated_entries():
     assert result.logs[0].optimization_type == "compression"
     assert result.logs[0].tokens_saved == 25
     assert query_raw_mock.await_count == 2
+
+
+@pytest.mark.asyncio
+async def test_cost_optimization_usage_logs_returns_empty_without_prisma():
+    with patch("litellm.proxy.proxy_server.prisma_client", None):
+        result = await cost_optimization_usage_logs(page=2, page_size=25)
+
+    assert result.logs == []
+    assert result.total == 0
+    assert result.page == 2
+    assert result.page_size == 25
+    assert result.total_pages == 0