refactor(cost): encapsulate streamed OpenRouter cost cache, clear per run

tests/test_cost_tracking.py

@@ -8,21 +8,22 @@ from unittest.mock import MagicMock, patch
 import litellm
 import pytest
 
-import strix.report.state as state_module
 from strix.config.models import (
     _configure_litellm_compatibility,
     _install_openrouter_stream_cost_capture,
 )
 from strix.report.state import (
+    ReportState,
     litellm_cost_callback,
     openrouter_stream_cost,
-    remember_streamed_openrouter_cost,
+    set_global_report_state,
+    streamed_openrouter_costs,
 )
 
 
 @pytest.fixture(autouse=True)
 def _clear_streamed_costs() -> None:
-    state_module._streamed_openrouter_costs.clear()
+    streamed_openrouter_costs.clear()
 
 
 def test_streaming_logging_stays_enabled_for_cost_callback() -> None:
@@ -181,7 +182,7 @@ def test_openrouter_stream_cost_extracts_plain_and_byok_totals() -> None:
 
 def test_cost_callback_recovers_streamed_openrouter_cost_by_response_id() -> None:
     report_state = MagicMock()
-    remember_streamed_openrouter_cost("gen-abc", {"cost": 0.42})
+    streamed_openrouter_costs.remember("gen-abc", {"cost": 0.42})
     # LiteLLM strips cost from the rebuilt streamed usage; only the id survives.
     response = SimpleNamespace(id="gen-abc", usage=SimpleNamespace(cost=None), _hidden_params={})
 
@@ -193,12 +194,12 @@ def test_cost_callback_recovers_streamed_openrouter_cost_by_response_id() -> Non
 
     report_state.record_observed_llm_cost.assert_called_once_with(0.42)
     # The entry is consumed so a later response cannot double-count it.
-    assert "gen-abc" not in state_module._streamed_openrouter_costs
+    assert streamed_openrouter_costs.take(response) is None
 
 
 def test_streamed_openrouter_cost_prefers_provider_report_over_estimate() -> None:
     report_state = MagicMock()
-    remember_streamed_openrouter_cost("gen-xyz", {"cost": 0.9})
+    streamed_openrouter_costs.remember("gen-xyz", {"cost": 0.9})
     response = SimpleNamespace(
         id="gen-xyz",
         usage=SimpleNamespace(prompt_tokens=10, completion_tokens=5, total_tokens=15),
@@ -215,14 +216,16 @@ def test_streamed_openrouter_cost_prefers_provider_report_over_estimate() -> Non
     estimate.assert_not_called()
 
 
-def test_remember_streamed_openrouter_cost_evicts_oldest_over_limit() -> None:
-    limit = state_module._STREAMED_OPENROUTER_COST_LIMIT
-    for i in range(limit + 5):
-        remember_streamed_openrouter_cost(f"gen-{i}", {"cost": 0.001})
+def test_streamed_openrouter_costs_ignores_entries_without_cost() -> None:
+    streamed_openrouter_costs.remember("gen-none", {"prompt_tokens": 10})
+    streamed_openrouter_costs.remember("", {"cost": 0.5})
+    assert streamed_openrouter_costs.take(SimpleNamespace(id="gen-none")) is None
 
-    assert len(state_module._streamed_openrouter_costs) == limit
-    assert "gen-0" not in state_module._streamed_openrouter_costs
-    assert f"gen-{limit + 4}" in state_module._streamed_openrouter_costs
+
+def test_streamed_openrouter_costs_cleared_on_new_run() -> None:
+    streamed_openrouter_costs.remember("gen-stale", {"cost": 0.7})
+    set_global_report_state(ReportState.__new__(ReportState))
+    assert streamed_openrouter_costs.take(SimpleNamespace(id="gen-stale")) is None
 
 
 def test_openrouter_stream_handler_records_cost() -> None:
@@ -243,4 +246,6 @@ def test_openrouter_stream_handler_records_cost() -> None:
     handler = handler_cls(streaming_response=iter([]), sync_stream=True)
     handler.chunk_parser(chunk)
 
-    assert state_module._streamed_openrouter_costs["gen-stream"] == pytest.approx(0.0035055)
+    assert streamed_openrouter_costs.take(SimpleNamespace(id="gen-stream")) == pytest.approx(
+        0.0035055
+    )