feat(usage): add unified provider usage backend

tests/webui/test_settings_routes.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import asyncio
 import json
+import threading
 from collections.abc import Awaitable, Callable, Mapping
 from pathlib import Path
 from types import SimpleNamespace
@@ -98,6 +99,45 @@ async def test_mcp_list_serializes_local_runtime_failure_snapshot(tmp_path) -> N
     assert snapshot_calls == 1
 
 
+@pytest.mark.asyncio
+async def test_usage_query_runs_off_the_event_loop(monkeypatch) -> None:
+    calling_thread = threading.get_ident()
+    worker_threads: list[int] = []
+
+    def usage_payload(**_kwargs):
+        worker_threads.append(threading.get_ident())
+        return {"days": []}
+
+    monkeypatch.setattr("nanobot.webui.settings_routes.settings_usage_payload", usage_payload)
+    request = SimpleNamespace(path="/api/settings/usage", headers=Headers())
+
+    response = await _router().dispatch(None, request, request.path)
+
+    assert response is not None
+    assert response.status_code == 200
+    assert worker_threads and worker_threads[0] != calling_thread
+
+
+@pytest.mark.asyncio
+async def test_full_settings_query_runs_off_the_event_loop(monkeypatch) -> None:
+    calling_thread = threading.get_ident()
+    worker_threads: list[int] = []
+    router = _router()
+
+    def settings_response():
+        worker_threads.append(threading.get_ident())
+        return http_json_response({"ok": True})
+
+    monkeypatch.setattr(router, "_handle_settings", settings_response)
+    request = SimpleNamespace(path="/api/settings", headers=Headers())
+
+    response = await router.dispatch(None, request, request.path)
+
+    assert response is not None
+    assert response.status_code == 200
+    assert worker_threads and worker_threads[0] != calling_thread
+
+
 @pytest.mark.asyncio
 async def test_mcp_reload_callback_is_bounded(
     monkeypatch: pytest.MonkeyPatch,