fix search runs with empty results

tests/test_backend_pipeline_repairs.py

@@ -69,6 +69,27 @@ def test_searxng_provider_normalizes_json_results() -> None:
     asyncio.run(run())
 
 
+def test_searxng_provider_sends_configured_engine_allow_list() -> None:
+    async def run() -> None:
+        seen_request: httpx.Request | None = None
+
+        def handler(request: httpx.Request) -> httpx.Response:
+            nonlocal seen_request
+            seen_request = request
+            return httpx.Response(200, json={"results": []})
+
+        provider = SearXNGProvider("http://searxng:8080", engines=("bing", "yahoo"))
+        provider._client = httpx.AsyncClient(transport=httpx.MockTransport(handler))
+        try:
+            await provider.search("test")
+            assert seen_request is not None
+            assert seen_request.url.params["engines"] == "bing,yahoo"
+        finally:
+            await provider._client.aclose()
+
+    asyncio.run(run())
+
+
 def test_orchestrator_registers_searxng_provider() -> None:
     orchestrator = ResearchOrchestrator(_config(), uuid4(), "test")
     provider = orchestrator._get_multi_search().get_provider("searxng")
@@ -104,6 +125,25 @@ def test_searching_accepts_normalized_result_with_empty_snippet() -> None:
     asyncio.run(run())
 
 
+def test_searching_with_no_usable_results_fails_instead_of_completing_empty() -> None:
+    """Provider-wide empty results must not become an empty completed report."""
+    async def run() -> None:
+        orchestrator = ResearchOrchestrator(_config(), uuid4(), "test")
+        multi_search = Mock()
+        multi_search.enabled_providers.return_value = ["searxng"]
+        multi_search.search = AsyncMock(return_value=[])
+        orchestrator._multi_search = multi_search
+
+        response = await orchestrator._step_searching()
+
+        assert response["success"] is False
+        assert response["url_count"] == 0
+        assert "no usable URLs" in response["error"]
+        assert orchestrator._search_results == []
+
+    asyncio.run(run())
+
+
 def test_fetching_uses_actual_bytes_and_respects_remaining_source_budget() -> None:
     async def run() -> None:
         budget = HardBudgetConfig(max_sources=2, max_total_download_bytes=1_000)