Handle yente transport failures gracefully

sanctions/src/main.py

@@ -239,13 +239,20 @@ async def screen(req: ScreenRequest):
     """Screen a name against OpenSanctions lists via yente."""
     try:
         results = await _query_yente(req.name, req.threshold)
-    except httpx.ConnectError:
+    except httpx.ConnectError as e:
         raise HTTPException(
             status_code=503,
             detail=f"yente service not reachable at {YENTE_URL}.",
-        )
+        ) from e
+    except httpx.TimeoutException as e:
+        raise HTTPException(
+            status_code=504,
+            detail=f"yente request timed out at {YENTE_URL}.",
+        ) from e
+    except httpx.RequestError as e:
+        raise HTTPException(status_code=503, detail=f"yente request failed: {e}") from e
     except httpx.HTTPStatusError as e:
-        raise HTTPException(status_code=502, detail=f"yente error: {e}")
+        raise HTTPException(status_code=502, detail=f"yente error: {e}") from e
 
     matches = [
         ScreenMatch(

sanctions/tests/test_main.py

@@ -5,6 +5,7 @@
 
 from unittest.mock import AsyncMock, patch
 
+import httpx
 import pytest
 from fastapi.testclient import TestClient
 
@@ -77,6 +78,23 @@ async def test_screen_no_matches():
     assert data["matches"] == []
 
 
+def test_screen_timeout_returns_gateway_timeout():
+    """Timeouts von yente werden als 504 statt als 500 zurueckgegeben."""
+    with patch(
+        "sanctions.src.main._query_yente",
+        new=AsyncMock(side_effect=httpx.ReadTimeout("timed out")),
+    ):
+        response = client.post(
+            "/api/screen",
+            json={"name": "Max Mustermann"},
+        )
+
+    assert response.status_code == 504
+    assert response.json() == {
+        "detail": "yente request timed out at http://localhost:8100."
+    }
+
+
 def test_screen_missing_body():
     """Fehlender Body → 422 Validation Error."""
     response = client.post("/api/screen", json={})