Forward judge_language through score, async, and session endpoints

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

tests/test_score_endpoint_language.py

@@ -0,0 +1,46 @@
+"""Tests that score endpoints forward the resolved judge_language to the scorer."""
+
+from unittest.mock import MagicMock, patch
+
+from fastapi.testclient import TestClient
+
+import webapp.api.score as score_mod
+from webapp.server import create_app
+
+
+def _client():
+    return TestClient(create_app())
+
+
+def test_score_route_forwards_judge_language(monkeypatch):
+    """A request with judge_language='zh' reaches inline_scorer.score."""
+    captured: dict = {}
+
+    def fake_score(**kwargs):
+        captured.update(kwargs)
+        return {"faithfulness": 0.9}
+
+    monkeypatch.setattr(score_mod.inline_scorer, "score", fake_score)
+    resp = _client().post("/api/score", json={
+        "question": "q", "answer": "a", "contexts": "c",
+        "ground_truth": "g", "metrics": ["faithfulness"], "judge_language": "zh",
+    })
+    assert resp.status_code == 200
+    assert captured.get("judge_language") == "zh"
+
+
+def test_score_route_defaults_language_to_en(monkeypatch):
+    """Omitting judge_language falls back to settings default ('en')."""
+    captured: dict = {}
+
+    def fake_score(**kwargs):
+        captured.update(kwargs)
+        return {"faithfulness": 0.9}
+
+    monkeypatch.setattr(score_mod.inline_scorer, "score", fake_score)
+    resp = _client().post("/api/score", json={
+        "question": "q", "answer": "a", "contexts": "c",
+        "ground_truth": "g", "metrics": ["faithfulness"],
+    })
+    assert resp.status_code == 200
+    assert captured.get("judge_language") == "en"