세션 평가와 교수자 분석 보강

apps/api/app/session_persistence.py

@@ -39,6 +39,13 @@ _APPROPRIATENESS_SCORE = {
 }
 
 
+def _coerce_error_message(error: BaseException | str) -> str:
+    if isinstance(error, BaseException):
+        message = str(error).strip()
+        return message or error.__class__.__name__
+    return str(error).strip() or "unknown session evaluation error"
+
+
 @dataclass(slots=True)
 class CaseContext:
     case_id: str
@@ -114,7 +121,7 @@ class SessionEvaluationWrite:
             scope=scope,
             stage=stage,
             payload={},
-            error=str(error),
+            error=_coerce_error_message(error),
         )
 
     def cache_record(self) -> dict[str, Any]:
@@ -1254,9 +1261,8 @@ async def load_session_evaluation(
                 session_id,
             )
             if row is None:
-                return (
-                    _EVALUATION_CACHE.get(session_id) if runtime_fallback_allowed() else None
-                ), False
+                cached = _EVALUATION_CACHE.get(session_id) if runtime_fallback_allowed() else None
+                return cached, cached is None
             return {
                 "status": row["status"],
                 "source": row["source"],