Fix selected_indices parsing for new datasets (stored as JSON string)

backend/api/selected_tools.py

@@ -88,10 +88,16 @@ def _load(variant: str) -> list:
         except Exception:
             pass
         total_tool_calls = sum(tool_counts.values()) if tool_counts else 0
+        sel_idx = row["selected_indices"]
+        if isinstance(sel_idx, str):
+            try:
+                sel_idx = json.loads(sel_idx)
+            except Exception:
+                sel_idx = []
         rows.append({
             "query_id": str(row["query_id"]),
             "rationale": row["rationale"],
-            "selected_indices": row["selected_indices"],
+            "selected_indices": sel_idx,
             "k_requested": int(row["k_requested"]),
             "k_effective": int(row["k_effective"]),
             "excerpt": row["excerpt"],