diff --git a/core/evolution/diagnose.py b/core/evolution/diagnose.py
index 312c74c..71315ff 100644
--- a/core/evolution/diagnose.py
+++ b/core/evolution/diagnose.py
@@ -2143,10 +2143,11 @@ async def run_diagnosis(
             traces = traces_by_question.get(key, [])
             vid = prediction.get("video_id", "")
             if vid not in tree_data_by_video:
+                qid = prediction.get("question_id", "")
                 # P5 fail-loud：诊断需真实树，调用方须为每个诊断视频加载 tree_data；
                 # 静默回退空树会让 ground_truth 恒空、error_type 归因坍缩（本次修复的根因）。
                 raise ValueError(
-                    f"诊断视频树未覆盖: video_id={vid!r} 不在注入的 tree_data 中"
+                    f"诊断视频树未覆盖: video_id={vid!r} question_id={qid!r} 不在注入的 tree_data 中"
                     "（调用方须为每个诊断视频加载树，P5 fail loud）"
                 )
             td = tree_data_by_video[vid]