M2b：删除旧 chat 体系——线性会话/叩心/情绪/纪念日模型与页面退役（迁移 003 双向验证），runs 去会话外键，测试全量修剪

backend/app/services/admin.py

@@ -262,14 +262,11 @@ async def get_trace(trace_id: str) -> TraceDetail:
                 *[audit.character_id for audit in audits if audit.character_id],
             }
         )
-        session_ids = (
-            sorted(await runtime_repo.list_session_ids_by_runs(session, run_ids)) if run_ids else []
-        )
         return TraceDetail(
             trace_id=trace_id,
             character_ids=character_ids,
             run_ids=run_ids,
-            session_ids=session_ids,
+            session_ids=[],
             items=items,
         )
 
@@ -342,15 +339,7 @@ async def list_traces(*, limit: int = 50) -> TraceListResponse:
         ).all():
             _entry(tid)["character_ids"].add(cid)
 
-        # 对话归属（events.run_id → runs.session_id）
-        for tid, sid in (
-            await session.execute(
-                select(Event.trace_id, Run.session_id)
-                .join(Run, Event.run_id == Run.id)
-                .where(Event.trace_id.is_not(None), Run.session_id.is_not(None))
-            )
-        ).all():
-            _entry(tid)["session_ids"].add(sid)
+        # 对话归属随线性会话模型退役；镜树归属随 M2c 司命台重设计接入（tree_id 聚合）
 
         total = len(merged)
         ordered = sorted(merged.values(), key=lambda e: e["last_seen"], reverse=True)