{
 "date": "2026-09-13",
 "exp": "loop closure: v6 plain-chain-end vs v6.2 GT-anchor-reversed-end",
 "shuffle_seed": 202609132,
 "arm_of": {
  "甲": "v6",
  "乙": "v62"
 },
 "files": {
  "甲": "bta_loop_A.mp4",
  "乙": "bta_loop_B.mp4"
 },
 "metrics": {
  "v6": {
   "dur": "23.7s",
   "wrap_diff": 56.6,
   "note": "回绕=60°跳变"
  },
  "v62": {
   "dur": "20.4s",
   "wrap_diff": 24.6,
   "note": "回绕≈3°档,对齐叠化"
  }
 },
 "verdict": {
  "kai_pick": "乙(=v6.2 GT锚倒放回环)",
  "date": "2026-09-13",
  "new_issue": "中段桌椅复制/重叠: 链式想象区共性缺陷(R2-R4), 缝叠化窗内也有视差鬼影; 两臂同源均存在, 与回环强化单变量无关",
  "followup": "候选修法: R2-R4 段 GT 密锚化(6锚全GT版=旧v4拓扑) 或 锚密度 60°→30°; 待 Kai 拍板"
 }
}