gate: a re-do of an already-playable file gets a 0.975 mean bar (owner decision)

One pass measured 11 attempts rejected purely on the window mean (0.9655-0.9795)
while accepted encodes had worse frame minima (0.33-0.90): the bar was splitting a
continuum, not separating defects. 0718 马斯克原理 failed with min 0.887 and 0.00% of
frames below 0.85. Those files already play (HEVC hvc1 + AAC) and a re-do exists only
to reclaim an old setting's bloat; reaching a 0.98 mean costs more than the source's
own bitrate, which the size ceiling forbids - so the strict bar stranded them with
their bloat while burning an encode every pass.

SSIM_MEAN_MIN_REDO = 0.975 now applies only when the run is re-doing a file that is
genuinely playable (HEVC hvc1 AND aac) from the snapshot original. The frame-share
test (>1% of frames below 0.85) is unchanged and is what catches a real defect.

Verified on ONE file before the tiers were restarted: 0321 随他们去 (rejected last
pass at mean 0.9789) -> ok, mean 0.9786, min 0.5092 with 5 of 1500 frames below 0.85
(fades), 633 MB -> 418 MB installed, live byte count == the encoded output.

STATE.md

@@ -54,6 +54,20 @@ bash /d/tmp/xcode/convert_new4.sh     # 逐个 --tier copy --path <file> --keep-
 
 - `1004 反内卷` 10:48:53 完成 ✓（535 MB → 535 MB，视频 100% 逐位不变，音频转 AAC，149 s，rc=0）
 
+## 图片闸门：re-do 用 0.975（业主决定 2026-10-08）
+
+第一轮实测：一趟里 11 次编码**只差在 mean**（0.9655–0.9795）就被拒，而被接受的那些帧最低分反而更差
+（0.33–0.90）—— 阈值在切一条连续的分布，不是在分开缺陷（`0718 马斯克原理`：min 0.887、**0.00%** 帧
+<0.85，照样被拒）。被拒的文件本来就已能播（HEVC hvc1 + AAC），re-do 的唯一目的是清掉旧设定的膨胀；
+而要够到 mean 0.98 得花掉超过源片自身的码率，会被 size ceiling 拦住 —— 结果是文件连同膨胀被永久搁置，
+而且每一趟还白烧一次编码。
+
+新规则（`library_run.SSIM_MEAN_MIN_REDO = 0.975`）：**只有**"重做一个已经在播的文件"才用 0.975，条件为
+live = HEVC hvc1 **且**音轨是 AAC（真能播）**且**本次是从快照原档重做；首次转换仍用 0.98。
+帧占比判据（>1% 帧 <0.85）两档都不变 —— 它才是抓真缺陷的那条：`失控`（0.9655）仍会被拒，
+`0808 陌生人效应`（0.9739）因为 live 是 H.264、根本不是 re-do，也仍走 0.98。
+先在一个文件上验证（`0321 随他们去`，上一轮 mean 0.9789 被拒）→ 见 `/d/tmp/xcode/run_pilot.log`。
+
 ## 目录与日志
 
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