gate policy: frame-share is the verdict for owner-approved items; park after 2 failed rounds

Owner decision 2026-10-10. Eight items were livelocked in the nvenc tier, burning ~3.3
GPU-hours per pass (initial encode + quality+2 retry) and never converting: they missed the
mean bar by 0.2-1.7 thousandths (0.9626-0.9778) while keeping only 0.20-0.93% of frames
below 0.85 - and per this repo's own comment the FRAME-SHARE test is the one that actually
catches a defect, the mean bar splits a continuum. With SIZE_CEIL=1.0 the mean bar is
unreachable for them by construction.

- library_run.py: POLICY (C:\AI\transcode-run\gate_policy.json) with
  * accept - named items are judged by the frame-share test; a mean under the bar is logged,
    not enforced. An item that trips the frame-share test is refused even if listed
    (0912 洞见, 1.33%, is deliberately absent).
  * park  - failed quality ROUNDS per item; at PARK_AFTER=2 the item is skipped with a
    visible SKIP status instead of being re-encoded. Counters persist in the same file.
- scripts/build_gate_policy.py: builds that file from the run log, taking each key verbatim
  from the '--- i/n <relative path>' line (no hand-copying). Result: 7 accepted, 1 refused.
- run/relaunch_nvenc.sh: start the GPU tier ALONE (relaunch_tiers.sh hardcodes both tiers).
- STATE.md: the policy, its rationale and the round counter.

STATE.md

@@ -62,6 +62,26 @@ 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）
 
+## 闸门策略文件（业主决定 2026-10-10）：`C:\AI\transcode-run\gate_policy.json`
+
+8 个项在 nvenc 档里反复失败、**每轮白烧 ~3.3 GPU 小时**（初始一次 + quality+2 一次），而且永远过不了：它们的
+mean 差 0.2–1.7 个千分点（0.9626–0.9778），但**帧占比只有 0.20–0.93%** —— 按本仓库自己的注释，抓真缺陷的是
+**帧占比 >1%** 那条，mean 那条只是在切一条连续分布。
+
+```json
+{
+ "accept": [ "7 个项（帧占比 ≤1%）的库内相对路径" ],
+ "park":   { "8 个项": 1 }
+}
+```
+
+- `accept`：名单内的项以**帧占比测试**为准，mean 低于门槛只记录不拦截。**帧占比 >1% 的项即使列在名单里也照样拒**
+  （《2020年\0912 洞见》1.33% 故意不在名单里）。
+- `park`：每项**失败轮数**；达到 `PARK_AFTER = 2` 就 **SKIP**（不再重编码），要重试就把它的条目删掉。
+  没有这条，同样的 8 个项每趟都重演一次、永远转不出来。
+- 生成器：`scripts/build_gate_policy.py`（键**逐字取自日志**的 `--- i/n <相对路径>` 行，不手抄）。
+- 停/起的单档启动器：`run/relaunch_nvenc.sh`（`relaunch_tiers.sh` 会连带拉起 x265，别用它单独起 GPU 档）。
+
 ## 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