Document full config signature validation

docs/harness-ablation/bad-start-stop-counterexample-20260626.md

@@ -281,3 +281,92 @@ TP4 将 best req/s/GPU 从 1.0000 提高到 1.7375。
 P0 measurement/stop-order slice: passed.
 P0 full coverage-relative harness: not yet passed.
 ```
+
+## 2026-06-26 normalized full-config validation
+
+Commit `48911b6` 修复了上一节暴露的新 blocker：no-repeat 不再只比较 patch
+signature，而是比较 normalized effective full config。
+
+实现语义：
+
+```text
+effective_config =
+  normalize(base_envs + env_patch,
+            base_flags + flag_patch)
+
+no_repeat_signature = stable_json(effective_config)
+```
+
+因此下面两个 proposal 在 validator 看来是同一个 full config：
+
+```text
+baseline patch: {}
+noop patch:    {"tensor-parallel-size": 8}
+```
+
+本地验证：
+
+```text
+PYTHONPATH=src python3 -m unittest discover -s tests
+Ran 145 tests OK
+```
+
+dash1 validation：
+
+```text
+run label = adversarial-badstart-fullsig-48911b6-20260626T133112Z
+git sha   = 48911b658bbf052d70d952d1cdf55ad6b50ba7a5
+machine   = dash1, 8x H20
+```
+
+Spec 仍使用同一个 adversarial bad-start：
+
+```text
+tensor-parallel-size = 8
+data-parallel-size = 1
+gpu-memory-utilization = 0.5
+max-num-seqs = 8
+search.auto_high.enabled = true
+LLM endpoint disabled
+```
+
+结果：
+
+| trial | proposal | best sampling_u | request_rate | req/s/GPU | pass |
+| --- | --- | ---: | ---: | ---: | ---: |
+| trial-0001 | baseline TP8, DP1, gmu0.5, mns8 | 0.935616858887 | 8.00 | 1.0000 | 1.0000 |
+| trial-0002 | `tensor-parallel-size=4` | 0.810867944369 | 6.95 | 1.7375 | 0.9832 |
+| trial-0003 | `tensor-parallel-size=4`, `gpu-memory-utilization=0.9` | 0.935616858887 | 8.00 | 2.0000 | 1.0000 |
+
+关键 observation：
+
+```text
+旧 trial-0003:
+  {"tensor-parallel-size": 8}
+  -> 等价于 baseline，但仍被执行
+
+新 trial-0003:
+  {"tensor-parallel-size": 4, "gpu-memory-utilization": 0.9}
+  -> 在已验证 TP4 topology 上继续测试 KV/cache headroom
+```
+
+这证明 normalized full-config signature 已经阻止了 patch-level no-op 重测。
+
+机制解释：
+
+1. baseline TP8 saturate search ceiling 只被记录为 measurement evidence；
+2. 因为 objective 是 `req/s/GPU`，topology/resource-efficiency contrast 仍未覆盖，所以
+   validator 不允许 stop；
+3. harness 先测试相邻低 TP topology，TP4 把 `req/s/GPU` 从 `1.0` 提高到 `1.7375`；
+4. no-repeat 用 full config signature block 掉等价 TP8 patch；
+5. harness 在 settled TP4 topology 上继续测试 runtime headroom，`gmu=0.9` 把
+   `req/s/GPU` 提高到 `2.0`。
+
+当前 verdict 更新为：
+
+```text
+P0 measurement/stop-order slice: passed.
+P0 normalized full-config no-repeat slice: passed.
+P0 single adversarial bad-start recovery: passed for this case.
+P0 distribution-level bad-start robustness: not yet proven.
+```