Preserve proof that cap64 has entered the hybrid training branch

Constraint: The cap64 run is still incomplete, so only branch-transition evidence can be recorded safely at this point
Rejected: Wait for the hybrid eval before checkpointing | Would lose the verified handoff that execution has moved beyond high_energy into hybrid training
Confidence: high
Scope-risk: narrow
Directive: Keep cap64 branch progression explicit so the next session can resume from the current strategy leg without re-inspection
Tested: Verified high_energy eval.json reports num_queries=32, top1=0.625, topk=1.0; verified active processes show external_adapters.py on /tmp/ab_smoke_seg_cap64_top2/hybrid and train.py on /tmp/ab_smoke_seg_cap64_top2/hybrid/fma/manifests; verified hybrid eval.json and report.json are still absent
Not-tested: Final hybrid cap64 metrics, final report.json, and any cap64 winner conclusion

+## 2026-06-02 cap64 hybrid 训练启动 checkpoint
+
+完成项：
+- 追加记录 cap64 的第二个策略分支已经启动。
+- 已确认主流程从 `manifest_tools.py audio-dir-to-splits` 进入 `hybrid train.py`。
+
+验证证据：
+- 当前进程显示：
+  - `external_adapters.py smoke-local ... /tmp/ab_smoke_seg_cap64_top2/hybrid`
+  - `train.py --data /tmp/ab_smoke_seg_cap64_top2/hybrid/fma/manifests ... --segment-strategy hybrid`
+- 截至本 checkpoint：
+  - `hybrid` 的 `eval.json` 尚未生成
+  - 总 `report.json` 尚未生成
+
 ## 2026-06-02 cap64 high_energy 首个结果 checkpoint
 
 完成项：

@@ -70,3 +70,5 @@ cd /workspace/acr-engine
 - 已补充 cap64 新鲜证据：`high_energy` 索引完成（`64 refs / 657 windows / 192-d`）并进入 `evaluate.py`。
 
 - 已补充 cap64 首个结果：`high_energy = top1 0.625 / topk 1.0 / num_queries 32`，并记录主流程切换到 `hybrid`。
+
+- 已补充 cap64 阶段推进：`hybrid` 已进入训练阶段。

@@ -61,5 +61,5 @@ test -f /tmp/ab_smoke_seg_cap48_top2_seed999/report.json && cat /tmp/ab_smoke_se
 
 - 新 benchmark：`/tmp/ab_smoke_seg_cap64_top2`
 - 当前阶段：`high_energy` 已完成评测，结果为 `top1=0.625 / topk=1.0 / num_queries=32`
-- 当前已切换到 `hybrid` 分支
+- 当前已切换到 `hybrid` 训练阶段
 - 下一 session 应优先检查 `hybrid` 结果与 `report.json` 是否生成

@@ -676,6 +676,6 @@ seed123 最终结论：
 - 配置：`subset_size=64`, `max_test_queries=32`, `seed=42`
 - 当前最新证据：
   - `high_energy` 已完成评测：`num_queries=32, top1=0.625, topk=1.0`
-  - cap64 主流程已切换到 `hybrid` 分支
+  - `hybrid` 已进入 `train.py` 阶段
   - 总 `report.json` 尚未生成