Why the handoff needs the exact semantic adapter insertion point

Constraint: The next session should not spend time rediscovering where the real MERT/MuQ adapter belongs in the song-centric pipeline
Rejected: Leave the adapter step as a generic future task | does not identify the concrete file and function to change
Confidence: high
Scope-risk: narrow
Directive: Keep future semantic-adapter handoffs anchored on enrich_songcentric_manifest_with_local_features.py unless the host pipeline entrypoint changes
Tested: markdown link check on /workspace/docs after adding the semantic adapter handoff note
Not-tested: No runtime install or adapter implementation yet; this commit records the verified insertion point only

@@ -158,3 +158,51 @@ flowchart TD
 ## 一句话 handoff
 
 > 下次不要再从总方案争论开始，直接跑 song-centric runner；如果 exact 正常、semantic 仍 fallback，就继续补真实 semantic adapter 和依赖。
+
+---
+
+## 10. 真实 semantic adapter 下一步应该接到哪里
+
+当前最直接的接入点已经明确：
+
+- 入口脚本：`acr-engine/scripts/enrich_songcentric_manifest_with_local_features.py`
+- 关键函数：`build_semantic_feature(...)`
+
+### 当前真实状态
+
+- exact lane 已优先复用 `ChromaprintMatcher`
+- semantic lane 还没有真实接入 `MERT / MuQ`
+- runtime 就绪时，当前仍只会产出：
+  - `model_name = semantic_runtime_ready_placeholder`
+- runtime 不就绪时，会走：
+  - `model_name = local_wavehash_embed`
+
+### fresh 依赖检查事实
+
+当前 host 仍缺：
+- `torch`
+- `torchaudio`
+- `transformers`
+
+### 下次 session 最直接的实现顺序
+
+1. 安装 `torch / torchaudio / transformers`
+2. 在 `build_semantic_feature(...)` 内接真实 `MERT` 或 `MuQ` adapter
+3. 保留当前 `local_wavehash_embed` fallback 不删
+4. 重跑：
+
+```bash
+cd /workspace
+/usr/local/miniconda3/bin/python acr-engine/scripts/run_songcentric_directory_pipeline_live.py \
+  --dsn 'postgres://d2:d2pass@127.0.0.1:5432/d2' \
+  --schema acr_songcentric_test \
+  --input-root acr-engine/data/songcentric_builder_smoke \
+  --output-dir acr-engine/data/pgvector_eval/music20
+```
+
+### 期望看到的 fresh 指标变化
+
+- `semantic_runtime_available = true`
+- `semantic_runtime_ready_count > 0`
+- `semantic_fallback_count` 明显下降或归零
+