feat(search): append raw entity fields after view_node summary

view_node 按题两轮摘要（summarize_node）会吞掉 entities/visible_text
字段信号，Agent 站在证据节点上仍漏读实体（benchmark 错题 M1，案例
786-2、872-3、750-1）。dispatcher 侧在摘要后确定性追加 [实体]/[画面
文字] 原文区块，LLM 无法吞掉。

- TreeEnvironment.node_entity_fields：按层级取 card 实体字段原文，
  去空白、去重、分号拼接；空字段省键；未知节点抛 KeyError
- _handle_view_node Phase 2.5：摘要后、子节点概览前追加实体区块
- 附带 ruff format 修正 test_tree_environment.py 两处既有格式

算法 #11（树环境语义搜索）数据访问层扩展，不改搜索算法本身。

tests/unit/test_tree_environment.py

@@ -250,7 +250,8 @@ class TestGetNodeText:
         """锚模式应返回带锚文本和 anchor_map 字典。"""
         env = TreeEnvironment(_make_test_index())
         text, anchor_map = env.get_node_text(
-            "vid_L1_000_L2_000_L3_000", anchor=True,
+            "vid_L1_000_L2_000_L3_000",
+            anchor=True,
         )
         # 锚文本包含 [cN] 标记
         assert "[c1]" in text
@@ -271,7 +272,8 @@ class TestGetNodeText:
         """无字幕的 L3 节点锚模式不应产生 [sN] 锚。"""
         env = TreeEnvironment(_make_test_index())
         text, anchor_map = env.get_node_text(
-            "vid_L1_000_L2_000_L3_001", anchor=True,
+            "vid_L1_000_L2_000_L3_001",
+            anchor=True,
         )
         assert anchor_map is not None
         assert not any(k.startswith("s") for k in anchor_map)
@@ -322,3 +324,93 @@ class TestGetChildrenInfo:
         env = TreeEnvironment(index)
         children = env.get_children_info("vid_L1_000")
         assert len(children[0]["summary"]) == 123  # 120 + "..."
+
+
+# ── node_entity_fields 测试（Spec-1 B）───────────────────────
+
+
+def _make_entity_test_index() -> TreeIndex:
+    """带实体字段的最小三层树（含一个空字段 L2）。"""
+    l3 = L3Node(
+        id="vid_L1_000_L2_000_L3_000",
+        card=L3Card(
+            frame_summary="一名男子戴耳机",
+            visible_entities=["Bluetooth headset (both ears)", "man"],
+            ongoing_actions=["talking"],
+            visible_text=["EARPHONE BOTTLE OPENER"],
+            spatial_layout="man center",
+            visual_attributes={},
+        ),
+        timestamp=10.0,
+    )
+    l2 = L2Node(
+        id="vid_L1_000_L2_000",
+        card=L2Card(
+            event_description="产品评测",
+            entities=["Bluetooth headset (both ears)", "reviewer"],
+            actions=["reviewing"],
+            action_subjects=["reviewer"],
+            visible_text=["$9.99"],
+            spatial_relations="",
+            state_changes=None,
+        ),
+        time_range=(0.0, 60.0),
+        children=[l3],
+    )
+    l2_empty = L2Node(
+        id="vid_L1_000_L2_001",
+        card=L2Card(
+            event_description="空镜",
+            entities=[],
+            actions=[],
+            action_subjects=[],
+            visible_text=[],
+            spatial_relations="",
+            state_changes=None,
+        ),
+        time_range=(60.0, 120.0),
+    )
+    l1 = L1Node(
+        id="vid_L1_000",
+        card=L1Card(
+            scene_summary="评测场景",
+            main_setting="室内",
+            key_entities=["reviewer"],
+            main_actions=["评测"],
+            topic_keywords=["数码"],
+            visible_text=[],
+            temporal_flow="线性",
+        ),
+        time_range=(0.0, 120.0),
+        children=[l2, l2_empty],
+    )
+    return TreeIndex(metadata=IndexMeta("/test.mp4", "video"), roots=[l1])
+
+
+class TestNodeEntityFields:
+    """node_entity_fields 方法测试（B 修复：dispatcher 追加原文）。"""
+
+    def test_l2_entities_and_visible_text(self) -> None:
+        """L2 节点应返回 entities 和 visible_text 原文。"""
+        env = TreeEnvironment(_make_entity_test_index())
+        fields = env.node_entity_fields("vid_L1_000_L2_000")
+        assert "Bluetooth headset (both ears)" in fields["实体"]
+        assert "$9.99" in fields["画面文字"]
+
+    def test_l3_visible_entities(self) -> None:
+        """L3 节点应返回 visible_entities 和 visible_text 原文。"""
+        env = TreeEnvironment(_make_entity_test_index())
+        fields = env.node_entity_fields("vid_L1_000_L2_000_L3_000")
+        assert "Bluetooth headset (both ears)" in fields["实体"]
+        assert "EARPHONE BOTTLE OPENER" in fields["画面文字"]
+
+    def test_empty_fields_omitted(self) -> None:
+        """实体/画面文字均为空时应返回空字典（不含空键）。"""
+        env = TreeEnvironment(_make_entity_test_index())
+        assert env.node_entity_fields("vid_L1_000_L2_001") == {}
+
+    def test_unknown_node_raises(self) -> None:
+        """查询不存在的节点应抛出 KeyError。"""
+        env = TreeEnvironment(_make_entity_test_index())
+        with pytest.raises(KeyError):
+            env.node_entity_fields("nonexistent")