feat(backend): knowledge iteration + vision + neo4j + response contract source

dependencies.py 拆分为 dependencies/ 包; 新增 vision/ragflow_ingestion/neo4j 客户端与 h5_ai_task; alembic 045 图置信度迁移; 响应契约统一收尾。

backend/app/models/knowledge_suggestion.py

@@ -8,9 +8,9 @@
 
 import uuid
 from datetime import datetime
-from typing import List, Optional
+from typing import Any, Dict, List, Optional
 
-from sqlalchemy import DateTime, Index, Integer, JSON, String, Text
+from sqlalchemy import Boolean, DateTime, Float, Index, JSON, String, Text
 from sqlalchemy.orm import Mapped, mapped_column
 
 from app.database import Base
@@ -114,6 +114,89 @@ class KnowledgeSuggestion(Base):
         comment="相关会话ID或标注ID列表",
     )
 
+    # --------------------------------------------------------------------------
+    # Tier0 扩展字段 — 图结构 + 置信度 + 受众 + 状态（D1/D3/D7/D8）
+    # --------------------------------------------------------------------------
+
+    # AI 生成置信度（0.0-1.0，D3 门控阈值 0.7）
+    confidence: Mapped[Optional[float]] = mapped_column(
+        Float,
+        nullable=True,
+        comment="AI 生成置信度（0.0-1.0）",
+    )
+
+    # 受众类型（D8：employee_quick_reply / engineer_workguide）
+    audience: Mapped[Optional[str]] = mapped_column(
+        String(30),
+        nullable=True,
+        comment="受众类型：employee_quick_reply / engineer_workguide",
+    )
+
+    # 图结构字段 — 问题名称（对应 Neo4j Issue.name）
+    issue: Mapped[Optional[str]] = mapped_column(
+        String(256),
+        nullable=True,
+        comment="图节点：问题名称",
+    )
+
+    # 图结构字段 — 动作名称（对应 Neo4j Action.name）
+    action: Mapped[Optional[str]] = mapped_column(
+        String(256),
+        nullable=True,
+        comment="图节点：动作名称",
+    )
+
+    # 图关系类型（LEADS_TO / RELATES_TO / CAN_JUMP_TO）
+    relation_type: Mapped[Optional[str]] = mapped_column(
+        String(30),
+        nullable=True,
+        comment="图关系类型",
+    )
+
+    # 父 Issue 名称（用于构建 Issue→Issue 关系）
+    parent_issue: Mapped[Optional[str]] = mapped_column(
+        String(256),
+        nullable=True,
+        comment="父 Issue 名称",
+    )
+
+    # 图结构扩展元数据（JSON，存放额外的图属性）
+    graph_meta: Mapped[Optional[Dict[str, Any]]] = mapped_column(
+        JSON,
+        nullable=True,
+        comment="图结构扩展元数据",
+    )
+
+    # 图同步状态（pending / synced / failed）
+    graph_sync_status: Mapped[str] = mapped_column(
+        String(20),
+        nullable=False,
+        default="pending",
+        comment="图同步状态：pending / synced / failed",
+    )
+
+    # AI 生成失败标记（Dify 不可用或置信度不足时置 True）
+    source_failed: Mapped[bool] = mapped_column(
+        Boolean,
+        nullable=False,
+        default=False,
+        comment="AI 生成失败标记",
+    )
+
+    # 入队列时间
+    queued_at: Mapped[Optional[datetime]] = mapped_column(
+        DateTime(timezone=True),
+        nullable=True,
+        comment="入独立队列时间",
+    )
+
+    # 应用到 KB 的时间
+    applied_at: Mapped[Optional[datetime]] = mapped_column(
+        DateTime(timezone=True),
+        nullable=True,
+        comment="应用到 KB 的时间",
+    )
+
     # 生成理由
     reason: Mapped[Optional[str]] = mapped_column(
         Text,
@@ -166,6 +249,9 @@ class KnowledgeSuggestion(Base):
         Index("idx_suggestion_status", "status"),
         Index("idx_suggestion_type", "suggestion_type"),
         Index("idx_suggestion_created", "created_at"),
+        Index("idx_suggestion_audience", "audience"),
+        Index("idx_suggestion_confidence", "confidence"),
+        Index("idx_suggestion_graph_sync", "graph_sync_status"),
     )
 
     def __repr__(self) -> str: