feat: LangGraph工作流核心 — Agent状态/节点/图 + 验证服务 + 知识库

agent/
  state.py: AgentState TypedDict（20字段含意图/压缩/会话/撤销）
  nodes.py: 17个节点函数（生成/修改/验证/纠错/意图分类/压缩/撤销/重置）
  graph.py: 17节点状态图，8意图路由分发

验证服务 validation_service/
  main.py: FastAPI服务，lxml XSD验证 + 结构化检查（字段引用/SQL/尺寸）

数据 data/
  sample_templates/: 4个JRXML示例模板
  corrections/: 3个错误修正案例

脚本 scripts/
  init_kb.py: Chroma知识库初始化

agent/graph.py

@@ -0,0 +1,225 @@
+"""LangGraph JRXML 生成代理的状态图定义。"""
+
+import os
+from typing import Literal
+
+from dotenv import load_dotenv
+from langgraph.graph import StateGraph, END
+
+from agent.state import AgentState
+from agent.nodes import (
+    load_session_node,
+    process_input,
+    manage_context,
+    save_state_snapshot,
+    classify_intent,
+    retrieve,
+    generate,
+    modify_jrxml,
+    handle_consult,
+    handle_undo,
+    handle_reset,
+    save_session_node,
+    validate,
+    explain_error,
+    correct_jrxml,
+    finalize,
+)
+
+load_dotenv()
+MAX_RETRY = int(os.getenv("MAX_RETRY", "3"))
+
+# ============================================================
+# 路由函数
+# ============================================================
+
+def route_by_intent(state: AgentState) -> Literal[
+    "retrieve", "modify_jrxml", "save_session",
+    "handle_consult", "handle_undo", "handle_reset"
+]:
+    """根据 classify_intent 的结果路由到对应的处理节点。"""
+    intent = state.get("intent", "initial_generation")
+
+    if intent == "initial_generation":
+        return "retrieve"
+    elif intent == "modify_report":
+        return "modify_jrxml"
+    elif intent in ("preview_report", "export_pdf", "export_jrxml"):
+        return "save_session"
+    elif intent == "consult_question":
+        return "handle_consult"
+    elif intent == "undo_modification":
+        return "handle_undo"
+    elif intent == "reset_session":
+        return "handle_reset"
+    else:
+        # 兜底：根据是否有报表判断
+        if state.get("current_jrxml"):
+            return "modify_jrxml"
+        return "retrieve"
+
+
+def route_after_generate(state: AgentState) -> Literal["save_session"]:
+    return "save_session"
+
+
+def route_after_modify(state: AgentState) -> Literal["save_session"]:
+    return "save_session"
+
+
+def route_after_undo(state: AgentState) -> Literal["save_session"]:
+    return "save_session"
+
+
+def route_after_save(state: AgentState) -> Literal["validate"]:
+    return "validate"
+
+
+def route_after_validate(state: AgentState) -> Literal["finalize", "explain_error"]:
+    if state.get("status") == "pass":
+        return "finalize"
+    return "explain_error"
+
+
+def route_after_explain(state: AgentState) -> Literal["correct_jrxml"]:
+    return "correct_jrxml"
+
+
+def route_after_correct(state: AgentState) -> Literal["validate", "finalize"]:
+    retry = state.get("retry_count", 0)
+    if retry >= MAX_RETRY:
+        return "finalize"
+    return "validate"
+
+
+# ============================================================
+# 图构建
+# ============================================================
+
+def build_graph() -> StateGraph:
+    workflow = StateGraph(AgentState)
+
+    # 现有节点
+    workflow.add_node("load_session", load_session_node)
+    workflow.add_node("process_input", process_input)
+    workflow.add_node("manage_context", manage_context)
+    workflow.add_node("save_session", save_session_node)
+    workflow.add_node("retrieve", retrieve)
+    workflow.add_node("generate", generate)
+    workflow.add_node("modify_jrxml", modify_jrxml)
+    workflow.add_node("validate", validate)
+    workflow.add_node("explain_error", explain_error)
+    workflow.add_node("correct_jrxml", correct_jrxml)
+    workflow.add_node("finalize", finalize)
+
+    # 新增节点：意图识别
+    workflow.add_node("save_state_snapshot", save_state_snapshot)
+    workflow.add_node("classify_intent", classify_intent)
+    workflow.add_node("handle_consult", handle_consult)
+    workflow.add_node("handle_undo", handle_undo)
+    workflow.add_node("handle_reset", handle_reset)
+
+    # ---- 入口和前置流程 ----
+    workflow.set_entry_point("load_session")
+    workflow.add_edge("load_session", "process_input")
+    workflow.add_edge("process_input", "manage_context")
+    workflow.add_edge("manage_context", "save_state_snapshot")
+    workflow.add_edge("save_state_snapshot", "classify_intent")
+
+    # ---- 意图路由 ----
+    workflow.add_conditional_edges(
+        "classify_intent",
+        route_by_intent,
+        {
+            "retrieve": "retrieve",
+            "modify_jrxml": "modify_jrxml",
+            "save_session": "save_session",
+            "handle_consult": "handle_consult",
+            "handle_undo": "handle_undo",
+            "handle_reset": "handle_reset",
+        },
+    )
+
+    # ---- 初始生成分支 ----
+    workflow.add_edge("retrieve", "generate")
+    workflow.add_conditional_edges(
+        "generate",
+        route_after_generate,
+        {"save_session": "save_session"},
+    )
+
+    # ---- 修改分支 ----
+    workflow.add_conditional_edges(
+        "modify_jrxml",
+        route_after_modify,
+        {"save_session": "save_session"},
+    )
+
+    # ---- 撤销分支 ----
+    workflow.add_conditional_edges(
+        "handle_undo",
+        route_after_undo,
+        {"save_session": "save_session"},
+    )
+
+    # ---- 保存后进入验证 ----
+    workflow.add_conditional_edges(
+        "save_session",
+        route_after_save,
+        {"validate": "validate"},
+    )
+
+    # ---- 验证 → 修正循环 ----
+    workflow.add_conditional_edges(
+        "validate",
+        route_after_validate,
+        {"finalize": "finalize", "explain_error": "explain_error"},
+    )
+    workflow.add_conditional_edges(
+        "explain_error",
+        route_after_explain,
+        {"correct_jrxml": "correct_jrxml"},
+    )
+    workflow.add_conditional_edges(
+        "correct_jrxml",
+        route_after_correct,
+        {"validate": "validate", "finalize": "finalize"},
+    )
+
+    # ---- 咨询 / 重置 → 直接结束 ----
+    workflow.add_edge("handle_consult", "finalize")
+    workflow.add_edge("handle_reset", "finalize")
+
+    # ---- 结束 ----
+    workflow.add_edge("finalize", END)
+
+    return workflow.compile()
+
+
+# ============================================================
+# 初始状态
+# ============================================================
+
+def create_initial_state() -> AgentState:
+    return AgentState(
+        conversation_history=[],
+        current_jrxml="",
+        user_input="",
+        status="",
+        error_msg="",
+        natural_explanation="",
+        retry_count=0,
+        user_modification_request="",
+        final_jrxml="",
+        stage="initial_generation",
+        retrieved_context="",
+        full_conversation_history=[],
+        compressed_history="",
+        current_token_count=0,
+        session_id="",
+        session_name="",
+        created_at="",
+        updated_at="",
+        intent="",
+        history_states=[],
+    )