feat: 增强差旅报销审核流程与票据智能推理

优化本体解析和编排器的差旅场景处理能力，完善报销单草稿
保存和费用明细同步逻辑，前端报销创建页面增加行程推理和
票据审核交互，新增助手会话快照工具函数，补充单元测试。

server/src/app/services/user_agent.py

@@ -97,6 +97,15 @@ GROUP_SCENE_LABELS = {
     "other": "其他费用",
 }
 
+EXPENSE_SCENE_SELECTION_OPTIONS = (
+    ("travel", "差旅费", "出差、长途交通、住宿、差旅补贴等场景。"),
+    ("transport", "交通费", "市内打车、停车、过路费等日常交通场景。"),
+    ("hotel", "住宿费", "单独住宿、酒店发票等场景。"),
+    ("entertainment", "业务招待费", "客户接待、宴请、招待等场景。"),
+    ("office", "办公费", "办公用品、耗材、办公设备等采购场景。"),
+    ("other", "其他费用", "暂不属于以上分类的报销场景。"),
+)
+
 KNOWLEDGE_MODEL_MAIN_TIMEOUT_SECONDS = 3
 KNOWLEDGE_MODEL_BACKUP_TIMEOUT_SECONDS = 5
 KNOWLEDGE_MODEL_TIMEOUT_SECONDS = KNOWLEDGE_MODEL_BACKUP_TIMEOUT_SECONDS
@@ -275,6 +284,17 @@ class UserAgentService:
         AgentFoundationService(self.db).ensure_foundation_ready()
         citations = self._build_citations(payload)
         suggested_actions = self._build_suggested_actions(payload)
+        if self._should_prompt_expense_scene_selection(payload):
+            return UserAgentResponse(
+                answer=self._build_expense_scene_selection_answer(payload),
+                citations=citations,
+                suggested_actions=suggested_actions,
+                query_payload=None,
+                draft_payload=None,
+                review_payload=None,
+                risk_flags=[],
+                requires_confirmation=False,
+            )
         risk_flags = self._resolve_risk_flags(payload)
         query_payload = self._build_query_payload(payload)
         draft_payload = (
@@ -1801,6 +1821,11 @@ class UserAgentService:
 
     @staticmethod
     def _should_build_draft_payload(payload: UserAgentRequest) -> bool:
+        if payload.ontology.scenario == "expense" and payload.tool_payload.get("preview_only"):
+            return any(
+                str(payload.tool_payload.get(key) or "").strip()
+                for key in ("claim_id", "claim_no")
+            )
         if payload.ontology.intent == "draft":
             return True
         if payload.ontology.scenario != "expense":
@@ -1817,6 +1842,21 @@ class UserAgentService:
         if payload.ontology.scenario == "knowledge":
             return []
 
+        if self._should_prompt_expense_scene_selection(payload):
+            return [
+                UserAgentSuggestedAction(
+                    label=label,
+                    action_type="select_expense_type",
+                    description=description,
+                    payload={
+                        "expense_type": code,
+                        "expense_type_label": label,
+                        "original_message": payload.message,
+                    },
+                )
+                for code, label, description in EXPENSE_SCENE_SELECTION_OPTIONS
+            ]
+
         if self._is_generic_expense_prompt(payload):
             return [
                 UserAgentSuggestedAction(
@@ -1886,6 +1926,35 @@ class UserAgentService:
             ),
         ]
 
+    def _should_prompt_expense_scene_selection(self, payload: UserAgentRequest) -> bool:
+        if payload.ontology.scenario != "expense":
+            return False
+        if payload.ontology.intent not in {"draft", "operate"}:
+            return False
+        if str(payload.context_json.get("review_action") or "").strip():
+            return False
+        review_form_values = self._resolve_review_form_values(payload)
+        if str(review_form_values.get("expense_type") or review_form_values.get("reimbursement_type") or "").strip():
+            return False
+        if self._resolve_attachment_count(payload) > 0 or self._resolve_ocr_documents(payload):
+            return False
+        return not any(
+            item.type == "expense_type" and str(item.normalized_value or item.value or "").strip()
+            for item in payload.ontology.entities
+        )
+
+    @staticmethod
+    def _build_expense_scene_selection_answer(payload: UserAgentRequest) -> str:
+        has_time = bool(payload.ontology.time_range.start_date or payload.ontology.time_range.raw)
+        context_hint = "我先识别到这是一次报销申请"
+        if has_time:
+            context_hint += "，并看到了业务发生时间"
+        return (
+            f"{context_hint}。但你还没有明确这笔单据属于哪类报销。"
+            "请先在下面选择报销场景，我会按你选择的场景再继续识别时间、地点、事由、金额和所需票据，"
+            "避免系统先入为主把项目支持、部署等描述误判成差旅。"
+        )
+
     def _build_review_payload(
         self,
         payload: UserAgentRequest,
@@ -3363,6 +3432,17 @@ class UserAgentService:
             )
 
         review_action = str(payload.context_json.get("review_action") or "").strip()
+        if payload.tool_payload.get("preview_only") and not review_action:
+            base_message = review_payload.body_message or self._build_review_intent_summary(
+                payload,
+                slot_cards=review_payload.slot_cards,
+                claim_groups=review_payload.claim_groups,
+            )
+            return (
+                f"{base_message} "
+                "本次只是核对预览，尚未保存为草稿；需要暂存时请点击“保存为草稿”，"
+                "需要正式提交时再点击“继续下一步”。"
+            )
         if review_action == "save_draft":
             if draft_payload is not None and draft_payload.claim_no:
                 return (