feat:新增事件决策/规则/聚合三段管道引擎

apps/server/services/event/decision_engine.py

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+"""事件决策引擎 (MVP-1 / P1)
+
+职责:
+
+1. 对统一 ``DetectionResult`` 中的每个检测应用置信度过滤
+2. 将底层 ``class_name`` 映射到统一 ``EventType``
+3. 产出 ``CandidateEvent`` 列表，供规则引擎与聚合器继续处理
+
+设计原则 (MVP 简化版):
+
+- 不做温度缩放 / 校准 (后续 MVP-3 再迭代)
+- 不做场景分类 (后续按需引入)
+- 类型映射规则可外部覆盖，避免硬编码
+"""
+
+from __future__ import annotations
+
+import logging
+from typing import Dict, List, Optional
+
+from models.event_schemas import (
+    CandidateEvent,
+    DetectionResult,
+    EventType,
+    SeverityLevel,
+    UnifiedDetection,
+)
+
+logger = logging.getLogger(__name__)
+
+
+# 默认的 class_name -> EventType 映射 (覆盖当前已有模型)
+DEFAULT_CLASS_TO_EVENT: Dict[str, EventType] = {
+    # 火灾
+    "fire": EventType.FIRE,
+    "flame": EventType.FIRE,
+    "smoke": EventType.SMOKE,
+    # 抽烟
+    "smoking": EventType.SMOKING,
+    "cigarette": EventType.SMOKING,
+    # 打架
+    "fight": EventType.FIGHT,
+    "fighting": EventType.FIGHT,
+    # 行为
+    "loitering": EventType.LOITERING,
+    "stationary": EventType.STATIONARY,
+    "intrusion": EventType.INTRUSION,
+    # 车辆
+    "vehicle": EventType.VEHICLE,
+    "car": EventType.VEHICLE,
+    "truck": EventType.VEHICLE,
+    "bus": EventType.VEHICLE,
+    "illegal_parking": EventType.ILLEGAL_PARKING,
+    # 人员
+    "person": EventType.PERSON,
+}
+
+# 事件类型 -> 默认严重性 (规则引擎可覆盖)
+DEFAULT_SEVERITY: Dict[EventType, SeverityLevel] = {
+    EventType.FIRE: SeverityLevel.CRITICAL,
+    EventType.SMOKE: SeverityLevel.HIGH,
+    EventType.SMOKING: SeverityLevel.MEDIUM,
+    EventType.FIGHT: SeverityLevel.HIGH,
+    EventType.LOITERING: SeverityLevel.MEDIUM,
+    EventType.STATIONARY: SeverityLevel.LOW,
+    EventType.INTRUSION: SeverityLevel.HIGH,
+    EventType.ILLEGAL_PARKING: SeverityLevel.MEDIUM,
+    EventType.VEHICLE: SeverityLevel.INFO,
+    EventType.PERSON: SeverityLevel.INFO,
+    EventType.UNKNOWN: SeverityLevel.INFO,
+}
+
+
+class EventDecisionEngine:
+    """事件决策引擎 (简化版)。
+
+    Args:
+        min_confidence: 全局最低置信度阈值，低于此值的检测会被丢弃
+        class_to_event: 自定义类别映射，会与默认映射合并 (覆盖)
+        ignore_event_types: 不希望产出的事件类型集合 (例如 PERSON 太频繁)
+    """
+
+    def __init__(
+        self,
+        min_confidence: float = 0.5,
+        class_to_event: Optional[Dict[str, EventType]] = None,
+        ignore_event_types: Optional[List[EventType]] = None,
+    ) -> None:
+        self.min_confidence = max(0.0, min(1.0, min_confidence))
+        self.class_to_event: Dict[str, EventType] = dict(DEFAULT_CLASS_TO_EVENT)
+        if class_to_event:
+            self.class_to_event.update(class_to_event)
+        self.ignore_event_types = set(ignore_event_types or [])
+
+    # ------------------------------------------------------------------
+    # 主入口
+    # ------------------------------------------------------------------
+
+    def decide(
+        self,
+        result: DetectionResult,
+        source_id: Optional[str] = None,
+    ) -> List[CandidateEvent]:
+        """根据检测结果产出候选事件列表。
+
+        Args:
+            result: 统一检测结果
+            source_id: 摄像头/视频流标识，用于后续聚合
+        """
+
+        if not result.success or not result.detections:
+            return []
+
+        events: List[CandidateEvent] = []
+        for det in result.detections:
+            event = self._build_candidate(det, source_id)
+            if event is not None:
+                events.append(event)
+
+        if events:
+            logger.debug(
+                "DecisionEngine 产出 %d 条候选事件 (source_id=%s, model=%s)",
+                len(events),
+                source_id,
+                result.model_id,
+            )
+        return events
+
+    # ------------------------------------------------------------------
+    # 内部
+    # ------------------------------------------------------------------
+
+    def _build_candidate(
+        self,
+        det: UnifiedDetection,
+        source_id: Optional[str],
+    ) -> Optional[CandidateEvent]:
+        if det.confidence < self.min_confidence:
+            return None
+
+        event_type = self.map_event_type(det.class_name)
+        if event_type in self.ignore_event_types:
+            return None
+
+        severity = DEFAULT_SEVERITY.get(event_type, SeverityLevel.INFO)
+
+        return CandidateEvent(
+            event_type=event_type,
+            severity=severity,
+            confidence=det.confidence,
+            detection=det,
+            source_id=source_id,
+        )
+
+    def map_event_type(self, class_name: str) -> EventType:
+        """将 class_name 映射为 EventType (大小写不敏感)。"""
+
+        if not class_name:
+            return EventType.UNKNOWN
+        return self.class_to_event.get(class_name.lower().strip(), EventType.UNKNOWN)
+
+
+__all__ = ["EventDecisionEngine", "DEFAULT_CLASS_TO_EVENT", "DEFAULT_SEVERITY"]