feat: auto committed

packages/shared-proto/proto/events.proto

@@ -58,3 +58,25 @@ message GradeEvent {
   string action = 8;
   map<string, string> metadata = 9;
 }
+
+// AI 用量计费事件（ai 服务发布，data-ana 消费落 ClickHouse）
+// 派生数据，豁免 Outbox（004 §12.2）；topic: edu.ai.usage（matrix.md §4 + ISSUE-02 裁决）
+message AIUsageEvent {
+  string event_id = 1;            // UUID，幂等去重
+  string aggregate_id = 2;        // workflow_id 或 request_id
+  string event_type = 3;          // 固定 "AIUsageRecorded"
+  int64 occurred_at = 4;          // Unix 毫秒时间戳
+  string user_id = 5;
+  string school_id = 6;           // 用于多租户配额
+  string request_id = 7;          // 链路追踪 ID
+  string provider = 8;            // openai/anthropic/baichuan/local_ollama
+  string model = 9;               // gpt-4o-mini/claude-3-haiku/...
+  string operation = 10;          // chat/generate_question/optimize_expression/lesson_preparation
+  uint32 prompt_tokens = 11;
+  uint32 completion_tokens = 12;
+  uint32 total_tokens = 13;
+  uint32 latency_ms = 14;
+  bool success = 15;
+  bool degraded = 16;             // 是否降级（LLM 不可用时）
+  map<string, string> metadata = 17;  // 额外上下文（subject/grade/difficulty 等）
+}