feat(agent): 持久化Trace并支持SSE恢复

docs/第二阶段接口契约-开发版.md

@@ -43,8 +43,8 @@
 | Transcription | GET | `/api/media/transcriptions/{job_id}/events` | 计划新增 | 订阅模型加载、分离和转写进度 |
 | Transcription | POST | `/api/media/transcriptions/{job_id}/cancel` | 计划新增 | 取消音频任务 |
 | Transcription | POST | `/api/media/transcriptions/{job_id}/notes` | 计划新增 | 将 Transcript 写入 Knowledge Core |
-| Agent Trace | GET | `/api/agent/runs/{run_id}/events` | 扩展 | 支持游标恢复并增加模型与权限事件 |
-| Agent Trace | GET | `/api/agent/runs/{run_id}/trace` | 计划新增 | 分页读取可回放 Trace 快照 |
+| Agent Trace | GET | `/api/agent/runs/{run_id}/events` | 已实现 | 支持游标恢复并增加模型与权限事件 |
+| Agent Trace | GET | `/api/agent/runs/{run_id}/trace` | 已实现 | 分页读取可回放 Trace 快照 |
 | Plugin Host | GET | `/api/plugins/{plugin_id}/host` | 计划新增 | 获取 MCP Host 健康状态 |
 | Plugin Host | POST | `/api/plugins/{plugin_id}/host/restart` | 计划新增 | 重启异常 Host 并重新发现 Tool |
 | Plugin Command | GET | `/api/plugin-contributions/commands` | 计划新增 | 获取前端可展示的 Command |
@@ -310,6 +310,7 @@ RunCancelled
 ```text
 ModelCallStarted
 ModelCallCompleted
+ModelCallFailed
 PermissionResolved
 ```
 
@@ -330,8 +331,10 @@ PermissionResolved
     "model_calls": 2,
     "tool_calls": 3,
     "duration_ms": 1530,
-    "token_usage": 2048
-  }
+    "token_usage": 2048,
+    "errors": 0
+  },
+  "config_snapshot": {}
 }
 ```
 
@@ -388,6 +391,7 @@ ToolCall 和 ToolResult 增加可选 `parent_model_call_id`、`duration_ms` 和
 AGENT_RUN_NOT_FOUND
 TRACE_NOT_AVAILABLE
 TRACE_CURSOR_EXPIRED
+TRACE_CURSOR_INVALID
 ```
 
 ---