事件协议：turn.completed 增加可选 failure 载荷，失败终态与正常终态同权入锚点

- direct_thread_wire 新增 DirectTurnFailure{kind,message} 类型，给 TurnCompleted 增可选 failure 字段，并补 turn_completed_failed 构造器与 failure 读取器
- with_user_item_id 显式带上 failure：原先把 TurnCompleted 写成 `..` 会静默吞掉失败载荷，身份与原因必须一起流转
- 新增 wire 用例：失败终态带载荷、正常终态不带且回写不补 null、缺载荷的 failed 事件仍可反序列化
- direct_thread_manager 增回归用例：turn.completed(status=failed) 必须顶替更早的 turn.started 成为 lifecycle_anchor，重放不会把已收口的回合看成"还在跑"
- 重新生成 ts-rs 绑定（新增 DirectTurnFailure.ts、DirectThreadEvent.ts 增 failure 字段）并按 prettier 格式化

apps/ai-game-creator-shell/src-tauri/src/agent/direct_thread_manager.rs

@@ -603,6 +603,30 @@ mod tests {
         ));
     }
 
+    /// 失败终态与正常终态同权：`turn.completed(status="failed")` 必须顶替更早的 `turn.started`
+    /// 成为锚点，否则队列被回收后新订阅只会看到 `turn.started`，把这轮已收口的回合重放成"还在跑"。
+    #[test]
+    fn failed_turn_completed_replaces_started_anchor() {
+        let mut manager = DirectThreadManager::with_limits(100, 100_000);
+        manager.append("thread-1", DirectThreadEvent::turn_started(1_000));
+        manager.append(
+            "thread-1",
+            DirectThreadEvent::turn_completed_failed(
+                crate::agent::DirectTurnFailure::new("host-dropped", "回合宿主任务提前结束"),
+                FIXED_AT_MS,
+            ),
+        );
+
+        let bootstrap = manager.subscribe("thread-1");
+        assert!(matches!(
+            bootstrap.events.as_slice(),
+            [DirectThreadEvent::TurnCompleted { status, failure, at, .. }]
+                if status == "failed"
+                    && failure.as_ref().is_some_and(|failure| failure.kind == "host-dropped")
+                    && *at == Some(FIXED_AT_MS)
+        ));
+    }
+
     /// 阶段时间必须随事件一起进队列：bootstrap 与重复订阅都拿到**原值**，
     /// 重放不得重新取钟（否则每次重连都会把已固定的起止时间改掉）。
     #[test]

apps/ai-game-creator-shell/src-tauri/src/agent/direct_thread_wire.rs

@@ -211,6 +211,30 @@ impl DirectThreadRequestKind {
     }
 }
 
+/// 失败终态的可下发载荷（`turn.completed.status == "failed"` 时必有，其余终态没有）。
+///
+/// `kind` 是稳定分类，只给界面选语气，不参与流程分支；`message` 是**已在宿主侧脱敏并截断**的
+/// 可展示原因——失败原因只走这一条通道，前端不再从命令返回或另一条 IPC 里另造文案。
+#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize, TS)]
+#[serde(rename_all = "camelCase", deny_unknown_fields)]
+#[ts(export, export_to = concat!(env!("CARGO_MANIFEST_DIR"), "/../src/view/project-development/chat/generated/"))]
+pub(crate) struct DirectTurnFailure {
+    /// 稳定失败分类：`timeout` / `model-failed` / `transport-failed` / `request-rejected` /
+    /// `host-dropped`。
+    pub(crate) kind: String,
+    /// 脱敏 + 截断后的失败原因。
+    pub(crate) message: String,
+}
+
+impl DirectTurnFailure {
+    pub(crate) fn new(kind: impl Into<String>, message: impl Into<String>) -> Self {
+        Self {
+            kind: kind.into(),
+            message: message.into(),
+        }
+    }
+}
+
 /// Thread Manager 下发的运行态事件。
 ///
 /// 顺序由数组顺序给出（同一个 subscriber 的 `consume` 按队列顺序返回），因此不需要 `seq`：
@@ -250,7 +274,13 @@ pub(crate) enum DirectThreadEvent {
     },
     #[serde(rename = "turn.completed")]
     TurnCompleted {
+        /// 终态语义：`completed` / `interrupted` / `aborted` 是正常收场；`failed` 是**失败**，
+        /// 此时必须带 `failure` 载荷。
         status: String,
+        /// 失败载荷：只有 `status == "failed"` 才有；失败原因只从这里下发一次。
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        #[ts(optional)]
+        failure: Option<DirectTurnFailure>,
         /// 本轮终态的阶段时间（毫秒）：宿主处理终态的毫秒钟，或 `durationMs` + 高精度起点的派生值。
         #[serde(default, skip_serializing_if = "Option::is_none")]
         #[ts(optional, as = "Option<f64>")]
@@ -301,11 +331,30 @@ impl DirectThreadEvent {
     pub(crate) fn turn_completed(status: String, at: u64) -> Self {
         Self::TurnCompleted {
             status,
+            failure: None,
             at: Some(at),
             user_item_id: None,
         }
     }
 
+    /// 失败终态：`status` 固定 `"failed"`，原因必须随事件一起带出去。
+    pub(crate) fn turn_completed_failed(failure: DirectTurnFailure, at: u64) -> Self {
+        Self::TurnCompleted {
+            status: "failed".to_string(),
+            failure: Some(failure),
+            at: Some(at),
+            user_item_id: None,
+        }
+    }
+
+    /// 失败载荷：只有失败终态有。
+    pub(crate) fn failure(&self) -> Option<&DirectTurnFailure> {
+        match self {
+            Self::TurnCompleted { failure, .. } => failure.as_ref(),
+            _ => None,
+        }
+    }
+
     /// 附上本轮开口用户条目的 canonical itemId。
     ///
     /// 只在构造之后补一次身份，避免 `turn.started` / `turn.completed` 的既有调用点（含各处兜底
@@ -317,8 +366,14 @@ impl DirectThreadEvent {
             .map(str::to_string);
         match self {
             Self::TurnStarted { at, .. } => Self::TurnStarted { at, user_item_id },
-            Self::TurnCompleted { status, at, .. } => Self::TurnCompleted {
+            Self::TurnCompleted {
                 status,
+                failure,
+                at,
+                ..
+            } => Self::TurnCompleted {
+                status,
+                failure,
                 at,
                 user_item_id,
             },
@@ -1351,4 +1406,56 @@ mod tests {
         );
         assert_eq!(item_event.user_item_id(), None);
     }
+
+    /// 失败终态：`status="failed"` 必须带 `failure{kind,message}`，正常终态不带；载荷跟着身份
+    /// 一起流转，缺载荷的 `failed` 事件仍能反序列化（前端按"没有原因"处理，不猜）。
+    #[test]
+    fn turn_completed_carries_failure_payload_only_when_failed() {
+        let failed = DirectThreadEvent::turn_completed_failed(
+            DirectTurnFailure::new("model-failed", "上游返回 500：模型服务暂不可用"),
+            4_000,
+        )
+        .with_user_item_id(Some("direct-codex:turn-1:user"));
+        assert_eq!(
+            failed.failure(),
+            Some(&DirectTurnFailure::new(
+                "model-failed",
+                "上游返回 500：模型服务暂不可用"
+            ))
+        );
+        assert_eq!(failed.user_item_id(), Some("direct-codex:turn-1:user"));
+        assert_eq!(
+            serde_json::to_value(&failed).expect("serialize failed turn"),
+            json!({
+                "type": "turn.completed",
+                "status": "failed",
+                "failure": {"kind": "model-failed", "message": "上游返回 500：模型服务暂不可用"},
+                "at": 4_000u64,
+                "userItemId": "direct-codex:turn-1:user",
+            })
+        );
+        assert_eq!(
+            serde_json::from_value::<DirectThreadEvent>(
+                serde_json::to_value(&failed).expect("serialize")
+            )
+            .expect("round trip"),
+            failed
+        );
+
+        // 正常终态不带载荷，也不回写 `failure: null`。
+        let completed = DirectThreadEvent::turn_completed("completed".to_string(), 5_000);
+        assert_eq!(completed.failure(), None);
+        assert_eq!(
+            serde_json::to_value(&completed).expect("serialize completed turn"),
+            json!({"type": "turn.completed", "status": "completed", "at": 5_000u64})
+        );
+
+        // 精简 / 旧形状：`failed` 但没有载荷也要能反序列化。
+        let sparse: DirectThreadEvent = serde_json::from_value(json!({
+            "type": "turn.completed",
+            "status": "failed",
+        }))
+        .expect("failed turn without failure payload");
+        assert_eq!(sparse.failure(), None);
+    }
 }

apps/ai-game-creator-shell/src/view/project-development/chat/generated/DirectThreadEvent.ts

@@ -2,6 +2,7 @@
 import type { DirectThreadDeltaKind } from './DirectThreadDeltaKind';
 import type { DirectThreadItem } from './DirectThreadItem';
 import type { DirectThreadRequestKind } from './DirectThreadRequestKind';
+import type { DirectTurnFailure } from './DirectTurnFailure';
 
 /**
  * Thread Manager 下发的运行态事件。
@@ -41,7 +42,15 @@ export type DirectThreadEvent =
     }
   | {
       type: 'turn.completed';
+      /**
+       * 终态语义：`completed` / `interrupted` / `aborted` 是正常收场；`failed` 是**失败**，
+       * 此时必须带 `failure` 载荷。
+       */
       status: string;
+      /**
+       * 失败载荷：只有 `status == "failed"` 才有；失败原因只从这里下发一次。
+       */
+      failure?: DirectTurnFailure;
       /**
        * 本轮终态的阶段时间（毫秒）：宿主处理终态的毫秒钟，或 `durationMs` + 高精度起点的派生值。
        */

apps/ai-game-creator-shell/src/view/project-development/chat/generated/DirectTurnFailure.ts

@@ -0,0 +1,19 @@
+// This file was generated by [ts-rs](https://github.com/Aleph-Alpha/ts-rs). Do not edit this file manually.
+
+/**
+ * 失败终态的可下发载荷（`turn.completed.status == "failed"` 时必有，其余终态没有）。
+ *
+ * `kind` 是稳定分类，只给界面选语气，不参与流程分支；`message` 是**已在宿主侧脱敏并截断**的
+ * 可展示原因——失败原因只走这一条通道，前端不再从命令返回或另一条 IPC 里另造文案。
+ */
+export type DirectTurnFailure = {
+  /**
+   * 稳定失败分类：`timeout` / `model-failed` / `transport-failed` / `request-rejected` /
+   * `host-dropped`。
+   */
+  kind: string;
+  /**
+   * 脱敏 + 截断后的失败原因。
+   */
+  message: string;
+};