diff --git a/crates/utopia-core/src/models.rs b/crates/utopia-core/src/models.rs
index 69cd1673..f4fb8879 100644
--- a/crates/utopia-core/src/models.rs
+++ b/crates/utopia-core/src/models.rs
@@ -194,6 +194,9 @@ pub struct AuditEventView {
     pub target_kind: String,
     pub target_id: Option<Uuid>,
     pub detail: serde_json::Value,
+    /// NULL = 引擎自动（裁决器合并、一致性检查、推理物化……）。界面靠它把
+    /// 「没有人」和「人已被移除」分开：后者 actor_id 还在，只是查不到显示名
+    pub actor_id: Option<Uuid>,
     pub actor_name: Option<String>,
     pub created_at: DateTime<Utc>,
 }
diff --git a/crates/utopia-store/src/audit.rs b/crates/utopia-store/src/audit.rs
index c2c48000..9cd1e63e 100644
--- a/crates/utopia-store/src/audit.rs
+++ b/crates/utopia-store/src/audit.rs
@@ -101,7 +101,7 @@ pub async fn review_history(
                         OR e.action LIKE 'conflict.%' OR e.action LIKE 'merge.%')";
     let rows: Vec<AuditEventView> = sqlx::query_as(&format!(
         "SELECT e.id, e.action, e.target_kind, e.target_id, e.detail,
-                u.display_name AS actor_name, e.created_at
+                e.actor_id, u.display_name AS actor_name, e.created_at
          FROM audit_events e LEFT JOIN users u ON u.id = e.actor_id
          WHERE {COND} ORDER BY e.created_at DESC LIMIT $2 OFFSET $3"
     ))
@@ -152,7 +152,7 @@ pub async fn list_for_kb(
 
     let rows: Vec<AuditEventView> = sqlx::query_as(&format!(
         "SELECT e.id, e.action, e.target_kind, e.target_id, e.detail,
-                u.display_name AS actor_name, e.created_at
+                e.actor_id, u.display_name AS actor_name, e.created_at
          FROM audit_events e LEFT JOIN users u ON u.id = e.actor_id
          {WHERE}
          ORDER BY e.created_at DESC LIMIT $6 OFFSET $7"
diff --git a/web/src/api.ts b/web/src/api.ts
index 59302ca0..4b835cad 100644
--- a/web/src/api.ts
+++ b/web/src/api.ts
@@ -132,6 +132,8 @@ export interface AuditEvent {
   target_kind: string;
   target_id: string | null;
   detail: Record<string, unknown>;
+  /** null = 引擎自动（裁决器、一致性检查、推理）；有 id 没名字 = 账号已移除 */
+  actor_id: string | null;
   actor_name: string | null;
   created_at: string;
 }
diff --git a/web/src/i18n/en.ts b/web/src/i18n/en.ts
index 05150fae..6b180e1e 100644
--- a/web/src/i18n/en.ts
+++ b/web/src/i18n/en.ts
@@ -1448,6 +1448,9 @@ export const en = {
     auditTotal: (n: number) => `${n} events`,
     activityEmpty: "Nothing recorded yet.",
     deletedUser: "a removed user",
+    // actor_id 为空的两种引擎动作：审阅队列里的自动裁决，和其余后台工作
+    adjudicator: "AI adjudicator",
+    engine: "the engine",
     auditActions: {
       "entity_type.created": "created entity type",
       "entity_type.updated": "updated entity type",
diff --git a/web/src/i18n/zh.ts b/web/src/i18n/zh.ts
index 68d90423..a598c984 100644
--- a/web/src/i18n/zh.ts
+++ b/web/src/i18n/zh.ts
@@ -1306,6 +1306,8 @@ export const zh: Strings = {
     auditTotal: (n: number) => `共 ${n} 条`,
     activityEmpty: "还没有记录。",
     deletedUser: "一位已移除的用户",
+    adjudicator: "AI 裁决器",
+    engine: "引擎",
     auditActions: {
       "entity_type.created": "创建了实体类型",
       "entity_type.updated": "更新了实体类型",
diff --git a/web/src/pages/KbSettings.tsx b/web/src/pages/KbSettings.tsx
index bed49999..d6eccbbf 100644
--- a/web/src/pages/KbSettings.tsx
+++ b/web/src/pages/KbSettings.tsx
@@ -492,7 +492,12 @@ function KbActivity({ kbId }: { kbId: string }) {
               </span>
               <span className="min-w-0 truncate">
                 <span className="text-neutral-200">
-                  {e.actor_name ?? S.kbset.deletedUser}
+                  {e.actor_name ??
+                    (e.actor_id
+                      ? S.kbset.deletedUser
+                      : e.action.startsWith("review.")
+                        ? S.kbset.adjudicator
+                        : S.kbset.engine)}
                 </span>{" "}
                 <span className="text-neutral-500">
                   {S.kbset.auditActions[e.action] ?? e.action}