diff --git a/apps/ai-game-creator-shell/src-tauri/src/ui_editor/commands/separation/persistence.rs b/apps/ai-game-creator-shell/src-tauri/src/ui_editor/commands/separation/persistence.rs
index 5b663c609..a2f0728c4 100644
--- a/apps/ai-game-creator-shell/src-tauri/src/ui_editor/commands/separation/persistence.rs
+++ b/apps/ai-game-creator-shell/src-tauri/src/ui_editor/commands/separation/persistence.rs
@@ -66,6 +66,17 @@ fn write_separation_state_blocking(path: &Path, state: &SeparationState) -> Resu
         app_log!("ui_separation.error stage=state_write reason=serialize error={error}");
         format!("序列化 separation state 失败：{error}")
     })?;
+    if bytes.len() > SEPARATION_STATE_MAX_BYTES {
+        app_log!(
+            "ui_separation.error stage=state_write reason=too_large bytes={} max_bytes={}",
+            bytes.len(),
+            SEPARATION_STATE_MAX_BYTES
+        );
+        return Err(format!(
+            "separation state 超过 {} 字节上限",
+            SEPARATION_STATE_MAX_BYTES
+        ));
+    }
     let parent = path.parent().ok_or_else(|| {
         app_log!("ui_separation.error stage=state_write reason=missing_parent");
         "separation state 路径缺少父目录".to_string()