feat(api): Support specifying app version for chat

api/app/services/app_service.py

@@ -619,6 +619,28 @@ class AppService:
         self._validate_app_accessible(app, workspace_id)
         return app
 
+    def get_release_by_version(self, app_id: uuid.UUID, version: int) -> AppRelease:
+        """按版本号获取发布快照
+
+        Args:
+            app_id: 应用ID
+            version: 版本号（整数，按应用内递增）
+
+        Returns:
+            AppRelease: 发布快照
+
+        Raises:
+            BusinessException: 版本不存在或已下线
+        """
+        from app.repositories.app_repository import get_release_by_version
+        release = get_release_by_version(self.db, app_id, version)
+        if not release:
+            raise BusinessException(
+                f"版本 {version} 不存在或已下线",
+                BizCode.RELEASE_NOT_FOUND,
+            )
+        return release
+
     def create_app(
             self,
             *,