我用的是 view/item/context

      "view/item/context": [
        {
          "command": "favourite.revealInOS.windows", // 在资源管理器中打开
          "when": "isWindows && view in ext:allFavouriteViews && viewItem =~ /^resource/",
          "group": "navigation"
        },
        {
          "command": "favourite.openToSide", // 从侧边栏打开
          "when": "view in ext:allFavouriteViews && viewItem =~ /^resource(Child)?$|^uri\\.resource(Child)?$/",
          "group": "navigation"
        },
        {
          "command": "favourite.deleteFavourite", // 从收藏夹中删除
          "when": "view in ext:allFavouriteViews && viewItem =~ /resource(\\.dir)?$/",
          "group": "operation"
        },
        {
          "command": "favourite.moveToTop", // 上移至顶
          "when": "view in ext:allFavouriteViews && viewItem =~ /resource(\\.dir)?$/",
          "group": "sort@1"
        },
        {
          "command": "favourite.moveUp", // 上移
          "when": "view in ext:allFavouriteViews && viewItem =~ /resource(\\.dir)?$/",
          "group": "sort@2"
        },
        {
          "command": "favourite.moveDown", // 下移
          "when": "view in ext:allFavouriteViews && viewItem =~ /resource(\\.dir)?$/",
          "group": "sort@3"
        },
        {
          "command": "favourite.moveToBottom", // 下移至底
          "when": "view in ext:allFavouriteViews && viewItem =~ /resource(\\.dir)?$/",
          "group": "sort@4"
        },
        {
          "command": "favourite.deleteAllFavourite", // 清空收藏夹
          "when": "view in ext:allFavouriteViews && viewItem =~ /resource(\\.dir)?$/",
          "group": "zbottom"
        }
      ],

结论：按 group 名升序排序 zbottom 以字母 z 开关排到最后，然后同一分组可以加 @1 数字排序