[khusamov]

Техподдержка ответила:

You should be able to define in your app.json:

"builds": {    "classic": {
        "toolkit": "classic",
        "theme": "theme-triton",
        "sass": {
            // "save": "classic/sass/save.json"
        }
    },

    "modern": {
        "toolkit": "modern",
        "theme": "theme-neptune",
        "sass": {
            // "save": "modern/sass/save.json"
        }
    }
},

Источник: https://www.sencha.com/forum/showthr...=1#post1121208