layout.json

{
  "title": "select_input_source example (available since Karabiner-Elements 11.1.9)",
  "rules": [
    {
      "description": "Change input source to U.S. by left_command, RussianWin by right_command. (available since Karabiner-Elements 11.1.9)",
      "manipulators": [
        {
          "type": "basic",
          "from": {
            "key_code": "left_command",
            "modifiers": {
              "optional": [
                "any"
              ]
            }
          },
          "to": [
            {
              "key_code": "left_command"
            }
          ],
          "to_if_alone": [
            {
              "select_input_source": {
                "input_source_id": "^com\\.apple\\.keylayout\\.US$"
              }
            }
          ]
        },
        {
          "type": "basic",
          "from": {
            "key_code": "right_command",
            "modifiers": {
              "optional": [
                "any"
              ]
            }
          },
          "to": [
            {
              "key_code": "right_command"
            }
          ],
          "to_if_alone": [
            {
              "select_input_source": {
                "input_source_id": "^com\\.apple\\.keylayout\\.RussianWin$"
              }
            }
          ]
        }
      ]
    }
  ]
}