Karabinier-Elements idempotent hotkeys configuration for switching between two keyboard layouts

input-source-switching.json

{
    "description": "Use idempotent hotkeys to switch between two keyboard layouts",
    "manipulators": [
        {
            "from": {
                "key_code": "1",
                "modifiers": {
                    "mandatory": ["left_command", "left_option"],
                    "optional": ["any"]
                }
            },
            "to": [
                {
                    "key_code": "1",
                    "modifiers": ["left_command", "left_option"]
                }
            ],
            "to_if_alone": [{ "select_input_source": { "input_source_id": "english" } }],
            "type": "basic"
        },
        {
            "from": {
                "key_code": "2",
                "modifiers": {
                    "mandatory": ["left_command", "left_option"],
                    "optional": ["any"]
                }
            },
            "to": [
                {
                    "key_code": "2",
                    "modifiers": ["left_command", "left_option"]
                }
            ],
            "to_if_alone": [{ "select_input_source": { "input_source_id": "russian" } }],
            "type": "basic"
        }
    ]
}

How to install:

• Karabiner-Elements Settings → Complex Modifications → Add your own rule
• See also

How to customize keyboard layouts:

• Figure out input_source_id values for your installed keyboard layouts using im-select tool.
• Replace english and russian in the configuration above with case-sensitive substring (or a regular expression) for each keyboard layout id. For instance, just use "english" for org.sil.ukelele.keyboardlayout.english-custom-layout.

References:

• Other configuration examples