Input language switching mods for Karabiner

input_source_switch.json

{
    "title":"Input source change",
    "rules": [
        {
            "description": "If pressed alone, CmdL for English, CmdR for Russian",
            "manipulators": [
                {
                    "from": {
                        "key_code": "left_command",
                        "modifiers": {"optional": ["any"]}
                    },
                    "to": {
                        "key_code": "left_command"
                    },
                    "to_if_alone": [
                        {"select_input_source": {"language": "en"}}
                    ],
                    "type": "basic"
                },
                {
                    "from": {
                        "key_code": "right_command",
                        "modifiers": {"optional": ["any"]}
                    },
                    "to": {
                        "key_code": "right_command"
                    },
                    "to_if_alone": [
                        {"select_input_source": {"language": "ru"}}
                    ],
                    "type": "basic"
                }
            ]
        },
        {
            "description": "Swap input source while CapsLock being held",
            "manipulators": [
                {
                    "conditions": [
                        {"type": "input_source_if", "input_sources": [{"language": "en"}]}
                    ],
                    "from": {
                        "key_code": "caps_lock",
                        "modifiers": {"optional": ["any"]}
                    },
                    "to": [
                        {"select_input_source": {"language": "ru"}}
                    ],
                    "to_after_key_up": [
                        {"select_input_source": {"language": "en"}}
                    ],
                    "type": "basic"
                },
                {
                    "conditions": [
                        {"type": "input_source_if", "input_sources": [{"language": "ru"}]}
                    ],
                    "from": {
                        "key_code": "caps_lock",
                        "modifiers": {"optional": ["any"]}
                    },
                    "to": [
                        {"select_input_source": {"language": "en"}}
                    ],
                    "to_after_key_up": [
                        {"select_input_source": {"language": "ru"}}
                    ],
                    "type": "basic"
                }
            ]
        }
    ]
}