OpenFilePicker

{
  "type": "object",
  "properties": {
    "action": {
      "const": "openFilePicker",
      "default": "openFilePicker",
      "type": "string"
    },
    "accept": {
      "type": [
        "string",
        "null"
      ],
      "default": null,
      "description": "File type filter (e.g. 'image/*', '.csv,.xlsx')"
    },
    "multiple": {
      "default": false,
      "description": "Allow selecting multiple files",
      "type": "boolean"
    },
    "maxSize": {
      "type": [
        "integer",
        "null"
      ],
      "default": null,
      "description": "Maximum file size in bytes"
    }
  },
  "required": [
    "action"
  ]
}