"Status": {
  "isRequired": true,
  lookupListConfig: {
    columns: ["Finish"]
  },
  dependencies: [
    {
      columns: ["Status"],
      methodName: "onStatusChanged"
    }
  ]
},

define("ActivityPageV2", ["ActivityPageV2Resources", "GeneralDetails"],
function(resources, GeneralDetails) {
	return {
		entitySchemaName: "Activity",
		details: /**SCHEMA_DETAILS*/{}/**SCHEMA_DETAILS*/,
		diff: /**SCHEMA_DIFF*/[
		]/**SCHEMA_DIFF*/,
		attributes: {
			"StatusValue": {
				dataValueType: this.Terrasoft.DataValueType.TEXT
			}
		},
		methods: {
			onEntityInitialized: function() {
				this.callParent(arguments);
				var statusValue = this.get("Status");
				this.set("StatusValue", statusValue);
			},
			onStatusChanged: function() {
				this.callParent(arguments);
				var oldStatus = this.get("StatusValue");
				var statusValue = this.get("Status");
 
				console.log("был: " + oldStatus.displayValue + ", стал: " + statusValue.displayValue);
				// тут любая логика проверки, и установки
				if (oldStatus.displayValue === "Не начата" && statusValue.displayValue === "В работе") {
					this.set("DetailedResult", "Взята в работу");
				}
 
				this.set("StatusValue", statusValue);
			}
		},
		rules: {},
		userCode: {}
	};
});

this.set("StatusValue", statusValue);