Add evaluateForEffect method to support expression evaluation for side effects

webview/src/model/Model.ts

@@ -161,6 +161,24 @@ export class Model {
 		this.pollingTimer.onTick.sub(() => {
 			this.refresh();
 		});
+
+		// Exposed globally (not passed into custom visualizer scripts'
+		// closures) for the same reason setVisualizationModule is below:
+		// setCustomVisualizerScript's `eval()` runs plugin code in this
+		// same window/global scope, so a plugin (see vis-plugins/node-
+		// table-visualizer.js) can reach these to support editing values
+		// in place, without threading a new parameter through the whole
+		// register()/getVisualization()/render() plugin contract.
+		(globalThis as any).debugVisualizerSetValue = (expression: string) =>
+			this.evaluateForEffect(expression);
+		(globalThis as any).debugVisualizerRefresh = () => this.refresh();
+	}
+
+	async evaluateForEffect(expression: string): Promise<{ success: boolean; message: string }> {
+		if (!this.server) {
+			return { success: false, message: "Not connected to the debug visualizer server." };
+		}
+		return this.server.evaluateForEffect({ expression });
 	}
 
 	@action