VS Code extension API to Undo changes on a non-active text editor

I'm writing a VS Code extension that opens a Webview adjacent to an existing text editor to visualize and edit an SCXML state chart.

Changes in the webview cause the text document to be rewritten (complete text replacement). If the user makes a mistake, I want them to be able to use to undo the change. If the user clicks in the text editor and invokes Undo, all works as expected. But I do not want the user to have to switch to the text editor to undo. I'd like to leave the webview focused. I can

How can I either:

• Send an Undo command to a specific text editor?
• Send a command to bring a specific text editor to the foreground?

Sending vscode.commands.executeCommand('undo') with the Webview active does not affect the text editor.

Following is the Typescript code I ended up writing, thanks to the accepted answer below. It jumps through some hoops to focus the editor in place, send the command, and then re-focus the webview.

// Locate the tab columns for the editor and webview, so they can be focused
// without opening a new copy in another column
private findTabs() {
   let edTabCol:  ViewColumn|null = null,
       webTabCol: ViewColumn|null = null;
   for (const tab of window.tabGroups.all.flatMap(group => group.tabs)) {
      if (tab.input instanceof vscode.TabInputText) {
         if (tab.input.uri.fsPath===this.editor.document.uri.fsPath) {
            edTabCol = tab.group.viewColumn;
         }
      } else if (tab.input instanceof vscode.TabInputWebview) {
         // TODO: input.viewType does not exactly match the viewType
         // supplied during creation of the webview; why?
         if (/scxml$/.test(tab.input.viewType)) {
            webTabCol = tab.group.viewColumn;
         }
      }
   }
   return {edTabCol, webTabCol};
}

// Undo by focusing text editor, sending undo, and restoring webview focus
private undo() {
   const {edTabCol, webTabCol} = this.findTabs();
   if (edTabCol) {
      const opts = {preserveFocus:false, preview:false, viewColumn:edTabCol};
      window.showTextDocument(this.editor.document, opts).then(() => {
         vscode.commands.executeCommand('undo').then(() => {
            if (webTabCol) this.panel.reveal(webTabCol, false);
         });
      });
   }
}

A couple of things to try to focus another editor (and after the undo you could switch right back to the webView and see if that is very noticeable to the user):

// as I recall the index is 0-based, note the index is in an array
await vscode.commands.executeCommand('workbench.action.openEditorAtIndex', [sourceIndex]);

so for the above you need to know that textDocument's index. There are also a series of commnads like workbench.action.openEditorAtIndex1, workbench.action.openEditorAtIndex2, etc.

const uri = vscode.Uri.file("C:\\Users\\Mark\\OneDrive\\Test Bed\\test.css");

// viewColumn is 1-based, same as which editorGroup
const openOptions = { preserveFocus: false, preview: false, viewColumn: 1 };  

await vscode.commands.executeCommand('vscode.open', uri, openOptions);

if that textDocument is already open this should just focus that one, not open another.

const uri = vscode.Uri.file("C:\\Users\\Mark\\OneDrive\\Test Bed\\test.css");
let showOptions = { viewColumn: 1, preserveFocus: false, preview: false };
await vscode.window.showTextDocument(uri, showOptions);

If you don't know that textDocument's viewColumn/editorGroup or index, you could loop through the TabGroups object and match with its uri, which I presume you do know. And of course a user could change the editorGroup or index, so if you need that code I can come up with an example for that. But in the meantime you can investigate the above methods.

Assuming you know the path of your base textDocument, this code will find it as a Tab which has a group.viewColumn property:

const allTabs = vscode.window.tabGroups.all.flatMap(tabGroup => tabGroup.tabs);
const theDocTab = allTabs.find(tab => tab.input?.uri.fsPath === "c:\\Users\\Mark\\OneDrive\\Test Bed\\test.css");

const uri = vscode.Uri.file("C:\\Users\\Mark\\OneDrive\\Test Bed\\test.css");
let showOptions = { viewColumn: theDocTab.group.viewColumn, preserveFocus: false, preview: false };
await vscode.window.showTextDocument(uri, showOptions);

Note the use of theDocTab.group.viewColumn in the showOptions and the form of tab.input?.uri.fsPath === "c:\\Users\\Mark\\OneDrive\\Test Bed\\test.css" - with a small c drive letter.