Make sure we pass through backupId in custom editors

Fixes #96484

src/vs/workbench/api/browser/mainThreadWebview.ts

@@ -610,8 +610,9 @@ namespace HotExitState {
 
 class MainThreadCustomEditorModel extends Disposable implements ICustomEditorModel, IWorkingCopy {
 
-	private _hotExitState: HotExitState.State = HotExitState.Allowed;
 	private readonly _fromBackup: boolean = false;
+	private _hotExitState: HotExitState.State = HotExitState.Allowed;
+	private _backupId: string | undefined;
 
 	private _currentEditIndex: number = -1;
 	private _savePoint: number = -1;
@@ -716,6 +717,10 @@ class MainThreadCustomEditorModel extends Disposable implements ICustomEditorMod
 		return this._viewType;
 	}
 
+	public get backupId() {
+		return this._backupId;
+	}
+
 	public pushEdit(editId: number, label: string | undefined) {
 		if (!this._editable) {
 			throw new Error('Document is not editable');
@@ -902,6 +907,7 @@ class MainThreadCustomEditorModel extends Disposable implements ICustomEditorMod
 			if (this._hotExitState === pendingState) {
 				this._hotExitState = HotExitState.Allowed;
 				backupData.meta!.backupId = backupId;
+				this._backupId = backupId;
 			}
 		} catch (e) {
 			// Make sure state has not changed in the meantime

src/vs/workbench/contrib/customEditor/browser/customEditorInput.ts

@@ -29,7 +29,7 @@ export class CustomEditorInput extends LazilyResolvedWebviewEditorInput {
 	private readonly _editorResource: URI;
 	private _defaultDirtyState: boolean | undefined;
 
-	public readonly backupId: string | undefined;
+	private readonly _backupId: string | undefined;
 
 	get resource() { return this._editorResource; }
 
@@ -54,7 +54,7 @@ export class CustomEditorInput extends LazilyResolvedWebviewEditorInput {
 		super(id, viewType, '', webview, webviewService, webviewWorkbenchService);
 		this._editorResource = resource;
 		this._defaultDirtyState = options.startsDirty;
-		this.backupId = options.backupId;
+		this._backupId = options.backupId;
 	}
 
 	public getTypeId(): string {
@@ -213,7 +213,7 @@ export class CustomEditorInput extends LazilyResolvedWebviewEditorInput {
 			this.viewType,
 			this.id,
 			new Lazy(() => undefined!),
-			{ startsDirty: this._defaultDirtyState, backupId: this.backupId }); // this webview is replaced in the transfer call
+			{ startsDirty: this._defaultDirtyState, backupId: this._backupId }); // this webview is replaced in the transfer call
 		this.transfer(newEditor);
 		newEditor.updateGroup(group);
 		return newEditor;
@@ -245,4 +245,11 @@ export class CustomEditorInput extends LazilyResolvedWebviewEditorInput {
 		this._moveHandler = undefined;
 		return other;
 	}
+
+	get backupId(): string | undefined {
+		if (this._modelRef) {
+			return this._modelRef.object.backupId;
+		}
+		return this._backupId;
+	}
 }

src/vs/workbench/contrib/customEditor/common/customEditor.ts

@@ -56,6 +56,7 @@ export interface ICustomEditorModelManager {
 export interface ICustomEditorModel extends IDisposable {
 	readonly viewType: string;
 	readonly resource: URI;
+	readonly backupId: string | undefined;
 
 	isReadonly(): boolean;
 

src/vs/workbench/contrib/customEditor/common/customTextEditorModel.ts

@@ -54,6 +54,10 @@ export class CustomTextEditorModel extends Disposable implements ICustomEditorMo
 		return this._model.object.isReadonly();
 	}
 
+	public get backupId() {
+		return undefined;
+	}
+
 	public isDirty(): boolean {
 		return this.textFileService.isDirty(this.resource);
 	}