Fixes #221245

src/vs/editor/browser/widget/diffEditor/diffEditorOptions.ts

@@ -101,6 +101,8 @@ export class DiffEditorOptions {
 		}))
 		.flatten()
 		.map(this, v => !!v);
+
+	public readonly inlineViewHideOriginalLineNumbers = this.compactMode;
 }
 
 function isSimpleDiff(diff: DiffState, supportsTrueDiffRendering: boolean): boolean {

src/vs/editor/browser/widget/diffEditor/diffEditorWidget.ts

@@ -385,8 +385,13 @@ export class DiffEditorWidget extends DelegatingEditor implements IDiffEditor {
 		} else {
 			gutterLeft = 0;
 
+			const shouldHideOriginalLineNumbers = this._options.inlineViewHideOriginalLineNumbers.read(reader);
 			originalLeft = gutterWidth;
-			originalWidth = Math.max(5, this._editors.original.getLayoutInfo().decorationsLeft);
+			if (shouldHideOriginalLineNumbers) {
+				originalWidth = 0;
+			} else {
+				originalWidth = Math.max(5, this._editors.original.getLayoutInfo().decorationsLeft);
+			}
 
 			modifiedLeft = gutterWidth + originalWidth;
 			modifiedWidth = fullWidth - modifiedLeft - overviewRulerPartWidth;

src/vs/workbench/contrib/chat/browser/codeBlockPart.ts

@@ -623,9 +623,11 @@ export class CodeCompareBlockPart extends Disposable {
 				useTrueInlineView: true,
 			},
 			renderSideBySideInlineBreakpoint: 300,
+			renderOverviewRuler: false,
 			compactMode: true,
 			hideUnchangedRegions: { enabled: true, contextLineCount: 1 },
 			renderGutterMenu: false,
+			lineNumbersMinChars: 1,
 			...options
 		}, { originalEditor: widgetOptions, modifiedEditor: widgetOptions }));
 	}