Update the chat panel title when the mode changes

src/vs/workbench/contrib/chat/browser/widgetHosts/editor/chatEditor.ts

@@ -130,6 +130,14 @@ export class ChatEditor extends AbstractEditorWithViewState<IChatEditorViewState
 		this._register(this.widget.onDidSubmitAgent(() => {
 			this.group.pinEditor(this.input);
 		}));
+		this._register(this.widget.onDidChangeViewModel((e) => {
+			if (e.currentSessionResource && this.input instanceof ChatEditorInput) {
+				const newModel = this.chatService.getSession(e.currentSessionResource);
+				if (newModel) {
+					this.input.updateModel(newModel);
+				}
+			}
+		}));
 		this.widget.render(parent);
 		this.widget.setVisible(true);
 	}

src/vs/workbench/contrib/chat/browser/widgetHosts/editor/chatEditorInput.ts

@@ -46,6 +46,7 @@ export class ChatEditorInput extends EditorInput implements IEditorCloseHandler
 	private cachedIcon: ThemeIcon | URI | undefined;
 
 	private readonly modelRef = this._register(new MutableDisposable<IChatModelReference>());
+	private readonly _modelChangeListener = this._register(new MutableDisposable());
 
 	private get model(): IChatModel | undefined {
 		return this.modelRef.value?.object;
@@ -231,11 +232,7 @@ export class ChatEditorInput extends EditorInput implements IEditorCloseHandler
 
 		this._sessionResource = this.model.sessionResource;
 
-		this._register(this.model.onDidChange((e) => {
-			// Invalidate icon cache when label changes
-			this.cachedIcon = undefined;
-			this._onDidChangeLabel.fire();
-		}));
+		this._trackModelChanges();
 
 		// Check if icon has changed after model resolution
 		const newIcon = this.resolveIcon();
@@ -248,6 +245,28 @@ export class ChatEditorInput extends EditorInput implements IEditorCloseHandler
 		return this._register(new ChatEditorModel(this.model));
 	}
 
+	/**
+	 * Updates the editor input to track a new model. Called when the widget swaps
+	 * from an untitled session to a real session.
+	 */
+	updateModel(model: IChatModel): void {
+		this._sessionResource = model.sessionResource;
+		this.modelRef.value = this.chatService.acquireExistingSession(model.sessionResource, 'ChatEditorInput#updateModel');
+		this._trackModelChanges();
+		this.cachedIcon = undefined;
+		this._onDidChangeLabel.fire();
+	}
+
+	private _trackModelChanges(): void {
+		if (!this.model) {
+			return;
+		}
+		this._modelChangeListener.value = this.model.onDidChange(() => {
+			this.cachedIcon = undefined;
+			this._onDidChangeLabel.fire();
+		});
+	}
+
 	private iconsEqual(a: ThemeIcon | URI, b: ThemeIcon | URI): boolean {
 		if (ThemeIcon.isThemeIcon(a) && ThemeIcon.isThemeIcon(b)) {
 			return a.id === b.id;

src/vs/workbench/contrib/chat/browser/widgetHosts/viewPane/chatViewPane.ts

@@ -597,6 +597,9 @@ export class ChatViewPane extends ViewPane implements IViewWelcomeDelegate {
 
 		// Track the active chat model and reveal it in the sessions control if side-by-side
 		this._register(chatWidget.onDidChangeViewModel(() => {
+			const model = chatWidget.viewModel?.model;
+			this.titleControl?.update(model);
+
 			if (this.sessionsViewerOrientation === AgentSessionsViewerOrientation.Stacked) {
 				return; // only reveal in side-by-side mode
 			}