Update chat in editor titles after rename tool

src/vs/platform/agentHost/node/agentHostStateManager.ts

@@ -1021,11 +1021,7 @@ export class AgentHostStateManager extends Disposable {
 		// titles become fully independent. Without this the default chat keeps
 		// an empty title (= inherit the session title), so renaming the session
 		// would also move the default chat tab and vice-versa.
-		const defaultChatUri = sessionState.defaultChat ?? buildDefaultChatUri(session);
-		const defaultEntry = sessionState.chats.find(c => c.resource === defaultChatUri);
-		if (defaultEntry && !defaultEntry.title && sessionState.title) {
-			this.updateChatTitle(session, defaultChatUri, sessionState.title);
-		}
+		this._snapshotDefaultChatTitle(session, sessionState);
 
 		const chatSummary: ChatSummary = {
 			...createDefaultChatSummary(this._toSummary(session, entry), chatUri),
@@ -1067,6 +1063,7 @@ export class AgentHostStateManager extends Disposable {
 			}
 			return existing;
 		}
+		this._snapshotDefaultChatTitle(session, sessionState);
 		const chatSummary: ChatSummary = {
 			...createDefaultChatSummary(this._toSummary(session, entry), chatUri),
 			title: options.title ?? '',
@@ -1077,7 +1074,7 @@ export class AgentHostStateManager extends Disposable {
 			...(options.origin ? { origin: options.origin } : {}),
 			interactivity: options.interactivity,
 		};
-		sessionState.chats = [...sessionState.chats, chatSummary];
+		entry.state.chats = [...entry.state.chats, chatSummary];
 		this._chatEntries.set(chatUri, {
 			session,
 			summary: chatSummary,
@@ -1089,6 +1086,14 @@ export class AgentHostStateManager extends Disposable {
 		return chatSummary;
 	}
 
+	private _snapshotDefaultChatTitle(session: URI, state: SessionState): void {
+		const defaultChat = state.defaultChat ?? buildDefaultChatUri(session);
+		const summary = state.chats.find(chat => chat.resource === defaultChat);
+		if (summary && !summary.title && state.title) {
+			this.updateChatTitle(session, defaultChat, state.title);
+		}
+	}
+
 	/**
 	 * Removes an additional chat from a session. Deletes its
 	 * {@link ChatState}, dispatches {@link ActionType.SessionChatRemoved}, and

src/vs/platform/agentHost/node/agentService.ts

@@ -1231,41 +1231,32 @@ export class AgentService extends Disposable implements IAgentService {
 	private async _renameChatFromTool(session: URI, chat: URI, title: string): Promise<IRenameTitleResult> {
 		validateRenameTitle(title, SessionServerToolName.RenameChat);
 		const isDefaultChat = isDefaultChatUri(chat.toString());
-		if (isDefaultChat && await this._isOnlySessionChat(session)) {
-			await persistSessionMetadataValues(this._sessionDataService, session.toString(), {
-				[SESSION_CUSTOM_TITLE_KEY]: title,
-				[SESSION_CUSTOM_TITLE_SOURCE_KEY]: AGENT_HOST_TITLE_SOURCE_AGENT,
-			});
-			if (this._stateManager.getSessionState(session.toString())?.title !== title) {
-				this._stateManager.dispatchServerAction(session.toString(), { type: ActionType.SessionTitleChanged, title });
-			}
-			this._sideEffects.markTitleRenamed(session.toString());
-			return { title };
-		}
 		if (!isDefaultChat && !await this._peerChatExists(session, chat)) {
 			throw new Error(`Invalid ${SessionServerToolName.RenameChat} input: chat must match a known non-default chat.`);
 		}
 
 		await persistSessionMetadataValues(this._sessionDataService, session.toString(), {
 			[customChatTitleMetadataKey(chat.toString())]: title,
 			[customChatTitleSourceMetadataKey(chat.toString())]: AGENT_HOST_TITLE_SOURCE_AGENT,
+			...(isDefaultChat ? {
+				[SESSION_CUSTOM_TITLE_KEY]: title,
+				[SESSION_CUSTOM_TITLE_SOURCE_KEY]: AGENT_HOST_TITLE_SOURCE_AGENT,
+			} : {}),
 		});
-		if (this._stateManager.getSessionState(session.toString())) {
+		const state = this._stateManager.getSessionState(session.toString());
+		if (state) {
+			if (isDefaultChat && state.title !== title) {
+				this._stateManager.dispatchServerAction(session.toString(), { type: ActionType.SessionTitleChanged, title });
+			}
 			this._stateManager.updateChatTitle(session.toString(), chat.toString(), title);
 		}
+		if (isDefaultChat) {
+			this._sideEffects.markTitleRenamed(session.toString());
+		}
 		this._sideEffects.markTitleRenamed(session.toString(), chat.toString());
 		return { title };
 	}
 
-	private async _isOnlySessionChat(session: URI): Promise<boolean> {
-		const state = this._stateManager.getSessionState(session.toString());
-		if (state) {
-			return state.chats.length === 1;
-		}
-		const persisted = await this._readPersistedPeerChatCatalog(session);
-		return persisted?.length === 0;
-	}
-
 	private async _peerChatExists(session: URI, chat: URI): Promise<boolean> {
 		if (this._stateManager.getSessionState(session.toString())?.chats.some(candidate => candidate.resource === chat.toString())) {
 			return true;

src/vs/platform/agentHost/node/agentSideEffects.ts

@@ -1703,13 +1703,16 @@ export class AgentSideEffects extends Disposable {
 			}
 			case ActionType.SessionTitleChanged: {
 				if (chatChannel) {
-					// The rename targeted a specific chat (default or additional),
-					// not the whole session. Route it to a per-chat title update so
-					// the session title stays independent.
 					this._stateManager.updateChatTitle(sessionChannel, chatChannel, action.title);
 					this._persistSessionFlag(sessionChannel, customChatTitleMetadataKey(chatChannel), action.title);
 					this._persistSessionFlag(sessionChannel, customChatTitleSourceMetadataKey(chatChannel), AGENT_HOST_TITLE_SOURCE_USER);
 					this._titleController.markTitleRenamed(sessionChannel, chatChannel);
+					if (isDefaultChatUri(chatChannel)) {
+						this._stateManager.dispatchServerAction(sessionChannel, action);
+						this._persistSessionFlag(sessionChannel, SESSION_CUSTOM_TITLE_KEY, action.title);
+						this._persistSessionFlag(sessionChannel, SESSION_CUSTOM_TITLE_SOURCE_KEY, AGENT_HOST_TITLE_SOURCE_USER);
+						this._titleController.markTitleRenamed(sessionChannel);
+					}
 					break;
 				}
 				this._persistSessionFlag(channel, SESSION_CUSTOM_TITLE_KEY, action.title);

src/vs/platform/agentHost/node/localCommands/renameLocalCommand.ts

@@ -40,15 +40,19 @@ export class RenameLocalCommand extends Disposable implements ILocalChatCommand
 			// completes the turn.
 			return;
 		}
-		const isAdditional = (uri: ProtocolURI): boolean => isAhpChatChannel(uri) && !isDefaultChatUri(uri);
-		const chatTarget = isAdditional(channel) ? channel : undefined;
+		const chatTarget = isAhpChatChannel(channel) ? channel : undefined;
 		const sessionChannel = isAhpChatChannel(channel) ? parseRequiredSessionUriFromChatUri(channel) : channel;
 		if (chatTarget) {
-			// Rename only this chat, independently of the session title.
 			this._context.updateChatTitle(sessionChannel, chatTarget, title);
 			this._context.markTitleRenamed(sessionChannel, chatTarget);
 			this._context.persistSessionFlag(sessionChannel, customChatTitleMetadataKey(chatTarget), title);
 			this._context.persistSessionFlag(sessionChannel, customChatTitleSourceMetadataKey(chatTarget), AGENT_HOST_TITLE_SOURCE_USER);
+			if (isDefaultChatUri(chatTarget)) {
+				this._context.dispatch(sessionChannel, { type: ActionType.SessionTitleChanged, title });
+				this._context.markTitleRenamed(sessionChannel);
+				this._context.persistSessionFlag(sessionChannel, SESSION_CUSTOM_TITLE_KEY, title);
+				this._context.persistSessionFlag(sessionChannel, SESSION_CUSTOM_TITLE_SOURCE_KEY, AGENT_HOST_TITLE_SOURCE_USER);
+			}
 		} else {
 			this._context.dispatch(sessionChannel, { type: ActionType.SessionTitleChanged, title });
 			this._context.markTitleRenamed(sessionChannel);

src/vs/platform/agentHost/test/node/agentHostStateManager.test.ts

@@ -1136,6 +1136,22 @@ suite('AgentHostStateManager', () => {
 			);
 		});
 
+		test('restored peer chat snapshots the inherited default chat title', () => {
+			manager.restoreSession(makeSessionSummary(), []);
+			const defaultChat = buildDefaultChatUri(sessionUri);
+			const beforeRestore = manager.getSessionState(sessionUri)?.chats.find(chat => chat.resource === defaultChat)?.title;
+
+			manager.registerRestoredChatSummary(sessionUri, peerChat, { title: 'Peer' });
+
+			assert.deepStrictEqual({
+				beforeRestore,
+				afterRestore: manager.getSessionState(sessionUri)?.chats.find(chat => chat.resource === defaultChat)?.title,
+			}, {
+				beforeRestore: '',
+				afterRestore: 'Test',
+			});
+		});
+
 		test('addChat is idempotent for an existing chat URI', () => {
 			manager.createSession(makeSessionSummary());
 			const first = manager.addChat(sessionUri, peerChat, { title: 'Peer' });

src/vs/platform/agentHost/test/node/agentService.test.ts

@@ -10538,6 +10538,14 @@ suite('AgentService (node dispatcher)', () => {
 			await db.setMetadata('customTitleSource', 'user');
 			await db.setMetadata(`customChatTitle:${peerChat}`, 'Previous peer title');
 			await db.setMetadata(`customChatTitleSource:${peerChat}`, 'user');
+			await timeout(0);
+			localService.stateManager.prepareSessionSummariesForListing([localService.stateManager.getSessionSummary(sessionUri)!]);
+			const summaryTitleChanged = new DeferredPromise<string>();
+			disposables.add(localService.onDidNotification(notification => {
+				if (notification.type === NotificationType.SessionSummaryChanged && notification.changes.title) {
+					void summaryTitleChanged.complete(notification.changes.title);
+				}
+			}));
 
 			const multiChatDefaultResult = await agent.serverToolHost!.executeTool(defaultChat, SessionServerToolName.RenameChat, {
 				title: 'Complete replacement default chat title',
@@ -10547,7 +10555,7 @@ suite('AgentService (node dispatcher)', () => {
 				title: 'Complete replacement peer chat title',
 			});
 			await db.finalRenamePersisted.p;
-			await timeout(0);
+			const summaryTitleChange = await summaryTitleChanged.p;
 
 			assert.deepStrictEqual({
 				singleChatResult,
@@ -10562,19 +10570,21 @@ suite('AgentService (node dispatcher)', () => {
 				persistedDefaultChatSource: await db.getMetadata(`customChatTitleSource:${defaultChat}`),
 				persistedChatTitle: await db.getMetadata(`customChatTitle:${peerChat}`),
 				persistedChatSource: await db.getMetadata(`customChatTitleSource:${peerChat}`),
+				summaryTitleChange,
 			}, {
 				singleChatResult: 'Renamed chat to "Single-chat title".',
 				multiChatDefaultResult: 'Renamed chat to "Complete replacement default chat title".',
 				chatResult: 'Renamed chat to "Complete replacement peer chat title".',
-				liveSessionTitle: 'Multi-chat session title',
+				liveSessionTitle: 'Complete replacement default chat title',
 				liveDefaultChatTitle: 'Complete replacement default chat title',
 				liveChatTitle: 'Complete replacement peer chat title',
-				persistedSessionTitle: 'Multi-chat session title',
-				persistedSessionSource: 'user',
+				persistedSessionTitle: 'Complete replacement default chat title',
+				persistedSessionSource: 'agent',
 				persistedDefaultChatTitle: 'Complete replacement default chat title',
 				persistedDefaultChatSource: 'agent',
 				persistedChatTitle: 'Complete replacement peer chat title',
 				persistedChatSource: 'agent',
+				summaryTitleChange: 'Complete replacement default chat title',
 			});
 		});
 

src/vs/platform/agentHost/test/node/agentSideEffects.test.ts

@@ -50,6 +50,7 @@ import { withChatSurfaceMeta } from '../../common/meta/agentChatSurfaceMeta.js';
 import { AgentHostCustomizationEnablementService, IAgentHostCustomizationEnablementService } from '../../node/agentHostCustomizationEnablementService.js';
 import { AgentHostStorageService } from '../../node/agentHostStorageService.js';
 import { applyMcpServerEnablement } from '../../node/shared/mcpCustomizationController.js';
+import { customChatTitleMetadataKey, customChatTitleSourceMetadataKey, SESSION_CUSTOM_TITLE_KEY, SESSION_CUSTOM_TITLE_SOURCE_KEY } from '../../node/shared/persistSessionMetadata.js';
 import { createNoopGitService, createNullSessionDataService, createSessionDataService, TestSessionDatabase } from '../common/sessionTestHelpers.js';
 import { MockAgent } from './mockAgent.js';
 import { TestAgentHostTerminalManager } from './testAgentHostTerminalManager.js';
@@ -1513,6 +1514,30 @@ suite('AgentSideEffects', () => {
 			assert.deepStrictEqual(agent.sendMessageCalls, []);
 			const state = stateManager.getSessionState(sessionUri.toString());
 			assert.strictEqual(state?.title, 'Test');
+		});
+
+		test('/rename updates both the session and default chat title once multi-chat', async () => {
+			setupSession();
+			const renameSideEffects = createRenameSideEffects();
+			stateManager.addChat(sessionUri.toString(), buildChatUri(sessionUri.toString(), 'peer'), { title: 'Peer' });
+			const action: ChatAction = {
+				type: ActionType.ChatTurnStarted,
+				turnId: 'turn-rename',
+				startedAt: '2025-01-01T00:00:00.000Z',
+				message: { text: '/rename Renamed Default', origin: { kind: MessageKind.User } },
+			};
+			stateManager.dispatchClientAction(defaultChatUri, action, { clientId: 'test', clientSeq: 1 });
+			renameSideEffects.handleAction(defaultChatUri, action);
+			await timeout(10);
+
+			const state = stateManager.getSessionState(sessionUri.toString());
+			assert.deepStrictEqual({
+				sessionTitle: state?.title,
+				defaultChatTitle: state?.chats.find(chat => chat.resource === defaultChatUri)?.title,
+			}, {
+				sessionTitle: 'Renamed Default',
+				defaultChatTitle: 'Renamed Default',
+			});
 			assert.strictEqual(stateManager.getActiveTurnId(sessionUri.toString()), undefined);
 		});
 
@@ -4913,6 +4938,50 @@ suite('AgentSideEffects', () => {
 			assert.strictEqual(await waitForMetadata('customTitle'), 'Custom Title');
 		});
 
+		test('default chat title change updates and persists the session title', async () => {
+			const sessionDataService = createSessionDataService(sessionDb);
+			const localStateManager = disposables.add(new AgentHostStateManager(new NullLogService()));
+			const localAgent = new MockAgent();
+			disposables.add(toDisposable(() => localAgent.dispose()));
+			const localSideEffects = createTestSideEffects(disposables, localStateManager, {
+				getAgent: () => localAgent,
+				agents: observableValue<readonly IAgent[]>('agents', [localAgent]),
+				sessionDataService,
+				onTurnComplete: () => { },
+			});
+			const defaultChat = buildDefaultChatUri(sessionUri);
+			localStateManager.createSession({
+				resource: sessionUri.toString(),
+				provider: 'mock',
+				title: 'Initial',
+				status: SessionStatus.Idle,
+				createdAt: new Date().toISOString(),
+				modifiedAt: new Date().toISOString(),
+			});
+			localStateManager.addChat(sessionUri.toString(), buildChatUri(sessionUri.toString(), 'peer'), { title: 'Peer' });
+
+			localSideEffects.handleAction(defaultChat, {
+				type: ActionType.SessionTitleChanged,
+				title: 'Renamed Default',
+			});
+
+			assert.deepStrictEqual({
+				sessionTitle: localStateManager.getSessionState(sessionUri.toString())?.title,
+				defaultChatTitle: localStateManager.getChatState(defaultChat)?.title,
+				persistedSessionTitle: await waitForMetadata(SESSION_CUSTOM_TITLE_KEY),
+				persistedSessionSource: await waitForMetadata(SESSION_CUSTOM_TITLE_SOURCE_KEY),
+				persistedChatTitle: await waitForMetadata(customChatTitleMetadataKey(defaultChat)),
+				persistedChatSource: await waitForMetadata(customChatTitleSourceMetadataKey(defaultChat)),
+			}, {
+				sessionTitle: 'Renamed Default',
+				defaultChatTitle: 'Renamed Default',
+				persistedSessionTitle: 'Renamed Default',
+				persistedSessionSource: 'user',
+				persistedChatTitle: 'Renamed Default',
+				persistedChatSource: 'user',
+			});
+		});
+
 		test('handleListSessions returns persisted custom title', async () => {
 			const sessionDataService = createSessionDataService(sessionDb);
 			const localAgent = new MockAgent();