[WIP] poc: branch-associated Chat Sessions

src/vs/workbench/contrib/chat/browser/actions/chatActions.ts

@@ -87,6 +87,7 @@ export const CHAT_CATEGORY = localize2('chat.category', 'Chat');
 export const ACTION_ID_NEW_CHAT = `workbench.action.chat.newChat`;
 export const ACTION_ID_NEW_EDIT_SESSION = `workbench.action.chat.newEditSession`;
 export const CHAT_OPEN_ACTION_ID = 'workbench.action.chat.open';
+export const CHAT_OPEN_HISTORICAL_SESSION_ACTION_ID = 'workbench.action.chat.openHistoricalSession';
 export const CHAT_SETUP_ACTION_ID = 'workbench.action.chat.triggerSetup';
 const TOGGLE_CHAT_ACTION_ID = 'workbench.action.chat.toggle';
 const CHAT_CLEAR_HISTORY_ACTION_ID = 'workbench.action.chat.clearHistory';
@@ -579,7 +580,7 @@ export function registerChatActions() {
 						separator,
 						{
 							label: i.title,
-							description: i.isActive ? `(${localize('currentChatLabel', 'current')})` : '',
+							description: i.isActive ? `(${i.createdOnBranch} - ${localize('currentChatLabel', 'current')})` : `${i.createdOnBranch}`,
 							chat: i,
 							buttons: i.isActive ? [renameButton] : [
 								renameButton,
@@ -1232,7 +1233,7 @@ export function registerChatActions() {
 			const suggestCtrl = SuggestController.get(widget.inputEditor);
 			if (suggestCtrl) {
 				const curText = widget.inputEditor.getValue();
-				const newValue = curText ? `@ ${curText}` : '@';
+				const newValue = curText ? `@${curText}` : '@';
 				if (!curText.startsWith('@')) {
 					widget.inputEditor.setValue(newValue);
 				}
@@ -1402,7 +1403,7 @@ export function registerChatActions() {
 
 		override async run(accessor: ServicesAccessor): Promise<void> {
 			const extensionsWorkbenchService = accessor.get(IExtensionsWorkbenchService);
-			extensionsWorkbenchService.openSearch(`@feature:${CopilotUsageExtensionFeatureId}`);
+			extensionsWorkbenchService.openSearch(`@feature: ${CopilotUsageExtensionFeatureId}`);
 		}
 	});
 
@@ -1984,3 +1985,42 @@ registerAction2(class EditToolApproval extends Action2 {
 		}
 	}
 });
+
+registerAction2(class OpenHistoricalChatSessionAction extends Action2 {
+	constructor() {
+		super({
+			id: CHAT_OPEN_HISTORICAL_SESSION_ACTION_ID,
+			title: localize2('openHistoricalChatSession', "Open Historical Chat Session"),
+			category: CHAT_CATEGORY,
+			f1: true,
+			precondition: ChatContextKeys.enabled
+		});
+	}
+
+	async run(accessor: ServicesAccessor, options?: { sessionId?: string }): Promise<void> {
+		const viewsService = accessor.get(IViewsService);
+		const editorService = accessor.get(IEditorService);
+
+		if (!options?.sessionId) {
+			console.log('No sessionId provided to openHistoricalSession command');
+			return;
+		}
+
+		try {
+			const sessionId = options.sessionId;
+			console.log(`Opening historical chat session with sessionId: ${sessionId}`);
+
+			// Try to open in chat view first
+			const view = await viewsService.openView<ChatViewPane>(ChatViewId);
+			if (view) {
+				await view.loadSession(sessionId);
+			} else {
+				// Fallback to opening in editor
+				const options: IChatEditorOptions = { target: { sessionId }, pinned: true };
+				await editorService.openEditor({ resource: ChatEditorInput.getNewEditorUri(), options }, ACTIVE_GROUP);
+			}
+		} catch (error) {
+			console.error('Failed to open historical chat session:', error);
+		}
+	}
+});

src/vs/workbench/contrib/chat/common/chatModel.ts

@@ -1153,6 +1153,10 @@ export interface ISerializableChatData3 extends Omit<ISerializableChatData2, 've
 	version: 3;
 	customTitle: string | undefined;
 	inputType?: string;
+	/** Git branch name when the session was created (best effort). */
+	createdOnBranch?: string;
+	/** Git branch name when the session was last activated/used (best effort). */
+	lastUsedOnBranch?: string;
 }
 
 /**
@@ -1368,6 +1372,11 @@ export class ChatModel extends Disposable implements IChatModel {
 		return this._creationDate;
 	}
 
+	/** Git branch name when this session was created (best effort, persisted). */
+	public createdOnBranch: string | undefined;
+	/** Git branch name when this session was last activated (best effort, persisted). */
+	public lastUsedOnBranch: string | undefined;
+
 	private _lastMessageDate: number;
 	get lastMessageDate(): number {
 		return this._lastMessageDate;
@@ -1455,6 +1464,12 @@ export class ChatModel extends Disposable implements IChatModel {
 		this._lastMessageDate = (isValid && initialData.lastMessageDate) || this._creationDate;
 		this._customTitle = isValid ? initialData.customTitle : undefined;
 
+		// Rehydrate branch metadata if present
+		if (isValid) {
+			this.createdOnBranch = initialData.createdOnBranch;
+			this.lastUsedOnBranch = initialData.lastUsedOnBranch;
+		}
+
 		this._initialRequesterUsername = initialData?.requesterUsername;
 		this._initialResponderUsername = initialData?.responderUsername;
 		this._initialRequesterAvatarIconUri = initialData?.requesterAvatarIconUri && URI.revive(initialData.requesterAvatarIconUri);
@@ -1884,7 +1899,9 @@ export class ChatModel extends Disposable implements IChatModel {
 			creationDate: this._creationDate,
 			isImported: this._isImported,
 			lastMessageDate: this._lastMessageDate,
-			customTitle: this._customTitle
+			customTitle: this._customTitle,
+			createdOnBranch: this.createdOnBranch,
+			lastUsedOnBranch: this.lastUsedOnBranch,
 		};
 	}
 

src/vs/workbench/contrib/chat/common/chatService.ts

@@ -611,6 +611,10 @@ export interface IChatDetail {
 	title: string;
 	lastMessageDate: number;
 	isActive: boolean;
+	/** Git branch when session was created (if recorded). */
+	createdOnBranch?: string;
+	/** Git branch when session was last used (if recorded). */
+	lastUsedOnBranch?: string;
 }
 
 export interface IChatProviderInfo {

src/vs/workbench/contrib/chat/common/chatServiceImpl.ts

@@ -17,6 +17,7 @@ import { StopWatch } from '../../../../base/common/stopwatch.js';
 import { URI } from '../../../../base/common/uri.js';
 import { OffsetRange } from '../../../../editor/common/core/ranges/offsetRange.js';
 import { localize } from '../../../../nls.js';
+import { ICommandService } from '../../../../platform/commands/common/commands.js';
 import { IConfigurationService } from '../../../../platform/configuration/common/configuration.js';
 import { IInstantiationService } from '../../../../platform/instantiation/common/instantiation.js';
 import { ILogService } from '../../../../platform/log/common/log.js';
@@ -33,6 +34,7 @@ import { IChatCompleteResponse, IChatDetail, IChatFollowup, IChatProgress, IChat
 import { ChatRequestTelemetry, ChatServiceTelemetry } from './chatServiceTelemetry.js';
 import { IChatSessionsService } from './chatSessionsService.js';
 import { ChatSessionStore, IChatTransfer2 } from './chatSessionStore.js';
+import { IGitStatus } from './gitStatusService.js';
 import { IChatSlashCommandService } from './chatSlashCommands.js';
 import { IChatTransferService } from './chatTransferService.js';
 import { ChatSessionUri } from './chatUri.js';
@@ -118,6 +120,8 @@ export class ChatService extends Disposable implements IChatService {
 		@IChatTransferService private readonly chatTransferService: IChatTransferService,
 		@IChatSessionsService private readonly chatSessionService: IChatSessionsService,
 		@IMcpService private readonly mcpService: IMcpService,
+		@IGitStatus private readonly gitStatus: IGitStatus,
+		@ICommandService private readonly commandService: ICommandService,
 	) {
 		super();
 
@@ -160,6 +164,18 @@ export class ChatService extends Disposable implements IChatService {
 			const models = this._sessionModels.observable.read(reader).values();
 			return Array.from(models).some(model => model.requestInProgressObs.read(reader));
 		});
+
+		// Listen for branch changes
+		this._register(this.gitStatus.onChangedBranch(async branch => {
+			console.log('Branch changed to:', branch);
+			const history = await this.getHistory();
+			const sessionId = history.find(h => h.lastUsedOnBranch === branch)?.sessionId;
+			if (sessionId) {
+				this.commandService.executeCommand('workbench.action.chat.openHistoricalSession', { sessionId });
+			} else {
+				this.commandService.executeCommand('workbench.action.chat.newChat');
+			}
+		}));
 	}
 
 	isEnabled(location: ChatAgentLocation): boolean {
@@ -303,6 +319,8 @@ export class ChatService extends Disposable implements IChatService {
 					title,
 					lastMessageDate: session.lastMessageDate,
 					isActive: true,
+					createdOnBranch: session.createdOnBranch,
+					lastUsedOnBranch: session.lastUsedOnBranch,
 				} satisfies IChatDetail;
 			});
 
@@ -331,12 +349,22 @@ export class ChatService extends Disposable implements IChatService {
 
 	private _startSession(someSessionHistory: IExportableChatData | ISerializableChatData | undefined, location: ChatAgentLocation, isGlobalEditingSession: boolean, token: CancellationToken, inputType?: string): ChatModel {
 		const model = this.instantiationService.createInstance(ChatModel, someSessionHistory, { initialLocation: location, inputType });
+		// Initialize branch metadata on creation
+		const branch = this.gitStatus.getCurrentBranch();
+		if (branch) {
+			if (!model.createdOnBranch) {
+				model.createdOnBranch = branch;
+			}
+			model.lastUsedOnBranch = branch;
+		}
 		if (location === ChatAgentLocation.Chat) {
 			model.startEditingSession(isGlobalEditingSession);
 		}
 
 		this._sessionModels.set(model.sessionId, model);
 		this.initializeSession(model, token);
+		// Persist immediately to capture branch info
+		this._chatSessionStore.storeSessions([model]);
 		return model;
 	}
 
@@ -349,6 +377,19 @@ export class ChatService extends Disposable implements IChatService {
 		this.activateDefaultAgent(model.initialLocation).catch(e => this.logService.error(e));
 	}
 
+	/**
+	 * Update session metadata to reflect that it has been actively used (selected, restored, or loaded).
+	 * Captures the current branch (best effort) for lastUsedOnBranch and persists the session metadata.
+	 */
+	private _markSessionUsed(model: ChatModel): void {
+		const branch = this.gitStatus.getCurrentBranch();
+		if (branch) {
+			model.lastUsedOnBranch = branch;
+		}
+		// Persist metadata update only (non-blocking)
+		this._chatSessionStore.storeSessions([model]);
+	}
+
 	async activateDefaultAgent(location: ChatAgentLocation): Promise<void> {
 		await this.extensionService.whenInstalledExtensionsRegistered();
 
@@ -382,6 +423,7 @@ export class ChatService extends Disposable implements IChatService {
 		this.trace('getOrRestoreSession', `sessionId: ${sessionId}`);
 		const model = this._sessionModels.get(sessionId);
 		if (model) {
+			this._markSessionUsed(model);
 			return model;
 		}
 
@@ -403,6 +445,7 @@ export class ChatService extends Disposable implements IChatService {
 			this._transferredSessionData = undefined;
 		}
 
+		this._markSessionUsed(session);
 		return session;
 	}
 
@@ -443,7 +486,9 @@ export class ChatService extends Disposable implements IChatService {
 	}
 
 	loadSessionFromContent(data: IExportableChatData | ISerializableChatData): IChatModel | undefined {
-		return this._startSession(data, data.initialLocation ?? ChatAgentLocation.Chat, true, CancellationToken.None);
+		const model = this._startSession(data, data.initialLocation ?? ChatAgentLocation.Chat, true, CancellationToken.None);
+		this._markSessionUsed(model);
+		return model;
 	}
 
 	async loadSessionForResource(resource: URI, location: ChatAgentLocation, token: CancellationToken): Promise<IChatModel | undefined> {
@@ -466,6 +511,7 @@ export class ChatService extends Disposable implements IChatService {
 		const content = await this.chatSessionService.provideChatSessionContent(chatSessionType, parsed.sessionId, CancellationToken.None);
 
 		const model = this._startSession(undefined, location, true, CancellationToken.None, chatSessionType);
+		this._markSessionUsed(model);
 		if (!this._contentProviderSessionModels.has(chatSessionType)) {
 			this._contentProviderSessionModels.set(chatSessionType, new Map());
 		}

src/vs/workbench/contrib/chat/common/chatSessionStore.ts

@@ -135,7 +135,7 @@ export class ChatSessionStore extends Disposable {
 			await this.fileService.writeFile(storageLocation, VSBuffer.fromString(content));
 
 			// Write succeeded, update index
-			index.entries[session.sessionId] = getSessionMetadata(session);
+			index.entries[session.sessionId] = getSessionMetadata(session, index.entries[session.sessionId]);
 		} catch (e) {
 			this.reportError('sessionWrite', 'Error writing chat session', e);
 		}
@@ -381,6 +381,7 @@ export class ChatSessionStore extends Disposable {
 	public getChatStorageFolder(): URI {
 		return this.storageRoot;
 	}
+
 }
 
 interface IChatSessionEntryMetadata {
@@ -389,6 +390,10 @@ interface IChatSessionEntryMetadata {
 	lastMessageDate: number;
 	isImported?: boolean;
 	initialLocation?: ChatAgentLocation;
+	/** Git branch name at time the session was first persisted (best effort). */
+	createdOnBranch?: string;
+	/** Git branch name at time the session was last written (best effort). */
+	lastUsedOnBranch?: string;
 
 	/**
 	 * This only exists because the migrated data from the storage service had empty sessions persisted, and it's impossible to know which ones are
@@ -440,7 +445,7 @@ function isChatSessionIndex(data: unknown): data is IChatSessionIndexData {
 	return true;
 }
 
-function getSessionMetadata(session: ChatModel | ISerializableChatData): IChatSessionEntryMetadata {
+function getSessionMetadata(session: ChatModel | ISerializableChatData, existingMetadata: IChatSessionEntryMetadata | undefined): IChatSessionEntryMetadata {
 	const title = session instanceof ChatModel ?
 		session.customTitle || (session.getRequests().length > 0 ? ChatModel.getDefaultTitle(session.getRequests()) : '') :
 		session.customTitle ?? (session.requests.length > 0 ? ChatModel.getDefaultTitle(session.requests) : '');
@@ -451,7 +456,9 @@ function getSessionMetadata(session: ChatModel | ISerializableChatData): IChatSe
 		lastMessageDate: session.lastMessageDate,
 		isImported: session.isImported,
 		initialLocation: session.initialLocation,
-		isEmpty: session instanceof ChatModel ? session.getRequests().length === 0 : session.requests.length === 0
+		isEmpty: session instanceof ChatModel ? session.getRequests().length === 0 : session.requests.length === 0,
+		createdOnBranch: session instanceof ChatModel ? (session.createdOnBranch ?? existingMetadata?.createdOnBranch) : (session as ISerializableChatData).createdOnBranch ?? existingMetadata?.createdOnBranch,
+		lastUsedOnBranch: session instanceof ChatModel ? (session.lastUsedOnBranch ?? existingMetadata?.lastUsedOnBranch) : (session as ISerializableChatData).lastUsedOnBranch ?? existingMetadata?.lastUsedOnBranch,
 	};
 }