Add contribution point for chat session create menu

This allows extension to contribute to a special split button for creating chat sessions. Currently this is shown in the title of each chat session view, but if we unify the sessions view we would likely move it to the panel title

Author: mjbvz

src/vs/platform/actions/common/actions.ts

@@ -273,6 +273,7 @@ export class MenuId {
 	static readonly ChatToolOutputResourceContext = new MenuId('ChatToolOutputResourceContext');
 	static readonly ChatMultiDiffContext = new MenuId('ChatMultiDiffContext');
 	static readonly ChatSessionsMenu = new MenuId('ChatSessionsMenu');
+	static readonly ChatSessionsCreateSubMenu = new MenuId('ChatSessionsCreateSubMenu');
 	static readonly ChatConfirmationMenu = new MenuId('ChatConfirmationMenu');
 	static readonly AccessibleView = new MenuId('AccessibleView');
 	static readonly MultiDiffEditorFileToolbar = new MenuId('MultiDiffEditorFileToolbar');

src/vs/workbench/contrib/chat/browser/chatSessions.contribution.ts

@@ -11,7 +11,7 @@ import { ThemeIcon } from '../../../../base/common/themables.js';
 import { URI } from '../../../../base/common/uri.js';
 import { generateUuid } from '../../../../base/common/uuid.js';
 import { localize, localize2 } from '../../../../nls.js';
-import { Action2, MenuId, MenuRegistry, registerAction2 } from '../../../../platform/actions/common/actions.js';
+import { Action2, IMenuService, MenuId, MenuRegistry, registerAction2 } from '../../../../platform/actions/common/actions.js';
 import { ContextKeyExpr, IContextKeyService } from '../../../../platform/contextkey/common/contextkey.js';
 import { InstantiationType, registerSingleton } from '../../../../platform/instantiation/common/extensions.js';
 import { ServicesAccessor } from '../../../../platform/instantiation/common/instantiation.js';
@@ -222,6 +222,7 @@ export class ChatSessionsService extends Disposable implements IChatSessionsServ
 		@IChatAgentService private readonly _chatAgentService: IChatAgentService,
 		@IExtensionService private readonly _extensionService: IExtensionService,
 		@IContextKeyService private readonly _contextKeyService: IContextKeyService,
+		@IMenuService private readonly _menuService: IMenuService,
 	) {
 		super();
 		this._register(extensionPoint.setHandler(extensions => {
@@ -368,22 +369,43 @@ export class ChatSessionsService extends Disposable implements IChatSessionsServ
 	}
 
 	private _registerMenuItems(contribution: IChatSessionsExtensionPoint): IDisposable {
-		return MenuRegistry.appendMenuItem(MenuId.ViewTitle, {
-			command: {
-				id: `${NEW_CHAT_SESSION_ACTION_ID}.${contribution.type}`,
-				title: localize('interactiveSession.openNewSessionEditor', "New {0}", contribution.displayName),
+		// If provider registers anything for the create submenu, let it fully control the creation
+		const contextKeyService = this._contextKeyService.createOverlay([
+			['chatSessionType', contribution.type]
+		]);
+
+		const menuActions = this._menuService.getMenuActions(MenuId.ChatSessionsCreateSubMenu, contextKeyService);
+		if (menuActions?.length) {
+			return MenuRegistry.appendMenuItem(MenuId.ViewTitle, {
+				group: 'navigation',
+				title: localize('interactiveSession.chatSessionSubMenuTitle', "Create chat session"),
 				icon: Codicon.plus,
-				source: {
-					id: contribution.extensionDescription.identifier.value,
-					title: contribution.extensionDescription.displayName || contribution.extensionDescription.name,
-				}
-			},
-			group: 'navigation',
-			order: 1,
-			when: ContextKeyExpr.and(
-				ContextKeyExpr.equals('view', `${VIEWLET_ID}.${contribution.type}`)
-			),
-		});
+				order: 1,
+				when: ContextKeyExpr.and(
+					ContextKeyExpr.equals('view', `${VIEWLET_ID}.${contribution.type}`)
+				),
+				submenu: MenuId.ChatSessionsCreateSubMenu,
+				isSplitButton: true
+			});
+		} else {
+			// We control creation instead
+			return MenuRegistry.appendMenuItem(MenuId.ViewTitle, {
+				command: {
+					id: `${NEW_CHAT_SESSION_ACTION_ID}.${contribution.type}`,
+					title: localize('interactiveSession.openNewSessionEditor', "New {0}", contribution.displayName),
+					icon: Codicon.plus,
+					source: {
+						id: contribution.extensionDescription.identifier.value,
+						title: contribution.extensionDescription.displayName || contribution.extensionDescription.name,
+					}
+				},
+				group: 'navigation',
+				order: 1,
+				when: ContextKeyExpr.and(
+					ContextKeyExpr.equals('view', `${VIEWLET_ID}.${contribution.type}`)
+				),
+			});
+		}
 	}
 
 	private _registerCommands(contribution: IChatSessionsExtensionPoint): IDisposable {

src/vs/workbench/contrib/chat/browser/chatSessions/view/sessionsViewPane.ts

@@ -121,6 +121,10 @@ export class SessionsViewPane extends ViewPane {
 				}
 			}
 		}));
+
+		if (provider) { // TODO: Why can this be undefined?
+			this.scopedContextKeyService.createKey('chatSessionType', provider.chatSessionType);
+		}
 	}
 
 	override shouldShowWelcome(): boolean {

src/vs/workbench/services/actions/common/menusExtensionPoint.ts

@@ -451,12 +451,20 @@ const apiMenus: IAPIMenu[] = [
 		proposed: 'chatParticipantPrivate'
 	},
 	{
+		// TODO: rename this to something like: `chatSessions/item/inline`
 		key: 'chat/chatSessions',
 		id: MenuId.ChatSessionsMenu,
 		description: localize('menus.chatSessions', "The Chat Sessions menu."),
 		supportsSubmenus: false,
 		proposed: 'chatSessionsProvider'
 	},
+	{
+		key: 'chatSessions/newSession',
+		id: MenuId.ChatSessionsCreateSubMenu,
+		description: localize('menus.chatSessionsNewSession', "Menu for new chat sessions."),
+		supportsSubmenus: false,
+		proposed: 'chatSessionsProvider'
+	},
 	{
 		key: 'chat/multiDiff/context',
 		id: MenuId.ChatMultiDiffContext,