Notify changes to Chat Session Options (#2361)

Author: DonJayamanne

src/extension/chatSessions/vscode-node/chatSessions.ts

@@ -119,6 +119,7 @@ export class ChatSessionsContrib extends Disposable implements IExtensionContrib
 
 		const copilotcliChatSessionParticipant = this._register(copilotcliAgentInstaService.createInstance(
 			CopilotCLIChatSessionParticipant,
+			copilotcliChatSessionContentProvider,
 			promptResolver,
 			copilotcliSessionItemProvider,
 			cloudSessionProvider,

src/extension/chatSessions/vscode-node/copilotCLIChatSessionsContribution.ts

@@ -278,13 +278,21 @@ export class CopilotCLIChatSessionItemProvider extends Disposable implements vsc
 	}
 }
 
-export class CopilotCLIChatSessionContentProvider implements vscode.ChatSessionContentProvider {
+export class CopilotCLIChatSessionContentProvider extends Disposable implements vscode.ChatSessionContentProvider {
+	private readonly _onDidChangeChatSessionOptions = this._register(new Emitter<vscode.ChatSessionOptionChangeEvent>());
+	readonly onDidChangeChatSessionOptions = this._onDidChangeChatSessionOptions.event;
 	constructor(
 		private readonly worktreeManager: CopilotCLIWorktreeManager,
 		@ICopilotCLIModels private readonly copilotCLIModels: ICopilotCLIModels,
 		@ICopilotCLIAgents private readonly copilotCLIAgents: ICopilotCLIAgents,
 		@ICopilotCLISessionService private readonly sessionService: ICopilotCLISessionService,
-	) { }
+	) {
+		super();
+	}
+
+	public notifySessionOptionsChange(resource: vscode.Uri, updates: ReadonlyArray<{ optionId: string; value: string }>): void {
+		this._onDidChangeChatSessionOptions.fire({ resource, updates });
+	}
 
 	async provideChatSessionContent(resource: Uri, token: vscode.CancellationToken): Promise<vscode.ChatSession> {
 		const copilotcliSessionId = SessionIdForCLI.parse(resource);
@@ -413,6 +421,7 @@ export class CopilotCLIChatSessionParticipant extends Disposable {
 	private CLI_CANCEL = vscode.l10n.t('Cancel');
 
 	constructor(
+		private readonly contentProvider: CopilotCLIChatSessionContentProvider,
 		private readonly promptResolver: CopilotCLIPromptResolver,
 		private readonly sessionItemProvider: CopilotCLIChatSessionItemProvider,
 		private readonly cloudSessionProvider: CopilotCloudSessionsProvider | undefined,
@@ -475,6 +484,21 @@ export class CopilotCLIChatSessionParticipant extends Disposable {
 				this.getModelId(id, request, token),
 				this.getAgent(id, request, token),
 			]);
+			if (isUntitled && (modelId || agent)) {
+				const promptFile = request ? await this.getPromptInfoFromRequest(request, token) : undefined;
+				if (promptFile) {
+					const changes: { optionId: string; value: string }[] = [];
+					if (agent) {
+						changes.push({ optionId: AGENTS_OPTION_ID, value: agent.name });
+					}
+					if (modelId) {
+						changes.push({ optionId: MODELS_OPTION_ID, value: modelId });
+					}
+					if (changes.length > 0) {
+						this.contentProvider.notifySessionOptionsChange(resource, changes);
+					}
+				}
+			}
 			const session = await this.getOrCreateSession(request, chatSessionContext, modelId, agent, stream, disposables, token);
 			if (!session || token.isCancellationRequested) {
 				return {};

src/extension/chatSessions/vscode-node/test/copilotCLIChatSessionParticipant.spec.ts

@@ -33,7 +33,7 @@ import { ChatSummarizerProvider } from '../../../prompt/node/summarizer';
 import { createExtensionUnitTestingServices } from '../../../test/node/services';
 import { MockChatResponseStream, TestChatRequest } from '../../../test/node/testHelpers';
 import type { IToolsService } from '../../../tools/common/toolsService';
-import { CopilotCLIChatSessionItemProvider, CopilotCLIChatSessionParticipant, CopilotCLIWorktreeManager } from '../copilotCLIChatSessionsContribution';
+import { CopilotCLIChatSessionContentProvider, CopilotCLIChatSessionItemProvider, CopilotCLIChatSessionParticipant, CopilotCLIWorktreeManager } from '../copilotCLIChatSessionsContribution';
 import { CopilotCloudSessionsProvider } from '../copilotCloudSessionsProvider';
 
 // Mock terminal integration to avoid importing PowerShell asset (.ps1) which Vite cannot parse during tests
@@ -189,8 +189,13 @@ describe('CopilotCLIChatSessionParticipant.handleRequest', () => {
 		sessionService = disposables.add(new CopilotCLISessionService(logService, sdk, instantiationService, new NullNativeEnvService(), new MockFileSystemService(), mcpHandler, new NullCopilotCLIAgents()));
 
 		manager = await sessionService.getSessionManager() as unknown as MockCliSdkSessionManager;
-
+		const contentProvider = new class extends mock<CopilotCLIChatSessionContentProvider>() {
+			override notifySessionOptionsChange(_resource: vscode.Uri, _updates: ReadonlyArray<{ optionId: string; value: string }>): void {
+				// no-op
+			}
+		}();
 		participant = new CopilotCLIChatSessionParticipant(
+			contentProvider,
 			promptResolver,
 			itemProvider,
 			cloudProvider,

src/extension/vscode.proposed.chatSessionsProvider.d.ts

@@ -179,10 +179,39 @@ declare module 'vscode' {
 		readonly requestHandler: ChatRequestHandler | undefined;
 	}
 
+	/**
+	 * Event fired when chat session options change.
+	 */
+	export interface ChatSessionOptionChangeEvent {
+		/**
+		 * Identifier of the chat session being updated.
+		 */
+		readonly resource: Uri;
+		/**
+		 * Collection of option identifiers and their new values. Only the options that changed are included.
+		 */
+		readonly updates: ReadonlyArray<{
+			/**
+			 * Identifier of the option that changed (for example `model`).
+			 */
+			readonly optionId: string;
+
+			/**
+			 * The new value assigned to the option. When `undefined`, the option is cleared.
+			 */
+			readonly value: string;
+		}>;
+	}
+
 	/**
 	 * Provides the content for a chat session rendered using the native chat UI.
 	 */
 	export interface ChatSessionContentProvider {
+		/**
+		 * Event that the provider can fire to signal that the options for a chat session have changed.
+		 */
+		readonly onDidChangeChatSessionOptions?: Event<ChatSessionOptionChangeEvent>;
+
 		/**
 		 * Provides the chat session content for a given uri.
 		 *