Fix session resource aliasing in chat sessions

src/vs/workbench/api/browser/mainThreadChatAgents2.ts

@@ -207,6 +207,22 @@ export class MainThreadChatAgents2 extends Disposable implements MainThreadChatA
 							if (newItem) {
 								chatSessionResource = newItem.resource;
 								isUntitled = false;
+
+								// Update the model's contributed session with the resolved resource
+								// so subsequent requests don't re-invoke newChatSessionItemHandler
+								// and getChatSessionFromInternalUri returns the real resource.
+								chatSession?.setContributedChatSession({
+									chatSessionType: contributedSession.chatSessionType,
+									chatSessionResource,
+									isUntitled: false,
+									initialSessionOptions: contributedSession.initialSessionOptions,
+								});
+
+								// Register alias so session-option lookups work with the new resource
+								this._chatSessionService.registerSessionResourceAlias(
+									contributedSession.chatSessionResource,
+									chatSessionResource
+								);
 							}
 						}
 

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

@@ -300,6 +300,7 @@ export class ChatSessionsService extends Disposable implements IChatSessionsServ
 	private readonly _sessionTypeInputPlaceholders: Map<string, string> = new Map();
 
 	private readonly _sessions = new ResourceMap<ContributedChatSessionData>();
+	private readonly _resourceAliases = new ResourceMap<URI>(); // real resource -> untitled resource
 
 	private readonly _hasCanDelegateProvidersKey: IContextKey<boolean>;
 
@@ -1078,20 +1079,33 @@ export class ChatSessionsService extends Disposable implements IChatSessionsServ
 	}
 
 	public hasAnySessionOptions(sessionResource: URI): boolean {
-		const session = this._sessions.get(sessionResource);
+		const session = this._sessions.get(this._resolveResource(sessionResource));
 		return !!session && !!session.options && Object.keys(session.options).length > 0;
 	}
 
 	public getSessionOption(sessionResource: URI, optionId: string): string | IChatSessionProviderOptionItem | undefined {
-		const session = this._sessions.get(sessionResource);
+		const session = this._sessions.get(this._resolveResource(sessionResource));
 		return session?.getOption(optionId);
 	}
 
 	public setSessionOption(sessionResource: URI, optionId: string, value: string | IChatSessionProviderOptionItem): boolean {
-		const session = this._sessions.get(sessionResource);
+		const session = this._sessions.get(this._resolveResource(sessionResource));
 		return !!session?.setOption(optionId, value);
 	}
 
+	/**
+	 * Resolve a resource through the alias map. If the resource is a real
+	 * resource that has been aliased to an untitled resource, return the
+	 * untitled resource (the canonical key in {@link _sessions}).
+	 */
+	private _resolveResource(resource: URI): URI {
+		return this._resourceAliases.get(resource) ?? resource;
+	}
+
+	public registerSessionResourceAlias(untitledResource: URI, realResource: URI): void {
+		this._resourceAliases.set(realResource, untitledResource);
+	}
+
 	/**
 	 * Store option groups for a session type
 	 */
@@ -1134,7 +1148,7 @@ export class ChatSessionsService extends Disposable implements IChatSessionsServ
 		for (const u of updates) {
 			this.setSessionOption(sessionResource, u.optionId, u.value);
 		}
-		this._onDidChangeSessionOptions.fire(sessionResource);
+		this._onDidChangeSessionOptions.fire(this._resolveResource(sessionResource));
 		this._logService.trace(`[ChatSessionsService] notifySessionOptionsChange: finished for ${sessionResource}`);
 	}
 

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

@@ -306,6 +306,12 @@ export interface IChatSessionsService {
 	 * Returns undefined if the controller doesn't have a handler or if no controller is registered.
 	 */
 	createNewChatSessionItem(chatSessionType: string, request: IChatAgentRequest, token: CancellationToken): Promise<IChatSessionItem | undefined>;
+
+	/**
+	 * Registers an alias so that session-option lookups by the real resource
+	 * are redirected to the canonical (untitled) resource in the internal session map.
+	 */
+	registerSessionResourceAlias(untitledResource: URI, realResource: URI): void;
 }
 
 export function isSessionInProgressStatus(state: ChatSessionStatus): boolean {

src/vs/workbench/contrib/chat/test/common/mockChatSessionsService.ts

@@ -229,6 +229,10 @@ export class MockChatSessionsService implements IChatSessionsService {
 		return undefined;
 	}
 
+	registerSessionResourceAlias(_untitledResource: URI, _realResource: URI): void {
+		// noop
+	}
+
 	registerChatModelChangeListeners(chatService: IChatService, chatSessionType: string, onChange: () => void): IDisposable {
 		// Store the emitter so tests can trigger it
 		this.onChange = onChange;