private async _sendMessage(chat: URI, prompt: string, attachments?: readonly MessageAttachment[], turnId?: string, senderClientId?: string, workingDirectory?: URI): Promise<void> {
// Additional (non-default) chats are backed by their own SDK
// chat hosted on the owning session entry, keyed by the chat URI.
if (context.isPeerChat) {
const entry = await this._ensureChatSession(context.session, chat);
if (!entry) {