/** One conversation, summarized (no message bodies). */
export interface ChatSessionSummary {
    sessionId: string;
    title: string | null;
    messageCount: number;
    lastMessageAt: Date | null;
    createdAt: Date;
}
export interface ChatSessionDetail extends ChatSessionSummary {
    messages: Array<{
        role: string;
        content: string;
        createdAt: Date;
    }>;
}
export interface ChatSessionReader {
    getSessionMessages(sessionId: string, limit?: number): Promise<Array<{
        role: string;
        content: string;
    }>>;
    listSessions(userId: string, limit?: number): Promise<ChatSessionSummary[]>;
    getSession(userId: string, sessionId: string, messageLimit?: number): Promise<ChatSessionDetail | null>;
}