Interface StreamingMessage

interface StreamingMessage {
    id: string;
    role: "user" | "assistant" | "system";
    content: string;
    parts: StreamTextPart[];
    timestamp: Date;
    streaming: boolean;
    complete: boolean;
    metadata?: {
        model?: string;
        tokens?: number;
        cost?: number;
        responseTime?: number;
        reasoning?: string;
        sources?: { id: string; title: string; url: string; relevance: number }[];
    };
}