How to save `data-` emitted from workflows in storage?

            const uiMessageChunks: UIMessageChunk[] = [];
            for await (const chunk of toAISdkStream(stream.fullStream, {})) {
                writer.write(chunk as UIMessageChunk);
                uiMessageChunks.push(chunk);
            }
            await mastra.getStorage()?.saveMessages({
                messages: [
                    {
                        id: uuid(),
                        role: 'assistant',
                        threadId: context.get('threadId'),
                        resourceId: context.get('resourceId'),
                        createdAt: new Date(),
                        type: 'assistant',
                        content: {
                            format: 2,
                            parts: uiMessageChunks,
                        },
                    },
                ],
            });