The Ghost Overwrite on Dual-Write Migration

/**
 * Dual-Write Sync Dispatcher
 * Dispatches updates synchronously to Primary DB and asynchronously to Replication Bus.
 */

export class SyncDispatcher {
  constructor(primaryDb, messageBus) {
    this.primaryDb = primaryDb;
    this.messageBus = messageBus;
  }

  async updateEntity(entityId, updates) {
    // Commit to primary database which increments entity.version
    const updatedRecord = this.primaryDb.update(entityId, updates);

    // AI Attempt: Forward record payload to async message bus for CDC replica
    // BUG: Omitted updatedRecord.version in event payload!
    const cdcEvent = {
      entityId: entityId,
      payload: { ...updatedRecord.data },
      timestamp: Date.now()
    };

    await this.messageBus.publish("cdc.entities", cdcEvent);
    return updatedRecord;
  }
}