(args: AppendArgs
): Promise `\n\n```typescript\ninterface EventRecord {\n pk: AggregatePK; // \"AGG#{type}#{id}\"\n sk: EventSK; // \"EVT#000000042\"\n itemType: 'event';\n source: Source;\n aggregateId: AggregateId;\n aggregateType: AggregateType;\n version: number;\n eventId: EventId;\n eventType: string;\n schemaVersion?: number;\n occurredAt: string; // ISO timestamp\n correlationId?: string;\n causationId?: string;\n actorId?: string;\n payload: Readonly ;\n}\n```\n\n### `AggregateHead`\n\n```typescript\ninterface AggregateHead {\n pk: AggregatePK;\n sk: 'HEAD';\n itemType: 'head';\n aggregateId: AggregateId;\n aggregateType: AggregateType;\n currentVersion: number;\n lastEventId?: EventId;\n lastIdemKey?: string;\n updatedAt: string;\n}\n```\n\n### Branded types\n\n`Source`, `AggregateId`, `AggregateType`, `EventId` — branded string types for type safety. Cast with `as Source`, etc.\n\n## DynamoDB Table Schema\n\nThe event store uses a single-table design:\n\n| Key | Format | Description |\n|-----|--------|-------------|\n| `pk` | `AGG#{aggregateType}#{aggregateId}` | Partition key |\n| `sk` | `EVT#{version}` or `HEAD` | Sort key |\n\nEvents are immutable INSERT records. HEAD is updated atomically with each event via DynamoDB transactions.\n","readmeFilename":"README.md"}