> 译文仅供阅读便利。具有规范效力的是英文原文。

# 事件流

```mermaid
flowchart LR
    subgraph TL["Semantic Timeline (append-only)"]
        direction LR
        E1["Created<br/>Event"] --> E2["Updated<br/>Event"]
        E2 --> E3["Approved<br/>Event"]
        E3 --> E4["Archived<br/>Event"]
    end

    TL ==> STATE[/"Derived State<br/>(current Projection)"/]

    classDef event fill:#eef3fb,stroke:#33415c,stroke-width:1px;
    classDef state fill:#e6f0ea,stroke:#2b6a4a,stroke-width:2px;
    class E1,E2,E3,E4 event;
    class STATE state;
```

*图注：事件不可变地累积在语义时间线上；当下的状态，是把它们重放一遍推导出来的，于是每一个状态都能经由它的事件讲清楚。*