# 架构

```mermaid
sequenceDiagram
  participant U as assistant-ui
  participant H as Fastify/Harness
  participant P as Pi AgentSession
  U->>H: POST message (202)
  H->>P: prompt(text,{images})
  P-->>H: session events
  H-->>U: ordered SSE events
  P->>H: save_report_draft
  H-->>U: approval.required
  U->>H: approve/deny
  H-->>P: resume/block
```

`packages/shared` 是无 Node 依赖协议；`packages/harness` 是无 React/Fastify 的核心；Fastify 只组合协议；Web 的 Store reducer 按 sequence 投影消息、Run、Tool 与 Approval。