flowchart TB
    subgraph Parent["Parent Page (embed.ts)"]
        direction TB
        CalAPI["Cal API<br/>(Cal.inline, Cal.modal, Cal.ui)"]
        ActionMgr["ActionManager<br/>(Event Listener)"]
        DoInIframe["doInIframe()<br/>(Command Sender)"]
        Queue["iframeDoQueue[]<br/>(Command Buffer)"]
        
        CalAPI --> DoInIframe
        DoInIframe -->|"if !iframeReady"| Queue
        Queue -->|"flush on ready"| DoInIframe
    end
    
    subgraph Transport["postMessage Transport"]
        direction TB
        ToIframe["parent.postMessage()<br/>{originator: 'CAL', method, arg}"]
        ToParent["iframe.postMessage()<br/>{originator: 'CAL', type, data}"]
    end
    
    subgraph Iframe["Iframe (embed-iframe.ts)"]
        direction TB
        MsgListener["window.addEventListener('message')"]
        Interface["interfaceWithParent<br/>{ui, parentKnowsIframeReady, connect}"]
        SDKAction["sdkActionManager<br/>(Event Emitter)"]
        EmbedStore["embedStore<br/>(State)"]
        
        MsgListener --> Interface
        Interface --> EmbedStore
        SDKAction -->|"fire()"| ToParent
    end
    
    DoInIframe -->|"Commands"| ToIframe
    ToIframe --> MsgListener
    
    ToParent --> ActionMgr
    
    style Parent fill:#e1f5fe,stroke:#01579b
    style Iframe fill:#fff3e0,stroke:#e65100
    style Transport fill:#f3e5f5,stroke:#7b1fa2