sequenceDiagram
    participant PT as Playwright Tests
    participant BF as Browser Fixture
    participant TS as Tunnel Server (WebSocket)
    participant HS as HTTP Server
    participant VSC as VS Code Extension
    participant BS as Browser Server
    participant LB as Local Browser

    Note over PT,LB: Context:  Enables local browser testing for remote VS Code environments (e.g., Codespaces)

    PT->>BF:  Trigger custom browser fixture
    
    par Fixture Setup
        BF->>HS: Launch localhost HTTP server
        BF->>TS: Launch WebSocket tunnel server (well-known port)
    end

    BF->>HS: browser.connect('http://localhost:<port>? browser=chromium&launchOptions={}')
    
    loop Polling
        VSC->>TS: Poll for connection (well-known port)
    end

    TS-->>VSC: WebSocket connection established
    
    BF->>VSC: Send handshake (browser type, launchOptions, Playwright version)
    
    VSC->>VSC: Install requested Playwright version
    VSC->>VSC: Install requested browser
    
    VSC->>BS: Launch browserServer via Playwright API
    BS->>LB: Start local browser instance
    
    VSC->>BS: Create WebSocket client connection
    
    VSC->>TS: Send acknowledgement (ready to go)
    
    par Setup Forwarding
        Note over BF,TS:  Fixture:  PT ↔ Tunnel Server
        Note over VSC,BS: Extension: Tunnel Server ↔ Browser Server
    end

    BF->>BF:  Flush buffered messages from test

    rect rgb(200, 230, 200)
        Note over PT,LB:  Transparent bidirectional communication established
        PT->>BF:  Playwright commands
        BF->>TS: Forward to tunnel
        TS->>VSC: Forward to extension
        VSC->>BS: Forward to browser server
        BS->>LB: Execute in local browser
        LB-->>BS: Response
        BS-->>VSC: Forward response
        VSC-->>TS: Forward to tunnel
        TS-->>BF: Forward to fixture
        BF-->>PT: Return to test
    end

    Note over PT,LB: 🎉 Profit!  Local browser available to remote tests transparently