graph TD
    subgraph KROW Mobile Applications
        direction LR
        Mobile_Client[<b>Mobile Client App</b><br>Flutter]
        Mobile_Staff[<b>Mobile Staff App</b><br>Flutter]
    end

    subgraph Firebase Backend Services - GCP
        direction TB
        Auth[Firebase Authentication]
        DataConnect[<b>Firebase Data Connect</b><br>GraphQL API &<br>Generated SDKs]
        SQL_DB[<b>Cloud SQL for PostgreSQL</b><br><i>Managed by Data Connect</i>]
    end

    Mobile_Client -- "Authenticates with" --> Auth
    Mobile_Client -- "Calls API via generated SDK" --> DataConnect

    Mobile_Staff -- "Authenticates with" --> Auth
    Mobile_Staff -- "Calls API via generated SDK" --> DataConnect

    DataConnect -- "Manages & Queries" --> SQL_DB
    
    style Mobile_Client fill:#eef,stroke:#333,stroke-width:2px
    style Mobile_Staff fill:#eef,stroke:#333,stroke-width:2px