%%metro title: Fan-In Merge
%%metro style: dark
%%metro line: main | Main | #0570b0
%%metro line: aux | Auxiliary | #2db572

graph LR
    subgraph source [Source]
        s1[Produce]
        s2[Prepare]
        s1 -->|main,aux| s2
    end

    subgraph step_a [Step A]
        a1[Process A]
        a2[Refine A]
        a1 -->|main| a2
    end

    subgraph step_b [Step B]
        b1[Process B]
        b2[Refine B]
        b1 -->|main| b2
    end

    subgraph sink [Sink]
        t1[Collect]
        t2[Report]
        t1 -->|main,aux| t2
    end

    %% Each section sends main to ALL downstream sections
    s2 -->|main| a1
    s2 -->|main| b1
    s2 -->|main| t1
    s2 -->|aux| t1
    a2 -->|main| b1
    a2 -->|main| t1
    b2 -->|main| t1
