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digraph BWE_DataFlow {
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    rankdir=LR;
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    node [shape=box, style=rounded];
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    // External inputs/outputs
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    TWCC [label="TWCC Feedback\n(from remote)", shape=ellipse, style=filled, fillcolor=lightblue];
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    Application [label="Application", shape=ellipse, style=filled, fillcolor=lightblue];
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    Network [label="Network\n(packets out)", shape=ellipse, style=filled, fillcolor=lightblue];
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    // Main orchestrator
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    SSBE [label="SendSide\nBandwidth\nEstimator", style="filled,rounded", fillcolor=gold];
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    // Delay-based path
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    DC [label="Delay\nController", style=filled, fillcolor=lightcoral];
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    AGA [label="Arrival Group\nAccumulator", style=filled, fillcolor=lightyellow];
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    TE [label="Trendline\nEstimator", style=filled, fillcolor=lightyellow];
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    RC [label="Rate Control\n(AIMD)", style=filled, fillcolor=lightyellow];
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    // Throughput measurement
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    ABE [label="Acked Bitrate\nEstimator", style=filled, fillcolor=lightcyan];
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    // Loss-based path
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    LC [label="Loss\nController", style=filled, fillcolor=lightpink];
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    // Probe system
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    PC [label="Probe\nControl", style=filled, fillcolor=plum];
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    PE [label="Probe\nEstimator", style=filled, fillcolor=plum];
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    // ALR system
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    ALR [label="ALR\nDetector", style=filled, fillcolor=wheat];
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    LCE [label="Link Capacity\nEstimator", style=filled, fillcolor=wheat];
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    // Pacer system
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    Pacer [label="Pacer\n(LeakyBucket +\nProbeClusterState)", style=filled, fillcolor=palegreen];
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    PacerCtrl [label="Pacer\nControl", style=filled, fillcolor=palegreen];
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    // Data flows
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    TWCC -> SSBE [label="TwccSendRecord[]"];
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    TWCC -> ABE [label="acked packets"];
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    SSBE -> Application [label="bandwidth estimate", color=blue, penwidth=2];
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    SSBE -> PacerCtrl [label="estimate"];
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    // Delay controller internal flow
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    DC -> AGA [label="acked packets"];
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    AGA -> TE [label="InterGroupDelayDelta"];
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    TE -> RC [label="BandwidthUsage\n(overuse/normal/underuse)"];
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    RC -> DC [label="estimated bitrate"];
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    // Delay controller to main
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    DC -> SSBE [label="delay estimate", color=red, penwidth=2];
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    // Acked bitrate flows
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    ABE -> DC [label="instantaneous\nbitrate"];
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    ABE -> LC [label="instantaneous\nbitrate"];
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    // Loss controller
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    LC -> SSBE [label="loss estimate", color=red, penwidth=2];
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    TWCC -> LC [label="packet results"];
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    // Probe system flows
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    PC -> SSBE [label="ProbeClusterConfig"];
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    SSBE -> PE [label="start probe\n(ProbeClusterConfig)", color=purple];
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    SSBE -> Pacer [label="start probe\n(ProbeClusterConfig)", color=purple];
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    Pacer -> SSBE [label="probe complete\n(cluster_id)", color=purple];
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    TWCC -> PE [label="TwccSendRecord[]\n(filtered by cluster)", color=purple];
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    PE -> SSBE [label="ProbeResult", color=purple, penwidth=2];
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    SSBE -> DC [label="probe result"];
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    // ALR system flows
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    ALR -> PC [label="ALR state\n(start time)"];
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    ALR -> LC [label="ALR state\n(start time)"];
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    SSBE -> ALR [label="media sent"];
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    PE -> LCE [label="ALR probe results", color=orange];
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    LCE -> LC [label="capacity estimate", color=orange, penwidth=2];
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    // Pacer control
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    PacerCtrl -> Pacer [label="pacing_rate\npadding_rate"];
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    // Pacer output
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    Pacer -> Network [label="paced packets\n(with cluster ID)", color=blue, penwidth=2];
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    // Grouping for visual clarity
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    subgraph cluster_delay {
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        label="Delay-Based Estimation";
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        style=dashed;
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        color=darkred;
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        DC; AGA; TE; RC;
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    }
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    subgraph cluster_probe {
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        label="Probe System";
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        style=dashed;
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        color=purple;
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        PC; PE;
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    }
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    subgraph cluster_pacer {
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        label="Pacing System";
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        style=dashed;
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        color=darkgreen;
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        Pacer; PacerCtrl;
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    }
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    subgraph cluster_alr {
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        label="ALR System";
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        style=dashed;
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        color=orange;
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        ALR; LCE;
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    }
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}
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