flowchart LR
    subgraph Sources["Data Sources"]
        HIS["Aveva Historian<br/>(SQL interface)<br/>Year 1 adapter"]
        RED["Redpanda Topics<br/>(ScadaBridge events)<br/>Year 2 adapter"]
        FUT["Future Sources<br/>(Ignition, Data Hub, etc.)"]
    end

    subgraph SnowBridge["SnowBridge (.NET service)"]
        direction TB
        SA["Source Adapters<br/>(pluggable per source)"]
        SEL["Selection Engine<br/>(which tags/topics → Snowflake)"]
        GOV["Governance Layer"]
        subgraph Approval["Approval Workflow"]
            SELF["Self-service<br/>(single tag, non-compliance)"]
            FOUR["Four-eyes review<br/>(new topic, compliance tier,<br/>high-cost impact)"]
        end
        UI["Operator Web UI + API<br/>(RBAC, audit trail,<br/>exportable state)"]
    end

    subgraph Snowflake["Snowflake"]
        LAND["Landing Tables<br/>(Snowpipe Streaming<br/>or COPY)"]
    end

    HIS --> SA
    RED --> SA
    FUT -.-> SA
    SA --> SEL
    UI --> GOV --> SEL
    GOV --> Approval
    SEL --> LAND
