DiagramDto

{
    "nodes": [
        {
            "id": "ch_events",
            "label": "CH events",
            "type": "source",
            "group": "write",
            "fieldCount": 164,
            "description": "MergeTree — append-only log (flat)"
        }
    ],
    "edges": [
        {
            "id": "mongo_to_kafka",
            "source": "mongodb",
            "target": "kafka",
            "label": "nested → flat",
            "description": "ClickHouseEventMapperService denormalizes nested objects",
            "fieldCount": 202
        }
    ]
}