Graph element event schema

Flink publishes deterministic JSON records to graph.elements.events. Schema 3.0 is a clean contract break: edge counters and the metrics field do not exist. Kafka keys are always element_id, so compaction retains the latest complete state or deletion for each graph element.

Envelope

Field	Type	Meaning
schema_version	string	Always "3.0"
event_id	string	Deterministic SHA-256 identity for this lifecycle transition
event_type	string	Always graph_element_state_changed
element_id	string	Stable node or relationship ID and Kafka key
observed_at_unix_nano	integer	Evidence or expiry time
emitted_at_unix_ms	integer	Processing time when Flink emitted the record
operation	string	upsert or delete
payload_hash	string or null	Canonical element hash for upserts
element	object or null	Complete node/edge state for upserts

Node upsert

{
  "schema_version": "3.0",
  "event_id": "...",
  "event_type": "graph_element_state_changed",
  "element_id": "service:checkout",
  "observed_at_unix_nano": 1700000000000000000,
  "emitted_at_unix_ms": 1700000000000,
  "operation": "upsert",
  "payload_hash": "...",
  "element": {
    "kind": "node",
    "id": "service:checkout",
    "type": "service",
    "attributes": {"service.name": "checkout"}
  }
}

Edge upsert

{
  "schema_version": "3.0",
  "event_id": "...",
  "event_type": "graph_element_state_changed",
  "element_id": "edge:...",
  "observed_at_unix_nano": 1700000000000000000,
  "emitted_at_unix_ms": 1700000000000,
  "operation": "upsert",
  "payload_hash": "...",
  "element": {
    "kind": "edge",
    "id": "edge:...",
    "type": "calls",
    "source_id": "service:storefront",
    "target_id": "service:checkout",
    "attributes": {}
  }
}

Delete

Deletes have payload_hash: null and element: null. The indexer removes the document selected by element_id; edge deletes are attempted across generated edge collections because the ID contains no semantic-type prefix.

The indexer rejects any version other than 3.0 and rejects an element containing metrics.