POST /api/blobs/{id}/relations.endpoint_readable_by_profile){
"confidence": "tentative",
"correlation_id": "807686c4-116c-44b3-a01c-b14b50e31bcc",
"invocation_id": "9efe53a2-0f4e-415e-a218-b405e1367798",
"model": "string",
"persona": "string",
"rationale": "string",
"reasoning": "string",
"direction": "blob_as_source",
"edge_kind": "express",
"label": "string",
"peer_id": "118d4485-cd94-4ecd-b71e-80f79647bc58",
"peer_table": "string",
"polarity": "forward",
"weight": 0
}