{
"name": "single-message",
"description": "A message with no threading headers forms a single-message thread.",
"spec": {
"source": "RFC 5256 / JWZ",
"url": "https://www.rfc-editor.org/rfc/rfc5256",
"behavior": "a message with no parent references is a root"
},
"input": [
{
"id": "<solo@example>",
"message_id": "<solo@example>",
"in_reply_to": null,
"references": [],
"subject": "Solo",
"date": "2026-05-15T09:00:00Z"
}
],
"expected": {
"threads": [
{
"root": "<solo@example>",
"messages": [
"<solo@example>"
]
}
]
}
}