{
"name": "reply-arrives-before-parent",
"description": "A reply can arrive before its parent and still be threaded under it.",
"spec": {
"source": "JWZ",
"url": "https://www.jwz.org/doc/threading.html",
"behavior": "phantom containers are materialized when their messages arrive later"
},
"input": [
{
"id": "<late-parent-reply@example>",
"message_id": "<late-parent-reply@example>",
"in_reply_to": "<late-parent-root@example>",
"references": [],
"subject": "Re: Late",
"date": "2026-05-15T09:05:00Z"
},
{
"id": "<late-parent-root@example>",
"message_id": "<late-parent-root@example>",
"in_reply_to": null,
"references": [],
"subject": "Late",
"date": "2026-05-15T09:00:00Z"
}
],
"expected": {
"threads": [
{
"root": "<late-parent-root@example>",
"messages": [
"<late-parent-root@example>",
"<late-parent-reply@example>"
]
}
]
}
}