{
"name": "stable-thread-ordering-with-caller-ids",
"description": "Independent threads are ordered by message date even when caller ids differ from Message-ID headers.",
"spec": {
"source": "public API contract",
"url": "https://www.rfc-editor.org/rfc/rfc5256",
"behavior": "caller ids are output identities, not internal container keys"
},
"input": [
{
"id": "mxr-later",
"message_id": "<later@example>",
"in_reply_to": null,
"references": [],
"subject": "Later",
"date": "2026-05-15T10:00:00Z"
},
{
"id": "mxr-earlier",
"message_id": "<earlier@example>",
"in_reply_to": null,
"references": [],
"subject": "Earlier",
"date": "2026-05-15T09:00:00Z"
}
],
"expected": {
"threads": [
{
"root": "mxr-earlier",
"messages": [
"mxr-earlier"
]
},
{
"root": "mxr-later",
"messages": [
"mxr-later"
]
}
]
}
}