mail-threading 0.1.3

JWZ email threading (RFC 5256). Reconstruct message threads from References/In-Reply-To headers, with subject fallback for broken clients.
Documentation 
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{
  "name": "subject-blob-normalization",
  "description": "RFC 5256 subject blobs such as list tags are ignored when a non-empty base subject remains.",
  "spec": {
    "source": "RFC 5256",
    "url": "https://www.rfc-editor.org/rfc/rfc5256",
    "behavior": "subj-blob prefixes are removed during base-subject extraction when they precede a non-empty subject base"
  },
  "input": [
    {
      "id": "blob-root",
      "message_id": "<blob-root@example>",
      "in_reply_to": null,
      "references": [],
      "subject": "[mxr] Topic",
      "date": "2026-05-15T09:00:00Z"
    },
    {
      "id": "blob-reply-after-prefix",
      "message_id": "<blob-reply-after-prefix@example>",
      "in_reply_to": null,
      "references": [],
      "subject": "Re: [mxr] Topic",
      "date": "2026-05-15T09:05:00Z"
    },
    {
      "id": "blob-reply-before-prefix",
      "message_id": "<blob-reply-before-prefix@example>",
      "in_reply_to": null,
      "references": [],
      "subject": "[mxr] Re: Topic",
      "date": "2026-05-15T09:10:00Z"
    }
  ],
  "expected": {
    "threads": [
      {
        "root": "blob-root",
        "messages": [
          "blob-root",
          "blob-reply-after-prefix",
          "blob-reply-before-prefix"
        ]
      }
    ]
  }
}