{
 "schema_version": "1.7.0",
 "id": "x_NXMC-2026-0030",
 "modified": "2026-10-19T02:33:38.839Z",
 "published": "2026-10-18T09:00:52.565Z",
 "summary": "MiMo-V2.5: structural change at 4da2748 (2026-04-28)",
 "details": "MiMo-V2.5: context window 262144 to 1048576 tokens; rope_theta 5000000 to 10000000; every position embedding changes; the chat template changed and renders differently (system+user, multi-turn, tool-call); prompts rendered with the old one no longer match what the model now expects, so cached prompts and eval sets need re-rendering (2026-04-28).\n\nRepository: https://huggingface.co/XiaomiMiMo/MiMo-V2.5. Revisions from 4da2748fc0a0123d817280b1b0cd3682a487a161 onward carry this change; a pin at c3f3abb0657e83f4894e1645f51072f975e62b93 or earlier does not.\n\nChanged keys:\n- max_position_embeddings: 262144 -> 1048576 (structural)\n- rope_theta: 5000000 -> 10000000 (structural)\n- tokenizer chat_template_sha256: a342c8de81a9881e -> e2da147933d7d30e (template)\n\nThis record says what the change does mechanically. It is not a report that anything broke for anyone.",
 "affected": [
  {
   "ranges": [
    {
     "type": "GIT",
     "repo": "https://huggingface.co/XiaomiMiMo/MiMo-V2.5",
     "events": [
      {
       "introduced": "4da2748fc0a0123d817280b1b0cd3682a487a161"
      }
     ]
    }
   ],
   "database_specific": {
    "model": "XiaomiMiMo/MiMo-V2.5",
    "previous_revision": "c3f3abb0657e83f4894e1645f51072f975e62b93"
   }
  }
 ],
 "references": [
  {
   "type": "INTRODUCED",
   "url": "https://huggingface.co/XiaomiMiMo/MiMo-V2.5/commit/4da2748fc0a0123d817280b1b0cd3682a487a161"
  },
  {
   "type": "PACKAGE",
   "url": "https://huggingface.co/XiaomiMiMo/MiMo-V2.5"
  },
  {
   "type": "WEB",
   "url": "https://www.neurarch.com/changes-feeds/models/XiaomiMiMo/MiMo-V2.5.html"
  }
 ],
 "database_specific": {
  "source": "neurarch model change tracker",
  "model": "XiaomiMiMo/MiMo-V2.5",
  "kind": "structural",
  "classes": [
   "structural",
   "template"
  ],
  "changed_keys": [
   {
    "file": "config",
    "key": "max_position_embeddings",
    "before": 262144,
    "after": 1048576,
    "class": "structural"
   },
   {
    "file": "config",
    "key": "rope_theta",
    "before": 5000000,
    "after": 10000000,
    "class": "structural"
   },
   {
    "file": "tokenizer",
    "key": "chat_template_sha256",
    "before": "a342c8de81a9881e",
    "after": "e2da147933d7d30e",
    "class": "template"
   }
  ],
  "impact": {
   "memory": true,
   "serving": true,
   "tokenizer": true,
   "licence": null
  },
  "breaking": true,
  "breaking_rule": "https://www.neurarch.com/changes-feeds/advisories/index.json#breaking_rule",
  "consequence": {
   "params": null,
   "weightsGbBf16": null,
   "trainPeakGb": null,
   "fingerprint": null,
   "context": {
    "before": 262144,
    "after": 1048576
   },
   "eos": null,
   "bos": null
  },
  "commit_date": "2026-04-28T12:42:00.000Z",
  "detected_at": "2026-10-18T09:00:52.565Z",
  "detected_by": "backfill",
  "days_since_first_commit": 0,
  "license": "CC-BY-4.0"
 }
}