{
 "schema_version": "1.7.0",
 "id": "x_NXMC-2026-0029",
 "modified": "2026-10-19T02:33:38.839Z",
 "published": "2026-10-18T09:00:52.565Z",
 "summary": "MiMo-V2.5: tokenizer change at c3f3abb (2026-04-27)",
 "details": "MiMo-V2.5: EOS changed from [151643,151645] to [151643,151645,1561672]; anything fine-tuned or served against the old value stops at a different token; 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; generation defaults changed (temperature unset to 1, top_p unset to 0.95); a call that does not pass these explicitly now generates differently (2026-04-27).\n\nRepository: https://huggingface.co/XiaomiMiMo/MiMo-V2.5. Revisions from c3f3abb0657e83f4894e1645f51072f975e62b93 onward carry this change; a pin at 4f78a4d18f532779ecc6cf3d33ce398a20f78328 or earlier does not.\n\nChanged keys:\n- tokenizer chat_template_sha256: beebeefcded62677 -> a342c8de81a9881e (template)\n- generation eos_token_id: [151643,151645] -> [151643,151645,1561672] (tokenizer)\n- generation temperature: unset -> 1 (generation-defaults)\n- generation top_p: unset -> 0.95 (generation-defaults)\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": "c3f3abb0657e83f4894e1645f51072f975e62b93"
      }
     ]
    }
   ],
   "database_specific": {
    "model": "XiaomiMiMo/MiMo-V2.5",
    "previous_revision": "4f78a4d18f532779ecc6cf3d33ce398a20f78328"
   }
  }
 ],
 "references": [
  {
   "type": "INTRODUCED",
   "url": "https://huggingface.co/XiaomiMiMo/MiMo-V2.5/commit/c3f3abb0657e83f4894e1645f51072f975e62b93"
  },
  {
   "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": "tokenizer",
  "classes": [
   "tokenizer",
   "template",
   "generation-defaults"
  ],
  "changed_keys": [
   {
    "file": "tokenizer",
    "key": "chat_template_sha256",
    "before": "beebeefcded62677",
    "after": "a342c8de81a9881e",
    "class": "template"
   },
   {
    "file": "generation",
    "key": "eos_token_id",
    "before": [
     151643,
     151645
    ],
    "after": [
     151643,
     151645,
     1561672
    ],
    "class": "tokenizer"
   },
   {
    "file": "generation",
    "key": "temperature",
    "before": null,
    "after": 1,
    "class": "generation-defaults"
   },
   {
    "file": "generation",
    "key": "top_p",
    "before": null,
    "after": 0.95,
    "class": "generation-defaults"
   }
  ],
  "impact": {
   "memory": false,
   "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": null,
   "eos": {
    "before": [
     151643,
     151645
    ],
    "after": [
     151643,
     151645,
     1561672
    ]
   },
   "bos": null
  },
  "commit_date": "2026-04-27T17:34:17.000Z",
  "detected_at": "2026-10-18T09:00:52.565Z",
  "detected_by": "backfill",
  "days_since_first_commit": 0,
  "license": "CC-BY-4.0"
 }
}