diff --git a/c/tools/make_glm_oracle.py b/c/tools/make_glm_oracle.py
index b623faf..b572a36 100644
--- a/c/tools/make_glm_oracle.py
+++ b/c/tools/make_glm_oracle.py
@@ -17,6 +17,45 @@ EN: computed AFTER the FP8 round-trip, so the reference matches exactly what the
 EN: ingests. Default: bf16 (original oracle unchanged)."""
 import json, sys, argparse
 from pathlib import Path
+
+# --- Version gate (must run BEFORE the heavy `from transformers import ...`,
+# which triggers transformers' lazy-loading and can in turn reset the in-memory
+# __version__ attribute; importlib.metadata reads the installed package version
+# directly and is immune to that). ---
+#
+# GLM-5.2's MLA attention uses interleaved (DeepSeek-style) RoPE, which is what
+# the C engine implements. transformers < 5.11.0 applied split-half (Llama-style)
+# RoPE in GlmMoeDsa* instead; an oracle built on those versions drifts and the
+# engine then scores 25/32 instead of the documented 32/32 (issue #281). Weights
+# come out identical across versions — only the forward pass differs — so there
+# is no safe "partial" run: a too-old transformers silently produces an invalid
+# ref_glm.json. Hard-fail rather than warn. EN: same.
+import transformers
+from importlib.metadata import version as _pkg_version, PackageNotFoundError
+
+_MIN_TRANSFORMERS = (5, 11)
+def _tf_version_tuple():
+    try:
+        v = _pkg_version("transformers")          # authoritative: installed dist metadata
+    except PackageNotFoundError:
+        v = getattr(transformers, "__version__", "0")   # fallback (editable/src installs)
+    out = []
+    for part in v.split(".")[:2]:                 # major.minor only
+        out.append(int("".join(c for c in part if c.isdigit()) or "0"))
+    while len(out) < 2:
+        out.append(0)
+    return tuple(out[:2])
+
+_tf_ver = _tf_version_tuple()
+if _tf_ver < _MIN_TRANSFORMERS:
+    sys.exit(
+        f"\nERROR: make_glm_oracle.py requires transformers >= "
+        f"{'.'.join(map(str, _MIN_TRANSFORMERS))}.0 (found {_tf_ver[0]}.{_tf_ver[1]}). "
+        f"GLM-5.2 MLA uses interleaved RoPE; older versions apply split-half RoPE "
+        f"and silently produce an oracle the engine scores 25/32 against (issue #281). "
+        f"Upgrade: pip install -U 'transformers>=5.11'\n"
+    )
+
 import torch
 from transformers import GlmMoeDsaConfig, GlmMoeDsaForCausalLM