fix(prune): Minitron HybridModel + GPT-family fused-TE-spec import/export

CHANGELOG.rst

@@ -26,7 +26,11 @@ Changelog
 - DeepSeek PTQ (``examples/deepseek/ptq.py``) now defaults to native top-k calibration with post-hoc per-layer peer-max sync of expert ``input_quantizer.amax``; the all-experts path is preserved behind ``--calib_all_experts``.
 - Add NVFP4 W4A16 weight-only quantization (``w4a16_nvfp4``): FP4 weights with group_size=16, BF16 activations, no calibration forward pass required. Use ``mtq.W4A16_NVFP4_CFG`` or ``--qformat w4a16_nvfp4`` in ``hf_ptq.py``. vLLM deployment support is in progress.
 
-0.44 (2026-05-18)
+**Bug Fixes**
+
+- Fix Megatron-Core HF importer to load fused ``TELayerNormColumnParallelLinear.layer_norm_weight`` from HF for GPT-family models (Qwen3 etc.) under ``--export-default-te-spec``. Importer now prefers per-context keys ``fused_input_layernorm`` / ``fused_pre_mlp_layernorm`` (fallback ``fused_norm`` for Nemotron-H backward compatibility); ``mcore_qwen.py`` provides the new rules. Without this fix, post-prune MMLU sat at chance.
+
+0.44 (2026-05-14)
 ^^^^^^^^^^^^^^^^^
 
 **New Features**

modelopt/torch/export/plugins/mcore_deepseek.py

@@ -43,6 +43,10 @@
     "linear_kv_up_proj": NameRemapping("model.layers.{}.self_attn.kv_b_proj."),
     "linear_proj": NameRemapping("model.layers.{}.self_attn.o_proj."),
     "pre_mlp_layernorm": NameRemapping("model.layers.{}.post_attention_layernorm."),
+    # Fused TE spec (mirrors the import side). MLA has no linear_qkv so
+    # fused_input_layernorm is inert today; fused_pre_mlp_layernorm reaches dense layers.
+    "fused_input_layernorm": NameRemapping("model.layers.{}.input_layernorm.weight"),
+    "fused_pre_mlp_layernorm": NameRemapping("model.layers.{}.post_attention_layernorm.weight"),
     # MLP for dense layers
     "linear_fc1": GatedMLPSlicing("model.layers.{}.mlp."),
     "linear_fc2": NameRemapping("model.layers.{}.mlp.down_proj."),
@@ -88,6 +92,11 @@
     "output_layer": NameRemapping("lm_head.", COL_TP),
     # Per-layer
     "input_layernorm": NameRemapping("model.layers.{}.input_layernorm.", REPLICATE),
+    # Fused TE spec (TELayerNormColumnParallelLinear) — see mcore_qwen.py for rationale.
+    # MLA has no linear_qkv so fused_input_layernorm is inert for DeepSeek today; included
+    # for parity in case a future spec fuses the layernorm into a Q/KV projection.
+    "fused_input_layernorm": NameRemapping("model.layers.{}.input_layernorm.weight"),
+    "fused_pre_mlp_layernorm": NameRemapping("model.layers.{}.post_attention_layernorm.weight"),
     "linear_q_proj": NameRemapping("model.layers.{}.self_attn.q_proj.", COL_TP),
     "linear_q_down_proj": NameRemapping("model.layers.{}.self_attn.q_a_proj.", REPLICATE),
     "linear_q_layernorm": NameRemapping("model.layers.{}.self_attn.q_a_layernorm.", REPLICATE),

modelopt/torch/export/plugins/mcore_gptoss.py

@@ -31,6 +31,8 @@
 gptoss_causal_lm_export: dict[str, CustomModuleMapping | bool] = {
     "word_embeddings": NameRemapping("model.embed_tokens."),
     "input_layernorm": NameRemapping("model.layers.{}.input_layernorm."),
+    # MoE-only on MLP side, so fused_pre_mlp_layernorm path is unreachable.
+    "fused_input_layernorm": NameRemapping("model.layers.{}.input_layernorm.weight"),
     "linear_qkv": QKVSlicing("model.layers.{}.self_attn."),
     "linear_proj": NameRemapping("model.layers.{}.self_attn.o_proj."),
     "softmax_offset": NameRemapping("model.layers.{}.self_attn.sinks"),
@@ -52,6 +54,10 @@
 gptoss_causal_lm_import: dict[str, CustomModuleMapping | bool] = {
     "word_embeddings": NameRemapping("model.embed_tokens.", COL_TP),
     "input_layernorm": NameRemapping("model.layers.{}.input_layernorm.", REPLICATE),
+    # Fused TE spec (TELayerNormColumnParallelLinear) — see mcore_qwen.py for rationale.
+    # gpt-oss is MoE-only on the MLP side (no layer.mlp.linear_fc1), so the importer's
+    # fused_pre_mlp_layernorm path is unreachable; only fused_input_layernorm is wired.
+    "fused_input_layernorm": NameRemapping("model.layers.{}.input_layernorm.weight"),
     "linear_qkv": QKVMerging("model.layers.{}.self_attn.", COL_TP),
     "linear_proj": NameRemapping("model.layers.{}.self_attn.o_proj.", ROW_TP),
     "softmax_offset": NameRemapping("model.layers.{}.self_attn.sinks", COL_TP),

modelopt/torch/export/plugins/mcore_llama.py

@@ -37,11 +37,13 @@
 llama_causal_lm_export: dict[str, CustomModuleMapping] = {
     "word_embeddings": NameRemapping("model.embed_tokens."),
     "input_layernorm": NameRemapping("model.layers.{}.input_layernorm."),
+    "fused_input_layernorm": NameRemapping("model.layers.{}.input_layernorm.weight"),
     "linear_qkv": QKVSlicing("model.layers.{}.self_attn."),
     "linear_proj": NameRemapping("model.layers.{}.self_attn.o_proj."),
     # KV cache quant export
     "core_attention": SelfAttentionScaling("model.layers.{}.self_attn."),
     "pre_mlp_layernorm": NameRemapping("model.layers.{}.post_attention_layernorm."),
+    "fused_pre_mlp_layernorm": NameRemapping("model.layers.{}.post_attention_layernorm.weight"),
     "linear_fc1": GatedMLPSlicing("model.layers.{}.mlp."),
     "linear_fc2": NameRemapping("model.layers.{}.mlp.down_proj."),
     "final_layernorm": NameRemapping("model.norm."),
@@ -51,6 +53,8 @@
 llama4_causal_lm_export: dict[str, CustomModuleMapping | bool] = {
     "word_embeddings": NameRemapping("language_model.model.embed_tokens."),
     "input_layernorm": NameRemapping("language_model.model.layers.{}.input_layernorm."),
+    # MoE-only on MLP side, so fused_pre_mlp_layernorm path is unreachable.
+    "fused_input_layernorm": NameRemapping("language_model.model.layers.{}.input_layernorm.weight"),
     # self_attn
     "linear_qkv": QKVSlicing("language_model.model.layers.{}.self_attn."),
     "linear_proj": NameRemapping("language_model.model.layers.{}.self_attn.o_proj."),
@@ -150,9 +154,12 @@
 llama_causal_lm_import: dict[str, CustomModuleMapping] = {
     "word_embeddings": NameRemapping("model.embed_tokens.", COL_TP),
     "input_layernorm": NameRemapping("model.layers.{}.input_layernorm.", REPLICATE),
+    # Fused TE spec (TELayerNormColumnParallelLinear) — see mcore_qwen.py for rationale.
+    "fused_input_layernorm": NameRemapping("model.layers.{}.input_layernorm.weight"),
     "linear_qkv": QKVMerging("model.layers.{}.self_attn.", COL_TP),
     "linear_proj": NameRemapping("model.layers.{}.self_attn.o_proj.", ROW_TP),
     "pre_mlp_layernorm": NameRemapping("model.layers.{}.post_attention_layernorm.", REPLICATE),
+    "fused_pre_mlp_layernorm": NameRemapping("model.layers.{}.post_attention_layernorm.weight"),
     "linear_fc1": GatedMLPMerging("model.layers.{}.mlp.", COL_TP),
     "linear_fc2": NameRemapping("model.layers.{}.mlp.down_proj.", ROW_TP),
     "final_layernorm": NameRemapping("model.norm.", REPLICATE),
@@ -162,6 +169,10 @@
 llama4_causal_lm_import: dict[str, CustomModuleMapping | bool] = {
     "word_embeddings": NameRemapping("language_model.model.embed_tokens.", COL_TP),
     "input_layernorm": NameRemapping("language_model.model.layers.{}.input_layernorm.", REPLICATE),
+    # Fused TE spec (TELayerNormColumnParallelLinear) — see mcore_qwen.py for rationale.
+    # Llama4 is MoE-only on the MLP side (no layer.mlp.linear_fc1), so the importer's
+    # fused_pre_mlp_layernorm path is unreachable; only fused_input_layernorm is wired.
+    "fused_input_layernorm": NameRemapping("language_model.model.layers.{}.input_layernorm.weight"),
     "linear_qkv": QKVMerging("language_model.model.layers.{}.self_attn.", COL_TP),
     "linear_proj": NameRemapping("language_model.model.layers.{}.self_attn.o_proj.", ROW_TP),
     "pre_mlp_layernorm": NameRemapping(

modelopt/torch/export/plugins/mcore_qwen.py

@@ -35,12 +35,17 @@
     "output_layer": NameRemapping("lm_head.", COL_TP),
     # Attention
     "input_layernorm": NameRemapping("model.layers.{}.input_layernorm.", REPLICATE),
+    # Fused TE spec (TELayerNormColumnParallelLinear): the LayerNorm weight lives on
+    # linear_qkv.layer_norm_weight, loaded directly from the HF norm tensor (no `.weight` suffix
+    # appended since the value is a Parameter, not a sub-module).
+    "fused_input_layernorm": NameRemapping("model.layers.{}.input_layernorm.weight"),
     "linear_qkv": QKVMerging("model.layers.{}.self_attn.", COL_TP),
     "linear_proj": NameRemapping("model.layers.{}.self_attn.o_proj.", ROW_TP),
     "q_layernorm": NameRemapping("model.layers.{}.self_attn.q_norm.", REPLICATE),
     "k_layernorm": NameRemapping("model.layers.{}.self_attn.k_norm.", REPLICATE),
     # MLP
     "pre_mlp_layernorm": NameRemapping("model.layers.{}.post_attention_layernorm.", REPLICATE),
+    "fused_pre_mlp_layernorm": NameRemapping("model.layers.{}.post_attention_layernorm.weight"),
     "linear_fc1": GatedMLPMerging("model.layers.{}.mlp.", COL_TP),
     "linear_fc2": NameRemapping("model.layers.{}.mlp.down_proj.", ROW_TP),
     # MoE
@@ -56,12 +61,14 @@
     "output_layer": NameRemapping("lm_head."),
     # Attention
     "input_layernorm": NameRemapping("model.layers.{}.input_layernorm."),
+    "fused_input_layernorm": NameRemapping("model.layers.{}.input_layernorm.weight"),
     "linear_qkv": QKVSlicing("model.layers.{}.self_attn."),
     "linear_proj": NameRemapping("model.layers.{}.self_attn.o_proj."),
     "q_layernorm": NameRemapping("model.layers.{}.self_attn.q_norm."),
     "k_layernorm": NameRemapping("model.layers.{}.self_attn.k_norm."),
     # MLP
     "pre_mlp_layernorm": NameRemapping("model.layers.{}.post_attention_layernorm."),
+    "fused_pre_mlp_layernorm": NameRemapping("model.layers.{}.post_attention_layernorm.weight"),
     "linear_fc1": GatedMLPSlicing("model.layers.{}.mlp."),
     "linear_fc2": NameRemapping("model.layers.{}.mlp.down_proj."),
     # MoE
@@ -76,10 +83,12 @@
     "output_layer": NameRemapping("lm_head.", COL_TP),
     # Attention
     "input_layernorm": NameRemapping("model.layers.{}.input_layernorm.", REPLICATE),
+    "fused_input_layernorm": NameRemapping("model.layers.{}.input_layernorm.weight"),
     "linear_qkv": QKVMerging("model.layers.{}.self_attn.", COL_TP),
     "linear_proj": NameRemapping("model.layers.{}.self_attn.o_proj.", ROW_TP),
     # MLP
     "pre_mlp_layernorm": NameRemapping("model.layers.{}.post_attention_layernorm.", REPLICATE),
+    "fused_pre_mlp_layernorm": NameRemapping("model.layers.{}.post_attention_layernorm.weight"),
     "linear_fc1": GatedMLPMerging("model.layers.{}.mlp.", COL_TP),
     "linear_fc2": NameRemapping("model.layers.{}.mlp.down_proj.", ROW_TP),
 }
@@ -90,10 +99,12 @@
     "output_layer": NameRemapping("lm_head."),
     # Attention
     "input_layernorm": NameRemapping("model.layers.{}.input_layernorm."),
+    "fused_input_layernorm": NameRemapping("model.layers.{}.input_layernorm.weight"),
     "linear_qkv": QKVSlicing("model.layers.{}.self_attn."),
     "linear_proj": NameRemapping("model.layers.{}.self_attn.o_proj."),
     # MLP
     "pre_mlp_layernorm": NameRemapping("model.layers.{}.post_attention_layernorm."),
+    "fused_pre_mlp_layernorm": NameRemapping("model.layers.{}.post_attention_layernorm.weight"),
     "linear_fc1": GatedMLPSlicing("model.layers.{}.mlp."),
     "linear_fc2": NameRemapping("model.layers.{}.mlp.down_proj."),
 }

modelopt/torch/export/plugins/megatron_importer.py

@@ -238,8 +238,9 @@ def _gated_mlp_merging(
             else:
                 prefix = prefix.replace("model", "mtp")
 
-        weight = module.state_dict().get("weight", None)
-        weight_scale = module.state_dict().get("weight_quantizer._scale", None)
+        module_state_dict = module.state_dict()
+        weight = module_state_dict.get("weight", None)
+        weight_scale = module_state_dict.get("weight_quantizer._scale", None)
 
         state_dict = {}
 
@@ -273,6 +274,15 @@ def _gated_mlp_merging(
         else:
             state_dict["weight"] = tensor.to(self.dtype).to(device=weight.device)
 
+        # Preserve the fused LayerNorm weight + TE _extra_state already on the module so
+        # the strict load_state_dict below doesn't fail for TELayerNormColumnParallelLinear
+        # (fused under --export-default-te-spec). The actual HF norm tensor is loaded
+        # separately via the `fused_pre_mlp_layernorm` rule.
+        layer_norm_weight = module_state_dict.get("layer_norm_weight", None)
+        if layer_norm_weight is not None:
+            state_dict["layer_norm_weight"] = layer_norm_weight
+            state_dict["_extra_state"] = module_state_dict.get("_extra_state")
+
         module.load_state_dict(state_dict)
 
     def _grouped_mlp_merging(
@@ -433,7 +443,10 @@ def _qkv_merging(
         layer_norm_weight = module_state_dict.get("layer_norm_weight", None)
         if layer_norm_weight is not None:
             state_dict["layer_norm_weight"] = layer_norm_weight
-            state_dict["_extra_state"] = None  # for TE modules require _extra_state key
+            # Preserve the TE metadata struct (FP8 amax history, recipe version, etc.) —
+            # `load_state_dict(..., strict=True)` requires the key, but blanking it could
+            # zero out per-module FP8 bookkeeping on TE versions that populate it.
+            state_dict["_extra_state"] = module_state_dict.get("_extra_state")
 
         module.load_state_dict(state_dict)
 
@@ -599,14 +612,32 @@ def _import_transformer_layer(self, layer, layer_id, layer_pbar, is_mtp: bool =
                     )
 
             # TE spec: input_layernorm is fused into linear_qkv (TELayerNormColumnParallelLinear).
-            # Load the fused layer_norm_weight from the HF norm path.
+            # Prefer the per-context key (`fused_input_layernorm`); fall back to the legacy
+            # single-key `fused_norm` for Nemotron-H style (one norm shared across slots).
+            # Missing both is a plugin misconfig — raise rather than silently random-init.
             if (
                 isinstance(layer.input_layernorm, IdentityOp)
                 and hasattr(attention, "linear_qkv")
                 and hasattr(attention.linear_qkv, "layer_norm_weight")
-                and "fused_norm" in self.rules
             ):
-                self.rules["fused_norm"](
+                fused_key = (
+                    "fused_input_layernorm"
+                    if "fused_input_layernorm" in self.rules
+                    else "fused_norm"
+                )
+                if fused_key not in self.rules:
+                    # Branch only fires when model uses fused TELayerNormColumnParallelLinear,
+                    # so missing rule is unambiguously a plugin misconfiguration; raise so it
+                    # doesn't silently ship a chance-accuracy checkpoint.
+                    raise KeyError(
+                        f"{self.arch} uses fused TELayerNormColumnParallelLinear for "
+                        "attention but neither `fused_input_layernorm` nor legacy "
+                        "`fused_norm` is in its import mapping; `linear_qkv.layer_norm_weight` "
+                        "would be left at random init. Add "
+                        '`fused_input_layernorm: NameRemapping("...input_layernorm.weight")` '
+                        f"to the {self.arch} import mapping."
+                    )
+                self.rules[fused_key](
                     attention.linear_qkv.layer_norm_weight, layer_id, is_mtp=is_mtp
                 )
 
@@ -707,14 +738,27 @@ def _import_transformer_layer(self, layer, layer_id, layer_pbar, is_mtp: bool =
                 self.rules["linear_fc2"](layer.mlp.linear_fc2, layer_id, is_mtp=is_mtp)
 
                 # TE spec: pre_mlp_layernorm is fused into linear_fc1
-                # (TELayerNormColumnParallelLinear).
-                # Load the fused layer_norm_weight from the HF norm path.
-                if (
-                    isinstance(layer.pre_mlp_layernorm, IdentityOp)
-                    and hasattr(layer.mlp.linear_fc1, "layer_norm_weight")
-                    and "fused_norm" in self.rules
+                # (TELayerNormColumnParallelLinear). See input_layernorm path above for the
+                # rule-key fallback rationale.
+                if isinstance(layer.pre_mlp_layernorm, IdentityOp) and hasattr(
+                    layer.mlp.linear_fc1, "layer_norm_weight"
                 ):
-                    self.rules["fused_norm"](
+                    fused_key = (
+                        "fused_pre_mlp_layernorm"
+                        if "fused_pre_mlp_layernorm" in self.rules
+                        else "fused_norm"
+                    )
+                    if fused_key not in self.rules:
+                        raise KeyError(
+                            f"{self.arch} uses fused TELayerNormColumnParallelLinear for "
+                            "MLP but neither `fused_pre_mlp_layernorm` nor legacy "
+                            "`fused_norm` is in its import mapping; "
+                            "`linear_fc1.layer_norm_weight` would be left at random init. "
+                            "Add `fused_pre_mlp_layernorm: NameRemapping("
+                            '"...post_attention_layernorm.weight")` '
+                            f"to the {self.arch} import mapping."
+                        )
+                    self.rules[fused_key](
                         layer.mlp.linear_fc1.layer_norm_weight, layer_id, is_mtp=is_mtp
                     )