model: add NVIDIA Nemotron-3-Puzzle-75B-A9B (NemotronHPuzzle) support (#25444)

* hparams: add per-layer n_ff_exp/n_expert_used arrays with scalar-or-array loading

G1/G2 infrastructure for variable-per-layer expert FFN size and top-k routing
(required for Puzzle-75B which has 5 distinct n_ff_exp values and 7 top-k values
across its 40 MoE layers).

Design: rename scalar members to _impl suffix (following existing convention),
add LLAMA_MAX_LAYERS arrays, add n_ff_exp(il)/n_expert_used(il) accessors with
scalar fallback. No new GGUF keys: reuses existing expert_feed_forward_length and
expert_used_count keys via get_key_or_arr (scalar -> broadcast, array -> per-layer).

- llama-hparams.h: n_ff_exp -> n_ff_exp_impl, n_expert_used -> n_expert_used_impl;
  add n_ff_exp_arr / n_expert_used_arr arrays; add per-layer accessor declarations.
- llama-hparams.cpp: implement n_ff_exp(il) and n_expert_used(il); out-of-range
  il returns impl safely (shared code, no abort).
- llama-model.cpp: central n_expert_used load changed to get_key_or_arr; derive
  impl as max-of-array for validations and backward compat; zero both new arrays;
  HunyuanVL override also zeroes n_expert_used_arr.
- llama-graph.cpp: aggregation loop in build_moe_ffn uses hparams.n_expert_used(il)
  so per-layer top-k bounds the ggml_view loop correctly.
- All other files: mechanical rename hparams.n_{ff_exp,expert_used} -> *_impl.
  Scalar arches are unaffected (broadcast fills all array slots with the single value).

(cherry picked from commit 269a81e03d66e1c353e1a203a0c03a03eb2b1a4e)

* nemotron-h: use per-layer n_ff_exp(il) and n_expert_used(il) at MoE call-sites

Load n_ff_exp via get_key_or_arr into hparams.n_ff_exp_arr in load_arch_hparams;
derive impl as max for existing uniform GGUFs.

In load_arch_tensors, compute n_ff_exp_i = hparams.n_ff_exp(i) with fallback to
n_ff(i)/n_expert_used(i) for GGUFs that omit expert_feed_forward_length.

In build_ffn_layer, pass hparams.n_expert_used(il) to build_moe_ffn so per-layer
top-k is used for expert routing selection.

All other nemotron-h behaviour (mamba2, attention, shared-exp, latent projection,
routed_scaling_factor, expert_weights_norm, sigmoid gating) is unchanged.

(cherry picked from commit b1878a101793cd4e59868ac72635a86ea694987c)

* arch/*.cpp + gguf-py: mechanical rename n_ff_exp->n_ff_exp_impl, n_expert_used->n_expert_used_impl

All non-nemotron arch files continue using the scalar impl member directly.
Behaviour is identical: the impl value is the broadcast value from the GGUF scalar.

gguf_writer: add_expert_feed_forward_length and add_expert_used_count now accept
int | Sequence[int], mirroring add_feed_forward_length, so converters can write
per-layer arrays with the same existing GGUF keys.

(cherry picked from commit 8f009f54bea5ef9a6a354123bd25e9d5ea2d5e03)

* convert: support NemotronHPuzzleForCausalLM (per-block MoE config)

Parse block_configs/mtp_block_configs into per-layer arrays (scalar-or-array
keys), append the MTP [attention, moe] sub-blocks as blk.88/blk.89 with
nextn tensors, accept the backbone.* prefix, and register the arch.
Also fix a pre-existing undeclared _experts attribute on NemotronHModel.

(cherry picked from commit d1a592f278336e78457454eb6c96bca917135f10)

* nemotron-h: distinguish Nemotron 3 Puzzle (75B.A9B) from Super (120B.A12B)

Both have 88 layers; the per-layer expert_used_count array (heterogeneous
for Puzzle, broadcast-uniform for Super) is the discriminator.

(cherry picked from commit f824e09dc812169589cf5662c92d149a4c18c30a)

* convert: accept the official Puzzle BF16 checkpoint's tensor naming

The officially distributed BF16 checkpoint (NVIDIA-Nemotron-Labs-3-Puzzle-
75B-A9B-BF16) names the trunk model.* (model.layers.*, model.embeddings,
model.norm_f) where the original release used the NemotronH-style
backbone.*, and spells the router bias e_score_correction_bias instead of
e_score_correction.bias. Normalize both at the top of
NemotronHPuzzleModel.modify_tensors so either checkpoint converts; every
tensor name in the official index (42683 keys, MTP head included) resolves
through the tensor map after normalization.

(cherry picked from commit 189b67fc2c9d50970416c94b3317a6e7baa49b03)

* laguna: use n_ff_exp_impl for the uniform-MoE FFN size

Laguna landed after this branch was cut and reads hparams.n_ff_exp as a
scalar. This series turns it into a per-layer array with an n_ff_exp(il)
accessor, so the three scalar reads no longer compile. Laguna is a
uniform MoE, so point them at the scalar fallback n_ff_exp_impl, same as
deepseek2/qwen3moe/gemma4 in this series. No behaviour change.

(cherry picked from commit dbedc9e19c50dca0acdfb402362e2707bee424ae)

* arch: extend the n_ff_exp/n_expert_used rename to archs added upstream

kimi-k3, dflash, bailingmoe3, deepseek4, granite-swa and the nemotron-h MTP
block still referenced the scalar fields by their old names. n_ff_exp and
n_expert_used are accessors now, so those reads no longer compile; point the
non-per-layer archs at the _impl scalars and use the indexed form where the
call site is per-layer.

* convert: keep Puzzle opted out of the NemotronH MTP export path

#26725 added MTP export to NemotronHModel, keyed on num_nextn_predict_layers.
Puzzle's config carries that key, but NemotronHPuzzleModel bypasses
NemotronHModel.__init__ (its per-block config needs a different setup), so
_mtp_bid was never assigned and modify_tensors raised AttributeError on any
mtp.* tensor. Puzzle's head is also laid out by mtp_block_configs, not the
mtp.layers.* form the base maps.

Set _mtp_bid to None, drop mtp.* in filter_tensors, and declare
supports_mtp_export = False so --mtp / --no-mtp fail at the CLI.

* llama: replace n_ff_exp/n_expert_used scalars with per-layer accessors

Follow-up to review feedback: the previous revision kept the scalar
hparams fields alongside the new per-layer arrays, which duplicated
state that get_key_or_arr already handles by broadcasting a scalar
value over every layer.

Drop both scalars and expose n_ff_exp(il) / n_expert_used(il) built
exactly like the existing n_head_kv(il) and n_ff(il) accessors: they
index the array and GGML_ABORT out of range, with il defaulting to 0
so genuinely uniform call sites stay a plain n_ff_exp().

Arch loaders now read both keys through get_key_or_arr over
n_layer_all, and the n_expert_used validation checks the maximum
across layers instead of a single field.

* llama: restore per-key required flags on the expert hparam reads

The scalar-to-array conversion passed required=false at every call site,
which silently made mandatory keys optional. Each read now carries the
same required flag it had before the conversion.

conversion/nemotron.py

@@ -5,6 +5,7 @@ from typing import Any, Callable, Iterable, TYPE_CHECKING
 import torch
 
 if TYPE_CHECKING:
+    from pathlib import Path
     from torch import Tensor
 
 from .base import MmprojModel, ModelBase, TextModel, gguf, logger
@@ -201,6 +202,7 @@ class NemotronHModel(GraniteHybridModel):
     model_arch = gguf.MODEL_ARCH.NEMOTRON_H
     is_moe: bool = False
     supports_mtp_export = True
+    _experts: list[dict[str, Tensor]] | None = None
 
     _SSM_LAYER_TYPES = {"mamba", "linear_attention"}
     _ATTN_LAYER_TYPES = {"attention", "full_attention"}
@@ -513,3 +515,88 @@ class NemotronHModel(GraniteHybridModel):
             experts = [k for d in self._experts for k in d.keys()]
             if len(experts) > 0:
                 raise ValueError(f"Unprocessed experts: {experts}")
+
+
+@ModelBase.register("NemotronHPuzzleForCausalLM")
+@ModelBase.example("nvidia/NVIDIA-Nemotron-Labs-3-Puzzle-75B-A9B-BF16")
+class NemotronHPuzzleModel(NemotronHModel):
+    """NVIDIA Puzzle: NemotronH with a per-block MoE config (block_configs).
+
+    The checkpoint also ships an MTP draft head (mtp.safetensors). It is skipped
+    here: there is no Puzzle MTP inference path in tree, and the head is laid out
+    by mtp_block_configs rather than the mtp.layers.* form NemotronHModel maps."""
+
+    model_arch = gguf.MODEL_ARCH.NEMOTRON_H_MOE
+    is_moe: bool = True
+    supports_mtp_export = False
+
+    def __init__(self, dir_model: "Path", *args, **kwargs):
+        hparams = dict(kwargs.pop("hparams", None) or ModelBase.load_hparams(dir_model, self.is_mistral_format))
+
+        self.block_configs: list[dict] = hparams["block_configs"]
+        self.n_layer_trunk = len(self.block_configs)
+
+        # block_configs carries the per-block MoE shape, and is the authority on the
+        # block pattern too: the layers_block_type the HF config wrapper computes is
+        # not sized to it.
+        hparams["num_hidden_layers"] = self.n_layer_trunk
+        hparams["layers_block_type"] = [bc["block_type"] for bc in self.block_configs]
+
+        self.model_arch = gguf.MODEL_ARCH.NEMOTRON_H_MOE
+
+        # Bypass NemotronHModel.__init__: it assumes a flat num_experts_per_tok /
+        # moe_intermediate_size and a layers_block_type sized to block_count, neither
+        # of which hold for Puzzle's per-block config.
+        GraniteHybridModel.__init__(self, dir_model, *args, hparams=hparams, **kwargs)
+
+        self.head_dim = self.find_hparam(["head_dim", "attention_head_dim"])
+        self.d_inner = self.find_hparam(["num_heads"]) * self.d_model
+
+        # NemotronHModel.__init__ folds an MTP block into block_count when the
+        # config carries num_nextn_predict_layers; Puzzle's config does, but its
+        # head has a different layout and no inference path, so stay opted out.
+        self._mtp_bid = None
+
+    def set_gguf_parameters(self):
+        GraniteHybridModel.set_gguf_parameters(self)
+
+        head_dim = self.head_dim
+        if head_dim is None:
+            raise ValueError("Could not find the attention head dim in config")
+        self.gguf_writer.add_key_length(head_dim)
+        self.gguf_writer.add_value_length(head_dim)
+
+        ffn_lengths = [bc.get("moe_intermediate_size") or 0 for bc in self.block_configs]
+        experts_used = [bc.get("num_experts_per_tok") or 0 for bc in self.block_configs]
+
+        self.gguf_writer.add_feed_forward_length(ffn_lengths)
+        self.gguf_writer.add_expert_feed_forward_length(ffn_lengths)
+        self.gguf_writer.add_expert_used_count(experts_used)
+
+        self.gguf_writer.add_expert_shared_feed_forward_length(self.hparams["moe_shared_expert_intermediate_size"])
+        self.gguf_writer.add_expert_count(self.hparams["n_routed_experts"])
+        self.gguf_writer.add_expert_shared_count(self.hparams["n_shared_experts"])
+        self.gguf_writer.add_expert_weights_norm(self.hparams["norm_topk_prob"])
+        self.gguf_writer.add_expert_weights_scale(self.hparams["routed_scaling_factor"])
+        self.gguf_writer.add_expert_group_count(self.hparams["n_group"])
+        self.gguf_writer.add_moe_latent_size(self.hparams["moe_latent_size"])
+
+    def modify_tensors(self, data_torch: Tensor, name: str, bid: int | None) -> Iterable[tuple[str, Tensor]]:
+        # The official BF16 checkpoint (NVIDIA-Nemotron-Labs-3-Puzzle-75B-A9B-BF16)
+        # names the trunk "model.*" (model.layers.*, model.embeddings, model.norm_f)
+        # where the original release used the NemotronH-style "backbone.*", and spells
+        # the router bias "e_score_correction_bias" instead of "e_score_correction.bias";
+        # normalize so both convert identically.
+        if name.startswith("model."):
+            name = "backbone." + name[len("model."):]
+        if name.endswith("mixer.gate.e_score_correction_bias"):
+            name = name[: -len("e_score_correction_bias")] + "e_score_correction.bias"
+
+        yield from super().modify_tensors(data_torch, name, bid)
+
+    @classmethod
+    def filter_tensors(cls, item: tuple[str, Callable[[], Tensor]]) -> tuple[str, Callable[[], Tensor]] | None:
+        # Drop the MTP head unconditionally; see the class docstring.
+        if item[0].startswith("mtp."):
+            return None
+        return super().filter_tensors(item)