model : add support for HrmTextForCausalLM (DFM Mimir 1B) (#27625)

* model : add support for HrmTextForCausalLM (DFM Mimir 1B)

HRM-Text runs two transformer stacks (low, high) in an alternating cycle over the same token stream. The low-cycle state z_l starts from a learned [n_embd] tensor and is broadcast over positions.

- conversion: new writer for the fused gqkv projection (order gate,q,k,v) remapped to llama.cpp q/k/v plus a separate sigmoid gate tensor
- loader: block_count = lps * h_cycles * (l_cycles + 1) cache slots aliasing 2*lps physical blocks via struct copies
- graph: looped build with sigmoid-gated attention, SwiGLU FFN and parameterless RMS norms; learned embedding_scale applied in build_inp_embd
- saver: pointer-deduplicated layer loop (looped archs alias tensors)
- tests: hrm_text fixture (lps 1, h 2, l 3) in test-llama-archs

Limitations:
causal attention only - the upstream prefix-LM mode is not implemented (the prefix_lm GGUF key round-trips unused).
The KV cache holds one entry per pass: 128 layers for Mimir 1B, i.e. 4x a same-width 32-layer model - about 3072 MiB at ctx 4096 in F16 (halves with q8_0 KV + FA).
Every token runs all 128 block passes, so decode cost is roughly 4x a dense model of equal width (2.65 t/s BF16, 8-thread desktop CPU).

Verified against the HF reference: identical argmax at 334/334 positions across 20 prompts (BF16 GGUF vs FP32 golden).
q8_0 requant: 95.8% top-1, all remaining misses inside the HF top-5 (accumulated error over 128 sequential blocks).

AI usage disclosure: YES
Used GLM-5.3 for the majority of code AI-generated under my direction, all gates verified locally.
All in all I could say that I have written less than 20% of the code and most of the heavy lifting has been done by the model. As such, this should be considered experimental.

* Update conversion/hrm_text.py

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@huggingface.co>

* Update src/llama-arch.cpp

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@huggingface.co>

* convert : add gguf_writer methods for hrm_text metadata

replace raw add_uint32/add_bool calls with dedicated GGUFWriter methods, following the add_embedding_scale pattern

Assisted-by: GLM-5.3

* convert : map regular hrm_text tensors via tensor_mapping

delegate unfused checkpoints to the base tensor mapping; training-style attn. names are renamed to self_attn. so the patterns match

Assisted-by: GLM-5.3

* model : format hrm-text build_* calls as in other models

one argument group per line, matching sibling model files

Assisted-by: GLM-5.3

* llama : move hrm z_l_init table entries out of the nemotron group

place the name and tensor-info entries with the other global input tensors

Assisted-by: GLM-5.3

* convert : slim down hrm_text comments

Assisted-by: GLM-5.3

* convert : build hrm_text block tensor names from the {bid} template

The tensor map holds concrete per-block names, so format the template
with the computed layer index before handing it to super().

* llama : name hrm metadata keys in their own hrm. namespace

The four keys are arch-independent, unlike the arch-substituted
Keys.LLM entries, so group them under Keys.HRM (like Keys.Split) and
rename the llm_kv entries to LLM_KV_HRM_*. Only our own GGUFs carry
the old hrm_text.* keys; they are regenerated.

* Update src/llama-model-saver.cpp

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@huggingface.co>

* llama : keep hrm metadata keys arch-substituted

Per review: the GGUF keys stay "{arch}.h_cycles" style, so the Python
members drop the LLM_KV_HRM_ prefix and keep arch templates; C++ keeps
the LLM_KV_HRM_* enums. GGUF output is unchanged - existing files and
HF uploads stay valid.

* Update gguf-py/gguf/constants.py

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@huggingface.co>

* Update src/llama-arch.cpp

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@huggingface.co>

* Update src/llama-arch.cpp

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@huggingface.co>

* convert : rename hrm writer methods to add_hrm_*

Generic names like add_h_cycles/add_prefix_lm are too broad on the
shared GGUFWriter; prefix them with hrm_ like the metadata keys.

* model : fix meta-split lookup for archs with aliased cache slots

Cache tensors of archs that alias physical blocks across looped slots
(hrm_text, nanbeige with num_loops > 1) can reference block indices
without weight tensor names. Take the output projection from the layer
array instead of asserting; all other lookups are unchanged.

* model : replicate hrm_text tensors on meta devices instead of splitting

The aliased cache slots rotate split states differently from their
physical weights, so the meta-split execution invariants (set_rows
requires the cache state to match the token indices) cannot hold for
any device count. Replicate all hrm_text tensors on every meta device
instead; single-device and non-meta paths are unchanged.

Assisted-by: Claude Sonnet

---------

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@huggingface.co>

conversion/__init__.py

@@ -123,6 +123,7 @@ TEXT_MODEL_MAP: dict[str, str] = {
     "HunYuanDenseV1ForCausalLM": "hunyuan",
     "HunYuanMoEV1ForCausalLM": "hunyuan",
     "HunYuanVLForConditionalGeneration": "hunyuan",
+    "HrmTextForCausalLM": "hrm_text",
     "HYV3ForCausalLM": "hunyuan",
     "HYV4ForCausalLM": "hy_v4",
     "IQuestCoderForCausalLM": "llama",

conversion/base.py

@@ -1633,6 +1633,9 @@ class TextModel(ModelBase):
         if chkhsh == "9e454714343b69b99b71795c1d27a68c2a1d15dab111f4d353109f966af29da7":
             # ref: https://huggingface.co/LiquidAI/LFM2.5-8B-A1B
             res = "lfm2"
+        if chkhsh == "846deafc5b0fa786186fa4ae6c7b49903cf2f1d1895bdb80b9120d60be135252":
+            # ref: https://huggingface.co/danish-foundation-models/DFM-Mimir
+            res = "gemma4"
         if chkhsh == "0a766d034107bc736a3f2dc4968fd62e54a3570f1454443e0c5a4cc6bd7941ed":
             # ref: https://huggingface.co/XHToken/Spark-X2.5-1.7B
             res = "spark2_5"

conversion/hrm_text.py

@@ -0,0 +1,79 @@
+from __future__ import annotations
+
+import re
+
+from typing import Iterable, TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from torch import Tensor
+
+from .base import ModelBase, TextModel, gguf
+
+
+@ModelBase.register("HrmTextForCausalLM")
+@ModelBase.example("danish-foundation-models/DFM-Mimir")
+class HrmTextModel(TextModel):
+    model_arch = gguf.MODEL_ARCH.HRM_TEXT
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        # training-style configs store the per-stack count in num_hidden_layers,
+        # transformers-style configs keep it in num_layers_per_stack
+        self.layers_per_stack = self.hparams.get("num_layers_per_stack") or self.hparams["num_hidden_layers"]
+        self.h_cycles = self.hparams["H_cycles"]
+        self.l_cycles = self.hparams["L_cycles"]
+
+        # block_count is the expanded cache-slot count; the file only holds
+        # 2 * layers_per_stack physical blocks
+        self.block_count = self.layers_per_stack * self.h_cycles * (self.l_cycles + 1)
+        self.tensor_map = gguf.get_tensor_name_map(self.model_arch, 2 * self.layers_per_stack)
+
+    def set_vocab(self):
+        self._set_vocab_gpt2()
+
+    def set_gguf_parameters(self):
+        super().set_gguf_parameters()
+
+        head_dim = self.hparams.get("head_dim") or self.hparams["hidden_size"] // self.hparams["num_attention_heads"]
+        self.gguf_writer.add_rope_dimension_count(head_dim)
+        self.gguf_writer.add_embedding_scale(self.hparams["embedding_scale"])
+        self.gguf_writer.add_hrm_layers_per_stack(self.layers_per_stack)
+        self.gguf_writer.add_hrm_h_cycles(self.h_cycles)
+        self.gguf_writer.add_hrm_l_cycles(self.l_cycles)
+        self.gguf_writer.add_hrm_prefix_lm(bool(self.hparams.get("prefix_lm", False)))
+
+    def modify_tensors(self, data_torch: Tensor, name: str, bid: int | None) -> Iterable[tuple[str, Tensor]]:
+        if name == "model.embed_tokens.weight":
+            yield self.format_tensor_name(gguf.MODEL_TENSOR.TOKEN_EMBD), data_torch
+            return
+        if name == "lm_head.weight":
+            yield self.format_tensor_name(gguf.MODEL_TENSOR.OUTPUT), data_torch
+            return
+        if name == "model.z_L_init":
+            yield self.format_tensor_name(gguf.MODEL_TENSOR.HRM_Z_L_INIT, suffix=""), data_torch
+            return
+
+        match = re.fullmatch(r"model\.([LH])_module\.layers\.(\d+)\.(.+)", name)
+        if match is None:
+            raise ValueError(f"can not map tensor: {name}")
+
+        stack, layer_s, tensor_name = match.groups()
+        # the L stack occupies blocks [0, layers_per_stack), the H stack follows it
+        layer_idx = int(layer_s) + (self.layers_per_stack if stack == "H" else 0)
+
+        if tensor_name == "attn.gqkv_proj.weight":
+            gate, q, k, v = data_torch.chunk(4, dim=0)
+            yield self.format_tensor_name(gguf.MODEL_TENSOR.ATTN_GATE, layer_idx), gate.contiguous()
+            yield self.format_tensor_name(gguf.MODEL_TENSOR.ATTN_Q, layer_idx), q.contiguous()
+            yield self.format_tensor_name(gguf.MODEL_TENSOR.ATTN_K, layer_idx), k.contiguous()
+            yield self.format_tensor_name(gguf.MODEL_TENSOR.ATTN_V, layer_idx), v.contiguous()
+        elif tensor_name == "mlp.gate_up_proj.weight":
+            gate, up = data_torch.chunk(2, dim=0)
+            yield self.format_tensor_name(gguf.MODEL_TENSOR.FFN_GATE, layer_idx), gate.contiguous()
+            yield self.format_tensor_name(gguf.MODEL_TENSOR.FFN_UP, layer_idx), up.contiguous()
+        else:
+            if tensor_name.startswith("attn."):
+                tensor_name = "self_attn." + tensor_name[len("attn."):]
+            tensor_name = "model.layers.{bid}." + tensor_name
+            yield from super().modify_tensors(data_torch, tensor_name.format(bid=layer_idx), layer_idx)