Refactor: convert_hf_to_gguf.py (#17114)

* move conversion code to a dedicated conversion directory and split the files akin to the src/models architecture

---------

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

conversion/youtuvl.py

@@ -0,0 +1,64 @@
+from __future__ import annotations
+
+from typing import Callable, Iterable, TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from torch import Tensor
+
+from .base import MmprojModel, ModelBase, gguf, logger
+
+
+@ModelBase.register("YoutuVLForConditionalGeneration")
+class YoutuVLVisionModel(MmprojModel):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        assert self.hparams_vision is not None
+        self.hparams_vision["image_size"] = self.hparams_vision.get("image_size", 560)
+
+    def set_gguf_parameters(self):
+        super().set_gguf_parameters()
+
+        self.gguf_writer.add_clip_projector_type(gguf.VisionProjectorType.YOUTUVL)
+        self.gguf_writer.add_vision_attention_layernorm_eps(self.hparams.get("layer_norm_eps", 1e-6))
+
+        # Handle activation function
+        hidden_act = str(self.hparams.get("hidden_act", "gelu_pytorch_tanh")).lower()
+        if hidden_act in ("gelu", "gelu_pytorch_tanh", "gelu_fast", "gelu_new", "gelu_accurate"):
+            self.gguf_writer.add_vision_use_gelu(True)
+        elif hidden_act == "silu":
+            self.gguf_writer.add_vision_use_silu(True)
+        else:
+            raise ValueError(f"Unsupported activation function for YOUTUVL: {hidden_act}")
+
+        self.gguf_writer.add_vision_spatial_merge_size(self.hparams.get("spatial_merge_size", 2))
+
+        window_size = self.hparams.get("window_size")
+        if window_size is not None:
+            self.gguf_writer.add_vision_window_size(window_size)
+        # fullatt_block_indexes contains explicit layer indices that use full attention
+        # e.g., [2, 5, 8, 11] means layers 2, 5, 8, 11 use full attention
+        # All other layers use window attention
+        fullatt_block_indexes = self.hparams.get("fullatt_block_indexes")
+        assert fullatt_block_indexes is not None, "fullatt_block_indexes is required for youtuvl"
+        # Store the explicit layer indices for YoutuVL (irregular pattern approach)
+        self.gguf_writer.add_vision_wa_layer_indexes(layers=fullatt_block_indexes)
+
+    @classmethod
+    def filter_tensors(cls, item: tuple[str, Callable[[], Tensor]]) -> tuple[str, Callable[[], Tensor]] | None:
+        name, gen = item
+
+        # Skip language model tensors
+        skip_prefixes = ('lm_head.', 'model.layers.', 'model.embed_tokens.', 'model.norm.')
+        if name.startswith(skip_prefixes):
+            return None
+
+        return super().filter_tensors(item)
+
+    def modify_tensors(self, data_torch: Tensor, name: str, bid: int | None) -> Iterable[tuple[str, Tensor]]:
+        # Try to map the tensor using TensorNameMap (handles vision encoder and projector)
+        try:
+            yield from super().modify_tensors(data_torch, name, bid)
+        except ValueError:
+            # If mapping fails, log warning and skip
+            logger.warning(f"Cannot map tensor: {name}")
+            return