convert : qwen2/3moe : set yarn metadata if present (#13331)

* set yarn metadata if present

* add comment about enabling YaRN

Co-authored-by: Xuan-Son Nguyen <son@huggingface.co>

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Co-authored-by: Xuan-Son Nguyen <son@huggingface.co>

convert_hf_to_gguf.py

@@ -2761,6 +2761,13 @@ class Qwen2MoeModel(TextModel):
         if (shared_expert_intermediate_size := self.hparams.get('shared_expert_intermediate_size')) is not None:
             self.gguf_writer.add_expert_shared_feed_forward_length(shared_expert_intermediate_size)
             logger.info(f"gguf: expert shared feed forward length = {shared_expert_intermediate_size}")
+        # YaRN is not enabled by default
+        # To enable it, please refer to this guide: https://huggingface.co/Qwen/Qwen3-30B-A3B#processing-long-texts
+        if self.hparams.get("rope_scaling") is not None and "factor" in self.hparams["rope_scaling"]:
+            if self.hparams["rope_scaling"].get("type") == "yarn":
+                self.gguf_writer.add_rope_scaling_type(gguf.RopeScalingType.YARN)
+                self.gguf_writer.add_rope_scaling_factor(self.hparams["rope_scaling"]["factor"])
+                self.gguf_writer.add_rope_scaling_orig_ctx_len(self.hparams["rope_scaling"]["original_max_position_embeddings"])
 
     _experts: list[dict[str, Tensor]] | None = None