Fix/save torchao model loading logic (#3621)

* make loading gpt-oss-BF16 faster. Linked to unsloth-zoo PR #314

* fix model loading and clean merged model directory

* revert default quant

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* revert mapper.py

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

unsloth/save.py

@@ -2769,7 +2769,13 @@ def unsloth_save_pretrained_torchao(
     for _ in range(3):
         gc.collect()
 
-    from transformers import AutoModel, AutoTokenizer, TorchAoConfig
+    from transformers import (
+        AutoModelForCausalLM,
+        AutoTokenizer,
+        TorchAoConfig,
+        AutoModelForImageTextToText,
+        AutoProcessor,
+    )
     from torchao import quantize_
 
     if torchao_config is None:
@@ -2781,14 +2787,25 @@ def unsloth_save_pretrained_torchao(
         torchao_config = Int8DynamicActivationInt8WeightConfig()
     quantization_config = TorchAoConfig(quant_type = torchao_config)
 
-    tokenizer = AutoTokenizer.from_pretrained(arguments["save_directory"])
+    is_vlm = False
+    if hasattr(self, "config") and hasattr(self.config, "architectures"):
+        is_vlm = any(
+            x.endswith(("ForConditionalGeneration", "ForVisionText2Text"))
+            for x in self.config.architectures
+        )
+        is_vlm = is_vlm or hasattr(self.config, "vision_config")
+    auto_model = AutoModelForImageTextToText if is_vlm else AutoModelForCausalLM
+    auto_processor = AutoProcessor if is_vlm else AutoTokenizer
+
+    tokenizer = auto_processor.from_pretrained(arguments["save_directory"])
 
     # TorchAO must only use bfloat16 for loading (float16 fails)
     if HAS_TORCH_DTYPE:
         kwargs = {"torch_dtype": torch.bfloat16}
     else:
         kwargs = {"dtype": torch.bfloat16}
-    model = AutoModel.from_pretrained(
+
+    model = auto_model.from_pretrained(
         arguments["save_directory"],
         device_map = "auto",
         quantization_config = quantization_config,
@@ -2812,6 +2829,13 @@ def unsloth_save_pretrained_torchao(
             torchao_save_directory, safe_serialization = safe_serialization
         )
         tokenizer.save_pretrained(torchao_save_directory)
+    if os.path.exists(save_directory):
+        try:
+            import shutil
+
+            shutil.rmtree(save_directory)
+        except:
+            pass
     for _ in range(3):
         gc.collect()