fix(transformers): add backward compatibility and skip conversion on older versions

Signed-off-by: ZX-ModelCloud <zx@modelcloud.ai>

Author: ZX-ModelCloud

defuser/__init__.py

@@ -3,19 +3,29 @@
 # SPDX-License-Identifier: Apache-2.0
 # Contact: qubitium@modelcloud.ai, x.com/qubitium
 
-from defuser.utils.common import env_flag
+from defuser.utils.common import env_flag, warn_if_public_api_transformers_unsupported
+from logbar import LogBar
 
 DEBUG_ON = env_flag("DEBUG")
 
-def convert_model(*args, **kwargs):
+logger = LogBar(__name__)
+
+
+def convert_model(*args, **kwargs) -> bool:
     """Lazily import conversion entrypoint to avoid import-time cycles."""
+    if warn_if_public_api_transformers_unsupported("convert_model()", logger):
+        return False
+
     from .defuser import convert_model as _convert_model
 
     return _convert_model(*args, **kwargs)
 
 
-def replace_fused_blocks(*args, **kwargs):
+def replace_fused_blocks(*args, **kwargs) -> bool:
     """Lazily import conversion entrypoint to avoid import-time cycles."""
+    if warn_if_public_api_transformers_unsupported("replace_fused_blocks()", logger):
+        return False
+
     from .defuser import replace_fused_blocks as _replace_fused_blocks
 
     return _replace_fused_blocks(*args, **kwargs)