Shim is_torch_fx_available instead of pinning transformers down

Pinning transformers to the 4.56 line (for MiniCPM) is impossible in this env:
it requires huggingface-hub<1.0 while Gradio 6.18 requires >=1.0. Keep
transformers current and restore the is_torch_fx_available symbol that
MiniCPM4.1-8B's bundled modeling code imports, before any remote code runs.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app.py

@@ -20,6 +20,25 @@ import spaces
 import torch
 from transformers import AutoModelForCausalLM, AutoTokenizer, TextIteratorStreamer
 
+# Compatibility shim: MiniCPM4.1-8B's bundled modeling code does
+# `from transformers.utils.import_utils import is_torch_fx_available`, which newer
+# transformers removed from that module. We can't pin transformers down (Gradio
+# 6.18 needs huggingface-hub>=1.0, which the old transformers line conflicts
+# with), so we restore the symbol before any remote code runs.
+import transformers.utils.import_utils as _iu  # noqa: E402
+if not hasattr(_iu, "is_torch_fx_available"):
+    try:
+        from transformers.utils import is_torch_fx_available as _fx  # type: ignore
+    except Exception:
+        try:
+            import torch.fx  # noqa: F401
+            def _fx():  # torch.fx imports fine -> treat as available
+                return True
+        except Exception:
+            def _fx():
+                return False
+    _iu.is_torch_fx_available = _fx
+
 from shards import SHARD_ORDER, SHARDS
 
 # ---------------------------------------------------------------------------- #

requirements.txt

@@ -1,7 +1,8 @@
 gradio
 spaces
-# MiniCPM4.1-8B's bundled modeling code imports is_torch_fx_available, which
-# newer transformers removed; pin to the 4.56 line OpenBMB tested against.
-transformers>=4.56,<4.57
+# Keep transformers current (Gradio 6.18 needs huggingface-hub>=1.0, which the
+# old 4.56 line conflicts with). MiniCPM's bundled code expects an older symbol
+# (is_torch_fx_available) that we shim in app.py instead of downgrading.
+transformers>=4.51.0
 torch
 accelerate