fix: pin transformers to 4.49.0 for DiffRhythm compatibility

Resolves tensor dimension mismatch error in rotary position embeddings.
DiffRhythm requires transformers 4.49.0 - newer versions (4.50+) cause
"The size of tensor a (32) must match the size of tensor b (64)" error
due to transformer block initialization changes.

Updated pivoine_diffrhythm.py documentation to reflect actual root cause
and link to upstream GitHub issues #44 and #48.

References:
- https://github.com/billwuhao/ComfyUI_DiffRhythm/issues/44
- https://github.com/billwuhao/ComfyUI_DiffRhythm/issues/48

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

comfyui/nodes/pivoine_diffrhythm.py

@@ -1,7 +1,14 @@
 """
 Pivoine DiffRhythm Node
-Custom wrapper for DiffRhythm that disables chunked decoding to prevent
-tensor dimension mismatch errors (32 vs 64) in VAE overlap logic.
+Custom wrapper for DiffRhythm that ensures correct transformer library version
+compatibility and provides fallback fixes for tensor dimension issues.
+
+Known Issue: DiffRhythm requires transformers==4.49.0. Newer versions (4.50+)
+cause "The size of tensor a (32) must match the size of tensor b (64)" error
+in rotary position embeddings due to transformer block initialization changes.
+
+Reference: https://github.com/billwuhao/ComfyUI_DiffRhythm/issues/44
+Reference: https://github.com/billwuhao/ComfyUI_DiffRhythm/issues/48
 
 Author: valknar@pivoine.art
 """
@@ -24,12 +31,16 @@ from DiffRhythmNode import DiffRhythmRun
 
 class PivoineDiffRhythmRun(DiffRhythmRun):
     """
-    Pivoine version of DiffRhythmRun with chunked decoding forcibly disabled.
+    Pivoine version of DiffRhythmRun with enhanced compatibility and error handling.
 
     Changes from original:
-    - Monkey-patches the infer() function to always use chunked=False
-    - Prevents tensor dimension mismatch in VAE (32 vs 64 channel error)
+    - Monkey-patches decode_audio to always use chunked=False for stability
+    - Ensures transformers library version compatibility (requires 4.49.0)
+    - Prevents tensor dimension mismatch in VAE decoding
     - Requires more VRAM (~12-16GB) but works reliably on RTX 4090
+
+    Note: If you encounter "tensor a (32) must match tensor b (64)" errors,
+    ensure transformers==4.49.0 is installed in your ComfyUI venv.
     """
 
     CATEGORY = "🌸Pivoine/Audio"

comfyui/requirements.txt

@@ -1,7 +1,7 @@
 torch
 torchvision
 torchaudio
-transformers
+transformers==4.49.0
 diffusers>=0.31.0
 accelerate
 safetensors