fix: handle all three inference-tensor sources in vocoder sanitization

remove_parametrizations() stores weight as a plain __dict__ tensor (not
nn.Parameter), making it invisible to _parameters iteration. Also, buffers
(Activation1d anti-aliasing filters) are inference tensors that break the
backward graph mid-network. Fix all three categories:
1. _parameters: clone().detach(), wrap as Parameter
2. plain __dict__ tensors: clone(), register_parameter (also makes trainable)
3. _buffers: clone() to strip inference flag without parametrizing

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

nodes/selva_bigvgan_trainer.py

@@ -277,15 +277,42 @@ def _do_train(vocoder, mel_converter, clips,
 
     _save_sample("baseline")
 
-    # Replace inference-tensor parameters with fresh trainable parameters.
-    # (Vocoder was loaded by ComfyUI before this thread existed; its parameters
-    # may carry the inference flag from that context. Here we're in a clean thread
-    # so all new tensors are normal.)
+    # Sanitize all inference tensors in the vocoder.
+    # Three categories to handle (all loaded in ComfyUI's inference_mode):
+    #
+    # 1. Registered parameters (_parameters): covers bias, alpha, etc.
+    #
+    # 2. Plain tensor attributes in __dict__: torch.nn.utils.parametrize.
+    #    remove_parametrizations() calls setattr(module, name, tensor) with
+    #    a raw tensor, NOT nn.Parameter. Module.__setattr__ stores raw tensors
+    #    in __dict__ (not _parameters), so our parameter loop misses them.
+    #    This is how BigVGAN's conv.weight ends up invisible to _parameters.
+    #    Fix: re-register as Parameter, which also makes them trainable.
+    #
+    # 3. Registered buffers (_buffers): Activation1d's anti-aliasing filter
+    #    tensors. Not trainable, but operations on inference buffers produce
+    #    inference tensor outputs — which breaks the backward graph mid-network.
+    #    Fix: clone to strip the inference flag (not registered as parameters).
     for module in vocoder.modules():
+        # Category 1: registered parameters
         for pname, param in list(module._parameters.items()):
             if param is not None:
-                fresh = param.data.clone().detach().requires_grad_(True)
-                module._parameters[pname] = nn_mod.Parameter(fresh)
+                module._parameters[pname] = nn_mod.Parameter(
+                    param.data.clone().detach(), requires_grad=True
+                )
+
+        # Category 2: plain tensor attributes (e.g. weight left by remove_parametrizations)
+        for name, val in list(module.__dict__.items()):
+            if (isinstance(val, torch.Tensor)
+                    and not isinstance(val, nn_mod.Parameter)
+                    and name not in module._buffers
+                    and name not in module._modules):
+                module.register_parameter(name, nn_mod.Parameter(val.clone()))
+
+        # Category 3: buffers (Activation1d filter, etc.) — clone, don't parametrize
+        for bname, buf in list(module._buffers.items()):
+            if buf is not None:
+                module._buffers[bname] = buf.clone()
 
     optimizer = torch.optim.AdamW(vocoder.parameters(), lr=lr, betas=(0.8, 0.99))
     vocoder.train()
@@ -305,22 +332,6 @@ def _do_train(vocoder, mel_converter, clips,
             with torch.no_grad():
                 target_mel = mel_converter(target_flat)           # [B, n_mels, T_mel]
 
-            if step == 0:
-                print(f"[BigVGAN DEBUG] inference_mode={torch.is_inference_mode_enabled()}", flush=True)
-                cp = vocoder.conv_pre
-                print(f"[BigVGAN DEBUG] conv_pre._parameters keys={list(cp._parameters.keys())}", flush=True)
-                for k, v in cp._parameters.items():
-                    if v is not None:
-                        print(f"[BigVGAN DEBUG]   _parameters[{k!r}].is_inference()={v.is_inference()}", flush=True)
-                has_p = hasattr(cp, 'parametrizations')
-                print(f"[BigVGAN DEBUG] has parametrizations={has_p}", flush=True)
-                if has_p:
-                    for attr, plist in cp.parametrizations.items():
-                        print(f"[BigVGAN DEBUG]   parametrizations[{attr!r}]={plist}", flush=True)
-                        for sub_name, sub_p in plist.named_parameters():
-                            print(f"[BigVGAN DEBUG]     {sub_name}.is_inference()={sub_p.is_inference()}", flush=True)
-                print(f"[BigVGAN DEBUG] conv_pre.weight.is_inference()={cp.weight.is_inference()}", flush=True)
-
             pred_wav = vocoder(target_mel)                        # [B, 1, T_wav]
 
             T = min(pred_wav.shape[-1], target_wav.shape[-1])