fix(network): alias skip_layers_start_percent to *_fraction

Adds backward compatibility for the old keyword that was renamed to
skip_layers_start_fraction across the Wan, WanI2V, and Cosmos Predict2
samplers. Existing callers passing skip_layers_start_percent will now
have it honored instead of silently swallowed by **kwargs.

Signed-off-by: Andrew White <andrewh@cdw.com>

Author: andrewwhitecdw

fastgen/networks/Wan/network.py

@@ -935,10 +935,15 @@ def sample(
             skip_layers (Optional[List[int]]): List of transformer layers to skip (used by SLG) during sampling.
             skip_layers_start_fraction (float): Fraction in [0, 1] of the sampling steps to complete
                 before skip-layer guidance becomes active.
+                ``skip_layers_start_percent`` is accepted as a deprecated alias.
 
         Returns:
             torch.Tensor: The sample output.
         """
+        # Backward compatibility: the old argument name was skip_layers_start_percent.
+        if "skip_layers_start_percent" in kwargs:
+            skip_layers_start_fraction = kwargs.pop("skip_layers_start_percent")
+
         assert self.schedule_type == "rf", f"{self.schedule_type} is not supported"
 
         self.unipc_scheduler.config.flow_shift = shift

fastgen/networks/WanI2V/network.py

@@ -352,6 +352,10 @@ def sample(
         For I2V models, the first latent frame must be preserved as the clean
         conditioning frame after each scheduler step.
         """
+        # Backward compatibility: the old argument name was skip_layers_start_percent.
+        if "skip_layers_start_percent" in kwargs:
+            skip_layers_start_fraction = kwargs.pop("skip_layers_start_percent")
+
         assert self.schedule_type == "rf", f"{self.schedule_type} is not supported"
 
         # Extract first_frame_cond for replacement after scheduler steps

fastgen/networks/cosmos_predict2/network.py

@@ -1173,6 +1173,7 @@ def sample(
             skip_layers: List of transformer layers to skip (for skip-layer guidance).
             skip_layers_start_fraction: Fraction in [0, 1] of the sampling steps to complete
                 before skip-layer guidance becomes active.
+                ``skip_layers_start_percent`` is accepted as a deprecated alias.
             fps: Frames per second tensor for temporal conditioning.
             conditioning_latents: Latent frames to condition on for video2world mode,
                 shape (B, C, T, H, W). If provided, enables video2world mode.
@@ -1185,6 +1186,10 @@ def sample(
         Returns:
             The denoised sample tensor.
         """
+        # Backward compatibility: the old argument name was skip_layers_start_percent.
+        if "skip_layers_start_percent" in kwargs:
+            skip_layers_start_fraction = kwargs.pop("skip_layers_start_percent")
+
         assert self.schedule_type == "rf", f"{self.schedule_type} is not supported"
 
         # Match official Cosmos Predict2.5 inference: a Karras ramp over [0.01, 200] in