Add handling for vace_context in context windows (#11386)

Co-authored-by: ozbayb <17261091+ozbayb@users.noreply.github.com>

comfy/context_windows.py

@@ -188,6 +188,12 @@ class IndexListContextHandler(ContextHandlerABC):
                                 audio_cond = cond_value.cond
                                 if audio_cond.ndim > 1 and audio_cond.size(1) == x_in.size(self.dim):
                                     new_cond_item[cond_key] = cond_value._copy_with(window.get_tensor(audio_cond, device, dim=1))
+                            # Handle vace_context (temporal dim is 3)
+                            elif cond_key == "vace_context" and hasattr(cond_value, "cond") and isinstance(cond_value.cond, torch.Tensor):
+                                vace_cond = cond_value.cond
+                                if vace_cond.ndim >= 4 and vace_cond.size(3) == x_in.size(self.dim):
+                                    sliced_vace = window.get_tensor(vace_cond, device, dim=3, retain_index_list=self.cond_retain_index_list)
+                                    new_cond_item[cond_key] = cond_value._copy_with(sliced_vace)
                             # if has cond that is a Tensor, check if needs to be subset
                             elif hasattr(cond_value, "cond") and isinstance(cond_value.cond, torch.Tensor):
                                 if  (self.dim < cond_value.cond.ndim and cond_value.cond.size(self.dim) == x_in.size(self.dim)) or \