feat(civitai): route DiT checkpoint downloads to the UNET folder

CivitAI has no model type for a standalone transformer, so DiT finetunes
are published as 'Checkpoint' like full models and all landed in
Stable-diffusion, where the single-file transformer loader never looks.
Route Checkpoint downloads to UNET unless the base model is a known full
checkpoint (SD1.x/2.x, SDXL and its Pony/Illustrious/NoobAI derivatives,
SVD, Kolors, Stable Cascade). Downloads with no base_model, or a
civitai_save_type_folders override, keep the previous behavior.

modules/civitai/download_civitai.py

@@ -752,7 +752,7 @@ def download_civit_model(model_url: str, model_name: str = '', model_path: str =
             from modules.civitai.filemanage_civitai import resolve_save_path
             folder = str(resolve_save_path(model_type or 'Checkpoint', model_name=model_name, base_model=base_model))
         else:
-            folder = str(get_type_folder(model_type or 'Checkpoint'))
+            folder = str(get_type_folder(model_type or 'Checkpoint', base_model=base_model))
     elif os.path.isabs(model_path):
         folder = model_path
     else:

modules/civitai/filemanage_civitai.py

@@ -23,8 +23,19 @@ TYPE_MAP = {
     'Other': ('ckpt_dir', 'Stable-diffusion'),
 }
 
+# CivitAI has no type for a standalone transformer, so DiT finetunes ship as
+# 'Checkpoint' like full models. Bases listed here are full checkpoints and stay
+# in Stable-diffusion; any other base is transformer-only in practice and routes
+# to UNET. Exact names: 'Pony' is SDXL but 'Pony V7' is AuraFlow.
+FULL_CHECKPOINT_BASES = {'Pony', 'Illustrious', 'NoobAI', 'SVD', 'SVD XT', 'Kolors', 'Stable Cascade'}
+FULL_CHECKPOINT_PREFIXES = ('SD 1', 'SD 2', 'SDXL')
 
-def get_type_folder(model_type: str) -> Path:
+
+def is_full_checkpoint_base(base_model: str) -> bool:
+    return base_model in FULL_CHECKPOINT_BASES or base_model.startswith(FULL_CHECKPOINT_PREFIXES)
+
+
+def get_type_folder(model_type: str, base_model: str = '') -> Path:
     from modules import shared, paths
     # Check for user-configured type folder overrides
     custom_json = getattr(shared.opts, 'civitai_save_type_folders', '') or ''
@@ -40,6 +51,8 @@ def get_type_folder(model_type: str) -> Path:
         except Exception as e:
             log.warning(f'CivitAI type folder override parse error: {e}')
     opt_attr, fallback_dir = TYPE_MAP.get(model_type, ('ckpt_dir', 'Stable-diffusion'))
+    if model_type == 'Checkpoint' and base_model and not is_full_checkpoint_base(base_model):
+        opt_attr, fallback_dir = 'unet_dir', 'UNET'
     if opt_attr:
         configured = getattr(shared.opts, opt_attr, '') or ''
         if configured:
@@ -51,7 +64,7 @@ def resolve_save_path(model_type: str, model_name: str = "", base_model: str = "
                       nsfw: bool = False, creator: str = "", model_id: int = 0,
                       version_id: int = 0, version_name: str = "") -> Path:
     from modules import shared
-    base_folder = get_type_folder(model_type)
+    base_folder = get_type_folder(model_type, base_model=base_model)
     if not getattr(shared.opts, 'civitai_save_subfolder_enabled', False):
         return base_folder
     template = getattr(shared.opts, 'civitai_save_subfolder', '{{BASEMODEL}}') or ''