fix(downloads): close routing gaps and map CivitAI ModelType.UNet to the checkpoint branch

Cross-checked both baseModel lists against CivitAI's official
baseModelRecords (packages/civitai-shared src/basemodel.constants.ts):

- CHECKPOINT_BASE_MODELS gains SD 2.0/2.1 768, SD 2.1 Unclip, SDXL 0.9 /
  1.0 LCM / Turbo / Distilled, Playground v2 and Stable Cascade
  (unCLIP-style but CheckpointLoader-loaded).
- DIFFUSION_MODEL_BASE_MODELS gains SVD XT, LTXV 2.5, Flux 3 Video,
  Wan Image 2.7, Wan Video 2.7 / 3.0, HiDream-O1, Boogu and the Ming
  Image Design families. API-only (Kling/Sora/Veo/Imagen...), 3D and
  audio baseModels are intentionally skipped.
- Pony V7 exclusion now backed by live-API evidence (model 1901521 is
  AuraFlow-architecture shipping .gguf variants).

CivitAI has no model-level diffusion ModelType: DiT models are uploaded
as "Checkpoint" or "UNet", with only uploader-chosen file types to tell
them apart. model.type "unet" previously fell through type derivation
and failed with 'not supported for download'; it now goes through the
checkpoint branch in both the download manager and the download routing
endpoint, so the standard chain (file type -> baseModel lists -> unknown
default) applies.

py/routes/handlers/download_routing_handlers.py

@@ -55,6 +55,11 @@ class DownloadRoutingHandler:
                 status=400,
             )
 
+        # CivitAI ModelType.UNet downloads go through the checkpoint branch,
+        # same as in the download manager.
+        if model_type.lower() == "unet":
+            model_type = "checkpoint"
+
         if model_type.lower() in VALID_OTHER_CIVITAI_TYPES:
             from ...services.settings_manager import get_settings_manager
 

py/services/download_manager.py

@@ -1523,7 +1523,11 @@ class DownloadManager:
                 return {"success": False, "error": "Failed to fetch model metadata"}
 
             model_type_from_info = version_info.get("model", {}).get("type", "").lower()
-            if model_type_from_info == "checkpoint":
+            # CivitAI ModelType has no model-level diffusion variant: DiT
+            # models are uploaded as "Checkpoint" or "UNet". Both go through
+            # the checkpoint branch so the standard diffusion routing chain
+            # (file type -> baseModel lists -> unknown default) applies.
+            if model_type_from_info in ("checkpoint", "unet"):
                 model_type = "checkpoint"
             elif model_type_from_info in VALID_LORA_TYPES:
                 model_type = "lora"

py/utils/constants.py

@@ -352,12 +352,15 @@ DIFFUSION_MODEL_BASE_MODELS = frozenset(
         "PixArt E",
         # Video diffusion models
         "CogVideoX",
+        "Flux 3 Video",
         "Hunyuan Video",
         "LTXV",
         "LTXV2",
         "LTXV 2.3",
+        "LTXV 2.5",
         "Mochi",
         "SVD",
+        "SVD XT",
         "Wan Video",
         "Wan Video 1.3B t2v",
         "Wan Video 14B t2v",
@@ -368,12 +371,19 @@ DIFFUSION_MODEL_BASE_MODELS = frozenset(
         "Wan Video 2.2 T2V-A14B",
         "Wan Video 2.5 T2V",
         "Wan Video 2.5 I2V",
+        "Wan Video 2.7",
+        "Wan Video 3.0",
         # Other diffusion models
+        "Boogu",
         "Ernie",
         "Ernie Turbo",
+        "HiDream-O1",
+        "Ming Image Design 0.1",
+        "Ming Image Design Layer 0.1",
         "MiniMax H3",
         "Nucleus",
         "Qwen",
+        "Wan Image 2.7",
         "ZImageBase",
         "ZImageTurbo",
         # Krea 2 — loaded via UNETLoader in ComfyUI
@@ -385,9 +395,12 @@ DIFFUSION_MODEL_BASE_MODELS = frozenset(
 # CheckpointLoaderSimple in ComfyUI). New DiT families appear on CivitAI all
 # the time, so download routing inverts the fallback: anything NOT in this
 # closed set (and not a known diffusion model) is treated as a diffusion
-# model by default (see py/services/download_routing.py).
-# "Pony V7" is deliberately excluded: it is not an SDXL-derivative full
-# checkpoint, so it follows the unknown-base-model default (diffusion).
+# model by default (see py/services/download_routing.py). Cross-checked
+# against CivitAI's official baseModelRecords (packages/civitai-shared
+# src/basemodel.constants.ts), not only the download skip list.
+# "Pony V7" is deliberately excluded: verified via the live API (model
+# 1901521) to be AuraFlow-architecture shipping .gguf variants (UNETLoader),
+# so it follows the unknown-base-model default (diffusion).
 CHECKPOINT_BASE_MODELS = frozenset(
     [
         # Stable Diffusion 1.x
@@ -397,7 +410,10 @@ CHECKPOINT_BASE_MODELS = frozenset(
         "SD 1.5 Hyper",
         # Stable Diffusion 2.x
         "SD 2.0",
+        "SD 2.0 768",
         "SD 2.1",
+        "SD 2.1 768",
+        "SD 2.1 Unclip",
         # Stable Diffusion 3.x
         "SD 3",
         "SD 3.5",
@@ -405,12 +421,20 @@ CHECKPOINT_BASE_MODELS = frozenset(
         "SD 3.5 Large",
         "SD 3.5 Large Turbo",
         # SDXL and its full-checkpoint derivatives
+        "SDXL 0.9",
         "SDXL 1.0",
+        "SDXL 1.0 LCM",
         "SDXL Lightning",
         "SDXL Hyper",
+        "SDXL Turbo",
+        "SDXL Distilled",
         "Pony",
         "Illustrious",
         "NoobAI",
+        # Other full-checkpoint families
+        "Playground v2",
+        # Stable Cascade is unCLIP-style but loads via CheckpointLoader
+        "Stable Cascade",
     ]
 )