fix(download): align location-step root selection with backend diffusion routing

The download modal's location step decided between checkpoint and unet
roots using only the CivitAI file-type signal, while the backend also
falls back to DIFFUSION_MODEL_BASE_MODELS. Models like Anima (file type
"Model") were offered checkpoint roots in the UI even though
use_default_paths would route them to the unet root.

- Extract the two-tier decision into py/services/download_routing.py and
  reuse it in DownloadManager._execute_download
- Add POST /api/lm/download/routing so the UI asks the backend for the
  routing decision; fall back to the local file-type check on failure
- ModelVersionsTab: search both checkpoint and unet roots when resolving
  an existing version's download path

py/routes/handlers/download_routing_handlers.py

@@ -0,0 +1,59 @@
+"""HTTP handler for download target routing decisions."""
+
+from __future__ import annotations
+
+import json
+import logging
+
+from aiohttp import web
+
+from ...services.download_routing import is_diffusion_model_download
+
+logger = logging.getLogger(__name__)
+
+
+class DownloadRoutingHandler:
+    """Expose the download-time checkpoint/diffusion-model routing decision.
+
+    The web UI calls this when the user reaches the download location step
+    so the root dropdown offers the same root set (checkpoint vs unet) that
+    the download manager would pick for ``use_default_paths``.
+    """
+
+    async def get_download_routing(self, request: web.Request) -> web.Response:
+        try:
+            payload = await request.json()
+        except json.JSONDecodeError:
+            return web.json_response(
+                {"success": False, "error": "Invalid JSON payload"}, status=400
+            )
+
+        model_type = payload.get("model_type", "")
+        base_model = payload.get("base_model") or ""
+        file_types = payload.get("file_types") or []
+
+        if not isinstance(model_type, str) or not model_type:
+            return web.json_response(
+                {"success": False, "error": "model_type is required"}, status=400
+            )
+        if not isinstance(base_model, str) or not isinstance(file_types, list):
+            return web.json_response(
+                {
+                    "success": False,
+                    "error": "base_model must be a string and file_types a list",
+                },
+                status=400,
+            )
+
+        is_diffusion = is_diffusion_model_download(
+            model_type,
+            file_types=(str(t) for t in file_types),
+            base_model=base_model,
+        )
+        return web.json_response(
+            {
+                "success": True,
+                "is_diffusion_model": is_diffusion,
+                "root_kind": "unet" if is_diffusion else model_type,
+            }
+        )

py/routes/handlers/misc_handlers.py

@@ -56,6 +56,7 @@ from ...utils.constants import (
 )
 from .hf_handlers import HfHandler
 from .agent_handlers import AgentHandler
+from .download_routing_handlers import DownloadRoutingHandler
 from .model_handlers import ModelCivitaiHandler
 from ...utils.civitai_utils import rewrite_preview_url
 from ...utils.example_images_paths import (
@@ -3884,6 +3885,7 @@ class MiscHandlerSet:
         base_model: BaseModelHandlerSet,
         hf_handler: Any = None,
         agent_handler: Any = None,
+        download_routing: Any = None,
     ) -> None:
         self.health = health
         self.settings = settings
@@ -3904,6 +3906,7 @@ class MiscHandlerSet:
         self.base_model = base_model
         self.hf_handler = hf_handler
         self.agent_handler = agent_handler
+        self.download_routing = download_routing
 
     def to_route_mapping(
         self,
@@ -3962,6 +3965,8 @@ class MiscHandlerSet:
             "get_agent_skills": self.agent_handler.get_agent_skills,
             "execute_agent_skill": self.agent_handler.execute_agent_skill,
             "cancel_agent_skill": self.agent_handler.cancel_agent_skill,
+            # Download routing handler
+            "get_download_routing": self.download_routing.get_download_routing,
             # Base model handlers
             "get_base_models": self.base_model.get_base_models,
             "refresh_base_models": self.base_model.refresh_base_models,

py/routes/misc_route_registrar.py

@@ -103,6 +103,10 @@ MISC_ROUTE_DEFINITIONS: tuple[RouteDefinition, ...] = (
     RouteDefinition(
         "GET", "/api/lm/hf-repo-files", "get_hf_repo_files"
     ),
+    # Download target routing decision (checkpoint vs diffusion model roots)
+    RouteDefinition(
+        "POST", "/api/lm/download/routing", "get_download_routing"
+    ),
     RouteDefinition(
         "POST", "/api/lm/download-hf-model", "download_hf_model"
     ),

py/routes/misc_routes.py

@@ -41,6 +41,7 @@ from .handlers.misc_handlers import (
 from .handlers.base_model_handlers import BaseModelHandlerSet
 from .handlers.hf_handlers import HfHandler
 from .handlers.agent_handlers import AgentHandler
+from .handlers.download_routing_handlers import DownloadRoutingHandler
 from .misc_route_registrar import MiscRouteRegistrar
 
 logger = logging.getLogger(__name__)
@@ -140,6 +141,7 @@ class MiscRoutes:
         base_model = BaseModelHandlerSet()
         hf_handler = HfHandler()
         agent_handler = AgentHandler()
+        download_routing = DownloadRoutingHandler()
 
         return self._handler_set_factory(
             health=health,
@@ -161,6 +163,7 @@ class MiscRoutes:
             base_model=base_model,
             hf_handler=hf_handler,
             agent_handler=agent_handler,
+            download_routing=download_routing,
         )
 
 

py/services/download_manager.py

@@ -20,7 +20,6 @@ from urllib.parse import urlparse
 from ..utils.models import LoraMetadata, CheckpointMetadata, EmbeddingMetadata
 from ..utils.constants import (
     CARD_PREVIEW_WIDTH,
-    DIFFUSION_MODEL_BASE_MODELS,
     MODEL_WEIGHT_FILE_TYPES,
     SUPPORTED_DOWNLOAD_SKIP_BASE_MODELS,
     VALID_LORA_TYPES,
@@ -32,6 +31,7 @@ from ..utils.utils import sanitize_folder_name
 from ..utils.exif_utils import ExifUtils
 from ..utils.metadata_manager import MetadataManager
 from .service_registry import ServiceRegistry
+from .download_routing import is_diffusion_model_download
 from .settings_manager import get_settings_manager
 from .metadata_service import get_default_metadata_provider, get_metadata_provider
 from .downloader import get_downloader, DownloadProgress, DownloadStreamControl
@@ -1621,26 +1621,12 @@ class DownloadManager:
                 }
 
             # Check if this checkpoint should be treated as a diffusion model
-            # Priority: (1) any file has type "UNet" or "Diffusion Model",
+            # (shared with the download routing endpoint so the UI location
-            #            (2) baseModel is in DIFFUSION_MODEL_BASE_MODELS
+            # step and the actual download agree on the target roots).
-            is_diffusion_model = False
+            is_diffusion_model = is_diffusion_model_download(
-            if model_type == "checkpoint":
+                model_type,
-                # Check file types first (more direct signal from CivitAI)
+                file_types=(f.get("type", "") for f in version_info.get("files", [])),
-                version_files = version_info.get("files", [])
+                base_model=base_model_value,
-                for f in version_files:
-                    f_type = f.get("type", "")
-                    if f_type in ("UNet", "Diffusion Model"):
-                        is_diffusion_model = True
-                        logger.info(
-                            f"File type '{f_type}' detected, routing checkpoint to unet folder"
-                        )
-                        break
-
-                # Fallback to baseModel name check
-                if not is_diffusion_model and base_model_value in DIFFUSION_MODEL_BASE_MODELS:
-                    is_diffusion_model = True
-                    logger.info(
-                        f"baseModel '{base_model_value}' is a known diffusion model, routing to unet folder"
             )
 
             # Existence check after the metadata fetch (#1058):

py/services/download_routing.py

@@ -0,0 +1,53 @@
+"""Shared download routing logic.
+
+Decides whether a download initiated from the checkpoint library should be
+routed to the unet/diffusion-model roots instead of the checkpoint roots.
+Used by both the download manager (at download time) and the download
+routing HTTP endpoint (when the user picks a location in the UI), so the
+two can never disagree.
+"""
+
+from __future__ import annotations
+
+import logging
+from typing import Iterable
+
+from ..utils.constants import DIFFUSION_MODEL_BASE_MODELS
+
+logger = logging.getLogger(__name__)
+
+# File types reported by the CivitAI API that indicate a raw diffusion
+# model (loaded via UNETLoader in ComfyUI) rather than a full checkpoint.
+DIFFUSION_FILE_TYPES = frozenset({"UNet", "Diffusion Model"})
+
+
+def is_diffusion_model_download(
+    model_type: str,
+    file_types: Iterable[str] = (),
+    base_model: str = "",
+) -> bool:
+    """Return True when a download should be routed to the unet roots.
+
+    Only applies to downloads initiated from the checkpoint library.
+    Priority: (1) any file has type "UNet" or "Diffusion Model" (the more
+    direct signal from CivitAI), (2) baseModel is a known diffusion model.
+    """
+    if model_type != "checkpoint":
+        return False
+
+    for file_type in file_types:
+        if file_type in DIFFUSION_FILE_TYPES:
+            logger.info(
+                "File type '%s' detected, routing checkpoint to unet folder",
+                file_type,
+            )
+            return True
+
+    if base_model in DIFFUSION_MODEL_BASE_MODELS:
+        logger.info(
+            "baseModel '%s' is a known diffusion model, routing to unet folder",
+            base_model,
+        )
+        return True
+
+    return False

static/js/api/apiConfig.js

@@ -184,6 +184,7 @@ export const DOWNLOAD_ENDPOINTS = {
     downloadGet: '/api/lm/download-model-get',
     cancelGet: '/api/lm/cancel-download-get',
     progress: '/api/lm/download-progress',
+    routing: '/api/lm/download/routing',
     exampleImages: '/api/lm/force-download-example-images', // Re-process example images ignoring previous status
     exampleImagesMissing: '/api/lm/download-example-images' // Download only missing example images
 };

static/js/components/shared/ModelVersionsTab.js

@@ -1390,8 +1390,22 @@ export function initVersionsTab({
 
         try {
             const client = ensureClient();
+            // On the checkpoints page a diffusion model lives under the unet
+            // roots, so both root sets are needed to locate the current file.
+            let roots;
+            if (modelType === 'checkpoints') {
+                const [checkpointRoots, unetRoots] = await Promise.all([
+                    client.fetchModelRoots(),
+                    client.fetchModelRoots('diffusion_model'),
+                ]);
+                roots = [
+                    ...(checkpointRoots?.roots || []),
+                    ...(unetRoots?.roots || []),
+                ];
+            } else {
                 const rootsData = await client.fetchModelRoots();
-            const roots = rootsData?.roots;
+                roots = rootsData?.roots;
+            }
             if (!Array.isArray(roots) || roots.length === 0) {
                 return null;
             }

static/js/managers/DownloadManager.js

@@ -3,6 +3,7 @@ import { showToast, setupAutoNewlineOnPaste } from '../utils/uiHelpers.js';
 import { state } from '../state/index.js';
 import { LoadingManager } from './LoadingManager.js';
 import { getModelApiClient, resetAndReload } from '../api/modelApiFactory.js';
+import { DOWNLOAD_ENDPOINTS } from '../api/apiConfig.js';
 import { isModelWeightFile } from '../utils/modelFileTypes.js';
 import { getStorageItem, setStorageItem } from '../utils/storageHelpers.js';
 import { FolderTreeManager } from '../components/FolderTreeManager.js';
@@ -954,12 +955,7 @@ export class DownloadManager {
     async proceedToLocationContent() {
 
         try {
-            const _isDiffusionModel = this.selectedFile
+            this._isDiffusionModel = await this._resolveIsDiffusionModel();
-                ? (this.selectedFile.type === 'UNet' || this.selectedFile.type === 'Diffusion Model')
-                : (this.currentVersion?.files || []).some(
-                    f => f.type === 'UNet' || f.type === 'Diffusion Model'
-                );
-            this._isDiffusionModel = _isDiffusionModel;
 
             let rootsData;
             if (this._isDiffusionModel && this.apiClient.modelType === 'checkpoints') {
@@ -1020,6 +1016,55 @@ export class DownloadManager {
         }
     }
 
+    /**
+     * Decide whether this download routes to the diffusion model (unet)
+     * roots rather than the checkpoint roots. The backend owns the routing
+     * rule (file type first, baseModel fallback), so the location step asks
+     * it; if the endpoint is unavailable we degrade to the local file-type
+     * signal, which matches the backend for well-annotated models.
+     */
+    async _resolveIsDiffusionModel() {
+        const localFileTypeCheck = this.selectedFile
+            ? (this.selectedFile.type === 'UNet' || this.selectedFile.type === 'Diffusion Model')
+            : (this.currentVersion?.files || []).some(
+                f => f.type === 'UNet' || f.type === 'Diffusion Model'
+            );
+
+        // Only checkpoint downloads can route to the diffusion model roots;
+        // without version metadata (e.g. Hugging Face downloads) the local
+        // signal is all we have.
+        if (this.apiClient.modelType !== 'checkpoints'
+            || (!this.selectedFile && !this.currentVersion)) {
+            return localFileTypeCheck;
+        }
+
+        try {
+            const fileTypes = this.selectedFile
+                ? [this.selectedFile.type]
+                : (this.currentVersion?.files || []).map(f => f.type);
+            const response = await fetch(DOWNLOAD_ENDPOINTS.routing, {
+                method: 'POST',
+                headers: { 'Content-Type': 'application/json' },
+                body: JSON.stringify({
+                    model_type: 'checkpoint',
+                    base_model: this.currentVersion?.baseModel || '',
+                    file_types: fileTypes,
+                }),
+            });
+            if (!response.ok) {
+                throw new Error(`routing endpoint returned ${response.status}`);
+            }
+            const data = await response.json();
+            if (typeof data.is_diffusion_model === 'boolean') {
+                return data.is_diffusion_model;
+            }
+        } catch (error) {
+            console.warn('[download] routing endpoint unavailable, '
+                + 'falling back to local file-type check:', error);
+        }
+        return localFileTypeCheck;
+    }
+
     loadDefaultPathSetting() {
         const modelType = this.apiClient.modelType;
         const storageKey = `use_default_path_${modelType}`;

tests/frontend/managers/downloadManager.routing.test.js

@@ -0,0 +1,146 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+
+const {
+  DOWNLOAD_MANAGER_MODULE,
+  MODAL_MANAGER_MODULE,
+  UI_HELPERS_MODULE,
+  STATE_MODULE,
+  LOADING_MANAGER_MODULE,
+  API_FACTORY_MODULE,
+  STORAGE_HELPERS_MODULE,
+  FOLDER_TREE_MANAGER_MODULE,
+  I18N_HELPERS_MODULE,
+  SUMMARY_MODULE,
+} = vi.hoisted(() => ({
+  DOWNLOAD_MANAGER_MODULE: new URL('../../../static/js/managers/DownloadManager.js', import.meta.url).pathname,
+  MODAL_MANAGER_MODULE: new URL('../../../static/js/managers/ModalManager.js', import.meta.url).pathname,
+  UI_HELPERS_MODULE: new URL('../../../static/js/utils/uiHelpers.js', import.meta.url).pathname,
+  STATE_MODULE: new URL('../../../static/js/state/index.js', import.meta.url).pathname,
+  LOADING_MANAGER_MODULE: new URL('../../../static/js/managers/LoadingManager.js', import.meta.url).pathname,
+  API_FACTORY_MODULE: new URL('../../../static/js/api/modelApiFactory.js', import.meta.url).pathname,
+  STORAGE_HELPERS_MODULE: new URL('../../../static/js/utils/storageHelpers.js', import.meta.url).pathname,
+  FOLDER_TREE_MANAGER_MODULE: new URL('../../../static/js/components/FolderTreeManager.js', import.meta.url).pathname,
+  I18N_HELPERS_MODULE: new URL('../../../static/js/utils/i18nHelpers.js', import.meta.url).pathname,
+  SUMMARY_MODULE: new URL('../../../static/js/components/DownloadBatchSummaryModal.js', import.meta.url).pathname,
+}));
+
+vi.mock(MODAL_MANAGER_MODULE, () => ({
+  modalManager: { showModal: vi.fn(), closeModal: vi.fn() },
+}));
+vi.mock(UI_HELPERS_MODULE, () => ({
+  showToast: vi.fn(),
+  setupAutoNewlineOnPaste: vi.fn(),
+}));
+vi.mock(STATE_MODULE, () => ({
+  state: { global: { settings: {} }, loadingManager: {} },
+}));
+vi.mock(LOADING_MANAGER_MODULE, () => ({
+  LoadingManager: vi.fn(() => ({})),
+}));
+vi.mock(API_FACTORY_MODULE, () => ({
+  getModelApiClient: vi.fn(),
+  resetAndReload: vi.fn(),
+}));
+vi.mock(STORAGE_HELPERS_MODULE, () => ({
+  getStorageItem: vi.fn((_key, defaultValue) => defaultValue),
+  setStorageItem: vi.fn(),
+}));
+vi.mock(FOLDER_TREE_MANAGER_MODULE, () => ({
+  FolderTreeManager: vi.fn(() => ({})),
+}));
+vi.mock(I18N_HELPERS_MODULE, () => ({
+  translate: vi.fn((_key, _vars, fallback) => fallback ?? ''),
+}));
+vi.mock(SUMMARY_MODULE, () => ({
+  showDownloadBatchSummary: vi.fn(),
+}));
+
+const { DownloadManager } = await import(DOWNLOAD_MANAGER_MODULE);
+
+describe('DownloadManager._resolveIsDiffusionModel', () => {
+  let manager;
+  let fetchMock;
+
+  beforeEach(() => {
+    manager = new DownloadManager();
+    manager.apiClient = { modelType: 'checkpoints' };
+    manager.selectedFile = null;
+    manager.selectedFiles = [];
+    manager.currentVersion = null;
+    fetchMock = vi.fn();
+    vi.stubGlobal('fetch', fetchMock);
+  });
+
+  afterEach(() => {
+    vi.unstubAllGlobals();
+  });
+
+  function mockRoutingResponse(data, ok = true) {
+    fetchMock.mockResolvedValue({
+      ok,
+      status: ok ? 200 : 500,
+      json: async () => data,
+    });
+  }
+
+  it('asks the backend and routes baseModel-only diffusion models to unet roots', async () => {
+    // The reported Anima case: file type is plain "Model".
+    manager.currentVersion = { baseModel: 'Anima', files: [{ type: 'Model' }] };
+    mockRoutingResponse({ success: true, is_diffusion_model: true, root_kind: 'unet' });
+
+    expect(await manager._resolveIsDiffusionModel()).toBe(true);
+
+    expect(fetchMock).toHaveBeenCalledWith('/api/lm/download/routing', {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({
+        model_type: 'checkpoint',
+        base_model: 'Anima',
+        file_types: ['Model'],
+      }),
+    });
+  });
+
+  it('returns the backend decision for regular checkpoints', async () => {
+    manager.currentVersion = { baseModel: 'SDXL 1.0', files: [{ type: 'Model' }] };
+    mockRoutingResponse({ success: true, is_diffusion_model: false, root_kind: 'checkpoint' });
+
+    expect(await manager._resolveIsDiffusionModel()).toBe(false);
+  });
+
+  it('sends only the selected file type when a file is selected', async () => {
+    manager.currentVersion = { baseModel: 'Flux.1 D', files: [{ type: 'Model' }, { type: 'UNet' }] };
+    manager.selectedFile = { type: 'UNet' };
+    mockRoutingResponse({ success: true, is_diffusion_model: true, root_kind: 'unet' });
+
+    expect(await manager._resolveIsDiffusionModel()).toBe(true);
+    expect(JSON.parse(fetchMock.mock.calls[0][1].body).file_types).toEqual(['UNet']);
+  });
+
+  it('falls back to the local file-type check when the endpoint fails', async () => {
+    manager.currentVersion = { baseModel: 'SDXL 1.0', files: [{ type: 'UNet' }] };
+    fetchMock.mockRejectedValue(new Error('network down'));
+
+    expect(await manager._resolveIsDiffusionModel()).toBe(true);
+  });
+
+  it('falls back to false when the endpoint fails and no local signal exists', async () => {
+    manager.currentVersion = { baseModel: 'Anima', files: [{ type: 'Model' }] };
+    mockRoutingResponse({}, false);
+
+    expect(await manager._resolveIsDiffusionModel()).toBe(false);
+  });
+
+  it('never calls the endpoint for non-checkpoint pages', async () => {
+    manager.apiClient = { modelType: 'loras' };
+    manager.currentVersion = { baseModel: 'Anima', files: [{ type: 'Model' }] };
+
+    expect(await manager._resolveIsDiffusionModel()).toBe(false);
+    expect(fetchMock).not.toHaveBeenCalled();
+  });
+
+  it('never calls the endpoint without version metadata (e.g. Hugging Face)', async () => {
+    expect(await manager._resolveIsDiffusionModel()).toBe(false);
+    expect(fetchMock).not.toHaveBeenCalled();
+  });
+});

tests/routes/test_download_routing_handlers.py

@@ -0,0 +1,93 @@
+"""Tests for the download routing HTTP handler."""
+
+import json
+
+import pytest
+
+from py.routes.handlers.download_routing_handlers import DownloadRoutingHandler
+
+
+class FakeRequest:
+    def __init__(self, payload):
+        self._payload = payload
+
+    async def json(self):
+        if isinstance(self._payload, Exception):
+            raise self._payload
+        return self._payload
+
+
+@pytest.mark.asyncio
+async def test_diffusion_base_model_routes_to_unet():
+    """The reported Anima case: file type "Model", baseModel "Anima"."""
+    handler = DownloadRoutingHandler()
+    response = await handler.get_download_routing(
+        FakeRequest(
+            {"model_type": "checkpoint", "base_model": "Anima", "file_types": ["Model"]}
+        )
+    )
+    payload = json.loads(response.text)
+    assert response.status == 200
+    assert payload == {"success": True, "is_diffusion_model": True, "root_kind": "unet"}
+
+
+@pytest.mark.asyncio
+async def test_unet_file_type_routes_to_unet():
+    handler = DownloadRoutingHandler()
+    response = await handler.get_download_routing(
+        FakeRequest(
+            {"model_type": "checkpoint", "base_model": "SDXL 1.0", "file_types": ["UNet"]}
+        )
+    )
+    payload = json.loads(response.text)
+    assert payload["is_diffusion_model"] is True
+    assert payload["root_kind"] == "unet"
+
+
+@pytest.mark.asyncio
+async def test_regular_checkpoint_stays_on_checkpoint_root():
+    handler = DownloadRoutingHandler()
+    response = await handler.get_download_routing(
+        FakeRequest(
+            {"model_type": "checkpoint", "base_model": "SDXL 1.0", "file_types": ["Model"]}
+        )
+    )
+    payload = json.loads(response.text)
+    assert payload["is_diffusion_model"] is False
+    assert payload["root_kind"] == "checkpoint"
+
+
+@pytest.mark.asyncio
+async def test_lora_is_never_diffusion():
+    handler = DownloadRoutingHandler()
+    response = await handler.get_download_routing(
+        FakeRequest({"model_type": "lora", "base_model": "Anima", "file_types": []})
+    )
+    payload = json.loads(response.text)
+    assert payload["is_diffusion_model"] is False
+    assert payload["root_kind"] == "lora"
+
+
+@pytest.mark.asyncio
+async def test_missing_model_type_rejected():
+    handler = DownloadRoutingHandler()
+    response = await handler.get_download_routing(FakeRequest({"base_model": "Anima"}))
+    assert response.status == 400
+
+
+@pytest.mark.asyncio
+async def test_invalid_file_types_rejected():
+    handler = DownloadRoutingHandler()
+    response = await handler.get_download_routing(
+        FakeRequest({"model_type": "checkpoint", "file_types": "Model"})
+    )
+    assert response.status == 400
+
+
+@pytest.mark.asyncio
+async def test_invalid_json_rejected():
+    handler = DownloadRoutingHandler()
+    response = await handler.get_download_routing(
+        FakeRequest(json.JSONDecodeError("bad", "", 0))
+    )
+    assert response.status == 400

tests/services/test_download_routing.py

@@ -0,0 +1,40 @@
+"""Tests for the shared download routing decision."""
+
+import pytest
+
+from py.services.download_routing import is_diffusion_model_download
+
+
+@pytest.mark.parametrize("file_type", ["UNet", "Diffusion Model"])
+def test_file_type_signal_routes_to_unet(file_type):
+    assert is_diffusion_model_download(
+        "checkpoint", file_types=[file_type], base_model="SDXL 1.0"
+    )
+
+
+def test_base_model_fallback_routes_to_unet():
+    """The reported Anima case: file type is plain "Model", but the
+    baseModel is a known diffusion model."""
+    assert is_diffusion_model_download(
+        "checkpoint", file_types=["Model"], base_model="Anima"
+    )
+
+
+def test_regular_checkpoint_stays_on_checkpoint_roots():
+    assert not is_diffusion_model_download(
+        "checkpoint", file_types=["Model"], base_model="SDXL 1.0"
+    )
+
+
+def test_non_checkpoint_types_never_route_to_unet():
+    assert not is_diffusion_model_download(
+        "lora", file_types=["UNet"], base_model="Anima"
+    )
+    assert not is_diffusion_model_download(
+        "embedding", file_types=["Diffusion Model"], base_model="Anima"
+    )
+
+
+def test_empty_inputs_stay_on_checkpoint_roots():
+    assert not is_diffusion_model_download("checkpoint")
+    assert not is_diffusion_model_download("checkpoint", file_types=[], base_model="")