fix(other-models): default downloads to a flat path, not {base_model}/{first_tag}

get_download_path_template() fell back to "{base_model}/{first_tag}" for any
unconfigured model type, so other-model downloads were silently nested under an
arbitrary CivitAI tag even though the settings UI exposes no template row for
"other" and priority_tags has no "other" entry (making {first_tag} resolve to
tags[0]).

Add DEFAULT_DOWNLOAD_PATH_TEMPLATES with other -> "" so unconfigured and
unknown types resolve to a flat layout under the already sub_type-scoped
default_other_roots; explicit settings.json values still win. Mirror the flat
default in the frontend DEFAULT_PATH_TEMPLATES and stop the download/move
default-path previews from rendering "/undefined" or a dangling slash.

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

@@ -0,0 +1,183 @@
+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,
+  mockApiClient,
+  mockLoadingManager,
+  mockFolderTreeManager,
+  mockState,
+} = vi.hoisted(() => {
+  const mockApiClient = {
+    modelType: 'loras',
+    apiConfig: {
+      config: {
+        displayName: 'LoRA',
+        singularName: 'lora',
+      },
+    },
+  };
+
+  const mockLoadingManager = {
+    showSimpleLoading: vi.fn(),
+    setStatus: vi.fn(),
+    hide: vi.fn(),
+  };
+
+  const mockFolderTreeManager = {
+    getSelectedPath: vi.fn(() => ''),
+  };
+
+  const mockState = {
+    global: {
+      settings: {
+        download_path_templates: {},
+      },
+    },
+    loadingManager: mockLoadingManager,
+  };
+
+  return {
+    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,
+    mockApiClient,
+    mockLoadingManager,
+    mockFolderTreeManager,
+    mockState,
+  };
+});
+
+vi.mock(MODAL_MANAGER_MODULE, () => ({
+  modalManager: {
+    showModal: vi.fn(),
+    closeModal: vi.fn(),
+  },
+}));
+
+vi.mock(UI_HELPERS_MODULE, () => ({
+  showToast: vi.fn(),
+  showActionToast: vi.fn(),
+  setupAutoNewlineOnPaste: vi.fn(),
+}));
+
+vi.mock(STATE_MODULE, () => ({
+  state: mockState,
+}));
+
+vi.mock(LOADING_MANAGER_MODULE, () => ({
+  LoadingManager: vi.fn(() => mockLoadingManager),
+}));
+
+vi.mock(API_FACTORY_MODULE, () => ({
+  getModelApiClient: vi.fn(() => mockApiClient),
+  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(() => mockFolderTreeManager),
+}));
+
+vi.mock(I18N_HELPERS_MODULE, () => ({
+  translate: vi.fn((_, __, fallback) => fallback ?? ''),
+}));
+
+vi.mock(SUMMARY_MODULE, () => ({
+  showDownloadBatchSummary: vi.fn(),
+}));
+
+describe('DownloadManager default-path preview', () => {
+  let DownloadManager;
+
+  beforeEach(async () => {
+    vi.resetModules();
+    vi.clearAllMocks();
+    ({ DownloadManager } = await import(DOWNLOAD_MANAGER_MODULE));
+
+    document.body.innerHTML = `
+      <select id="modelRoot"><option value="/models/vae">/models/vae</option></select>
+      <div id="targetPathDisplay"></div>
+    `;
+    document.getElementById('modelRoot').value = '/models/vae';
+
+    mockState.global.settings.download_path_templates = {};
+  });
+
+  afterEach(() => {
+    document.body.innerHTML = '';
+  });
+
+  function useOtherClient(manager) {
+    mockApiClient.modelType = 'other';
+    mockApiClient.apiConfig.config = { displayName: 'Other Model', singularName: 'other' };
+    manager.apiClient = mockApiClient;
+  }
+
+  it('renders the bare root for a flat (empty) other template', () => {
+    mockState.global.settings.download_path_templates = { other: '' };
+    const manager = new DownloadManager();
+    useOtherClient(manager);
+    manager.useDefaultPath = true;
+
+    manager.updateTargetPath();
+
+    const text = document.getElementById('targetPathDisplay').textContent;
+    expect(text).toBe('/models/vae');
+    expect(text).not.toContain('undefined');
+  });
+
+  it('renders the bare root when the other template key is absent', () => {
+    mockState.global.settings.download_path_templates = {};
+    const manager = new DownloadManager();
+    useOtherClient(manager);
+    manager.useDefaultPath = true;
+
+    manager.updateTargetPath();
+
+    const text = document.getElementById('targetPathDisplay').textContent;
+    expect(text).toBe('/models/vae');
+    expect(text).not.toContain('undefined');
+  });
+
+  it('appends a configured template to the root', () => {
+    mockState.global.settings.download_path_templates = { other: '{base_model}' };
+    const manager = new DownloadManager();
+    useOtherClient(manager);
+    manager.useDefaultPath = true;
+
+    manager.updateTargetPath();
+
+    expect(document.getElementById('targetPathDisplay').textContent).toBe('/models/vae/{base_model}');
+  });
+
+  it('renders the manual selection when default paths are off', () => {
+    mockFolderTreeManager.getSelectedPath.mockReturnValue('nested/folder');
+    const manager = new DownloadManager();
+    useOtherClient(manager);
+    manager.useDefaultPath = false;
+
+    manager.updateTargetPath();
+
+    expect(document.getElementById('targetPathDisplay').textContent).toBe('/models/vae/nested/folder');
+  });
+});

tests/services/test_download_manager_other.py

@@ -428,6 +428,29 @@ async def test_default_paths_use_per_sub_type_root(
 
     assert result["success"] is True
     assert str(tmp_path / "vae") in str(captured["save_dir"])
+    assert captured["relative_path"] == ""
+
+
+@pytest.mark.asyncio
+async def test_default_paths_other_is_flat_without_configured_template(
+    monkeypatch, scanners, metadata_provider, tmp_path
+):
+    """Regression: an unconfigured 'other' template must resolve to a flat
+    layout at the sub_type root instead of the {base_model}/{first_tag}
+    fallback (which scattered files into arbitrary CivitAI-tag folders)."""
+    get_settings_manager().settings["download_path_templates"].pop("other", None)
+
+    captured = {}
+    _capture_execute(monkeypatch, captured)
+
+    manager = DownloadManager()
+    result = await manager.download_from_civitai(
+        model_version_id=99, use_default_paths=True
+    )
+
+    assert result["success"] is True
+    assert captured["relative_path"] == ""
+    assert str(tmp_path / "vae") in str(captured["save_dir"])
 
 
 @pytest.mark.asyncio

tests/services/test_settings_manager.py

@@ -345,6 +345,26 @@ def test_download_path_template_invalid_json(manager):
     )
 
 
+def test_download_path_template_defaults_flat_for_other(manager):
+    """'other' has no settings-UI row and no priority_tags entry, so an
+    unconfigured template must resolve to a flat layout rather than the
+    {base_model}/{first_tag} fallback (which scatters files into arbitrary
+    CivitAI-tag folders)."""
+    manager.settings["download_path_templates"] = {}
+
+    assert manager.get_download_path_template("other") == ""
+
+    # An explicit user configuration still wins.
+    manager.settings["download_path_templates"] = {"other": "{base_model}"}
+    assert manager.get_download_path_template("other") == "{base_model}"
+
+
+def test_download_path_template_unknown_type_is_flat(manager):
+    manager.settings["download_path_templates"] = {}
+
+    assert manager.get_download_path_template("not-a-model-type") == ""
+
+
 def test_auto_set_default_roots(manager):
     # Clear any previously auto-set values to test fresh behavior
     manager.settings["default_lora_root"] = ""