Merge #774 head 51264ec0 into the release branch

Takes the contributor's wording for the picker title and the toast, the
preview refresh after the preflight and the clearer 409 text, and keeps
the fuller tests and the invariants paragraph from the release branch.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/clone-custom-folder-ui.test.ts

@@ -123,7 +123,7 @@ describe('Clone Repo custom folder', () => {
       allowNewFolder: boolean;
       onSelect(p: string): void;
     };
-    expect(options.title).toBe('Choose the parent folder for the clone');
+    expect(options.title).toBe('Choose the folder to clone inside');
     expect(options.directoriesOnly).toBe(true);
     // A parent that does not exist yet is refused, so the picker has to be able to make it.
     expect(options.allowNewFolder).toBe(true);
@@ -140,7 +140,7 @@ describe('Clone Repo custom folder', () => {
     app.showToast = vi.fn();
     (doc.getElementById('cloneCustomPathToggle') as HTMLInputElement).checked = true;
     await app.cloneCase();
-    expect(app.showToast).toHaveBeenCalledWith('Choose the parent folder for the clone', 'error');
+    expect(app.showToast).toHaveBeenCalledWith('Choose the folder to clone inside', 'error');
     expect(fetchMock).not.toHaveBeenCalled();
   });
 
@@ -159,4 +159,30 @@ describe('Clone Repo custom folder', () => {
     expect(app.showToast).toHaveBeenCalledWith('Please enter a case name', 'error');
     expect(fetchMock).not.toHaveBeenCalled();
   });
+
+  it('refreshes the preview when the preflight replaces the case name', () => {
+    const { app, doc, set } = bootClone();
+    set('cloneRepoUrl', 'https://github.com/opticon454/bifrost?tab=readme-ov-file');
+    set('cloneCaseName', 'bifrost-tab-readme-ov-file');
+    set('cloneCasePath', '/mnt/projects');
+    app.updateCloneCasePathPreview();
+    expect(doc.getElementById('cloneCasePathPreview')?.textContent).toBe(
+      'Will clone into: /mnt/projects/bifrost-tab-readme-ov-file'
+    );
+    app._applyClonePreflight({ gitAvailable: true, parse: { cloneable: true, suggestedName: 'bifrost' } }, '');
+    expect((doc.getElementById('cloneCaseName') as HTMLInputElement).value).toBe('bifrost');
+    expect(doc.getElementById('cloneCasePathPreview')?.textContent).toBe('Will clone into: /mnt/projects/bifrost');
+  });
+
+  it('previews the name taken from the URL as it is typed', () => {
+    const { app, doc, set, win } = bootClone();
+    app.isCliAvailable = () => true; // lives in settings-ui.js, which this test does not load
+    set('cloneCaseName', '');
+    set('cloneCasePath', '/mnt/projects');
+    set('cloneRepoUrl', 'https://github.com/opticon454/bifrost');
+    app.onCloneUrlInput();
+    win.clearTimeout(app._clonePreflightTimer);
+    expect((doc.getElementById('cloneCaseName') as HTMLInputElement).value).toBe('bifrost');
+    expect(doc.getElementById('cloneCasePathPreview')?.textContent).toBe('Will clone into: /mnt/projects/bifrost');
+  });
 });