fix(clone): keep the preview and the wording on the parent folder

The "Will clone into" line named a folder the request would not use: the
preflight replaces the page's guessed case name with the server's (for a
URL such as .../repo?tab=readme the guess is repo-tab-readme and the server
says repo) and nothing refreshed the preview, so it stayed on the old name
while the field and the request moved on. It is now refreshed there too.

The Browse picker's title and the empty-field toast still said "Choose the
folder to clone into", the old exact-target meaning. Both now ask for the
parent folder, matching the field's label.

CLAUDE.md and the invariants paragraph split the two meanings: path on the
API is the exact folder, the Clone Repo tab's field is a parent and the page
sends <folder>/<case name>.

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

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

@@ -2,7 +2,10 @@
  * @fileoverview Frontend test for Clone Repo's custom folder (session-ui.js `cloneCase()` /
  * `_cloneTargetPath()`): the chosen folder is the PARENT, so the clone request carries
  * `<folder>/<case name>` exactly as Create New does, and without the checkbox no `path` is sent
- * (the server then clones to `~/codeman-cases/<name>`). Runs against the real index.html markup.
+ * (the server then clones to `~/codeman-cases/<name>`). The "Will clone into" line has to name the
+ * folder the request will really use, so it follows every way the name or the folder can change:
+ * typing, the URL, the preflight's suggested name and the Browse picker. Runs against the real
+ * index.html markup.
  *
  * Port: none.
  */
@@ -33,7 +36,8 @@ function bootClone() {
   const set = (id: string, value: string) => ((doc.getElementById(id) as HTMLInputElement).value = value);
   set('cloneRepoUrl', 'https://github.com/opticon454/bifrost');
   set('cloneCaseName', 'bifrost');
-  return { app, doc, set, fetchMock };
+  const preview = () => doc.getElementById('cloneCasePathPreview')?.textContent;
+  return { app, win, doc, set, preview, fetchMock };
 }
 
 async function requestBody(fetchMock: ReturnType<typeof vi.fn>) {
@@ -72,4 +76,80 @@ describe('Clone Repo custom folder', () => {
     const { body } = await requestBody(fetchMock);
     expect(body.path).toBeUndefined();
   });
+
+  it.each([
+    ['/mnt/projects', '/mnt/projects/bifrost'],
+    ['/mnt/projects///', '/mnt/projects/bifrost'],
+    ['  /mnt/projects/  ', '/mnt/projects/bifrost'],
+    ['/', '/bifrost'],
+    ['~', '~/bifrost'],
+    ['~/', '~/bifrost'],
+  ])('joins the parent %j to the case name', (parent, target) => {
+    const { app, set } = bootClone();
+    set('cloneCasePath', parent);
+    expect(app._cloneTargetPath()).toBe(target);
+  });
+
+  it('follows the name the preflight settles on, which is the one the request will carry', async () => {
+    const { app, doc, set, preview, fetchMock } = bootClone();
+    (doc.getElementById('cloneCustomPathToggle') as HTMLInputElement).checked = true;
+    set('cloneCasePath', '/mnt/projects');
+    // The page's own guess for a URL copied out of a browser tab; the server reads the repo as `repo`.
+    set('cloneCaseName', 'repo-tab-readme');
+    app.updateCloneCasePathPreview();
+    expect(preview()).toBe('Will clone into: /mnt/projects/repo-tab-readme');
+    app._applyClonePreflight(
+      {
+        parse: { cloneable: true, suggestedName: 'repo', provider: 'GitHub', owner: 'owner', repo: 'repo' },
+        gitAvailable: true,
+      },
+      'https://github.com/owner/repo?tab=readme'
+    );
+    expect(preview()).toBe('Will clone into: /mnt/projects/repo');
+    await app.cloneCase();
+    const { body } = await requestBody(fetchMock);
+    expect(body).toMatchObject({ name: 'repo', path: '/mnt/projects/repo' });
+  });
+
+  it('sends the folder Browse picked as the parent, and titles the picker as the parent', async () => {
+    const { app, win, doc, preview, fetchMock } = bootClone();
+    const open = vi.fn();
+    (win as unknown as { PathPicker: { open: unknown } }).PathPicker = { open };
+    (doc.getElementById('cloneCustomPathToggle') as HTMLInputElement).checked = true;
+    app.openCloneCasePathPicker();
+    const options = open.mock.calls[0]![0] as { title: string; directoriesOnly: boolean; onSelect(p: string): void };
+    expect(options.title).toBe('Choose the parent folder for the clone');
+    expect(options.directoriesOnly).toBe(true);
+    options.onSelect('/mnt/projects');
+    expect((doc.getElementById('cloneCasePath') as HTMLInputElement).value).toBe('/mnt/projects');
+    expect(preview()).toBe('Will clone into: /mnt/projects/bifrost');
+    await app.cloneCase();
+    const { body } = await requestBody(fetchMock);
+    expect(body.path).toBe('/mnt/projects/bifrost');
+  });
+
+  it('asks for the parent folder before cloning when the checkbox is on and the field is empty', async () => {
+    const { app, doc, fetchMock } = bootClone();
+    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(fetchMock).not.toHaveBeenCalled();
+  });
+
+  it('builds no target and sends nothing without a case name', async () => {
+    const { app, doc, set, preview, fetchMock } = bootClone();
+    app.showToast = vi.fn();
+    (doc.getElementById('cloneCustomPathToggle') as HTMLInputElement).checked = true;
+    set('cloneCasePath', '/mnt/projects');
+    set('cloneCaseName', '');
+    app.updateCloneCasePathPreview();
+    expect(app._cloneTargetPath()).toBe('');
+    expect(preview()).toBe(
+      'Pick the folder the repository should be cloned inside. It goes into a subfolder named after the case.'
+    );
+    await app.cloneCase();
+    expect(app.showToast).toHaveBeenCalledWith('Please enter a case name', 'error');
+    expect(fetchMock).not.toHaveBeenCalled();
+  });
 });