fix(usage): minimize session receipts and clarify privacy controls

frontend/src/features/settings/__tests__/ProductUsageTab.test.tsx

@@ -67,6 +67,31 @@ beforeEach(() => {
 });
 afterEach(cleanup);
 describe('product usage controls', () => {
+  it('offers identity-free audit receipts after opt-out without restoring participation controls', async () => {
+    vi.mocked(service.status).mockResolvedValue({
+      ...status,
+      privacy_receipts: {
+        last_deletion: {
+          receipt_version: 'local-audit.v1',
+          kind: 'deletion',
+          status: 'collector-confirmed'
+        }
+      }
+    });
+    mount();
+    expect(
+      await screen.findByRole('button', { name: 'productUsage.auditDownload' })
+    ).toBeEnabled();
+    expect(
+      screen.getByText('productUsage.auditDescription')
+    ).toBeInTheDocument();
+    expect(
+      screen.queryByLabelText('productUsage.hash')
+    ).not.toBeInTheDocument();
+    expect(
+      screen.queryByText('productUsage.feedbackTitle')
+    ).not.toBeInTheDocument();
+  });
   it('requires the disclosure and an unchecked-by-default consent before enabling', async () => {
     mount();
     fireEvent.click(await screen.findByText('productUsage.review'));

frontend/src/features/settings/tabs/ProductUsageTab.tsx

@@ -191,13 +191,13 @@ export default function ProductUsageTab() {
       await queryClient.invalidateQueries({ queryKey: ['productUsage'] });
     }
   };
-  const download = (value: unknown) => {
+  const download = (value: unknown, filename = 'picpeak-usage-packets.json') => {
     const url = URL.createObjectURL(
       new Blob([JSON.stringify(value, null, 2)], { type: 'application/json' })
     );
     const anchor = document.createElement('a');
     anchor.href = url;
-    anchor.download = 'picpeak-usage-packets.json';
+    anchor.download = filename;
     anchor.click();
     window.setTimeout(() => URL.revokeObjectURL(url), 1000);
   };
@@ -300,6 +300,26 @@ export default function ProductUsageTab() {
           )}
         </div>
       </Card>
+      {data.privacy_receipts &&
+        Object.keys(data.privacy_receipts).length > 0 && (
+          <Card padding="md" className="space-y-4">
+            <h3 className="text-lg font-semibold">
+              {t('productUsage.auditTitle')}
+            </h3>
+            <p>{t('productUsage.auditDescription')}</p>
+            <Button
+              variant="outline"
+              onClick={() =>
+                download(
+                  data.privacy_receipts,
+                  'picpeak-usage-privacy-receipts.json'
+                )
+              }
+            >
+              {t('productUsage.auditDownload')}
+            </Button>
+          </Card>
+        )}
       {active && (
         <>
           <Card padding="md" className="space-y-4">