# [Accessibility & polish] Loading, labeling, and messaging cleanup in Data Export

# [Accessibility & polish] Loading, labeling, and messaging cleanup in Data Export

## Summary
A cluster of smaller UX/accessibility issues in the Data Export flow. Most were fixed before merge; one has a confirmed second, unfixed instance flagged in the final review.

## Items

1. **Reduced motion — second spinner instance, still open.** The preview spinner at `DataExportPreview.tsx` (originally ~line 324) was fixed to respect `prefers-reduced-motion`. But the *final* review (submitted after the last inline-comment batch, closest thing to last word before merge) flagged a **second, separate** spinner instance at `DataExportPreview.tsx` lines 318-320 that still applies `animate-spin` with no `motion-reduce` override — explicitly called a "duplicate" of the earlier finding, meaning it wasn't caught by the first fix. **Likely still open — verify.**
2. **Live region semantics** — the spinner lacked `role`/`aria-live` attributes. **Marked addressed.**
3. **Label association** — File Title inputs in the sidebar lacked `htmlFor`/`id` pairing. **Marked addressed.**
4. **Misleading empty-state copy** — the empty-state message implied the preview refreshes automatically when filters change behind the modal. **Marked addressed.**
5. **Whitespace-only search** — the site search filter treated a whitespace-only query inconsistently between filtering and messaging. **Marked addressed.**

## Affected files
- `src/nexus/src/modules/data-download/components/DataExportPreview.tsx`
- `src/nexus/src/modules/data-download/components/DataExportSidebar.tsx`
- `src/nexus/src/modules/data-download/components/SiteSelectionDialog.tsx`

## Suggested fix
Check `DataExportPreview.tsx` lines ~318-320 for a second `animate-spin` usage and add `motion-reduce:animate-none` (or an equivalent static fallback) there too.

## Acceptance criteria
- [ ] Every loading spinner in the Data Export flow (not just the first one found) respects `prefers-reduced-motion`
- [ ] Confirm items 2-5 above are genuinely fixed in the merged code