Possible infinite back-navigation loop on dashboard page

[vanatteveldt]

Observed behaviour

Clicking the browser back button on the dashboard page (e.g. /projects/dutch_news_media/dashboard?tab=summary) appeared to get stuck in an infinite refresh/redirect loop. Could not be reproduced — may have been a one-time fluke.

Diagnosis

The likely root cause is this useEffect in frontend/src/routes/projects.$project.dashboard.tsx:

useEffect(() => {
  setQueryState(serializeQuery(query));
}, [query, setQueryState]);

This effect fires on every mount, including when the user arrives via back-navigation. setQueryState from nuqs uses history.push by default, meaning it adds a new browser history entry.

The risk: if serializeQuery(deserializeQuery(savedQueryString)) produces a different compressed string than what is already in the URL (lz-string compression is not guaranteed to produce identical output when round-tripping), nuqs sees a changed value and pushes a new history entry. The result:

1. User clicks back → dashboard mounts with ?query=ABC
2. Effect fires → re-serialises → produces ?query=XYZ → pushes new history entry
3. User clicks back → lands on ?query=ABC again → repeat

Decision

Not fixing for now, since the issue could not be reproduced. If it recurs, the fix is to skip the setQueryState call on the initial mount (only push when the query changes after mount):

const isMounted = useRef(false);
useEffect(() => {
  if (!isMounted.current) { isMounted.current = true; return; }
  setQueryState(serializeQuery(query));
}, [query, setQueryState]);