Second root cause of the browser-back flake: the board is a lazy chunk
behind Suspense fallback={null} and waitForAppShell only proves the
header, so a synchronous getByText raced chunk resolution under
sharded-lane load (failure DOM showed a header-only page). The first
board lookup in both back-nav tests is now the async finder — the
correct wait mechanism, no widened timeouts. Complements the
once-queue purge fix; 3/3 solo runs green.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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