cachedPanel method
The cached panel, if there is a usable one — parsed, never rendered from bytes this build cannot read.
Never touches the network: a cache hit or miss is a storage question,
not a server one. A cold start calls this first to paint immediately,
then calls panel as usual to revalidate behind it. Implementations
with no cache configured return null unconditionally.
Implementation
@override
Future<PanelSchema?> cachedPanel() => _schemaCache.cachedPanel();