Function run_native 

pub fn run_native(spec: Option<&str>) -> Result<(), Box<dyn Error>>

Runs the native desktop viewer until the window is closed.

spec optionally names a study to load (an open_storage_read_only spec — a local journal/SQLite path or supported remote observer URL. None opens the bundled deterministic demo. An explicitly supplied spec is authoritative: loading or analysis failure is returned instead of being replaced with demo data.

Errors

Returns the storage/analysis error for an explicitly requested study, or [eframe::Error] if the windowing/GL backend cannot start.