The track toast published under ONE stable portal id, replacing the
previous notification in place — and Plasma never re-presents a same-id
replacement as a banner, show-as-new hint included (measured on-desktop:
a same-id replacement with the hint produced no popup while a fresh id
bannered every time). So only the first track after boot could ever
toast. Each publish now uses track-now-playing-<generation> and removes
the previously published id first, keeping the no-pileup lifecycle;
withdraw (stop, opt-out, shutdown) removes whichever id was last
published.
cc
vicrodh
f6574cdb93