A rapid A→B→A flip now costs no plugin work: the restore cancels the still-pending
park outright. A park that has already written one FX carries a `partial` flag and is
superseded by its inverse rather than cancelled, so a half-parked chain is never stranded.
A switch wrote all seven ext-state keys to record that view_state moved,
re-serializing the bank book and the tracking ledger for nothing. Both entry
surfaces now take saveViewStateOnly; every other caller keeps the full save.
Fixes a hidden-parent solo replay that could silence the mix. Also closes the N-mode segment silent no-op, amends the invariant comment, trims view.cpp under 600 lines, hedges two SDK inferences, drops a dead null-check.
Solo is cached, cleared and replayed per mode on a real switch only; the switch is refused visibly while the transport runs. The footer segment now routes through the activate actions, so a panel switch finally persists.
daniel