A sidebar-manager plugin had no SDK door for moving or hiding nav rows —
today it hides core rows with CSS display:none and re-parents React-owned
children. Give it a preference store core reads at render.
host.sidebar.hide(navId, hidden?) and host.sidebar.setOrder(ids) write the
persisted nav-preference store; the sidebar applies them through one pure
function (orderSidebarNav) so the semantics are testable: hidden ids drop,
named ids come first in that order, unnamed rows keep their default relative
order after them, unknown ids are inert. The preference never mutates the
default list — removing the plugin leaves every row where it was.
Wishlist item 4 of #116305; unblocks sidebar-manager (#115973).
632a5cd1c8