ArrowDown moved focus into the tree, but the picker passed no Selectable /
SelectedKeyChanged, so Enter/Space on a treeitem only moved the roving tabindex —
the pick lived on the label span's @onclick, i.e. mouse only. The tree now runs in
Selectable mode and BOTH gestures arrive at one handler (OnTreeKeyActivatedAsync)
through TreeView's SelectedKeyChanged: an `i:{id}` key selects that instance, an
`a:{id}` key toggles the branch. The label's own @onclick is gone — the click
already bubbles into TreeView's content span, so a second handler there would fire
the callback twice. SelectedKey stays unbound (a combobox shows its pick in the
field, not as a row highlight, and binding it would arm TreeView's
selected-key-not-in-tree reset on every render while the pick is filtered out);
SelectedCssClass is emptied to match.
a11y: the field gains an accessible name via a new AriaLabel parameter (default
"Instance") and an optional InputId so a page can point a <label for> at it;
aria-controls is rendered only while the panel exists, instead of always pointing
at an id that is absent when closed.
Also drops the unused @using of Commons.Entities.Instances from the .razor.
Tests: keyboard activation on an instance row and on an area row, a
one-selection-per-gesture guard across mouse and keyboard, and the labelling
assertions. CentralUI suite 1331 passed / 0 failed; build 0 warnings.
Claude-Session: https://claude.ai/code/session_01NcMG6xXdsJbmD2wYAgkK29
Joseph Doherty
a33a2f4456