OptionalhotkeyOverride the default 'alt' hotkey trigger. Pass null to omit.
OptionalkeybindingOverride the default { key: 'I' } keybinding. Pass null to omit
the keybinding entirely (palette-only or hotkey-only wiring).
Called when the user picks a color. null means "no node was hit
with a color" — currently only reachable when colorOf returns null
on a real hit; empty-click is a no-op in v1.
Map a node id to a color string, or
nullif the node has no color to sample. Called on click with the id of the topmost node under the click point.