decouple tree helpers and selections

src/lib/Branch.svelte

@@ -29,15 +29,6 @@
 
 	const getNodeId = (node: Node) => `${treeId}-${helper.path(node)}`;
 
-	// get children nodes
-	function getChildren(tree: Tree) {
-		const directChildren = helper.getDirectChildren(tree, helper.path(branchRootNode));
-
-		const orderedChildren = helper.dragDrop.OrderByPriority(directChildren);
-
-		return orderedChildren;
-	}
-
 	function setExpansion(node: Node, changeTo: boolean) {
 		dispatch('internal-expand', { node: node, changeTo });
 	}
@@ -135,7 +126,7 @@
 	class:child-menu={childDepth > 0}
 	class={childDepth === 0 ? classes.treeClass : ''}
 >
-	{#each getChildren(tree) as node (getNodeId(node))}
+	{#each helper.getDirectChildren(tree, helper.path(branchRootNode)) as node (getNodeId(node))}
 		{@const nesthighlighed = highlightNesting(node, highlightedNode, validTarget, canNest)}
 		{@const insertHighlighted = highlightInsert(node, highlightedNode, validTarget, canNest)}
 		{@const expanded = isExpanded(node, childDepth, expandTo)}

src/lib/Checkbox.svelte

@@ -2,6 +2,7 @@
 	import { createEventDispatcher } from 'svelte';
 	import { SelectionModes, type Node } from './types.js';
 	import type { TreeHelper } from '$lib/index.js';
+	import { SelectionProvider } from '$lib/providers/selection-provider.js';
 
 	export let checkboxes: SelectionModes;
 	export let helper: TreeHelper;
@@ -12,13 +13,16 @@
 	export let readonly = false;
 
 	let indeterminate: boolean;
+
 	$: {
 		if (helper.props.visualState(node) == 'indeterminate') {
 			indeterminate = true;
 		} else {
 			indeterminate = false;
 		}
 	}
+	// TODO pass from root
+	$: selectionProvider = new SelectionProvider(helper, recursive);
 
 	const dispatch = createEventDispatcher();
 
@@ -28,7 +32,7 @@
 </script>
 
 {#if checkboxes == SelectionModes.perNode || checkboxes == SelectionModes.all}
-	{#if helper.selection.isSelectable(node, checkboxes)}
+	{#if selectionProvider.isSelectable(node, checkboxes)}
 		<!-- select node -->
 		{#if !recursive || (recursive && !helper.props.hasChildren(node))}
 			<input