diff --git a/.github/workflows/CI.yaml b/.github/workflows/CI.yaml
index 46f272b..ad1e490 100644
--- a/.github/workflows/CI.yaml
+++ b/.github/workflows/CI.yaml
@@ -19,9 +19,9 @@ jobs:
     if: (github.event_name == 'push' || github.event.pull_request.head.repo.full_name != github.repository)
     steps:
       - name: Cancel Previous Runs
-      uses: styfle/cancel-workflow-action@85880fa0301c86cca9da44039ee3bb12d3bedbfa # 0.12.1
-      with:
-          access_token: ${{ github.token }}
+        uses: styfle/cancel-workflow-action@85880fa0301c86cca9da44039ee3bb12d3bedbfa # 0.12.1
+        with:
+            access_token: ${{ github.token }}
 
   php_syntax_errors:
     name: 1️⃣ PHP - Syntax errors
diff --git a/phpstan-baseline.neon b/phpstan-baseline.neon
new file mode 100644
index 0000000..4acd070
--- /dev/null
+++ b/phpstan-baseline.neon
@@ -0,0 +1,15 @@
+parameters:
+	ignoreErrors:
+
+		-
+			message: '#^Call to an undefined method Kalnoy\\Nestedset\\Contracts\\NodeQueryBuilder\<Tmodel of Illuminate\\Database\\Eloquent\\Model\>\:\:whereIn\(\)\.$#'
+			identifier: method.notFound
+			count: 1
+			path: src/QueryBuilder.php
+
+		-
+			message: '#^Dynamic call to static method Kalnoy\\Nestedset\\QueryBuilder\<Tmodel of Illuminate\\Database\\Eloquent\\Model\>\:\:whereRaw\(\)\.$#'
+			identifier: staticMethod.dynamicCall
+			count: 1
+			path: src/QueryBuilder.php
+
diff --git a/phpstan.neon b/phpstan.neon
index 1e5e209..a0e5e0d 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -1,18 +1,17 @@
 includes:
 	- vendor/larastan/larastan/extension.neon
 	- vendor/lychee-org/phpstan-lychee/phpstan.neon
+	- phpstan-baseline.neon
 
 parameters:
-	level: 3
+	level: 6
 	paths:
 		- src
+		- tests/models/
 	excludePaths:
 	stubFiles:
 	ignoreErrors:
-		# - identifier: missingType.generics
-		- '#Interface must be located in "Contract" or "Contracts" namespace#'
-		- '#Dynamic call to static method Kalnoy\\Nestedset\\QueryBuilder<.*>::select\(\).#'
-		- '#Dynamic call to static method Kalnoy\\Nestedset\\QueryBuilder<.*>::from\(\).#'
-		# - '#Dynamic call to static method Kalnoy\\Nestedset\\QueryBuilder<.*>::whereRaw\(\).#'
-		- '#Dynamic call to static method Kalnoy\\Nestedset\\QueryBuilder<.*>::whereNested\(\).#'
-		- '#Dynamic call to static method Kalnoy\\Nestedset\\QueryBuilder<.*>::whereIn\(\).#'
+		- '#.*covariant.*#'
+		- '#.*contravariant.*#'
+		-
+			message: '#^Call to an undefined method Kalnoy\\Nestedset\\Contracts\\Node<.*>::assert.*\(\)\.$#'
\ No newline at end of file
diff --git a/src/AncestorsRelation.php b/src/AncestorsRelation.php
index 2fabefe..1d2b5f9 100644
--- a/src/AncestorsRelation.php
+++ b/src/AncestorsRelation.php
@@ -3,17 +3,17 @@
 namespace Kalnoy\Nestedset;
 
 use Illuminate\Database\Eloquent\Model;
+use Kalnoy\Nestedset\Contracts\Node;
+use Kalnoy\Nestedset\Contracts\NodeQueryBuilder;
 
 /**
  * @template Tmodel of Model
  *
- * @phpstan-type NodeModel Node<Tmodel>&Tmodel
- *
- * @disregard P1037
+ * @phpstan-type NodeModel \Kalnoy\Nestedset\Contracts\Node<Tmodel>&Tmodel
  *
  * @extends BaseRelation<Tmodel>
  */
-class AncestorsRelation extends BaseRelation
+final class AncestorsRelation extends BaseRelation
 {
 	/**
 	 * Set the base constraints on the relation query.
@@ -36,14 +36,14 @@ public function addConstraints()
 	 *
 	 * @return bool
 	 */
-	protected function matches(Model $model, $related): bool
+	protected function matches(Node $model, Node $related): bool
 	{
 		return $related->isAncestorOf($model);
 	}
 
 	/**
-	 * @param QueryBuilder<Tmodel> $query
-	 * @param NodeModel            $model
+	 * @param NodeQueryBuilder<Tmodel> $query
+	 * @param NodeModel                $model
 	 *
 	 * @return void
 	 */
@@ -57,6 +57,7 @@ protected function addEagerConstraint($query, $model)
 	 */
 	protected function relationExistenceCondition(string $hash, string $table, string $lft, string $rgt): string
 	{
+		/** @disregard P1013 */
 		$key = $this->getBaseQuery()->getGrammar()->wrap($this->parent->getKeyName());
 
 		return "{$table}.{$rgt} between {$hash}.{$lft} and {$hash}.{$rgt} and $table.$key <> $hash.$key";
diff --git a/src/BaseRelation.php b/src/BaseRelation.php
index e263b4d..a59a708 100644
--- a/src/BaseRelation.php
+++ b/src/BaseRelation.php
@@ -7,23 +7,24 @@
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\Relation;
 use Illuminate\Database\Query\Builder;
+use Kalnoy\Nestedset\Contracts\NestedSetCollection;
+use Kalnoy\Nestedset\Contracts\Node;
+use Kalnoy\Nestedset\Contracts\NodeQueryBuilder;
 
 /**
  * @template Tmodel of Model
  *
- * @phpstan-type NodeModel Node<Tmodel>&Tmodel
+ * @phpstan-type NodeModel  Node<Tmodel>&Tmodel
  *
- * @extends Relation<NodeModel,NodeModel,EloquentCollection<int,NodeModel>>
+ * @extends Relation<NodeModel,NodeModel,NestedSetCollection<Tmodel>>
  *
  * @property NodeModel $related
  * @property NodeModel $parent
- *
- * @method NodeModel getParent()
  */
 abstract class BaseRelation extends Relation
 {
 	/**
-	 * @var QueryBuilder<Tmodel>
+	 * @var NodeQueryBuilder<Tmodel>
 	 */
 	protected $query;
 
@@ -42,8 +43,8 @@ abstract class BaseRelation extends Relation
 	/**
 	 * AncestorsRelation constructor.
 	 *
-	 * @param QueryBuilder<Tmodel> $builder
-	 * @param NodeModel            $model
+	 * @param QueryBuilder<NodeModel> $builder
+	 * @param NodeModel               $model
 	 */
 	public function __construct(QueryBuilder $builder, Model $model)
 	{
@@ -60,11 +61,11 @@ public function __construct(QueryBuilder $builder, Model $model)
 	 *
 	 * @return bool
 	 */
-	abstract protected function matches(Model&Node $model, Node $related): bool;
+	abstract protected function matches(Node $model, Node $related): bool;
 
 	/**
-	 * @param QueryBuilder<Tmodel> $query
-	 * @param NodeModel            $model
+	 * @param NodeQueryBuilder<Tmodel> $query
+	 * @param NodeModel                $model
 	 *
 	 * @return void
 	 */
@@ -90,6 +91,7 @@ abstract protected function relationExistenceCondition(string $hash, string $tab
 	public function getRelationExistenceQuery(EloquentBuilder $query, EloquentBuilder $parentQuery,
 		$columns = ['*'],
 	) {
+		/** @disregard P1006 */
 		$query = $this->getParent()->replicate()->newScopedQuery()->select($columns);
 
 		$table = $query->getModel()->getTable();
@@ -106,7 +108,7 @@ public function getRelationExistenceQuery(EloquentBuilder $query, EloquentBuilde
 			$grammar->wrap($this->parent->getLftName()),
 			$grammar->wrap($this->parent->getRgtName()));
 
-		return $query->whereRaw($condition); /** @phpstan-ignore-line */
+		return $query->whereRaw($condition);
 	}
 
 	/**
@@ -137,11 +139,11 @@ public function getRelationCountHash($incrementJoinCount = true)
 	/**
 	 * Get the results of the relationship.
 	 *
-	 * @return Collection<NodeModel>
+	 * @return NestedSetCollection<NodeModel>
 	 */
 	public function getResults()
 	{
-		/** @var Collection<NodeModel> */
+		/** @disregard P1013 */
 		$result = $this->query->get();
 
 		return $result;
@@ -164,6 +166,7 @@ public function addEagerConstraints(array $models)
 		$this->query->whereNested(function (Builder $inner) use ($models) {
 			// We will use this query in order to apply constraints to the
 			// base query builder
+			/** @disregard P1013 */
 			$outer = $this->parent->newQuery()->setQuery($inner);
 
 			foreach ($models as $model) {
@@ -187,6 +190,7 @@ public function match(array $models, EloquentCollection $results, $relation)
 			/** @disregard P1006 */
 			$related = $this->matchForModel($model, $results);
 
+			/** @disregard P1013 */
 			$model->setRelation($relation, $related);
 		}
 
@@ -197,16 +201,16 @@ public function match(array $models, EloquentCollection $results, $relation)
 	 * @param NodeModel                         $model
 	 * @param EloquentCollection<int,NodeModel> $results
 	 *
-	 * @return Collection<Tmodel>
+	 * @return NestedSetCollection<Tmodel>
 	 */
 	protected function matchForModel(Model $model, EloquentCollection $results)
 	{
-		/** @var Collection<Tmodel> */
 		$result = $this->related->newCollection();
 
 		foreach ($results as $related) {
 			/** @disregard P1006 */
 			if ($this->matches($model, $related)) {
+				/** @disregard P1013 */
 				$result->push($related);
 			}
 		}
diff --git a/src/Collection.php b/src/Collection.php
index de80624..cd45945 100644
--- a/src/Collection.php
+++ b/src/Collection.php
@@ -4,15 +4,19 @@
 
 use Illuminate\Database\Eloquent\Collection as EloquentCollection;
 use Illuminate\Database\Eloquent\Model;
+use Kalnoy\Nestedset\Contracts\NestedSetCollection;
+use Kalnoy\Nestedset\Exceptions\NestedSetException;
 
 /**
  * @template Tmodel of Model
  *
- * @phpstan-type NodeModel Node<Tmodel>&Tmodel
+ * @phpstan-type NodeModel \Kalnoy\Nestedset\Contracts\Node<Tmodel>&Model
  *
  * @extends EloquentCollection<array-key,NodeModel>
+ *
+ * @implements NestedSetCollection<Tmodel>
  */
-final class Collection extends EloquentCollection
+final class Collection extends EloquentCollection implements NestedSetCollection
 {
 	/**
 	 * Fill `parent` and `children` relationships for every node in the collection.
@@ -34,16 +38,20 @@ public function linkNodes()
 		/** @var NodeModel $node */
 		foreach ($this->items as $node) {
 			if ($node->getParentId() === null) {
+				/** @disregard */
 				$node->setRelation('parent', null);
 			}
 
-			/** @var array<int,NodeModel> */ 
-			$children = $groupedNodes->get($node->getKey(), []); /** @phpstan-ignore varTag.type */
+			$children = $groupedNodes->get($node->getKey(), []);
 
-			foreach ($children as $child) {
-				$child->setRelation('parent', $node);
+			if (count($children) > 0) {
+				foreach ($children as $child) {
+					/** @disregard */
+					$child->setRelation('parent', $node);
+				}
 			}
 
+			/** @disregard */
 			$node->setRelation('children', EloquentCollection::make($children));
 		}
 
@@ -59,9 +67,9 @@ public function linkNodes()
 	 *
 	 * @param mixed $root
 	 *
-	 * @return Collection<Tmodel>
+	 * @return NestedSetCollection<Tmodel>
 	 */
-	public function toTree($root = false)
+	public function toTree($root = false): NestedSetCollection
 	{
 		if ($this->isEmpty()) {
 			return new static();
@@ -123,23 +131,22 @@ protected function getRootNodeId($root = false)
 	 *
 	 * @param bool $root
 	 *
-	 * @return Collection<Tmodel>
+	 * @return NestedSetCollection<Tmodel>
 	 */
-	public function toFlatTree($root = false): Collection
+	public function toFlatTree($root = false): NestedSetCollection
 	{
 		/** @Var Collection<Tmodel> */
 		$result = new Collection();
 
 		if ($this->isEmpty()) {
-			return $result; /** @phpstan-ignore-line */
+			return $result;
 		}
 
 		/** @var NodeModel */
 		$first = $this->first();
-		/** @var Collection<NodeModel> */
-		$groupedNodes = $this->groupBy($first->getParentIdName()); /** @phpstan-ignore varTag.type */
+		$groupedNodes = $this->groupBy($first->getParentIdName());
 
-		return $result->flattenTree($groupedNodes, $this->getRootNodeId($root)); /** @phpstan-ignore-line */
+		return $result->flattenTree($groupedNodes, $this->getRootNodeId($root));
 	}
 
 	/**
@@ -148,16 +155,18 @@ public function toFlatTree($root = false): Collection
 	 * @param Collection<Tmodel> $groupedNodes
 	 * @param array-key          $parentId
 	 *
-	 * @return Collection<Tmodel>
+	 * @return NestedSetCollection<Tmodel>
 	 */
-	protected function flattenTree(Collection $groupedNodes, $parentId): Collection
+	protected function flattenTree(Collection $groupedNodes, $parentId): NestedSetCollection
 	{
-		/** @var array<int,NodeModel> */
-		$nodes = $groupedNodes->get($parentId, []); /** @phpstan-ignore varTag.type */
-		foreach ($nodes as $node) {
-			$this->push($node);
+		$nodes = $groupedNodes->get($parentId, []);
 
-			$this->flattenTree($groupedNodes, $node->getKey());
+		if (count($nodes) > 0) {
+			foreach ($nodes as $node) {
+				$this->push($node);
+
+				$this->flattenTree($groupedNodes, $node->getKey());
+			}
 		}
 
 		return $this;
diff --git a/src/Contracts/NestedSetCollection.php b/src/Contracts/NestedSetCollection.php
new file mode 100644
index 0000000..e241719
--- /dev/null
+++ b/src/Contracts/NestedSetCollection.php
@@ -0,0 +1,48 @@
+<?php
+
+namespace Kalnoy\Nestedset\Contracts;
+
+/**
+ * @template-covariant Tmodel of \Illuminate\Database\Eloquent\Model
+ *
+ * @phpstan-type NodeModel Node<Tmodel>&Tmodel
+ *
+ * @require-extends \Illuminate\Database\Eloquent\Collection
+ *
+ * @method NestedSetCollection<NodeModel> groupBy(string $column)
+ * @method array<int,NodeModel>           all()
+ */
+interface NestedSetCollection
+{
+	/**
+	 * Fill `parent` and `children` relationships for every node in the collection.
+	 *
+	 * This will overwrite any previously set relations.
+	 *
+	 * @return NestedSetCollection<Tmodel>
+	 */
+	public function linkNodes();
+
+	/**
+	 * Build a tree from a list of nodes. Each item will have set children relation.
+	 *
+	 * To successfully build tree "id", "_lft" and "parent_id" keys must present.
+	 *
+	 * If `$root` is provided, the tree will contain only descendants of that node.
+	 *
+	 * @param mixed $root
+	 *
+	 * @return NestedSetCollection<Tmodel>
+	 */
+	public function toTree($root = false): NestedSetCollection;
+
+	/**
+	 * Build a list of nodes that retain the order that they were pulled from
+	 * the database.
+	 *
+	 * @param bool $root
+	 *
+	 * @return NestedSetCollection<Tmodel>
+	 */
+	public function toFlatTree($root = false): NestedSetCollection;
+}
diff --git a/src/Node.php b/src/Contracts/Node.php
similarity index 69%
rename from src/Node.php
rename to src/Contracts/Node.php
index fd2c0cc..5b7ddb0 100644
--- a/src/Node.php
+++ b/src/Contracts/Node.php
@@ -1,11 +1,11 @@
 <?php
 
-namespace Kalnoy\Nestedset;
+namespace Kalnoy\Nestedset\Contracts;
 
 use Illuminate\Database\Eloquent\Builder as EloquentBuilder;
-use Illuminate\Database\Eloquent\Collection as EloquentCollection;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
 use Illuminate\Database\Eloquent\Relations\HasMany;
+use Illuminate\Database\Eloquent\Relations\Relation;
 use Illuminate\Database\Query\Builder as BaseQueryBuilder;
 
 /**
@@ -23,6 +23,18 @@
  * @template Tmodel of \Illuminate\Database\Eloquent\Model
  *
  * @phpstan-type NodeModel Node<Tmodel>&Tmodel
+ *
+ * @require-extends \Illuminate\Database\Eloquent\Model
+ *
+ * @method mixed        getKey()
+ * @method mixed        getKeyName()
+ * @method Node<Tmodel> setRelation($relation, $value)
+ * @method mixed        save()
+ * @method string       getTable()
+ * @method mixed        getAttribute($key)
+ * @method string       getDeletedAtColumn()
+ * @method Node<Tmodel> getRelationValue($key)
+ * @method bool         usesSoftDelete()
  */
 interface Node
 {
@@ -48,74 +60,74 @@ public function children(): HasMany;
 	/**
 	 * Get query for descendants of the node.
 	 *
-	 * @return DescendantsRelation<Tmodel>
+	 * @return Relation<NodeModel,NodeModel,NestedSetCollection<Tmodel>>
 	 */
-	public function descendants(): DescendantsRelation;
+	public function descendants(): Relation;
 
 	/**
 	 * Get query for siblings of the node.
 	 *
-	 * @return QueryBuilder<Tmodel>
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function siblings(): QueryBuilder;
+	public function siblings(): NodeQueryBuilder;
 
 	/**
 	 * Get the node siblings and the node itself.
 	 *
-	 * @return QueryBuilder<Tmodel>
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function siblingsAndSelf(): QueryBuilder;
+	public function siblingsAndSelf(): NodeQueryBuilder;
 
 	/**
 	 * Get query for the node siblings and the node itself.
 	 *
 	 * @param string[] $columns
 	 *
-	 * @return EloquentCollection<int,NodeModel>
+	 * @return NestedSetCollection<Tmodel>
 	 */
-	public function getSiblingsAndSelf(array $columns = ['*']): EloquentCollection;
+	public function getSiblingsAndSelf(array $columns = ['*']): NestedSetCollection;
 
 	/**
 	 * Get query for siblings after the node.
 	 *
-	 * @return QueryBuilder<Tmodel>
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function nextSiblings(): QueryBuilder;
+	public function nextSiblings(): NodeQueryBuilder;
 
 	/**
 	 * Get query for siblings before the node.
 	 *
-	 * @return QueryBuilder<Tmodel>
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function prevSiblings(): QueryBuilder;
+	public function prevSiblings(): NodeQueryBuilder;
 
 	/**
 	 * Get query for nodes after current node.
 	 *
-	 * @return QueryBuilder<Tmodel>
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function nextNodes(): QueryBuilder;
+	public function nextNodes(): NodeQueryBuilder;
 
 	/**
 	 * Get query for nodes before current node in reversed order.
 	 *
-	 * @return QueryBuilder<Tmodel>
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function prevNodes(): QueryBuilder;
+	public function prevNodes(): NodeQueryBuilder;
 
 	/**
 	 * Get query ancestors of the node.
 	 *
-	 * @return AncestorsRelation<Tmodel>
+	 * @return Relation<NodeModel,NodeModel,NestedSetCollection<Tmodel>>
 	 */
-	public function ancestors(): AncestorsRelation;
+	public function ancestors(): Relation;
 
 	/**
 	 * Make this node a root node.
 	 *
 	 * @return $this
 	 */
-	public function makeRoot(): Node;
+	public function makeRoot(): self;
 
 	/**
 	 * Save node as root.
@@ -131,7 +143,7 @@ public function saveAsRoot(): bool;
 	 *
 	 * @return $this
 	 */
-	public function rawNode(int $lft, int $rgt, mixed $parentId): Node;
+	public function rawNode(int $lft, int $rgt, mixed $parentId): self;
 
 	/**
 	 * Move node up given amount of positions.
@@ -154,27 +166,27 @@ public function down(int $amount = 1): bool;
 	/**
 	 * @since 2.0
 	 *
-	 * @param BaseQueryBuilder|EloquentBuilder<Tmodel>|QueryBuilder<Tmodel> $query
+	 * @param BaseQueryBuilder|EloquentBuilder<Tmodel>|NodeQueryBuilder<Tmodel> $query
 	 *
-	 * @return QueryBuilder<Tmodel>
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function newEloquentBuilder(BaseQueryBuilder|EloquentBuilder|QueryBuilder $query): QueryBuilder;
+	public function newEloquentBuilder(BaseQueryBuilder|EloquentBuilder|NodeQueryBuilder $query): NodeQueryBuilder;
 
 	/**
 	 * Get a new base query that includes deleted nodes.
 	 *
 	 * @since 1.1
 	 *
-	 * @param (QueryBuilder<Tmodel>)|string|null $table
+	 * @param NodeQueryBuilder<Tmodel>|string|null $table
 	 *
-	 * @return QueryBuilder<Tmodel>
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function newNestedSetQuery(QueryBuilder|string|null $table = null): QueryBuilder;
+	public function newNestedSetQuery(NodeQueryBuilder|string|null $table = null): NodeQueryBuilder;
 
 	/**
 	 * @param ?string $table
 	 *
-	 * @return QueryBuilder<Tmodel>
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
 	public function newScopedQuery($table = null);
 
@@ -189,16 +201,16 @@ public function applyNestedSetScope($query, $table = null);
 	/**
 	 * @param string[] $attributes
 	 *
-	 * @return QueryBuilder<Tmodel>
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public static function scoped(array $attributes): QueryBuilder;
+	public static function scoped(array $attributes): NodeQueryBuilder;
 
 	/**
 	 * @param array<int,NodeModel> $models
 	 *
-	 * @return Collection<Tmodel>
+	 * @return NestedSetCollection<Tmodel>
 	 */
-	public function newCollection(array $models = []): Collection;
+	public function newCollection(array $models = []): NestedSetCollection;
 
 	/**
 	 * Get node height (rgt - lft + 1).
@@ -226,6 +238,9 @@ public function setParentIdAttribute(mixed $value): void;
 	 */
 	public function isRoot(): bool;
 
+	/**
+	 * Get whether node is a leaf.
+	 */
 	public function isLeaf(): bool;
 
 	/**
@@ -285,35 +300,35 @@ public function getPrevNode(array $columns = ['*']): Node;
 	/**
 	 * @param string[] $columns
 	 *
-	 * @return Collection<Tmodel>
+	 * @return NestedSetCollection<Tmodel>
 	 */
 	public function getAncestors(array $columns = ['*']);
 
 	/**
 	 * @param string[] $columns
 	 *
-	 * @return Collection<Tmodel>
+	 * @return NestedSetCollection<Tmodel>
 	 */
 	public function getDescendants(array $columns = ['*']);
 
 	/**
 	 * @param string[] $columns
 	 *
-	 * @return Collection<Tmodel>
+	 * @return NestedSetCollection<Tmodel>
 	 */
 	public function getSiblings(array $columns = ['*']);
 
 	/**
 	 * @param string[] $columns
 	 *
-	 * @return Collection<Tmodel>
+	 * @return NestedSetCollection<Tmodel>
 	 */
 	public function getNextSiblings(array $columns = ['*']);
 
 	/**
 	 * @param string[] $columns
 	 *
-	 * @return Collection<Tmodel>
+	 * @return NestedSetCollection<Tmodel>
 	 */
 	public function getPrevSiblings(array $columns = ['*']);
 
@@ -322,14 +337,14 @@ public function getPrevSiblings(array $columns = ['*']);
 	 *
 	 * @return NodeModel
 	 */
-	public function getNextSibling(array $columns = ['*']);
+	public function getNextSibling(array $columns = ['*']): Node;
 
 	/**
 	 * @param string[] $columns
 	 *
 	 * @return NodeModel
 	 */
-	public function getPrevSibling(array $columns = ['*']);
+	public function getPrevSibling(array $columns = ['*']): Node;
 
 	/**
 	 * @return array<int>
@@ -341,21 +356,21 @@ public function getBounds();
 	 *
 	 * @return NodeModel
 	 */
-	public function setLft(int $value): Node;
+	public function setLft(int $value): self;
 
 	/**
 	 * @param $value
 	 *
 	 * @return NodeModel
 	 */
-	public function setRgt(int $value): Node;
+	public function setRgt(int $value): self;
 
 	/**
 	 * @param array-key|null $id
 	 *
 	 * @return NodeModel
 	 */
-	public function setParentId(mixed $id): Node;
+	public function setParentId(mixed $id): self;
 
 	/**
 	 * @param string[]|null $except
@@ -380,7 +395,7 @@ public function appendNode(Node $node): bool;
 	 *
 	 * @return NodeModel
 	 */
-	public function appendToNode(Node $parent): Node;
+	public function appendToNode(Node $parent): self;
 
 	/**
 	 * Prepend a node to the new parent.
@@ -389,7 +404,7 @@ public function appendToNode(Node $parent): Node;
 	 *
 	 * @return NodeModel
 	 */
-	public function prependToNode(Node $parent): Node;
+	public function prependToNode(Node $parent): self;
 
 	/**
 	 * Get whether the node is an ancestor of other node, including immediate parent.
@@ -403,7 +418,7 @@ public function isAncestorOf(Node $other): bool;
 	/**
 	 * Get whether a node is a descendant of other node.
 	 *
-	 * @param NodeModel $other
+	 * @param Node<Tmodel> $other
 	 *
 	 * @return bool
 	 */
@@ -421,7 +436,7 @@ public function isSelfOrDescendantOf(Node $other);
 	/**
 	 * Create a new Query.
 	 *
-	 * @return QueryBuilder<Tmodel>
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
 	public function newQuery();
 }
diff --git a/src/Contracts/NodeQueryBuilder.php b/src/Contracts/NodeQueryBuilder.php
new file mode 100644
index 0000000..e5787ff
--- /dev/null
+++ b/src/Contracts/NodeQueryBuilder.php
@@ -0,0 +1,395 @@
+<?php
+
+namespace Kalnoy\Nestedset\Contracts;
+
+use Illuminate\Contracts\Database\Eloquent\Builder;
+use Illuminate\Database\Query\Builder as BaseQueryBuilder;
+
+/**
+ * @template Tmodel of \Illuminate\Database\Eloquent\Model
+ *
+ * @phpstan-type NodeModel Node<Tmodel>
+ *
+ * @require-extends Illuminate\Database\Eloquent\Builder<NodeModel>
+ *
+ * @method NodeQueryBuilder<Tmodel>                    select(string[] $columns)
+ * @method Tmodel                                      getModel()
+ * @method NodeQueryBuilder<Tmodel>                    from(string $table)
+ * @method NodeQueryBuilder<Tmodel>                    getQuery()
+ * @method NodeQueryBuilder<Tmodel>                    whereRaw(string $sql, string[] $bindings = [], string $boolean = 'and')
+ * @method \Illuminate\Database\Query\Grammars\Grammar getGrammar()
+ * @method NodeQueryBuilder<Tmodel>                    whereNested(\Closure|string $callback, string $boolean = 'and')
+ * @method NestedSetCollection<Tmodel>                 get(string[] $columns = ['*'])
+ * @method int                                         max(string $column)
+ * @method NodeQueryBuilder<Tmodel>                    where(string|string[]|\Closure $column, mixed $operator = null, mixed $value = null, string $boolean = 'and')
+ * @method NodeModel|null                              first(string[]|string $columns = ['*'])
+ * @method NodeModel                                   findOrFail(int|string $id)
+ * @method NodeQueryBuilder<Tmodel>                    skip(int $value)
+ * @method NodeQueryBuilder<Tmodel>                    take(int $value)
+ * @method NodeQueryBuilder<Tmodel>                    orderBy(string $column, string $direction = 'asc')
+ * @method NodeQueryBuilder<Tmodel>                    when(bool $value, \Closure $callback)
+ * @method BaseQueryBuilder                            toBase()
+ */
+interface NodeQueryBuilder extends Builder
+{
+	/**
+	 * Get node's `lft` and `rgt` values.
+	 *
+	 * @since 2.0
+	 *
+	 * @param NodeModel $id
+	 * @param bool      $required
+	 *
+	 * @return array<int,int>
+	 */
+	public function getNodeData(mixed $id, $required = false): array;
+
+	/**
+	 * Get plain node data.
+	 *
+	 * @since 2.0
+	 *
+	 * @param NodeModel $id
+	 * @param bool      $required
+	 *
+	 * @return array<int,int>
+	 */
+	public function getPlainNodeData(mixed $id, $required = false): array;
+
+	/**
+	 * Scope limits query to select just root node.
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function whereIsRoot(): NodeQueryBuilder;
+
+	/**
+	 * Limit results to ancestors of specified node.
+	 *
+	 * @since 2.0
+	 *
+	 * @param NodeModel $id
+	 * @param bool      $andSelf
+	 * @param string    $boolean
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function whereAncestorOf(mixed $id, bool $andSelf = false, string $boolean = 'and'): NodeQueryBuilder;
+
+	/**
+	 * @param NodeModel $id
+	 * @param bool      $andSelf
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function orWhereAncestorOf(mixed $id, $andSelf = false): NodeQueryBuilder;
+
+	/**
+	 * @param NodeModel $id
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function whereAncestorOrSelf(mixed $id): NodeQueryBuilder;
+
+	/**
+	 * Get ancestors of specified node.
+	 *
+	 * @since 2.0
+	 *
+	 * @param NodeModel $id
+	 * @param string[]  $columns
+	 *
+	 * @return NestedSetCollection<Tmodel>
+	 */
+	public function ancestorsOf(mixed $id, array $columns = ['*']): NestedSetCollection;
+
+	/**
+	 * @param NodeModel $id
+	 * @param string[]  $columns
+	 *
+	 * @return NestedSetCollection<Tmodel>
+	 */
+	public function ancestorsAndSelf(mixed $id, array $columns = ['*']): NestedSetCollection;
+
+	/**
+	 * Add node selection statement between specified range.
+	 *
+	 * @since 2.0
+	 *
+	 * @param int[]  $values
+	 * @param string $boolean
+	 * @param bool   $not
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function whereNodeBetween(array $values, $boolean = 'and', $not = false): NodeQueryBuilder;
+
+	/**
+	 * Add node selection statement between specified range joined with `or` operator.
+	 *
+	 * @since 2.0
+	 *
+	 * @param int[] $values
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function orWhereNodeBetween(array $values): NodeQueryBuilder;
+
+	/**
+	 * Add constraint statement to descendants of specified node.
+	 *
+	 * @since 2.0
+	 *
+	 * @param ?NodeModel $id
+	 * @param string     $boolean
+	 * @param bool       $not
+	 * @param bool       $andSelf
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function whereDescendantOf(mixed $id, $boolean = 'and', $not = false, $andSelf = false): NodeQueryBuilder;
+
+	/**
+	 * @param NodeModel $id
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function whereNotDescendantOf(mixed $id): NodeQueryBuilder;
+
+	/**
+	 * @param NodeModel $id
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function orWhereDescendantOf(mixed $id): NodeQueryBuilder;
+
+	/**
+	 * @param NodeModel $id
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function orWhereNotDescendantOf(mixed $id): NodeQueryBuilder;
+
+	/**
+	 * @param NodeModel $id
+	 * @param string    $boolean
+	 * @param bool      $not
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function whereDescendantOrSelf(mixed $id, string $boolean = 'and', bool $not = false): NodeQueryBuilder;
+
+	/**
+	 * Get descendants of specified node.
+	 *
+	 * @since 2.0
+	 *
+	 * @param NodeModel $id
+	 * @param string[]  $columns
+	 * @param bool      $andSelf
+	 *
+	 * @return NestedSetCollection<Tmodel>
+	 */
+	public function descendantsOf(mixed $id, array $columns = ['*'], bool $andSelf = false): NestedSetCollection;
+
+	/**
+	 * @param NodeModel $id
+	 * @param string[]  $columns
+	 *
+	 * @return NestedSetCollection<Tmodel>
+	 */
+	public function descendantsAndSelf($id, array $columns = ['*']): NestedSetCollection;
+
+	/**
+	 * Constraint nodes to those that are after specified node.
+	 *
+	 * @since 2.0
+	 *
+	 * @param NodeModel $id
+	 * @param string    $boolean
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function whereIsAfter($id, $boolean = 'and'): NodeQueryBuilder;
+
+	/**
+	 * Constraint nodes to those that are before specified node.
+	 *
+	 * @since 2.0
+	 *
+	 * @param NodeModel $id
+	 * @param string    $boolean
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function whereIsBefore($id, $boolean = 'and'): NodeQueryBuilder;
+
+	/**
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function whereIsLeaf(): NodeQueryBuilder;
+
+	/**
+	 * @param string[] $columns
+	 *
+	 * @return NestedSetCollection<Tmodel>
+	 */
+	public function leaves(array $columns = ['*']): NestedSetCollection;
+
+	/**
+	 * Include depth level into the result.
+	 *
+	 * @param string $as
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function withDepth($as = 'depth'): NodeQueryBuilder;
+
+	/**
+	 * Exclude root node from the result.
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function withoutRoot(): NodeQueryBuilder;
+
+	/**
+	 * Equivalent of `withoutRoot`.
+	 *
+	 * @since 2.0
+	 * @deprecated since v4.1
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function hasParent(): NodeQueryBuilder;
+
+	/**
+	 * Get only nodes that have children.
+	 *
+	 * @since 2.0
+	 * @deprecated since v4.1
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function hasChildren(): NodeQueryBuilder;
+
+	/**
+	 * Order by node position.
+	 *
+	 * @param string $dir
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function defaultOrder($dir = 'asc'): NodeQueryBuilder;
+
+	/**
+	 * Order by reversed node position.
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function reversed(): NodeQueryBuilder;
+
+	/**
+	 * Move a node to the new position.
+	 *
+	 * @param mixed $key
+	 * @param int   $position
+	 *
+	 * @return int
+	 */
+	public function moveNode($key, $position): int;
+
+	/**
+	 * Make or remove gap in the tree. Negative height will remove gap.
+	 *
+	 * @since 2.0
+	 *
+	 * @param int $cut
+	 * @param int $height
+	 *
+	 * @return int
+	 */
+	public function makeGap($cut, $height): int;
+
+	/**
+	 * Get statistics of errors of the tree.
+	 *
+	 * @since 2.0
+	 *
+	 * @return array{oddness:int,duplicates:int,wrong_parent:int,missing_parent:int}
+	 */
+	public function countErrors(): array;
+
+	/**
+	 * Get the number of total errors of the tree.
+	 *
+	 * @since 2.0
+	 *
+	 * @return int
+	 */
+	public function getTotalErrors(): int;
+
+	/**
+	 * Get whether the tree is broken.
+	 *
+	 * @since 2.0
+	 *
+	 * @return bool
+	 */
+	public function isBroken(): bool;
+
+	/**
+	 * Fixes the tree based on parentage info.
+	 *
+	 * Nodes with invalid parent are saved as roots.
+	 *
+	 * @param ?NodeModel $root
+	 *
+	 * @return int The number of changed nodes
+	 */
+	public function fixTree($root = null): int;
+
+	/**
+	 * @param NodeModel $root
+	 *
+	 * @return int
+	 */
+	public function fixSubtree($root): int;
+
+	/**
+	 * Rebuild the tree based on raw data.
+	 *
+	 * If item data does not contain primary key, new node will be created.
+	 *
+	 * @param array<array-key,NodeModel[]>[] $data
+	 * @param bool                           $delete Whether to delete nodes that exists but not in the data array
+	 * @param ?NodeModel                     $root
+	 *
+	 * @return int
+	 */
+	public function rebuildTree(array $data, $delete = false, $root = null): int;
+
+	/**
+	 * @param null                  $root
+	 * @param array<string,mixed>[] $data
+	 * @param bool                  $delete
+	 *
+	 * @return int
+	 */
+	public function rebuildSubtree($root, array $data, $delete = false): int;
+
+	/**
+	 * @param string|null $table
+	 *
+	 * @return NodeQueryBuilder<Tmodel>
+	 */
+	public function applyNestedSetScope($table = null): NodeQueryBuilder;
+
+	/**
+	 * Get the root node.
+	 *
+	 * @param string[] $columns
+	 *
+	 * @return NodeModel|null
+	 */
+	public function root(array $columns = ['*']): Node|null;
+}
\ No newline at end of file
diff --git a/src/DescendantsRelation.php b/src/DescendantsRelation.php
index 2e13bcc..02ed7bb 100644
--- a/src/DescendantsRelation.php
+++ b/src/DescendantsRelation.php
@@ -3,17 +3,18 @@
 namespace Kalnoy\Nestedset;
 
 use Illuminate\Database\Eloquent\Model;
+use Kalnoy\Nestedset\Contracts\Node;
 
 /**
  * @template Tmodel of Model
  *
- * @phpstan-type NodeModel Node<Tmodel>&Tmodel
+ * @phpstan-type NodeModel \Kalnoy\Nestedset\Contracts\Node<Tmodel>
  *
  * @disregard P1037
  *
  * @extends BaseRelation<Tmodel>
  */
-class DescendantsRelation extends BaseRelation
+final class DescendantsRelation extends BaseRelation
 {
 	/**
 	 * Set the base constraints on the relation query.
@@ -45,7 +46,7 @@ protected function addEagerConstraint($query, $model)
 	 *
 	 * @return bool
 	 */
-	protected function matches(Model $model, $related): bool
+	protected function matches(Node $model, Node $related): bool
 	{
 		return $related->isDescendantOf($model);
 	}
diff --git a/src/NestedSetException.php b/src/Exceptions/NestedSetException.php
similarity index 86%
rename from src/NestedSetException.php
rename to src/Exceptions/NestedSetException.php
index 38bad44..2d31573 100644
--- a/src/NestedSetException.php
+++ b/src/Exceptions/NestedSetException.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Kalnoy\Nestedset;
+namespace Kalnoy\Nestedset\Exceptions;
 
 /**
  * Exception thrown when something really went wrong.
diff --git a/src/NestedSet.php b/src/NestedSet.php
index 933b444..510bc1c 100644
--- a/src/NestedSet.php
+++ b/src/NestedSet.php
@@ -3,6 +3,7 @@
 namespace Kalnoy\Nestedset;
 
 use Illuminate\Database\Schema\Blueprint;
+use Kalnoy\Nestedset\Contracts\Node;
 
 class NestedSet
 {
diff --git a/src/NodeTrait.php b/src/NodeTrait.php
index 6f3ae7b..bb18f04 100644
--- a/src/NodeTrait.php
+++ b/src/NodeTrait.php
@@ -3,19 +3,29 @@
 namespace Kalnoy\Nestedset;
 
 use Carbon\Carbon;
+use Illuminate\Database\Eloquent\Builder as EloquentBuilder;
 use Illuminate\Database\Eloquent\Collection as EloquentCollection;
-use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
 use Illuminate\Database\Eloquent\Relations\HasMany;
+use Illuminate\Database\Eloquent\Relations\Relation;
+use Illuminate\Database\Query\Builder as BaseQueryBuilder;
 use Illuminate\Support\Arr;
+use Kalnoy\Nestedset\Contracts\NestedSetCollection;
+use Kalnoy\Nestedset\Contracts\Node;
+use Kalnoy\Nestedset\Contracts\NodeQueryBuilder;
 
 /**
- * @template Tmodel extends Model
+ * @template Tmodel extends \Illuminate\Database\Eloquent\Model
+ * @template Tmodelkey of array-key
+ *
+ * @method void setRelation(string $relation, mixed $value)
  */
 trait NodeTrait
 {
 	/**
 	 * Pending operation.
+	 *
+	 * @var array<int,string>|null
 	 */
 	protected array|null $pending = null;
 
@@ -49,11 +59,11 @@ public static function bootNodeTrait(): void
 		});
 
 		if (static::usesSoftDelete()) {
-			static::restoring(function ($model) {
-				static::$deletedAt = $model->{$model->getDeletedAtColumn()};
+			static::restoring(function ($model) { /** @phpstan-ignore staticMethod.notFound */
+				static::$deletedAt = $model->{$model->getDeletedAtColumn()}; /** @phpstan-ignore property.dynamicName */
 			});
 
-			static::restored(function ($model) {
+			static::restored(function ($model) { /** @phpstan-ignore staticMethod.notFound */
 				$model->restoreDescendants(static::$deletedAt);
 			});
 		}
@@ -64,9 +74,9 @@ public static function bootNodeTrait(): void
 	 *
 	 * @param string $action
 	 *
-	 * @return $this
+	 * @return self
 	 */
-	protected function setNodeAction($action): Node
+	protected function setNodeAction($action): self
 	{
 		$this->pending = func_get_args();
 
@@ -76,15 +86,15 @@ protected function setNodeAction($action): Node
 	/**
 	 * Call pending action.
 	 */
-	protected function callPendingAction()
+	protected function callPendingAction(): void
 	{
 		$this->moved = false;
 
-		if (!$this->pending && !$this->exists) {
+		if (($this->pending === null || $this->pending === []) && !$this->exists) {
 			$this->makeRoot();
 		}
 
-		if (!$this->pending) {
+		if ($this->pending === null || $this->pending === []) {
 			return;
 		}
 
@@ -104,9 +114,9 @@ public static function usesSoftDelete(): bool
 		static $softDelete;
 
 		if (is_null($softDelete)) {
-			$instance = new static();
+			$instance = new self();
 
-			return $softDelete = method_exists($instance, 'bootSoftDeletes');
+			return $softDelete = method_exists($instance, 'bootSoftDeletes'); /** @phpstan-ignore function.alreadyNarrowedType, function.impossibleType */
 		}
 
 		return $softDelete;
@@ -123,7 +133,7 @@ protected function actionRaw(): bool
 	/**
 	 * Make a root node.
 	 */
-	protected function actionRoot()
+	protected function actionRoot(): bool
 	{
 		// Simplest case that do not affect other nodes.
 		if (!$this->exists) {
@@ -143,18 +153,18 @@ protected function actionRoot()
 	 */
 	protected function getLowerBound(): int
 	{
-		return (int) $this->newNestedSetQuery()->max($this->getRgtName());
+		return (int) $this->newNestedSetQuery()->max($this->getRgtName()); /** @phpstan-ignore staticMethod.dynamicCall, cast.useless */
 	}
 
 	/**
 	 * Append or prepend a node to the parent.
 	 *
-	 * @param Node $parent
-	 * @param bool $prepend
+	 * @param Node<Tmodel> $parent
+	 * @param bool         $prepend
 	 *
 	 * @return bool
 	 */
-	protected function actionAppendOrPrepend(Node $parent, $prepend = false)
+	protected function actionAppendOrPrepend(Node $parent, $prepend = false): bool
 	{
 		$parent->refreshNode();
 
@@ -172,13 +182,13 @@ protected function actionAppendOrPrepend(Node $parent, $prepend = false)
 	/**
 	 * Apply parent model.
 	 *
-	 * @param Model|null $value
+	 * @param Node<Tmodel>|null $value
 	 *
-	 * @return $this
+	 * @return self
 	 */
 	protected function setParent($value)
 	{
-		$this->setParentId($value ? $value->getKey() : null)
+		$this->setParentId($value !== null ? $value->getKey() : null)
 			->setRelation('parent', $value);
 
 		return $this;
@@ -187,8 +197,8 @@ protected function setParent($value)
 	/**
 	 * Insert node before or after another node.
 	 *
-	 * @param Node $node
-	 * @param bool $after
+	 * @param Node<Tmodel> $node
+	 * @param bool         $after
 	 *
 	 * @return bool
 	 */
@@ -217,31 +227,31 @@ public function refreshNode(): void
 	/**
 	 * Relation to the parent.
 	 *
-	 * @return BelongsTo
+	 * @return BelongsTo<Tmodel,Tmodel>
 	 */
 	public function parent(): BelongsTo
 	{
-		return $this->belongsTo(get_class($this), $this->getParentIdName())
+		return $this->belongsTo(get_class($this), $this->getParentIdName()) /** @phpstan-ignore-line staticMethod.dynamicCall */
 			->setModel($this);
 	}
 
 	/**
 	 * Relation to children.
 	 *
-	 * @return HasMany
+	 * @return HasMany<Tmodel,Tmodel>
 	 */
 	public function children(): HasMany
 	{
-		return $this->hasMany(get_class($this), $this->getParentIdName())
+		return $this->hasMany(get_class($this), $this->getParentIdName()) /** @phpstan-ignore-line staticMethod.dynamicCall */
 			->setModel($this);
 	}
 
 	/**
 	 * Get query for descendants of the node.
 	 *
-	 * @return DescendantsRelation
+	 * @return Relation<covariant Tmodel,covariant Tmodel,NestedSetCollection<Tmodel>>
 	 */
-	public function descendants(): DescendantsRelation
+	public function descendants(): Relation
 	{
 		return new DescendantsRelation($this->newQuery(), $this);
 	}
@@ -249,9 +259,9 @@ public function descendants(): DescendantsRelation
 	/**
 	 * Get query for siblings of the node.
 	 *
-	 * @return QueryBuilder
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function siblings(): QueryBuilder
+	public function siblings(): NodeQueryBuilder
 	{
 		return $this->newScopedQuery()
 			->where($this->getKeyName(), '<>', $this->getKey())
@@ -261,9 +271,9 @@ public function siblings(): QueryBuilder
 	/**
 	 * Get the node siblings and the node itself.
 	 *
-	 * @return \Kalnoy\Nestedset\QueryBuilder
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function siblingsAndSelf(): QueryBuilder
+	public function siblingsAndSelf(): NodeQueryBuilder
 	{
 		return $this->newScopedQuery()
 			->where($this->getParentIdName(), '=', $this->getParentId());
@@ -272,11 +282,11 @@ public function siblingsAndSelf(): QueryBuilder
 	/**
 	 * Get query for the node siblings and the node itself.
 	 *
-	 * @param array $columns
+	 * @param string[] $columns
 	 *
-	 * @return \Illuminate\Database\Eloquent\Collection
+	 * @return NestedSetCollection<Tmodel>
 	 */
-	public function getSiblingsAndSelf(array $columns = ['*']): EloquentCollection
+	public function getSiblingsAndSelf(array $columns = ['*']): NestedSetCollection
 	{
 		return $this->siblingsAndSelf()->get($columns);
 	}
@@ -284,9 +294,9 @@ public function getSiblingsAndSelf(array $columns = ['*']): EloquentCollection
 	/**
 	 * Get query for siblings after the node.
 	 *
-	 * @return QueryBuilder
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function nextSiblings(): QueryBuilder
+	public function nextSiblings(): NodeQueryBuilder
 	{
 		return $this->nextNodes()
 			->where($this->getParentIdName(), '=', $this->getParentId());
@@ -295,9 +305,9 @@ public function nextSiblings(): QueryBuilder
 	/**
 	 * Get query for siblings before the node.
 	 *
-	 * @return QueryBuilder
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function prevSiblings(): QueryBuilder
+	public function prevSiblings(): NodeQueryBuilder
 	{
 		return $this->prevNodes()
 			->where($this->getParentIdName(), '=', $this->getParentId());
@@ -306,9 +316,9 @@ public function prevSiblings(): QueryBuilder
 	/**
 	 * Get query for nodes after current node.
 	 *
-	 * @return QueryBuilder
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function nextNodes(): QueryBuilder
+	public function nextNodes(): NodeQueryBuilder
 	{
 		return $this->newScopedQuery()
 			->where($this->getLftName(), '>', $this->getLft());
@@ -317,20 +327,20 @@ public function nextNodes(): QueryBuilder
 	/**
 	 * Get query for nodes before current node in reversed order.
 	 *
-	 * @return QueryBuilder
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function prevNodes(): QueryBuilder
+	public function prevNodes(): NodeQueryBuilder
 	{
 		return $this->newScopedQuery()
-			->where($this->getLftName(), '<', $this->getLft());
+			->where($this->getLftName(), '<', $this->getLft()); /** @phpstan-ignore method.notFound */
 	}
 
 	/**
 	 * Get query ancestors of the node.
 	 *
-	 * @return AncestorsRelation
+	 * @return Relation<covariant Tmodel,covariant Tmodel,NestedSetCollection<Tmodel>>
 	 */
-	public function ancestors(): AncestorsRelation
+	public function ancestors(): Relation
 	{
 		return new AncestorsRelation($this->newQuery(), $this);
 	}
@@ -338,7 +348,7 @@ public function ancestors(): AncestorsRelation
 	/**
 	 * Make this node a root node.
 	 *
-	 * @return $this
+	 * @return Node<Tmodel>
 	 */
 	public function makeRoot(): Node
 	{
@@ -364,7 +374,7 @@ public function saveAsRoot(): bool
 	/**
 	 * Append and save a node.
 	 *
-	 * @param Node&Tmodel $node
+	 * @param Node<Tmodel> $node
 	 *
 	 * @return bool
 	 */
@@ -377,7 +387,7 @@ public function appendNode(Node $node): bool
 	/**
 	 * Prepend and save a node.
 	 *
-	 * @param Node $node
+	 * @param Node<Tmodel> $node
 	 *
 	 * @return bool
 	 */
@@ -389,11 +399,11 @@ public function prependNode(Node $node): bool
 	/**
 	 * Append a node to the new parent.
 	 *
-	 * @param Node&Tmodel $parent
+	 * @param Node<Tmodel> $parent
 	 *
-	 * @return Node&Tmodel
+	 * @return self
 	 */
-	public function appendToNode(Node $parent): Node
+	public function appendToNode(Node $parent): self
 	{
 		return $this->appendOrPrependTo($parent);
 	}
@@ -401,22 +411,22 @@ public function appendToNode(Node $parent): Node
 	/**
 	 * Prepend a node to the new parent.
 	 *
-	 * @param Node $parent
+	 * @param Node<Tmodel> $parent
 	 *
 	 * @return $this
 	 */
 	public function prependToNode(Node $parent): Node
 	{
-		return $this->appendOrPrependTo($parent, true);
+		return $this->appendOrPrependTo($parent, true); /** @phpstan-ignore return.type */
 	}
 
 	/**
-	 * @param Node $parent
-	 * @param bool $prepend
+	 * @param Node<Tmodel> $parent
+	 * @param bool         $prepend
 	 *
-	 * @return Node
+	 * @return self
 	 */
-	public function appendOrPrependTo(Node $parent, bool $prepend = false)
+	protected function appendOrPrependTo(Node $parent, bool $prepend = false): self
 	{
 		$this->assertNodeExists($parent)
 			->assertNotDescendant($parent)
@@ -430,32 +440,32 @@ public function appendOrPrependTo(Node $parent, bool $prepend = false)
 	/**
 	 * Insert self after a node.
 	 *
-	 * @param Node $node
+	 * @param Node<Tmodel> $node
 	 *
 	 * @return $this
 	 */
 	public function afterNode(Node $node)
 	{
-		return $this->beforeOrAfterNode($node, true);
+		return $this->beforeOrAfterNode($node, true); /** @phpstan-ignore return.type */
 	}
 
 	/**
 	 * Insert self before node.
 	 *
-	 * @param Node $node
+	 * @param Node<Tmodel> $node
 	 *
 	 * @return $this
 	 */
 	public function beforeNode(Node $node)
 	{
-		return $this->beforeOrAfterNode($node);
+		return $this->beforeOrAfterNode($node); /** @phpstan-ignore return.type */
 	}
 
 	/**
-	 * @param Node&Tmodel $node
-	 * @param bool        $after
+	 * @param Node<Tmodel> $node
+	 * @param bool         $after
 	 *
-	 * @return Node
+	 * @return Node<Tmodel>
 	 */
 	public function beforeOrAfterNode(Node $node, bool $after = false)
 	{
@@ -475,7 +485,7 @@ public function beforeOrAfterNode(Node $node, bool $after = false)
 	/**
 	 * Insert self after a node and save.
 	 *
-	 * @param Node $node
+	 * @param Node<Tmodel> $node
 	 *
 	 * @return bool
 	 */
@@ -487,7 +497,7 @@ public function insertAfterNode(Node $node)
 	/**
 	 * Insert self before a node and save.
 	 *
-	 * @param Node $node
+	 * @param Node<Tmodel> $node
 	 *
 	 * @return bool
 	 */
@@ -508,7 +518,7 @@ public function insertBeforeNode(Node $node)
 	 * @param int            $rgt
 	 * @param Tmodelkey|null $parentId
 	 *
-	 * @return Node
+	 * @return Node<Tmodel>
 	 */
 	public function rawNode(int $lft, int $rgt, mixed $parentId): Node
 	{
@@ -531,7 +541,7 @@ public function up(int $amount = 1): bool
 			->skip($amount - 1)
 			->first();
 
-		if (!$sibling) {
+		if ($sibling === null) {
 			return false;
 		}
 
@@ -552,7 +562,7 @@ public function down(int $amount = 1): bool
 			->skip($amount - 1)
 			->first();
 
-		if (!$sibling) {
+		if ($sibling === null) {
 			return false;
 		}
 
@@ -584,9 +594,9 @@ protected function insertAt($position)
 	 *
 	 * @param int $position
 	 *
-	 * @return int
+	 * @return bool
 	 */
-	protected function moveNode(int $position)
+	protected function moveNode(int $position): bool
 	{
 		$updated = $this->newNestedSetQuery()
 				->moveNode($this->getKey(), $position) > 0;
@@ -607,7 +617,7 @@ protected function moveNode(int $position)
 	 *
 	 * @return bool
 	 */
-	protected function insertNode(int $position)
+	protected function insertNode(int $position): bool
 	{
 		$this->newNestedSetQuery()->makeGap($position, 2);
 
@@ -622,12 +632,12 @@ protected function insertNode(int $position)
 	/**
 	 * Update the tree when the node is removed physically.
 	 */
-	protected function deleteDescendants()
+	protected function deleteDescendants(): void
 	{
 		$lft = $this->getLft();
 		$rgt = $this->getRgt();
 
-		$method = $this->usesSoftDelete() && $this->forceDeleting
+		$method = $this->usesSoftDelete() && $this->forceDeleting /** @phpstan-ignore property.notFound, staticMethod.dynamicCall */
 			? 'forceDelete'
 			: 'delete';
 
@@ -653,6 +663,7 @@ protected function deleteDescendants()
 		// need for it.
 		// The grammar compiler removes the superfluous "ORDER BY" for
 		// PostgreSQL.
+		/** @phpstan-ignore method.dynamicName, staticMethod.dynamicCall */
 		$this->descendants()
 			->orderBy($this->getLftName(), 'desc')
 			->{$method}();
@@ -672,23 +683,24 @@ protected function deleteDescendants()
 	/**
 	 * Restore the descendants.
 	 *
-	 * @param $deletedAt
+	 * @param Carbon $deletedAt
 	 */
-	protected function restoreDescendants($deletedAt)
+	protected function restoreDescendants(Carbon $deletedAt): void
 	{
-		$this->descendants()
+		$this->descendants() 		/** @phpstan-ignore staticMethod.dynamicCall, method.notFound */
 			->where($this->getDeletedAtColumn(), '>=', $deletedAt)
 			->restore();
 	}
 
 	/**
-	 * @param BaseQueryBuilder|EloquentBuilder<Tmodel>|QueryBuilder<Tmodelkey,Tmodel> $query
+	 * @param BaseQueryBuilder|EloquentBuilder<Tmodel>|QueryBuilder<Tmodel> $query
 	 *
-	 * @return QueryBuilder<Tmodelkey,Tmodel>
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function newEloquentBuilder($query): QueryBuilder
+	public function newEloquentBuilder($query): NodeQueryBuilder
 	{
 		/** @disregard P1006 */
+		/** @var QueryBuilder<Tmodel> */
 		return new QueryBuilder($query);
 	}
 
@@ -697,12 +709,13 @@ public function newEloquentBuilder($query): QueryBuilder
 	 *
 	 * @since 1.1
 	 *
-	 * @return QueryBuilder
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function newNestedSetQuery($table = null): QueryBuilder
+	public function newNestedSetQuery($table = null): NodeQueryBuilder
 	{
+		/** @phpstan-ignore staticMethod.dynamicCall */
 		$builder = $this->usesSoftDelete()
-			? $this->withTrashed()
+			? $this->withTrashed()  /** @phpstan-ignore method.notFound, staticMethod.dynamicCall (it does exists!) */
 			: $this->newQuery();
 
 		return $this->applyNestedSetScope($builder, $table);
@@ -711,9 +724,9 @@ public function newNestedSetQuery($table = null): QueryBuilder
 	/**
 	 * @param string $table
 	 *
-	 * @return QueryBuilder
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function newScopedQuery($table = null): QueryBuilder
+	public function newScopedQuery($table = null): NodeQueryBuilder
 	{
 		return $this->applyNestedSetScope($this->newQuery(), $table);
 	}
@@ -726,11 +739,12 @@ public function newScopedQuery($table = null): QueryBuilder
 	 */
 	public function applyNestedSetScope($query, $table = null)
 	{
-		if (!$scoped = $this->getScopeAttributes()) {
+		$scoped = $this->getScopeAttributes();
+		if ($scoped === null || $scoped === []) { /** @phpstan-ignore identical.alwaysFalse */
 			return $query;
 		}
 
-		if (!$table) {
+		if ($table === null) {
 			$table = $this->getTable();
 		}
 
@@ -743,7 +757,7 @@ public function applyNestedSetScope($query, $table = null)
 	}
 
 	/**
-	 * @return array
+	 * @return string[]|null
 	 */
 	protected function getScopeAttributes()
 	{
@@ -751,13 +765,13 @@ protected function getScopeAttributes()
 	}
 
 	/**
-	 * @param array $attributes
+	 * @param string[] $attributes
 	 *
-	 * @return QueryBuilder
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public static function scoped(array $attributes): QueryBuilder
+	public static function scoped(array $attributes): NodeQueryBuilder
 	{
-		$instance = new static();
+		$instance = new self();
 
 		$instance->setRawAttributes($attributes);
 
@@ -765,9 +779,9 @@ public static function scoped(array $attributes): QueryBuilder
 	}
 
 	/**
-	 * {@inheritdoc}
+	 * @return NestedSetCollection<Tmodel>
 	 */
-	public function newCollection(array $models = []): Collection
+	public function newCollection(array $models = []): NestedSetCollection
 	{
 		return new Collection($models);
 	}
@@ -777,15 +791,18 @@ public function newCollection(array $models = []): Collection
 	 *
 	 * Use `children` key on `$attributes` to create child nodes.
 	 *
-	 * @param Node $parent
+	 * @param array<string,mixed> $attributes
+	 * @param Node<Tmodel>        $parent
+	 *
+	 * @return Node<Tmodel>
 	 */
 	public static function create(array $attributes = [], ?Node $parent = null)
 	{
 		$children = Arr::pull($attributes, 'children');
 
-		$instance = new static($attributes);
+		$instance = new self($attributes);
 
-		if ($parent) {
+		if ($parent !== null) {
 			$instance->appendToNode($parent);
 		}
 
@@ -801,8 +818,9 @@ public static function create(array $attributes = [], ?Node $parent = null)
 		}
 
 		$instance->refreshNode();
+		$instance->setRelation('children', $relation);
 
-		return $instance->setRelation('children', $relation);
+		return $instance;
 	}
 
 	/**
@@ -822,7 +840,7 @@ public function getNodeHeight(): int
 	 */
 	public function getDescendantCount(): int
 	{
-		return ceil($this->getNodeHeight() / 2) - 1;
+		return (int) ceil($this->getNodeHeight() / 2) - 1;
 	}
 
 	/**
@@ -836,12 +854,11 @@ public function getDescendantCount(): int
 	 */
 	public function setParentIdAttribute(mixed $value): void
 	{
-		if ($this->getParentId() == $value) {
+		if ($this->getParentId() === $value) {
 			return;
 		}
 
-		if ($value) {
-			/** @var Node&Tmodel */
+		if ($value !== null) {
 			$node = $this->newScopedQuery()->findOrFail($value);
 			$this->appendToNode($node);
 		} else {
@@ -859,7 +876,7 @@ public function isRoot(): bool
 
 	public function isLeaf(): bool
 	{
-		return $this->getLft() + 1 == $this->getRgt();
+		return $this->getLft() + 1 === $this->getRgt();
 	}
 
 	/**
@@ -919,7 +936,7 @@ public function getParentId(): mixed
 	 *
 	 * @param string[] $columns
 	 *
-	 * @return Node
+	 * @return Node<Tmodel>
 	 */
 	public function getNextNode(array $columns = ['*']): Node
 	{
@@ -933,7 +950,7 @@ public function getNextNode(array $columns = ['*']): Node
 	 *
 	 * @param string[] $columns
 	 *
-	 * @return Node
+	 * @return Node<Tmodel>
 	 */
 	public function getPrevNode(array $columns = ['*']): Node
 	{
@@ -943,27 +960,27 @@ public function getPrevNode(array $columns = ['*']): Node
 	/**
 	 * @param string[] $columns
 	 *
-	 * @return Collection
+	 * @return NestedSetCollection<Tmodel>
 	 */
 	public function getAncestors(array $columns = ['*'])
 	{
-		return $this->ancestors()->get($columns);
+		return $this->ancestors()->get($columns); /** @phpstan-ignore return.type */
 	}
 
 	/**
 	 * @param string[] $columns
 	 *
-	 * @return Collection|Node[]
+	 * @return NestedSetCollection<Tmodel>
 	 */
 	public function getDescendants(array $columns = ['*'])
 	{
-		return $this->descendants()->get($columns);
+		return $this->descendants()->get($columns); /** @phpstan-ignore return.type */
 	}
 
 	/**
 	 * @param string[] $columns
 	 *
-	 * @return Collection|Node[]
+	 * @return NestedSetCollection<Tmodel>
 	 */
 	public function getSiblings(array $columns = ['*'])
 	{
@@ -973,7 +990,7 @@ public function getSiblings(array $columns = ['*'])
 	/**
 	 * @param string[] $columns
 	 *
-	 * @return Collection|Node[]
+	 * @return NestedSetCollection<Tmodel>
 	 */
 	public function getNextSiblings(array $columns = ['*'])
 	{
@@ -983,7 +1000,7 @@ public function getNextSiblings(array $columns = ['*'])
 	/**
 	 * @param string[] $columns
 	 *
-	 * @return Collection|Node[]
+	 * @return NestedSetCollection<Tmodel>
 	 */
 	public function getPrevSiblings(array $columns = ['*'])
 	{
@@ -993,9 +1010,9 @@ public function getPrevSiblings(array $columns = ['*'])
 	/**
 	 * @param string[] $columns
 	 *
-	 * @return Node
+	 * @return Node<Tmodel>
 	 */
-	public function getNextSibling(array $columns = ['*'])
+	public function getNextSibling(array $columns = ['*']): Node
 	{
 		return $this->nextSiblings()->defaultOrder()->first($columns);
 	}
@@ -1003,9 +1020,9 @@ public function getNextSibling(array $columns = ['*'])
 	/**
 	 * @param string[] $columns
 	 *
-	 * @return Node
+	 * @return Node<Tmodel>
 	 */
-	public function getPrevSibling(array $columns = ['*'])
+	public function getPrevSibling(array $columns = ['*']): Node
 	{
 		return $this->prevSiblings()->defaultOrder('desc')->first($columns);
 	}
@@ -1013,7 +1030,7 @@ public function getPrevSibling(array $columns = ['*'])
 	/**
 	 * Get whether a node is a descendant of other node.
 	 *
-	 * @param Node $other
+	 * @param Node<Tmodel> $other
 	 *
 	 * @return bool
 	 */
@@ -1026,7 +1043,7 @@ public function isDescendantOf(Node $other): bool
 	/**
 	 * Get whether a node is itself or a descendant of other node.
 	 *
-	 * @param Node $other
+	 * @param Node<Tmodel> $other
 	 *
 	 * @return bool
 	 */
@@ -1045,25 +1062,25 @@ public function isSelfOrDescendantOf(Node $other)
 	 */
 	public function isChildOf(Node $other)
 	{
-		return $this->getParentId() == $other->getKey();
+		return $this->getParentId() === $other->getKey();
 	}
 
 	/**
 	 * Get whether the node is a sibling of another node.
 	 *
-	 * @param Node $other
+	 * @param Node<Tmodel> $other
 	 *
 	 * @return bool
 	 */
 	public function isSiblingOf(Node $other)
 	{
-		return $this->getParentId() == $other->getParentId();
+		return $this->getParentId() === $other->getParentId();
 	}
 
 	/**
 	 * Get whether the node is an ancestor of other node, including immediate parent.
 	 *
-	 * @param Node $other
+	 * @param Node<Tmodel> $other
 	 *
 	 * @return bool
 	 */
@@ -1075,7 +1092,7 @@ public function isAncestorOf(Node $other): bool
 	/**
 	 * Get whether the node is itself or an ancestor of other node, including immediate parent.
 	 *
-	 * @param Node $other
+	 * @param Node<Tmodel> $other
 	 *
 	 * @return bool
 	 */
@@ -1095,7 +1112,7 @@ public function hasMoved()
 	}
 
 	/**
-	 * @return array
+	 * @return string[]
 	 */
 	protected function getArrayableRelations()
 	{
@@ -1114,11 +1131,11 @@ protected function getArrayableRelations()
 	 */
 	protected function hardDeleting()
 	{
-		return !$this->usesSoftDelete() || $this->forceDeleting;
+		return !$this->usesSoftDelete() || $this->forceDeleting; /** @phpstan-ignore property.notFound, staticMethod.dynamicCall */
 	}
 
 	/**
-	 * @return array
+	 * @return array{0:int,1:int}
 	 */
 	public function getBounds()
 	{
@@ -1128,7 +1145,7 @@ public function getBounds()
 	/**
 	 * @param $value
 	 *
-	 * @return Node $this
+	 * @return Node<Tmodel> $this
 	 */
 	public function setLft(int $value): Node
 	{
@@ -1140,7 +1157,7 @@ public function setLft(int $value): Node
 	/**
 	 * @param $value
 	 *
-	 * @return Node $this
+	 * @return Node<Tmodel> $this
 	 */
 	public function setRgt(int $value): Node
 	{
@@ -1152,7 +1169,7 @@ public function setRgt(int $value): Node
 	/**
 	 * @param Tmodelkey|null $value
 	 *
-	 * @return Node&Tmodel
+	 * @return Node<Tmodel>&Tmodel
 	 */
 	public function setParentId(mixed $value): Node
 	{
@@ -1162,7 +1179,7 @@ public function setParentId(mixed $value): Node
 	}
 
 	/**
-	 * @return Node
+	 * @return Node<Tmodel>
 	 */
 	protected function dirtyBounds()
 	{
@@ -1173,13 +1190,13 @@ protected function dirtyBounds()
 	}
 
 	/**
-	 * @param Node $node
+	 * @param Node<Tmodel> $node
 	 *
-	 * @return Node
+	 * @return Node<Tmodel>
 	 */
 	protected function assertNotDescendant(Node $node)
 	{
-		if ($node == $this || $node->isDescendantOf($this)) {
+		if ($node === $this || $node->isDescendantOf($this)) {
 			throw new \LogicException('Node must not be a descendant.');
 		}
 
@@ -1187,13 +1204,13 @@ protected function assertNotDescendant(Node $node)
 	}
 
 	/**
-	 * @param Node $node
+	 * @param Node<Tmodel> $node
 	 *
-	 * @return Node&Tmodel
+	 * @return Node<Tmodel>&Tmodel
 	 */
 	protected function assertNodeExists(Node $node)
 	{
-		if (!$node->getLft() || !$node->getRgt()) {
+		if ($node->getLft() === null || $node->getRgt() === null) {
 			throw new \LogicException('Node must exists.');
 		}
 
@@ -1201,16 +1218,19 @@ protected function assertNodeExists(Node $node)
 	}
 
 	/**
-	 * @param Node&Tmodel $node
+	 * @param Node<Tmodel>&Tmodel $node
+	 *
+	 * @phpstan-ignore generics.notSubtype
 	 */
 	protected function assertSameScope(Node $node): void
 	{
-		if (!$scoped = $this->getScopeAttributes()) {
+		$scoped = $this->getScopeAttributes();
+		if ($scoped === null || $scoped === []) { /** @phpstan-ignore identical.alwaysFalse */
 			return;
 		}
 
 		foreach ($scoped as $attr) {
-			if ($this->getAttribute($attr) != $node->getAttribute($attr)) {
+			if ($this->getAttribute($attr) !== $node->getAttribute($attr)) {
 				throw new \LogicException('Nodes must be in the same scope');
 			}
 		}
@@ -1219,7 +1239,9 @@ protected function assertSameScope(Node $node): void
 	/**
 	 * @param string[]|null $except
 	 *
-	 * @return \Illuminate\Database\Eloquent\Model
+	 * @return Node<Tmodel>&Tmodel
+	 *
+	 * @phpstan-ignore generics.notSubtype
 	 */
 	public function replicate(?array $except = null): Node
 	{
@@ -1229,7 +1251,7 @@ public function replicate(?array $except = null): Node
 			$this->getRgtName(),
 		];
 
-		$except = $except ? array_unique(array_merge($except, $defaults)) : $defaults;
+		$except = ($except !== null && $except !== []) ? array_unique(array_merge($except, $defaults)) : $defaults;
 
 		return parent::replicate($except);
 	}
diff --git a/src/QueryBuilder.php b/src/QueryBuilder.php
index 2288098..3e4cbd4 100644
--- a/src/QueryBuilder.php
+++ b/src/QueryBuilder.php
@@ -3,13 +3,16 @@
 namespace Kalnoy\Nestedset;
 
 use Illuminate\Database\Eloquent\Builder;
-use Illuminate\Database\Eloquent\Collection as EloquentCollection;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\ModelNotFoundException;
 use Illuminate\Database\Query\Builder as BaseQueryBuilder;
 use Illuminate\Database\Query\Builder as Query;
 use Illuminate\Database\Query\Expression;
 use Illuminate\Support\Arr;
+use Kalnoy\Nestedset\Contracts\NestedSetCollection;
+use Kalnoy\Nestedset\Contracts\Node;
+use Kalnoy\Nestedset\Contracts\NodeQueryBuilder;
+use Kalnoy\Nestedset\Exceptions\NestedSetException;
 
 /**
  * @template Tmodel of \Illuminate\Database\Eloquent\Model
@@ -17,8 +20,10 @@
  * @phpstan-type NodeModel Node<Tmodel>&Tmodel
  *
  * @extends Builder<NodeModel>
+ *
+ * @implements NodeQueryBuilder<Tmodel>
  */
-class QueryBuilder extends Builder
+class QueryBuilder extends Builder implements NodeQueryBuilder
 {
 	/**
 	 * @var NodeModel
@@ -35,7 +40,7 @@ class QueryBuilder extends Builder
 	 *
 	 * @return array<int,int>
 	 */
-	public function getNodeData(mixed $id, $required = false)
+	public function getNodeData(mixed $id, $required = false): array
 	{
 		$query = $this->toBase();
 
@@ -61,7 +66,7 @@ public function getNodeData(mixed $id, $required = false)
 	 *
 	 * @return array<int,int>
 	 */
-	public function getPlainNodeData(mixed $id, $required = false)
+	public function getPlainNodeData(mixed $id, $required = false): array
 	{
 		return array_values($this->getNodeData($id, $required));
 	}
@@ -69,9 +74,9 @@ public function getPlainNodeData(mixed $id, $required = false)
 	/**
 	 * Scope limits query to select just root node.
 	 *
-	 * @return QueryBuilder<Tmodel>
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function whereIsRoot(): QueryBuilder
+	public function whereIsRoot(): NodeQueryBuilder
 	{
 		$this->query->whereNull($this->model->getParentIdName());
 
@@ -87,9 +92,9 @@ public function whereIsRoot(): QueryBuilder
 	 * @param bool      $andSelf
 	 * @param string    $boolean
 	 *
-	 * @return QueryBuilder<Tmodel>
+	 * @return NodeQueryBuilder<Tmodel>
 	 */
-	public function whereAncestorOf(mixed $id, bool $andSelf = false, string $boolean = 'and')
+	public function whereAncestorOf(mixed $id, bool $andSelf = false, string $boolean = 'and'): NodeQueryBuilder
 	{
 		$keyName = $this->model->getTable() . '.' . $this->model->getKeyName();
 
@@ -156,9 +161,9 @@ public function whereAncestorOrSelf(mixed $id): QueryBuilder
 	 * @param NodeModel $id
 	 * @param string[]  $columns
 	 *
-	 * @return EloquentCollection<int,NodeModel>
+	 * @return NestedSetCollection<Tmodel>
 	 */
-	public function ancestorsOf(mixed $id, array $columns = ['*'])
+	public function ancestorsOf(mixed $id, array $columns = ['*']): NestedSetCollection
 	{
 		return $this->whereAncestorOf($id)->get($columns);
 	}
@@ -167,9 +172,9 @@ public function ancestorsOf(mixed $id, array $columns = ['*'])
 	 * @param NodeModel $id
 	 * @param string[]  $columns
 	 *
-	 * @return EloquentCollection<int,NodeModel>
+	 * @return NestedSetCollection<Tmodel>
 	 */
-	public function ancestorsAndSelf(mixed $id, array $columns = ['*'])
+	public function ancestorsAndSelf(mixed $id, array $columns = ['*']): NestedSetCollection
 	{
 		return $this->whereAncestorOf($id, true)->get($columns);
 	}
@@ -185,7 +190,7 @@ public function ancestorsAndSelf(mixed $id, array $columns = ['*'])
 	 *
 	 * @return QueryBuilder<Tmodel>
 	 */
-	public function whereNodeBetween(array $values, $boolean = 'and', $not = false)
+	public function whereNodeBetween(array $values, $boolean = 'and', $not = false): NodeQueryBuilder
 	{
 		$this->query->whereBetween($this->model->getTable() . '.' . $this->model->getLftName(), $values, $boolean, $not);
 
@@ -201,7 +206,7 @@ public function whereNodeBetween(array $values, $boolean = 'and', $not = false)
 	 *
 	 * @return QueryBuilder<Tmodel>
 	 */
-	public function orWhereNodeBetween(array $values)
+	public function orWhereNodeBetween(array $values): NodeQueryBuilder
 	{
 		return $this->whereNodeBetween($values, 'or');
 	}
@@ -211,16 +216,16 @@ public function orWhereNodeBetween(array $values)
 	 *
 	 * @since 2.0
 	 *
-	 * @param ?NodeModel $id
-	 * @param string     $boolean
-	 * @param bool       $not
-	 * @param bool       $andSelf
+	 * @param ?Node<Tmodel> $id
+	 * @param string        $boolean
+	 * @param bool          $not
+	 * @param bool          $andSelf
 	 *
 	 * @return QueryBuilder<Tmodel>
 	 */
 	public function whereDescendantOf(mixed $id, $boolean = 'and', $not = false,
 		$andSelf = false,
-	) {
+	): NodeQueryBuilder {
 		if (NestedSet::isNode($id)) {
 			$data = $id->getBounds();
 		} else {
@@ -241,39 +246,39 @@ public function whereDescendantOf(mixed $id, $boolean = 'and', $not = false,
 	 *
 	 * @return QueryBuilder<Tmodel>
 	 */
-	public function whereNotDescendantOf(mixed $id)
+	public function whereNotDescendantOf(mixed $id): NodeQueryBuilder
 	{
 		return $this->whereDescendantOf($id, 'and', true);
 	}
 
 	/**
-	 * @param NodeModel $id
+	 * @param Node<Tmodel> $id
 	 *
 	 * @return QueryBuilder<Tmodel>
 	 */
-	public function orWhereDescendantOf(mixed $id)
+	public function orWhereDescendantOf(mixed $id): NodeQueryBuilder
 	{
 		return $this->whereDescendantOf($id, 'or');
 	}
 
 	/**
-	 * @param NodeModel $id
+	 * @param Node<Tmodel> $id
 	 *
 	 * @return QueryBuilder<Tmodel>
 	 */
-	public function orWhereNotDescendantOf(mixed $id)
+	public function orWhereNotDescendantOf(mixed $id): NodeQueryBuilder
 	{
 		return $this->whereDescendantOf($id, 'or', true);
 	}
 
 	/**
-	 * @param NodeModel $id
-	 * @param string    $boolean
-	 * @param bool      $not
+	 * @param Node<Tmodel> $id
+	 * @param string       $boolean
+	 * @param bool         $not
 	 *
 	 * @return QueryBuilder<Tmodel>
 	 */
-	public function whereDescendantOrSelf(mixed $id, string $boolean = 'and', bool $not = false)
+	public function whereDescendantOrSelf(mixed $id, string $boolean = 'and', bool $not = false): NodeQueryBuilder
 	{
 		return $this->whereDescendantOf($id, $boolean, $not, true);
 	}
@@ -287,9 +292,9 @@ public function whereDescendantOrSelf(mixed $id, string $boolean = 'and', bool $
 	 * @param string[]  $columns
 	 * @param bool      $andSelf
 	 *
-	 * @return EloquentCollection<int,NodeModel>|Collection<Tmodel>
+	 * @return NestedSetCollection<Tmodel>
 	 */
-	public function descendantsOf(mixed $id, array $columns = ['*'], bool $andSelf = false)
+	public function descendantsOf(mixed $id, array $columns = ['*'], bool $andSelf = false): NestedSetCollection
 	{
 		try {
 			return $this->whereDescendantOf($id, 'and', false, $andSelf)->get($columns);
@@ -302,9 +307,9 @@ public function descendantsOf(mixed $id, array $columns = ['*'], bool $andSelf =
 	 * @param NodeModel $id
 	 * @param string[]  $columns
 	 *
-	 * @return EloquentCollection<int,NodeModel>
+	 * @return NestedSetCollection<Tmodel>
 	 */
-	public function descendantsAndSelf($id, array $columns = ['*'])
+	public function descendantsAndSelf($id, array $columns = ['*']): NestedSetCollection
 	{
 		return $this->descendantsOf($id, $columns, true);
 	}
@@ -352,7 +357,7 @@ protected function whereIsBeforeOrAfter(mixed $id, string $operator, string $boo
 	 *
 	 * @return QueryBuilder<Tmodel>
 	 */
-	public function whereIsAfter($id, $boolean = 'and')
+	public function whereIsAfter($id, $boolean = 'and'): NodeQueryBuilder
 	{
 		return $this->whereIsBeforeOrAfter($id, '>', $boolean);
 	}
@@ -367,7 +372,7 @@ public function whereIsAfter($id, $boolean = 'and')
 	 *
 	 * @return QueryBuilder<Tmodel>
 	 */
-	public function whereIsBefore($id, $boolean = 'and')
+	public function whereIsBefore($id, $boolean = 'and'): NodeQueryBuilder
 	{
 		return $this->whereIsBeforeOrAfter($id, '<', $boolean);
 	}
@@ -375,19 +380,19 @@ public function whereIsBefore($id, $boolean = 'and')
 	/**
 	 * @return QueryBuilder<Tmodel>
 	 */
-	public function whereIsLeaf()
+	public function whereIsLeaf(): NodeQueryBuilder
 	{
 		list($lft, $rgt) = $this->wrappedColumns();
 
-		return $this->whereRaw("$lft = $rgt - 1"); /** @phpstan-ignore-line */
+		return $this->whereRaw("$lft = $rgt - 1");
 	}
 
 	/**
 	 * @param string[] $columns
 	 *
-	 * @return EloquentCollection<int,NodeModel>
+	 * @return NestedSetCollection<Tmodel>
 	 */
-	public function leaves(array $columns = ['*'])
+	public function leaves(array $columns = ['*']): NestedSetCollection
 	{
 		return $this->whereIsLeaf()->get($columns);
 	}
@@ -399,7 +404,7 @@ public function leaves(array $columns = ['*'])
 	 *
 	 * @return QueryBuilder<Tmodel>
 	 */
-	public function withDepth($as = 'depth')
+	public function withDepth($as = 'depth'): NodeQueryBuilder
 	{
 		if ($this->query->columns === null) {
 			$this->query->columns = ['*'];
@@ -543,7 +548,7 @@ public function reversed(): QueryBuilder
 	 *
 	 * @return int
 	 */
-	public function moveNode($key, $position)
+	public function moveNode($key, $position): int
 	{
 		list($lft, $rgt) = $this->model->newNestedSetQuery()
 									   ->getPlainNodeData($key, true);
@@ -595,7 +600,7 @@ public function moveNode($key, $position)
 	 *
 	 * @return int
 	 */
-	public function makeGap($cut, $height)
+	public function makeGap($cut, $height): int
 	{
 		$params = compact('cut', 'height');
 
@@ -614,7 +619,7 @@ public function makeGap($cut, $height)
 	 *
 	 * @param array{height:int,cut?:int,distance?:int,lft?:int,rgt?:int,to?:int,from?:int} $params
 	 *
-	 * @return array<string,Expression>
+	 * @return array<string,Expression<non-falsy-string>>
 	 */
 	protected function patch(array $params): array
 	{
@@ -637,7 +642,7 @@ protected function patch(array $params): array
 	 * @param string                                                                       $col
 	 * @param array{height:int,cut?:int,distance?:int,lft?:int,rgt?:int,to?:int,from?:int} $params
 	 *
-	 * @return Expression
+	 * @return Expression<non-falsy-string>
 	 */
 	protected function columnPatch(string $col, array $params): Expression
 	{
@@ -828,7 +833,7 @@ protected function getMissingParentQuery()
 	 *
 	 * @return int
 	 */
-	public function getTotalErrors()
+	public function getTotalErrors(): int
 	{
 		return array_sum($this->countErrors());
 	}
@@ -840,7 +845,7 @@ public function getTotalErrors()
 	 *
 	 * @return bool
 	 */
-	public function isBroken()
+	public function isBroken(): bool
 	{
 		return $this->getTotalErrors() > 0;
 	}
@@ -854,7 +859,7 @@ public function isBroken()
 	 *
 	 * @return int The number of changed nodes
 	 */
-	public function fixTree($root = null)
+	public function fixTree($root = null): int
 	{
 		$columns = [
 			$this->model->getKeyName(),
@@ -865,7 +870,7 @@ public function fixTree($root = null)
 
 		$dictionary = $this->model
 			->newNestedSetQuery()
-			->when($root, function (self $query) use ($root) {
+			->when($root !== null, function (self $query) use ($root) {
 				return $query->whereDescendantOf($root);
 			})
 			->defaultOrder()
@@ -881,7 +886,7 @@ public function fixTree($root = null)
 	 *
 	 * @return int
 	 */
-	public function fixSubtree($root)
+	public function fixSubtree($root): int
 	{
 		return $this->fixTree($root);
 	}
@@ -892,7 +897,7 @@ public function fixSubtree($root)
 	 *
 	 * @return int
 	 */
-	protected function fixNodes(array &$dictionary, $parent = null)
+	protected function fixNodes(array &$dictionary, $parent = null): int
 	{
 		$parentId = $parent !== null ? $parent->getKey() : null;
 		$cut = $parent !== null ? $parent->getLft() + 1 : 1;
@@ -969,10 +974,10 @@ protected static function reorderNodes(
 	 *
 	 * @return int
 	 */
-	public function rebuildTree(array $data, $delete = false, $root = null)
+	public function rebuildTree(array $data, $delete = false, $root = null): int
 	{
-		if ($this->model->usesSoftDelete()) { /** @phpstan-ignore-line */
-			$this->withTrashed(); /** @phpstan-ignore-line */
+		if ($this->model->usesSoftDelete()) {
+			$this->withTrashed(); /** @phpstan-ignore method.notFound (it does exists!) */
 		}
 
 		$existing = $this
@@ -987,8 +992,8 @@ public function rebuildTree(array $data, $delete = false, $root = null)
 
 		$this->buildRebuildDictionary($dictionary, $data, $existing, $parentId);
 
-		if ($existing !== null && $existing !== []) {
-			if ($delete && !$this->model->usesSoftDelete()) { /** @phpstan-ignore-line */
+		if ($existing !== []) {
+			if ($delete && !$this->model->usesSoftDelete()) {
 				$this->model
 					->newScopedQuery()
 					->whereIn($this->model->getKeyName(), array_keys($existing))
@@ -997,12 +1002,12 @@ public function rebuildTree(array $data, $delete = false, $root = null)
 				foreach ($existing as $model) {
 					$dictionary[$model->getParentId()][] = $model;
 
-					if ($delete && $this->model->usesSoftDelete() && /** @phpstan-ignore-line */
-						!$model->{$model->getDeletedAtColumn()} /** @phpstan-ignore-line */
+					if ($delete && $this->model->usesSoftDelete() &&
+						!$model->{$model->getDeletedAtColumn()} /** @phpstan-ignore property.dynamicName */
 					) {
 						$time = $this->model->fromDateTime($this->model->freshTimestamp());
 
-						$model->{$model->getDeletedAtColumn()} = $time; /** @phpstan-ignore-line */
+						$model->{$model->getDeletedAtColumn()} = $time; /** @phpstan-ignore property.dynamicName */
 					}
 				}
 			}
@@ -1018,7 +1023,7 @@ public function rebuildTree(array $data, $delete = false, $root = null)
 	 *
 	 * @return int
 	 */
-	public function rebuildSubtree($root, array $data, $delete = false)
+	public function rebuildSubtree($root, array $data, $delete = false): int
 	{
 		return $this->rebuildTree($data, $delete, $root);
 	}
@@ -1077,7 +1082,7 @@ protected function buildRebuildDictionary(array &$dictionary,
 	 *
 	 * @return QueryBuilder<Tmodel>
 	 */
-	public function applyNestedSetScope($table = null)
+	public function applyNestedSetScope($table = null): NodeQueryBuilder
 	{
 		return $this->model->applyNestedSetScope($this, $table);
 	}
diff --git a/tests/models/Category.php b/tests/models/Category.php
index e2217a1..e3ce3a5 100644
--- a/tests/models/Category.php
+++ b/tests/models/Category.php
@@ -2,19 +2,23 @@
 
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\SoftDeletes;
-use Kalnoy\Nestedset\Node;
+use Kalnoy\Nestedset\Contracts\Node;
 use Kalnoy\Nestedset\NodeTrait;
 
+/**
+ * @implements Node<Category>
+ */
 class Category extends Model implements Node
 {
 	use SoftDeletes;
+	/** @use NodeTrait<Category,int> */
 	use NodeTrait;
 
 	protected $fillable = ['name', 'parent_id'];
 
 	public $timestamps = false;
 
-	public static function resetActionsPerformed()
+	public static function resetActionsPerformed(): void
 	{
 		static::$actionsPerformed = 0;
 	}
diff --git a/tests/models/DuplicateCategory.php b/tests/models/DuplicateCategory.php
index 91f2e2d..6a64503 100644
--- a/tests/models/DuplicateCategory.php
+++ b/tests/models/DuplicateCategory.php
@@ -1,11 +1,15 @@
 <?php
 
 use Illuminate\Database\Eloquent\Model;
-use Kalnoy\Nestedset\Node;
+use Kalnoy\Nestedset\Contracts\Node;
 use Kalnoy\Nestedset\NodeTrait;
 
+/**
+ * @implements Node<DuplicateCategory>
+ */
 class DuplicateCategory extends Model implements Node
 {
+	/** @use NodeTrait<DuplicateCategory,int> */
 	use NodeTrait;
 
 	protected $table = 'categories';
diff --git a/tests/models/MenuItem.php b/tests/models/MenuItem.php
index ea17d12..cadb9fa 100644
--- a/tests/models/MenuItem.php
+++ b/tests/models/MenuItem.php
@@ -1,23 +1,30 @@
 <?php
 
 use Illuminate\Database\Eloquent\Model;
-use Kalnoy\Nestedset\Node;
+use Kalnoy\Nestedset\Contracts\Node;
 use Kalnoy\Nestedset\NodeTrait;
 
+/**
+ * @implements Node<MenuItem>
+ */
 class MenuItem extends Model implements Node
 {
+	/** @use NodeTrait<MenuItem,int> */
 	use NodeTrait;
 
 	public $timestamps = false;
 
 	protected $fillable = ['menu_id', 'parent_id'];
 
-	public static function resetActionsPerformed()
+	public static function resetActionsPerformed(): void
 	{
 		static::$actionsPerformed = 0;
 	}
 
-	protected function getScopeAttributes()
+	/**
+	 * @return list<string>
+	 */
+	protected function getScopeAttributes(): array
 	{
 		return ['menu_id'];
 	}