import { type ValidatorFn } from '@angular/forms';
import { type DfDataModel, type DfId } from '../../ng-draw-flow.interfaces';
import { type DfSignalValidator } from '../graph-validation.interfaces';
export interface DfIsolatedNodesError {
    readonly hasIsolatedNodes: true;
    readonly isolatedNodes: readonly DfId[];
}
/** Finds disconnected nodes without depending on an Angular form control. */
export declare function dfValidateIsolatedNodes(model: DfDataModel | null | undefined): DfIsolatedNodesError | null;
/**
 * Validator that checks for *isolated* (disconnected) nodes — nodes that do **not** appear in any connection.
 *
 * ### Validation error shape
 * ```ts
 * {
 *   hasIsolatedNodes: boolean;
 *   isolatedNodes: DfId[] // array of nodeIds without connections
 * }
 * ```
 * When there are **no** isolated nodes, it returns `null` so the control is valid.
 */
export declare function dfIsolatedNodesValidator(): ValidatorFn;
/** Creates a validator accepted directly by Signal Forms `validate()`. */
export declare function dfIsolatedNodesSignalValidator(): DfSignalValidator;