/** Shared lifecycle-safe resolver used by each flow-canvas companion. */
export declare class FlowCanvasCompanionController<T extends HTMLElement>{private readonly host;private readonly isCapable;private readonly onTargetChange;private observer?;private observerDocument?;private generation;private _target;constructor(host:HTMLElement&{for:string;},isCapable:(element:HTMLElement)=>element is T,onTargetChange:(next:T|null,previous:T|null)=>void);get target():T|null;connect():void;disconnect():void;adopt():void;targetIdChanged():void;private root;private candidate;private setTarget;private reconcile;private watchRoot;}