/**
 * Structured error types for the target resolution system.
 *
 * Every browser action (click, type, select, get) that targets a DOM element
 * goes through the unified resolver. When resolution fails, one of these
 * structured errors is thrown so that AI agents and adapter authors get
 * actionable diagnostics instead of a generic "Element not found".
 *
 * Numeric-ref codes (from snapshot indices):
 *   - not_found: the ref no longer exists in the DOM
 *   - stale_ref: the ref still exists but points to a different element
 *
 * CSS-selector codes (from `--selector <css>` entrypoints):
 *   - invalid_selector:       selector syntax rejected by querySelectorAll
 *   - selector_not_found:     0 matches
 *   - selector_ambiguous:     >1 matches for a write op without --nth
 *   - selector_nth_out_of_range: --nth beyond matches_n
 *   - not_editable:           target exists but cannot accept text input
 *   - not_checkable:          target exists but cannot be checked/unchecked
 *   - not_file_input:         target exists but is not a usable file input
 */
export type TargetErrorCode = 'not_found' | 'stale_ref' | 'invalid_selector' | 'selector_not_found' | 'selector_ambiguous' | 'selector_nth_out_of_range' | 'not_editable' | 'not_checkable' | 'not_file_input';
export interface TargetErrorInfo {
    code: TargetErrorCode;
    message: string;
    hint: string;
    candidates?: string[];
    /** CSS-path match count, when the error was raised mid-resolution */
    matches_n?: number;
}
export declare class TargetError extends Error {
    readonly code: TargetErrorCode;
    readonly hint: string;
    readonly candidates?: string[];
    readonly matches_n?: number;
    constructor(info: TargetErrorInfo);
    /** Serialize for structured output to AI agents */
    toJSON(): TargetErrorInfo;
}