/**
 * Central error handling and sanitization for the LiteLLM backend.
 *
 * Ensures that:
 * - Upstream auth failures (401/403) don't log out Backstage sessions
 * - Upstream 5xx errors are generic and don't leak implementation details
 * - Upstream 4xx errors are sanitized and capped
 * - Non-JSON error bodies are not embedded in responses
 * - All error logging happens server-side only
 */
import { Response } from 'express';
import { LoggerService } from '@backstage/backend-plugin-api';
/**
 * Type guard: narrows unknown to {status: number; body: Record<string, unknown>}.
 * Used to detect custom errors that have status and body properties.
 */
export declare function isHttpishError(error: unknown): error is {
    status: number;
    body: Record<string, unknown>;
};
/**
 * Safely extract a message string from any error type.
 * Returns empty string if no message can be extracted.
 */
export declare function errorMessage(error: unknown): string;
/**
 * Sanitizes a message by:
 * - Redacting Bearer tokens and sk- keys
 * - Stripping HTML tags
 * - Collapsing consecutive whitespace
 * - Truncating to 500 characters
 *
 * @param msg The raw message (may contain HTML, newlines, secrets, etc.)
 * @returns A safe, printable message
 */
export declare function sanitizeUpstreamMessage(msg: string): string;
/**
 * Maps any error type to an HTTP response shape {status, body}.
 *
 * Behaviour:
 * - LiteLLMUpstreamError 401/403 → 502 generic (prevent session logout)
 * - LiteLLMUpstreamError 5xx or network → 502 generic
 * - LiteLLMUpstreamError 4xx (other) → 400 with sanitized message + param if present
 * - KeyServiceError / ProvisioningError / objects with status+body → pass through
 * - Backstage-style errors (name: InputError/NotAllowedError/NotFoundError/ConflictError) → map to 400/403/404/409
 * - Anything else → 500 (message logged server-side, not returned)
 *
 * @returns {status, body, logLevel} for HTTP response; undefined _logMessage is only present for 500s
 */
export declare function toHttpError(error: unknown): {
    status: number;
    body: Record<string, unknown>;
    logLevel: 'debug' | 'info' | 'warn' | 'error';
    _logMessage?: string;
};
/**
 * Express error handler helper. Logs the real error server-side and responds
 * via toHttpError.
 *
 * @param res Express Response object
 * @param error The caught error (any type)
 * @param logger Logger instance with error/warn/info/debug methods
 * @param context Contextual label for the log entry (e.g. 'fetch user info')
 */
export declare function sendError(res: Response, error: unknown, logger: LoggerService, context: string): void;