interface ValidationIssue {
    param: string;
    value: string;
    message: string;
    severity: "error" | "warning";
}
interface ValidateOptions {
    /** Promote warnings (unknown provider, unknown params) to errors. */
    strict?: boolean;
}
/**
 * Validate an LLM connection string.
 *
 * Parses and normalizes the string, then checks params against provider specs.
 * For gateway providers (OpenRouter, Vercel), detects the sub-provider from the
 * model prefix and validates against the sub-provider's rules when known.
 * Returns a list of issues found. An empty array means all params look valid.
 */
declare function validate(connectionString: string, options?: ValidateOptions): ValidationIssue[];

export { type ValidateOptions, type ValidationIssue, validate };