/**
 * compaction/errors — the one refusal compaction makes out loud.
 *
 * Pattern: Typed terminal error (peer of PolicyHaltError).
 * Role:    core/ layer.
 * Emits:   N/A.
 */
/**
 * Thrown when compaction is configured but the provider reports no token
 * usage, so the threshold cannot be COUNTED.
 *
 * Compaction is counted, not guessed. Given a provider that reports nothing,
 * the library has three options: guess the window size (a lie), silently do
 * nothing (a configured budget that never applies — config that lies), or say
 * so. It says so, by name, at the first iteration boundary where a completed
 * call reported zero tokens in AND zero out.
 *
 * Terminal: `Agent.run` does not wrap this in `RunCheckpointError`, because
 * resuming would walk into the same wall with the same provider.
 */
export declare class CompactionUnmeasurableError extends Error {
    readonly name = "CompactionUnmeasurableError";
    /** `provider.name` of the adapter that reported nothing. */
    readonly provider: string;
    constructor(provider: string);
}