/**
 * Context-overflow error detection helpers.
 *
 * Provider error messages vary — Anthropic returns "prompt is too long",
 * OpenAI returns "context_length_exceeded", Bedrock returns "Input is too
 * long", Google returns a size-limit phrase. This module centralises the
 * phrase list so the agent graph's emergency-prune retry can classify
 * errors consistently instead of duplicating inline substring matches at
 * each call site.
 *
 * The strict check (`isContextOverflowError`) matches only known phrases.
 * The loose check (`isLikelyContextOverflowError`) also matches a heuristic
 * regex for providers we haven't explicitly catalogued. Both filter out
 * false positives (rate-limit, auth, quota, billing) that might otherwise
 * trigger an unnecessary prune retry.
 */
/**
 * Extracts a human-readable error message from an unknown error value.
 * Walks common shapes: strings, Error instances, `{ message }`,
 * `{ error: string }`, `{ error: { message } }`. Falls back to
 * JSON.stringify or String() so callers never have to null-check.
 */
export declare function extractErrorMessage(error: unknown): string;
/**
 * Strict check: returns true only for known, unambiguous context-overflow
 * phrases. Use when the recovery action is expensive (full prune + retry)
 * and false positives are undesirable.
 */
export declare function isContextOverflowError(errorMessage?: string): boolean;
/**
 * Loose check: returns true for known phrases OR heuristic regex matches.
 * Preferred by the graph's emergency-prune retry because the cost of a
 * false positive is one extra retry with a smaller context, while the
 * cost of a false negative is an opaque provider failure surfaced to
 * the user.
 */
export declare function isLikelyContextOverflowError(errorMessage?: string): boolean;