import Anthropic from '@anthropic-ai/sdk';
/** The identity Anthropic requires as the FIRST system block when a request is
 * authenticated with a subscription OAuth token — the token is authorised only
 * for Claude-Code-shaped requests. Overridable via `ANTHROPIC_OAUTH_SYSTEM` for
 * resilience if the required string changes. Used by the adapter's buildRequest. */
export declare function oauthSystemIdentity(env?: NodeJS.ProcessEnv): string;
/** Resolve the client for a call plus whether it authenticates with a
 * subscription OAuth token (which needs the Claude-Code system identity on every
 * request). The no-per-call-key client is cached (the common path); a BYOK
 * per-call key builds a fresh client and is never the OAuth path. Throws a clear
 * error when no credential is configured. */
export declare function resolveClient(perCallApiKey: string | null): {
    client: Anthropic;
    oauth: boolean;
};
/** A 401 from the Anthropic SDK — an authentication rejection (a rejected or
 * expired OAuth token, a missing/blocked Claude-Code identity, a bad key), as
 * opposed to a transient 429/5xx that the caller's retry ladder handles. A 403 is
 * deliberately EXCLUDED: it is authorization (permission denied on the org /
 * project), not a bad token, so it must not trigger the metered-key fallback. */
export declare function isAuthError(err: unknown): boolean;
/** Latch OAuth off after a 401 and warn ONCE — loudly, because the fallback
 * bills the metered key, the very cost the OAuth path exists to avoid. Never
 * silent: a user who set CLAUDE_CODE_OAUTH_TOKEN must SEE that it was rejected
 * and that spend has moved onto ANTHROPIC_API_KEY. Only the HTTP status is
 * emitted — never the error message or any token (secret-handling). */
export declare function noteOAuthRejected(err: unknown): void;
/** Test seam: reset the cached client + the fallback latch between tests.
 * INTERNAL — imported directly by the co-located tests, never re-exported to
 * consumers, so it never appears on the package's public surface. */
export declare function resetClientStateForTests(): void;
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