/**
 * Exa credential resolution (tech-plan §7, Credential Resolution).
 *
 * Single source of truth for the Exa API key. Whitespace-only values
 * are treated as absent, matching the descriptor's `isConfigured`
 * contract.
 *
 * Boundary rules (ARCHITECTURE.md §2):
 *   - May import the normalized-error contract only.
 *   - Must NOT import transport, command presentation, or another
 *     Provider's Adapter.
 *
 * Missing credentials are surfaced as {@link ConfigurationError}
 * (exit 3), distinct from {@link AuthError} (exit 1) which means the
 * Provider REJECTED a presented credential.
 */
/** Credential environment names read by this module (#232 derivation pin). */
export declare const ENV_NAMES: readonly ["EXA_API_KEY"];
/**
 * Resolve the Exa API key without throwing. Returns `undefined`
 * when no non-blank value is present.
 */
export declare function resolveExaApiKey(env: NodeJS.ProcessEnv): string | undefined;
/**
 * Resolve the Exa API key or throw {@link ConfigurationError}
 * (exit 3) when it is missing. Call this at every capability
 * invocation gate.
 */
export declare function requireExaApiKey(env: NodeJS.ProcessEnv): string;
/**
 * True when a non-blank Exa API key is configured. Metadata-only:
 * performs no transport construction and reads no other Provider's
 * credentials.
 */
export declare function isExaConfigured(env: NodeJS.ProcessEnv): boolean;
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