/**
 * Perplexity API credential resolution.
 *
 * Single source of truth for the Perplexity API key (`PERPLEXITY_API_KEY`).
 */
/** Credential environment names read by this module (#232 derivation pin). */
export declare const ENV_NAMES: readonly ["PERPLEXITY_API_KEY"];
export declare function resolvePerplexityApiKey(env: NodeJS.ProcessEnv): string | undefined;
export declare function requirePerplexityApiKey(env: NodeJS.ProcessEnv): string;
export declare function isPerplexityConfigured(env: NodeJS.ProcessEnv): boolean;
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