/**
 * Shared environment-variable parsing utilities.
 *
 * Every function accepts an optional {@link EnvSource} so tests can inject
 * values without mutating `process.env`.
 *
 * @module
 */
/** A bag of environment variables — defaults to `process.env`. */
export type EnvSource = Record<string, string | undefined>;
/** Read a string env var, returning `fallback` when unset or empty. */
export declare function envString(name: string, fallback: string, env?: EnvSource): string;
/** Read an optional string env var; returns `undefined` when unset or empty. */
export declare function envOptionalString(name: string, env?: EnvSource): string | undefined;
/**
 * Parse a port number (integer 1–65535) from an env var.
 * Returns `fallback` when unset. Throws on invalid values.
 */
export declare function envPort(name: string, fallback: number, env?: EnvSource): number;
/**
 * Parse an integer env var with optional min/max bounds.
 * Returns `fallback` when unset, non-finite, or outside bounds.
 * Truncates toward zero (matching `parseInt` semantics).
 */
export declare function envInt(name: string, fallback: number, opts?: {
    min?: number;
    max?: number;
    env?: EnvSource;
}): number;
/**
 * Parse a non-negative float env var.
 * Returns `fallback` when unset, non-finite, or negative.
 */
export declare function envNum(name: string, fallback: number, env?: EnvSource): number;
/**
 * Parse a strict boolean flag: `"1"` → `true`, anything else → `false`.
 * Matches the `GRACKLE_SKIP_*` / `GRACKLE_ALLOW_*` convention.
 */
export declare function envFlag(name: string, env?: EnvSource): boolean;
/**
 * Parse a broad boolean: `"1"` / `"true"` → `true`, `"0"` / `"false"` → `false`,
 * unset/empty/unrecognized → `fallback`. Matches the `GRACKLE_KNOWLEDGE_ENABLED`
 * convention. Unrecognized values preserve the fallback so a typo doesn't
 * silently flip a feature flag.
 */
export declare function envBool(name: string, fallback: boolean, env?: EnvSource): boolean;
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