/**
 * Receipt Hash Policy — two-tier SSOT for all receipt payloads in @holoscript/core.
 *
 * ## Tiers
 *
 * | Tier       | Algorithm | Output length | When to use                                        |
 * |------------|-----------|---------------|----------------------------------------------------|
 * | `'fast'`   | FNV-1a 32 | 8 hex chars   | Non-adversarial, high-throughput, local receipts   |
 * | `'secure'` | SHA-256   | 64 hex chars  | Chain-anchored, adversarial-peer, on-chain records |
 *
 * **Default is `'fast'`** — this matches the non-adversarial threat model that governs
 * most simulation receipts (internal replay, developer tooling, local twin). Use
 * `'secure'` when a receipt will be anchored on-chain (x402/CAEL base anchor) or
 * shared across trust boundaries where collision resistance matters.
 *
 * ## Usage
 *
 *   import { hashReceiptPayload, RECEIPT_HASH_POLICY_DEFAULT } from './hash-policy';
 *
 *   // Fast path (DomainSimulationReceipt, internal receipts):
 *   const tag = hashReceiptPayload(payload);         // uses 'fast'
 *
 *   // Secure path (chain-anchored receipts):
 *   const tag = hashReceiptPayload(payload, 'secure');
 *
 * ## Format tags
 *
 * Both functions prefix the raw hex with a format tag so receipts are
 * self-identifying even without the policy field:
 *   `fast`   → `"fnv1a32:<8 hex>"`
 *   `secure` → `"sha256:<64 hex>"`
 *
 * ## Rationale
 *
 * Prior to this file, the fnv1a32 implementation was duplicated:
 *   - `packages/core/src/receipts/DomainSimulationReceipt.ts` (private local fn)
 *   - `packages/engine/src/simulation/sha256.ts` (byte-domain variant)
 *   - `packages/core/src/reconstruction/replayFingerprint.ts` (double-FNV, 16 chars)
 *
 * Those existing callers are left unchanged (they are locked by tests). All NEW
 * receipt hashing should go through this module.
 *
 * See: research/2026-06-16_language-extension-roadmap.md §H1 hash-policy
 *      packages/engine/src/simulation/sha256.ts (engine-level mode dispatch)
 */
/**
 * The two tiers of receipt hashing.
 * Match the engine's `HashMode` naming intent but kept independent
 * so @holoscript/core does not import from @holoscript/engine.
 */
export type ReceiptHashPolicy = 'fast' | 'secure';
/** Default policy: FNV-1a 32 — fast, non-adversarial, non-cryptographic. */
export declare const RECEIPT_HASH_POLICY_DEFAULT: ReceiptHashPolicy;
/**
 * Hash a canonicalized receipt payload string using the specified policy.
 *
 * For `'fast'` (default): synchronous, returns a prefixed string immediately.
 * For `'secure'`: returns a Promise — await it or use `hashReceiptPayloadAsync`.
 *
 * The output is always prefixed with the format tag so receipts are
 * self-identifying: `"fnv1a32:<hex>"` or `"sha256:<hex>"`.
 */
export declare function hashReceiptPayload(canonicalized: string, policy?: 'fast'): string;
export declare function hashReceiptPayload(canonicalized: string, policy: 'secure'): Promise<string>;
/**
 * Async variant — always returns a Promise regardless of policy tier.
 * Useful in async contexts where the synchronous fast path is still valid.
 */
export declare function hashReceiptPayloadAsync(canonicalized: string, policy?: ReceiptHashPolicy): Promise<string>;
/**
 * Parse a format-tagged hash string produced by `hashReceiptPayload`.
 * Returns `{ policy, hex }` or `null` if the tag is not recognized.
 *
 * Useful for receipt verification: infer the tier from the stored hash
 * without requiring a separate `hashAlgorithm` field.
 */
export declare function parseReceiptHash(tagged: string): {
    policy: ReceiptHashPolicy;
    hex: string;
} | null;
/**
 * Format-level consistency check: does the hash string's prefix match
 * the expected policy? Used to detect mid-receipt policy tampering.
 */
export declare function receiptHashMatchesPolicy(tagged: string, policy: ReceiptHashPolicy): boolean;