/**
 * Persisted quota ledger — pure persistence + keying helpers, no quota
 * decision logic (that lives in `quota-governor.ts`).
 *
 * Layout: `.bober/seo/quota-ledger.json`.
 *
 * Every write is atomic via temp-file + rename (mirrors
 * `src/incident/timeline.ts:86-92` atomicWriteJson / `src/state/run-state.ts:41-52`).
 *
 * Concurrent read-modify-write calls to the SAME resolved path are serialized
 * via a module-scoped per-path promise-chain mutex (mirrors
 * `src/telemetry/emit.ts:57,85-86`) so two `SeoQuotaGovernor` instances
 * sharing a ledger path never lose an update.
 *
 * Fail-closed discrimination: a MISSING ledger (ENOENT) is a fresh, empty
 * ledger (offline / first-run => allow). An EXISTING-but-unparseable or
 * unreadable ledger is the `"corrupt"` sentinel (fail-closed => at-ceiling).
 * This is deliberately NOT the blanket catch used by `readRunState`
 * (`src/state/run-state.ts:61-68`), which collapses both cases to `null`.
 *
 * Sprint 7 — spec-20260715-ultimate-seo-suite.
 */
import type { SeoQuotaLedger } from "./types.js";
/** `YYYY-MM-DD` date key; daily counters reset on this boundary. */
export declare function dateKey(now: Date): string;
/** Composite per-site/per-user scope key (`${siteUrl}|${userId}`). */
export declare function scopeKey(scope: {
    siteUrl?: string;
    userId?: string;
}): string;
/**
 * Read the ledger from disk.
 *
 * - Missing file (ENOENT) => fresh empty ledger `{}` (offline/first-run, NOT corrupt).
 * - Existing-but-unreadable (permissions, etc.) or unparseable JSON => `"corrupt"`
 *   sentinel so the caller can fail closed (treat spend as at-ceiling).
 */
export declare function readLedger(path: string): Promise<SeoQuotaLedger | "corrupt">;
/**
 * Atomically overwrite the ledger: write a unique temp file, then rename
 * (POSIX-atomic) so a crash mid-write can never leave a torn/corrupt file.
 */
export declare function writeLedgerAtomic(path: string, ledger: SeoQuotaLedger): Promise<void>;
/**
 * Run `fn` exclusively with respect to any other `withLedgerLock` call on
 * the same resolved path. Chains onto the previous run regardless of
 * whether it resolved or rejected, so one failure never wedges the chain.
 */
export declare function withLedgerLock<T>(path: string, fn: () => Promise<T>): Promise<T>;
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