/**
 * Is this error the S3/STS "access denied" class? Expected when a scoped
 * member/guest credential touches a key outside its granted ACL prefixes
 * (the server's `SCOPE_EXCEEDS_PARENT` surfaces as a 403 AccessDenied /
 * Forbidden).
 */
export declare function isAccessDenied(err: unknown): boolean;
/** Host resource snapshot used to decide the default transfer fan-out. */
export interface HostLoadProbe {
    /** Logical CPU count (0 when unknown). */
    cores: number;
    /** 1-minute load average (0 on platforms without it, e.g. Windows). */
    load1: number;
    /**
     * Memory *available to applications* as a fraction of total (0..1). This is
     * NOT `os.freemem() / os.totalmem()`: on macOS and Linux the OS keeps most
     * "free" RAM as reclaimable file cache, so raw free-page counts report a
     * near-full machine as memory-starved. `readAvailableMemoryFraction`
     * measures available memory per-platform instead.
     */
    availableMemFraction: number;
}
/**
 * Measure memory *available to applications* as a fraction of total RAM.
 *
 * `os.freemem()` counts only unused pages; both macOS and Linux hold most idle
 * RAM as reclaimable cache, so it drastically understates what an app can get
 * (an idle 16 GB Mac reports ~8% "free" while ~75% is actually available).
 * Reading it as pressure would pin every pass to the busy tier. We instead read
 * the platform's available figure; any failure falls back optimistically (1.0)
 * so a bad probe never throttles — the upload byte budget is the real
 * memory-safety net.
 */
export declare function readAvailableMemoryFraction(): number;
/** Read the current host load. Pure I/O; callers inject a probe in tests. */
export declare function readHostLoad(): HostLoadProbe;
/**
 * True when the host is already under meaningful CPU or memory load from other
 * processes. `cores === 0` (unknown) disables the CPU signal rather than
 * dividing by zero; `load1 === 0` (Windows has no load average) likewise leaves
 * the CPU signal inert, so those hosts fall back to the memory signal only.
 */
export declare function machineAlreadyBusy(probe: HostLoadProbe): boolean;
/**
 * Concurrency for the per-file transfer pool (uploads + downloads).
 *
 * An explicit, valid `HQ_SYNC_TRANSFER_CONCURRENCY` always wins. Otherwise the
 * default adapts to the host: 64-way normally, 32-way when the machine is
 * already busy (see `machineAlreadyBusy`). Callers capture the probe at pass
 * entry — BEFORE the walk/hash pass — and inject it, so the reading reflects
 * other processes rather than sync's own load; tests inject a synthetic probe.
 */
export declare function resolveTransferConcurrency(probe?: HostLoadProbe): number;
/**
 * A run-scoped permit pool for payload transfers.
 *
 * Most syncs have one engine, whose local executor uses
 * {@link resolveTransferConcurrency}. Company fanout intentionally starts
 * several independent engines at once, though, so the runner gives each one
 * the same semaphore when `HQ_SYNC_MAX_CONCURRENCY` is configured. That makes
 * the documented bandwidth-governor ceiling apply to the whole run rather
 * than once per company.
 */
export declare class TransferSemaphore {
    private available;
    private readonly waiters;
    constructor(capacity: number);
    withPermit<T>(fn: () => Promise<T>): Promise<T>;
}
/**
 * Total in-flight upload-body bytes the upload pool may hold at once. Because
 * `uploadFile` buffers whole files, this — not the worker count — is what
 * bounds sync's peak memory. Sized from AVAILABLE memory (the pass-entry
 * probe's `availableMemFraction`), so a memory-tight host gets a small budget
 * that cannot exhaust what is left while an idle host is capped at 1 GiB. No
 * hard floor: a tiny budget is safe because the pool always admits one item
 * when nothing is in flight, so a single oversized file still uploads. Override
 * for tuning/tests with `HQ_SYNC_UPLOAD_BYTE_BUDGET_MB` (absolute, fractional
 * MB accepted).
 */
export declare function resolveUploadByteBudget(availableMemFraction?: number, totalMemBytes?: number): number;
/**
 * Resolve active company from .hq/config.json.
 */
export declare function resolveActiveCompany(hqRoot: string): string | undefined;
/**
 * Returns true when the remote object appears to have moved since the
 * journal entry's last-recorded sync. When both sides expose content lineage,
 * compare the remote published SHA-256 to the journal's local baseline before
 * considering the ETag. ETags remain version/concurrency tokens and are the
 * back-compat fallback for legacy objects and list-only results.
 */
export declare function hasRemoteChanged(remote: {
    lastModified: Date;
    etag: string;
    contentHash?: string;
}, entry: {
    syncedAt: string;
    remoteEtag?: string;
    hash?: string;
}): boolean;
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