/**
 * dsh-widgets — the shared host HTTP plumbing.
 *
 * `memoTtl` (the per-key TTL + single-flight cache the channels share),
 * `readJsonBody` (the size-capped request body reader) and the two policy
 * constants they are written against. Split out of `src/index.ts` (Phase H1).
 */
/** How long a JSON route body may be re-served without recomputing it.
 *
 *  The rail is allowed to poll (a Command Code window moves while the reader
 *  watches), and a reader may keep several tabs open, so without a cache every
 *  tab buys its own round of upstream calls and its own log fold. 20 s is short
 *  enough that no client sees a stale number it could have acted on, and long
 *  enough to collapse a burst — including the degraded-payload retry — into one
 *  upstream pass. Errors are never cached. */
export declare const ROUTE_CACHE_MS = 20000;
/**
 * Per-key TTL + single-flight memo for a route body.
 *
 * `force` (the `?refresh=1` path) skips the TTL but still JOINS an in-flight
 * computation, so two tabs asking at the same instant still produce one fold.
 * A rejected computation is never stored.
 *
 * @param ttlMs - how long a stored value stays fresh.
 * @returns a reader that computes on miss and shares one promise on a burst.
 */
export declare function memoTtl<T>(ttlMs: number): (key: string, compute: () => Promise<T> | T, force?: boolean) => Promise<T>;
/** Accumulate a Node IncomingMessage body into a JSON value (size-capped). */
export declare function readJsonBody(req: unknown): Promise<unknown>;