# createSyncClient \[Connect a transport and drive the sync loop] `createSyncClient` connects a WebSocket [transport](/framework/ws) to a `ModelRegistry` so inbound server pushes land in the normalized stores and per-state update counters tick up. In React you pass the result to [`StoreProvider`'s `syncClient` prop](/react/sync-client); elsewhere you drive it directly. ```ts import { createSyncClient } from "rxfy-client"; const syncClient = createSyncClient({ registry, // IModelRegistry — the same one your store / StoreProvider uses transport, // SyncTransport — e.g. createWsClient() from rxfy-ws/client renewUrl, // optional — the app's grant-renewal endpoint, e.g. "/api/live/renew" renewLeadMs, // optional — how far before expiry to renew (default 60_000 ms) }); ``` There is no `session` option: the client never carries a session id. Each grant is a stateless signed capability the client presents on the wire; the server verifies it rather than looking up a session it minted (see [Grants](/framework/server/grants)). **What `createSyncClient` does:** * Records each lifted `$grant` together with the entity topics its payload normalized into, and sends a `subscribe` frame carrying the grant plus those topics — the client's entire outbound protocol. * Calls `transport.onMessage` once. Incoming `"patch"` messages are applied directly to the named model store (`registry.namedStores().get(name)?.set(id, data)`); incoming `"stale"` messages increment the matching channel counter. * Renews grants near their expiry by POSTing the expiring grants to `renewUrl` (which runs the app's own auth) and re-subscribing with the reissued grants. A denied renewal drops the entry, and that state goes static until a refetch mints a fresh grant. * Replays its full grant set on reconnect, via the transport's `onOpen` handler. * Exposes `subscribe(grant, entities)` and `channel(name)` — the latter returns a `ChannelCounter` (`{ available$: Observable, reset: () => void }`). * Exposes `stop()` — completes all channel counters and stops the renewal loop. ## Types * `SyncClient` — what `createSyncClient` returns (`subscribe`, `channel`, `stop`, …). * `SyncClientConfig` — the config object above. * `SyncTransport` — the structural transport interface (`onMessage`, `onOpen`, `send`); [`rxfy-ws`](/framework/ws) provides one (`ClientTransport`), or [bring your own](/framework/ws/custom-transport). * `ChannelCounter` — `{ available$: Observable, reset: () => void }`, one per state channel.