API reference › @evolu/common › local‑first/Relay › RelayConfig

Defined in: packages/common/src/local-first/Relay.ts:43

Extends

Extended by

Properties

isOwnerAllowed?

readonly optional isOwnerAllowed?: (ownerId: string & Brand<"Id"> & Brand<"OwnerId">, options: {
  signal: AbortSignal;
}) => Awaitable<boolean>;

Defined in: packages/common/src/local-first/Relay.ts:126

Optional callback to check if an OwnerId is allowed to access the relay. If this callback is not provided, all owners are allowed.

The callback receives the OwnerId and an options object with an abort AbortSignal, and returns a Awaitable boolean: true to allow access, or false to deny.

The callback can be synchronous (for SQLite or in-memory checks) or asynchronous (for calling remote APIs).

The callback returns a boolean rather than an error type because error handling and logging are the responsibility of the callback implementation.

OwnerId is used rather than short-lived tokens because this only controls relay access, not write permissions. Since all data is encrypted on the relay, OwnerId exposure is safe.

Owners specify which relays to connect to via OwnerTransport. In WebSocket-based implementations, this check occurs before accepting the connection, with the OwnerId typically extracted from the URL query string (e.g., ws://localhost:4000?ownerId=...). The relay requires the URL to be in the correct format for OwnerId extraction.

Example

import {
  AppName,
  createAppOwner,
  createEvolu,
  createOwnerWebSocketTransport,
  createOwnerSecret,
  createRandomBytes,
  id,
  type AnyTask,
} from "@evolu/common";
import type { RelayConfig } from "@evolu/common/local-first";

// Create once, persist the mnemonic securely, and restore it on later runs.
const appOwner = createAppOwner(
  createOwnerSecret({ randomBytes: createRandomBytes() }),
);
// Client: include the OwnerId so the relay can authenticate the connection.
const transport = createOwnerWebSocketTransport({
  url: "wss://relay.evolu.dev",
  ownerId: appOwner.id,
});

const createTodoEvolu = createEvolu(
  { todo: { id: id("Todo") } },
  {
    appName: AppName.orThrow("AuthenticatedRelayExample"),
    appOwner,
    transports: [transport],
  },
);
expectTypeOf(createTodoEvolu).toExtend<AnyTask>();

// Relay: accept owners allowed by the app's access policy.
type IsOwnerAllowed = NonNullable<RelayConfig["isOwnerAllowed"]>;
const allowedOwnerIds = new Set([appOwner.id]);
const isOwnerAllowed: IsOwnerAllowed = (ownerId, { signal }) =>
  !signal.aborted && allowedOwnerIds.has(ownerId);

expect(
  isOwnerAllowed(appOwner.id, {
    signal: new AbortController().signal,
  }),
).toBe(true);
expect(transport.url).toContain(`ownerId=${appOwner.id}`);

isOwnerWithinQuota

readonly isOwnerWithinQuota: (ownerId: string & Brand<"Id"> & Brand<"OwnerId">, requiredBytes: number & Brand<"NonNaN"> & Brand<"Finite"> & Brand<"Int"> & Brand<"NonNegative"> & Brand<"Positive">) => Awaitable<boolean>;

Defined in: packages/common/src/local-first/Storage.ts:98

Callback called before an attempt to write, to check if an OwnerId has sufficient quota for the write.

The callback receives the OwnerId and the total bytes that would be stored after the write (current stored bytes plus incoming bytes), and returns a Awaitable boolean: true to allow the write, or false to deny it due to quota limits.

The callback can be synchronous (for SQLite or in-memory checks) or asynchronous (for calling remote APIs).

The callback returns a boolean rather than an error because error handling and logging are the responsibility of the callback implementation.

Relay deployments configure this callback. Client applications can observe a denied relay write as a ProtocolQuotaError by subscribing once to the shared EvoluErrorDep.evoluError store returned by createEvoluDeps.

Example

import {
  createAppOwner,
  createOwnerSecret,
  createRandomBytes,
  PositiveInt,
} from "@evolu/common";
import type { StorageConfig } from "@evolu/common/local-first";

// Create once, persist the mnemonic securely, and restore it on later runs.
const appOwner = createAppOwner(
  createOwnerSecret({ randomBytes: createRandomBytes() }),
);
const maxBytes = PositiveInt.orThrow(1024);
const relayStorageConfig: StorageConfig = {
  isOwnerWithinQuota: (ownerId, requiredBytes) =>
    ownerId === appOwner.id && requiredBytes <= maxBytes,
};

expect(
  await relayStorageConfig.isOwnerWithinQuota(
    appOwner.id,
    PositiveInt.orThrow(2048),
  ),
).toBe(false);

Inherited from

StorageConfig.isOwnerWithinQuota

name?

readonly optional name?: string & Brand<"UrlSafeString"> & Brand<"Name">;

Defined in: packages/common/src/local-first/Relay.ts:50

The relay name.

Implementations can use this for identification purposes (e.g., database file name, logging).

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