Client and resources

JanuaryClient takes exactly one authentication option:

Option	Use
clientTokenProvider, plus optional tokenRetryPolicy	The SDK fetches, caches, and refreshes client tokens (Authentication).
accessToken	One ct-… client token your app refreshes itself; create a new client when it changes.

new JanuaryClient(
  | { accessToken: string; fetch?: typeof globalThis.fetch }
  | {
      clientTokenProvider: JanuaryTokenProvider | JanuaryTokenProviderCallback;
      tokenRetryPolicy?: JanuaryTokenRetryPolicy;
      fetch?: typeof globalThis.fetch;
    }
)

interface JanuaryTokenProvider {
  fetchClientToken(): Promise<JanuaryClientTokenResponse>;
}

type JanuaryTokenProviderCallback =
  () => Promise<JanuaryClientTokenResponse>;

type JanuaryClientTokenResponse =
  | { token: string; expiresIn: number }
  | { token: string; expires_in: number };

The provider must return a nonblank token with a finite lifetime over 60 seconds, the refresh leeway. fetch replaces the Fetch implementation. The client always calls January's production API; there is no base-URL option. The token cache belongs to the client, so use one client per signed-in user (Client lifecycle).

JanuaryTokenRetryPolicy fields are all optional; the defaults are in Retries, refresh, and cancellation.

Resources

Resource	Operations
foods	autocomplete, search, get, lookupBarcode, suggestAlternatives
restaurants	search, searchMenuItems, getMenuItems
foodAnalysis	analyzePhoto, analyzeDescription, correct
foodLogs	create, list, getSummary, get, update, delete
waterLogs	create, list, delete
weightLogs	create, list
glucose	predict

The scope each operation needs is in Backend token endpoint. Every request accepts an optional signal: AbortSignal. Errors are described in Error handling and, for the API's codes, in REST errors.

Scoped clients

forUser(context: PartnerUserContext): JanuaryPartnerUserClient
forUser(endUserId: string, endUserTimezone?: string): JanuaryPartnerUserClient

forUser returns a JanuaryPartnerUserClient with the same seven resources, bound to one end-user ID and timezone. Prefer the object form, and use the scoped client for every call.

The resources on JanuaryClient itself take the same requests plus the user context: log requests require endUserId and accept endUserTimezone, and glucose requests accept both. Food, restaurant, and food-analysis requests keep an optional endUserId only for source compatibility; the SDK never sends it. With a client token, the SDK sends no end-user ID on any call.

Local helpers

FoodPortion.from(...) (Foods API) and the browser-only preparePhotoScanImage(...) (Restaurants and food analysis API) run without a network call. VoiceCaptureSession is described in Voice capture.