JavaScript: Wait with a deadline

withDeadline(run, options) from kizunasync/supabase races a promise-returning function against a timer. auth-js issues getSession() and refreshSession() with no fetch timeout and no AbortSignal, so on a half-open socket either call can hang indefinitely and hold the caller's slot with it. createSupabaseKizunaSync wraps both calls in it; call it directly only when composing a client by hand.

Examples#

Basic#

// src/session.ts
import { withDeadline } from 'kizunasync/supabase'
import { supabase } from './supabase-client'

const result = await withDeadline(() => supabase.auth.getSession(), {
  timeoutMs: 10_000,
  onTimeout: () => new Error('getSession timed out'),
})

Parameters#

Name	Type	Required	Description
`run`	`() => Promise<T>`	Yes	The call to bound. Started once, so a synchronous throw becomes a rejection rather than escaping the call to `withDeadline` itself.
`options.timeoutMs`	`number`	Yes	Milliseconds `run()` may take before the deadline wins. A value at or below `0` disables the deadline entirely: no timer is armed, and `run()` is returned as is.
`options.onTimeout`	`() => Error`	Yes	Builds the rejection thrown when the deadline wins. Called lazily, only when the timer fires, so it can attach fresh context.
`options.setTimer` / `options.clearTimer`	`(callback: () => void, delayMs: number) => unknown` / `(handle: unknown) => void`	No	Injectable timer pair. Default: the platform `setTimeout` and `clearTimeout`.

Returns#

Promise<T>, settling with whichever of run() or the deadline settles first.

Errors#

Rejects with whatever options.onTimeout() returns when the deadline wins before run() settles, or with whatever run() itself rejects with otherwise.

Notes#

This helper bounds how long the caller waits, and nothing more. auth-js exposes no way to abort getSession() or refreshSession(), so a call that loses the race keeps running in the background. The helper observes that late settlement internally, so it can never surface as an unhandled rejection. For those two calls a late completion only updates local auth storage, which is harmless to drop.

createSupabaseKizunaSync uses it for the sessionTimeoutMs deadline on the session read before every pull and push, on the anonymous sign-in the anonymousSignIn option runs, and on the foreground refresh, documented on Initializing. Create the Storage transfer uses a separate deadline pair for the byte-moving requests, because a body under a slow link legitimately needs longer than a session lookup.

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