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The video uses a specific AI coding tool to demonstrate the setup, but the configuration works 1:1 with Cursor, Claude Code, or any other tool. Despia is web framework and tooling agnostic, so the only thing that matters is the SDK call with the scheme parameters.
sendlocalpushmsg:// schedules a local notification on the device after a delay you specify in seconds. The OS surfaces the notification even if your app is closed, and tapping it opens the URL you passed in. Everything happens client-side, no server, no network call, no OneSignal account required.
This feature is fully supported and a good fit for short-lived, contextual reminders that the user just set themselves (a 10-minute timer, a “remember to drink water in 2 hours” tap). For anything else, especially anything where your backend is the source of truth (scheduled marketing, transactional alerts, time-zone-aware drip sequences), use OneSignal instead. OneSignal’s send_after and delayed_option: timezone parameters cover the same scheduling space with the durability and observability of server-sent push.

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Installation

npm install despia-native

import despia from 'despia-native';

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How it works

The scheme packs four values into a single URL: delay in seconds, message body, title, and deep-link URL. The runtime registers the notification with the OS scheduler and returns immediately. There is no return value and no callback when the notification fires. 
import despia from 'despia-native'

const isDespia = navigator.userAgent.toLowerCase().includes('despia')

if (isDespia) {
    despia('sendlocalpushmsg://push.send?s=5=msg!Don't forget to save&!#Quick reminder&!#https://myapp.com/save')
}
The format is fixed: s= followed by the delay, =msg! followed by the body, &!# followed by the title, &!# followed by the deep-link URL. The unusual delimiters exist so the scheme parser can tell the four fields apart even when their values contain spaces or punctuation.

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Scheme parameters

ParameterPosition in URLWhat it carries
Delays={n}Seconds until the notification fires. Use 0 for immediate, larger values for scheduled
Message=msg!{body}The notification body text the user reads
Title&!#{title}The notification title shown above the body
Deep link&!#{url}The URL to open in the WebView when the user taps the notification
Encode any user-supplied values with encodeURIComponent to avoid breaking the parser when the message or title contains &, #, !, or =. 
function scheduleReminder(seconds, title, body, url) {
    if (!isDespia) return

    const t = encodeURIComponent(title)
    const b = encodeURIComponent(body)
    const u = encodeURIComponent(url)

    despia(`sendlocalpushmsg://push.send?s=${seconds}=msg!${b}&!#${t}&!#${u}`)
}

scheduleReminder(60, 'Stretch break', 'Time to stand up', 'https://myapp.com/wellness')

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Schedule a self-set reminder

The natural fit for offline push is a reminder the user just set themselves. The interaction is one-shot, the delay is short, and the user already knows what’s coming, so a server is unnecessary. 
import { useState } from 'react'
import despia from 'despia-native'

const isDespia = navigator.userAgent.toLowerCase().includes('despia')

function TimerButton() {
    const [minutes, setMinutes] = useState(10)

    function startTimer() {
        if (!isDespia) return

        const seconds = minutes * 60
        const body    = encodeURIComponent(`Your ${minutes}-minute timer is up`)
        const title   = encodeURIComponent('Timer')
        const url     = encodeURIComponent('https://myapp.com/timer')

        despia(`sendlocalpushmsg://push.send?s=${seconds}=msg!${body}&!#${title}&!#${url}`)
    }

    return (
        <div>
            <input
                type="number"
                value={minutes}
                onChange={e => setMinutes(Number(e.target.value))}
            />
            <button onClick={startTimer}>Start {minutes}-minute timer</button>
        </div>
    )
}

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When to reach for OneSignal instead

Offline push is the right tool when the user just set the reminder, the delay is short, and missing the notification would not break anything. Reach for OneSignal when any of the following apply:
NeedWhy offline push falls shortWhat OneSignal gives you
Schedule from your backendOffline push only fires from a JavaScript call inside the appsend_after parameter on the REST API, scheduled server-side
Deliver at a specific local time across time zonesSeconds-based delays drift relative to the user’s clockdelayed_option: 'timezone' plus delivery_time_of_day
Send to users who do not have the app openThe app has to run for the schedule to registerCloud-delivered, no app launch required
Cancel or update a notification after schedulingNo cancel API, the notification fires regardless of app state changesNotification IDs returned by the REST API for later cancellation
Audit which users received which notificationsFully client-side, no record exists outside the deviceFull delivery analytics in the OneSignal dashboard
Target by tag, segment, or behaviorEach call is per-device with no targeting layerfilters and included_segments for behavioral targeting
For anything where your backend should be the source of truth, OneSignal is worth the integration cost. Offline push is best kept to user-initiated, in-the-moment reminders.

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Resources

NPM Package

despia-native

Support

support@despia.com