OneSignal

OneSignal stores each person as a User with up to 20 Subscriptions (an app install, a browser, an email address, a phone number), and the External ID you pass to OneSignal.login is what joins them: without it every Subscription is its own anonymous User that segments, tags and transactional sends cannot treat as one. Everything here targets the User Model (mobile SDKs v5+, Web SDK v16+); code written from Player Model names (include_player_ids, include_external_user_ids, setExternalUserId, onesignal.com/api/v1, userKey) is outdated, and the Supabase guides still use them. Push cannot deliver until the platform credentials exist, and "Delivered" only means FCM, APNs or the browser push service accepted the message. Supabase itself is supabase SKILL.md; OneSignal-neutral email deliverability is email-practices SKILL.md.

Apply only the routes and checks for the selected job. Read a linked skill's named file from its installed folder when available, or from the linked source. Report an unavailable required reference instead of inventing it. [skill-authoring, DISTRIBUTION.md#composing-skills]