Firebase Cloud Messaging
Deliver push through Firebase with registration tokens that stay valid as devices change.
What it adds
A Firebase-backed push channel with server-side token lifecycle management, consistent payload handling across platforms, and safe handling of the routes a notification opens.
What your agent is told to do
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What your agent is told to do
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Store one record per device registration, tied to the account signed in at the time, the platform it came from, and when it was last confirmed working, and let one account hold many of them.
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Send from the app's existing background-job system with the provider credentials held server-side, and treat every send as a job that can be retried rather than work done inline during a request.
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Decide, per notification type, whether the payload is meant to be displayed by the platform or handled by the app, and keep that decision the same on every platform. The same event behaving as a visible alert on one platform and a silent update on another produces bugs nobody can reproduce.
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Treat the destination carried in a notification as untrusted input. Resolve it to a route on open and re-authorise the recipient against the current record before showing anything.
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If the app also carries the OneSignal push brief, do not run both as independent senders. One of them owns registration, preference filtering, and deduplication for the whole app, and the other is removed or reduced to a delivery transport underneath it.
Edge cases it handles
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Edge cases it handles
8- The provider will reject tokens that have been rotated, revoked, or belong to a reinstalled app. Remove or replace those registrations on the error rather than leaving them to fail on every future send.
- One person may use several devices, and one device may be used by several people. Keep registrations distinct per device, and reassign rather than duplicate when a new account signs in on a device already registered.
- A notification tapped hours later may point at a record that has since been deleted, moved, or revoked. The open path must check access at that moment and fall back to a sensible screen instead of trusting the link it was given.
- Retried background jobs and repeated provider callbacks must not produce a second notification. Key each send on the event and the registration so a replay is recognised and discarded.
- Send failures come in two kinds: permanent ones that mean the registration is dead, and temporary ones that mean try again later. Retry only the second kind, with increasing delays, or a provider outage will empty the device table.
- Lock-screen previews expose whatever is in the payload. Keep sensitive detail out of the visible portion and let the app fetch it after the user has unlocked and authenticated.
- When the provider is unavailable, the rest of the app must continue working and the user should still see the event in the app's own notification surface.
- Time-sensitive notifications need an expiry so a queue drained after an outage does not deliver a batch of stale alerts at once.
Definition of done
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Definition of done
9- Registrations are stored per device with the owning account and platform, and many per account are supported.
- Tokens rejected as permanently invalid are removed on the failure, while temporary failures are retried with backoff.
- A given event and registration pair produces one notification even when jobs or provider callbacks repeat.
- Display versus silent handling for each notification type is identical across platforms.
- Opening a notification re-checks permission on the target record before rendering it.
- Provider credentials exist only on the server and never in client-visible code.
- A provider outage degrades to in-app notifications with no user-visible errors elsewhere.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
OneSignal Push Notifications
OneSignal Push Notifications
Send push notifications to the right devices, with user preferences respected.
What it does
A push delivery path through OneSignal covering subscription registration, audience targeting, per-channel preferences, and delivery outcomes recorded against the app's own records.
How it works
- 1 Find the events the app already notifies on by email or in-app, and treat push as another channel for those same events rather than a separate notification system with its own triggers.
- 2 Record the link between a push subscription and an account on the server, established at sign-in and severed at sign-out, so a device that changes hands does not keep receiving the previous user's notifications.
- 3 Hold the provider credentials server-side and send every message from the app's existing background-job system, so a slow or failing provider never blocks a web request.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/onesignal-push-notifications
Mailgun Transactional Email
Mailgun Transactional Email
Send transactional email through Mailgun without losing bounce and complaint state.
What it does
A Mailgun delivery path bound to the correct region and sending domain, with durable suppression and event handling.
How it works
- 1 Put Mailgun behind the app's existing mail layer as one adapter. It is an alternative to the other transactional email integrations, not an addition; whichever adapter is in place, the template contract and suppression handling above it are unchanged.
- 2 Bind the region and sending domain in server-side configuration and validate at startup that they are consistent. A credential issued in one region will simply not work against another, and the failure looks like an authentication problem rather than a configuration one.
- 3 Check the suppression state for an address before a message is queued, not after the provider rejects it, so bouncing and complaining addresses stop consuming send attempts.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/mailgun-transactional-email
Resend Transactional Email
Resend Transactional Email
Send application email through Resend with verified domains and tracked delivery.
What it does
A Resend delivery path with domain verification gating production sends, controlled attachments, and recorded delivery events.
How it works
- 1 Put Resend behind the app's existing mail layer as one adapter. This entry is an alternative to the other transactional email integrations rather than a companion to them; the mail layer, template contract, and suppression handling stay the same whichever adapter is in place.
- 2 Gate production delivery on a verified sending domain. Until verification is confirmed, keep the app in a mode that redirects or suppresses delivery rather than sending from an unverified address into spam folders.
- 3 Send from the app's background-job system, keyed on a stable per-message identifier, and store the provider's identifier on the record as soon as it is returned.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/resend-transactional-email
How it works
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Copy the link
Grab the Markdown instruction URL for this feature.
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Give it to your AI
Paste it into Claude Code, Cursor, v0, Lovable — whatever you build with.
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It inspects, then implements
Your agent reads your existing app first, then adds the feature to fit it.
Works with your stack
These instructions are written to adapt. They tell the agent to detect your framework, match your existing design system, and reuse what you already have — rather than assuming a particular stack.
Need it tighter than that? Customize the feature and tell it exactly what you're running.