Klaviyo Profile and Event Sync
Sync customer profiles and behavioural events to Klaviyo for segmentation and lifecycle mail.
What it adds
Two related streams: profile attributes kept current, and product events sent with stable identifiers for segmentation.
What your agent is told to do
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What your agent is told to do
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Keep profiles and events as two distinct streams with two distinct mappings. A profile attribute describes the person's current state, an event describes something that happened at a time — mixing them produces segments that cannot be reasoned about.
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Give every event a stable identifier derived from the source record and the occurrence, and send the time the event actually happened rather than the time the job ran, so retries and delayed jobs do not distort metrics.
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Track email consent and SMS consent as independent values with their own source and timestamp, and never let a change to one imply anything about the other.
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Define an allowlist of the profile attributes and event properties that may leave the app, and send nothing outside it. Free-text fields, internal notes, payment details, and anything resembling special-category data stay in the app.
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If the app already syncs to another email provider, decide in one place which system is authoritative for consent and let this brief read that decision. This feature owns the event stream; it must never mutate subscription state as a side effect of an event.
Edge cases it handles
8
Edge cases it handles
8- Retried jobs and redelivered webhooks resend the same event. Without a stable per-occurrence identifier, a single purchase is counted three times and every revenue segment built on it is wrong.
- Profile attributes and event properties serve different purposes and must not be merged. Writing an event's details onto the profile overwrites the person's current state with a snapshot of one moment, and it cannot be undone from the app.
- Email and SMS consent are separate permissions with separate legal footing. Treating one as implying the other sends messages a customer never agreed to receive.
- Anonymous activity collected before signup has to attach to the known profile afterwards without duplicating history or claiming a shared device's activity for the wrong person. Link only on an explicit, verified identification, and leave it anonymous when unsure.
- Event payloads are the easiest place for sensitive data to escape, because they are assembled ad hoc from whatever the code has to hand. Allowlist the properties, and review what a new event type carries before it ships.
- Backfills exhaust rate limits quickly. Batch and throttle historical sends, keep them behind live traffic in priority, and make a backfill resumable from where it stopped.
- Tokens expire and connections are revoked. Hold events in the queue, mark the connection broken in the app, and resume from the held queue rather than dropping a period of history.
- When the provider is unreachable, the user-facing action must still succeed. Queue the profile update and the event, and never present the outage to the customer.
Definition of done
9
Definition of done
9- Every event carries a stable identifier and its real occurrence time, and resends do not inflate counts.
- Profile attributes and event properties are mapped and written separately.
- Email and SMS consent are stored, sent, and changed independently.
- Anonymous activity links to a known profile only on verified identification.
- Only allowlisted attributes and properties leave the app.
- Backfills are throttled, resumable, and lower priority than live traffic.
- The event stream never changes subscription state.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
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
Firebase Cloud Messaging
Firebase Cloud Messaging
Deliver push through Firebase with registration tokens that stay valid as devices change.
What it does
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.
How it works
- 1 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.
- 2 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.
- 3 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.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/firebase-cloud-messaging
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
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.