Kit Subscriber Sync
Send subscribers to Kit with the form, tags, and fields matching how they signed up.
What it adds
A sync that maps each app signup path to a specific Kit form or sequence and keeps subscriber fields and tags aligned.
What your agent is told to do
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What your agent is told to do
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Enumerate the distinct ways someone becomes a subscriber in the app — each signup form, lead magnet, checkout, and import — and map each one to exactly one destination form or sequence, configured rather than hardcoded.
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Store the provider's subscriber ID alongside the local record and use it for subsequent updates, but keep the app's own user or lead ID as the identity of record. The provider ID identifies a subscription, not a person.
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Make every enrollment idempotent using a key derived from the subscriber and the destination, so a retried job confirms the existing enrollment instead of adding a second one.
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Read the subscriber's current state before writing. Someone who unsubscribed must stay unsubscribed, and a new signup by an unsubscribed address needs a fresh, recorded opt-in before you resubscribe them.
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Do not resolve tags and forms by name at send time. Names get edited, and a rename will quietly create a new tag while the old one keeps its audience — resolve to stable identifiers at mapping time and re-validate them.
Edge cases it handles
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Edge cases it handles
8- One app signup can plausibly belong to several forms or sequences. Force the mapping to pick one destination per entry point, because ambiguity here produces subscribers who receive two overlapping onboarding sequences.
- An unsubscribed address that signs up again is not an instruction to resubscribe. Preserve the unsubscribe, capture the new consent explicitly with a timestamp and source, and only then re-enable sending.
- Job retries and provider retries both re-run enrollment. Without an idempotency key per subscriber and destination, one signup adds the same tag twice and starts the sequence from the beginning again.
- Tags and forms get renamed or deleted between configuration and use. A mapping pointing at something that no longer exists must pause with a message naming it, and must never create a replacement by name on the fly.
- Provider subscriber IDs are not global identity. Two app users sharing a household email, or one user changing their address, will break any model that treats the provider ID as the person — key on the app's own record instead.
- If the app syncs to more than one email provider, exactly one of them must be designated authoritative for consent, and this brief must read that decision rather than making its own. Two providers each restoring the other's unsubscribes is worse than no sync.
- Tokens expire and connections get revoked from the provider side. Hold queued enrollments, show the connection as broken, and resume from the held queue on reconnection.
- When the provider is unreachable, the app's signup must still succeed and the confirmation must not promise an email that has not been queued anywhere.
Definition of done
9
Definition of done
9- Each signup path resolves to exactly one configured form or sequence.
- Retried jobs never add a duplicate tag or restart a sequence.
- An unsubscribed address is not resubscribed without a newly recorded opt-in.
- Renamed or deleted tags and forms pause the mapping with a named error rather than being recreated.
- Provider subscriber IDs are stored as references, and the app's own record remains the identity of record.
- Consent authority is defined in one place when multiple email providers are connected.
- A provider outage leaves the signup successful and the enrollment queued.
- 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
Slack Channel Alerts
Slack Channel Alerts
Send the events a team actually needs into a Slack channel without flooding it.
What it does
Operator-configured routing of selected app events into Slack channels, with grouping, throttling, and reliable delivery.
How it works
- 1 List the events genuinely worth interrupting a team for — failed payments, high-value signups, error thresholds, approvals waiting — and make each individually selectable per channel. An all-or-nothing firehose gets muted within a week and then nobody sees the one that mattered.
- 2 Run the connection through the provider's authorisation flow, then confirm the workspace and channel at setup by posting a test message the operator has to acknowledge. Store the resulting credential server-side only.
- 3 Write each message so it stands alone: what happened, to whom, when, and a link back into the app. Optional fields that are absent must be omitted cleanly rather than rendering as empty labels.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/slack-channel-alerts
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.