Webhook events

Event	What it signals	Growth Rail action
`PostRegister`	User signup confirmed by provider.	Record signup proof; join to pending SDK attribution claim.

How attribution works

A verified provider event proves the signup happened — but not that the user was referred. Growth Rail completes a referral only when that event joins to the opaque attribution claim previously captured by the SDK on the referring user's device.

Identity rule: Growth Rail joins events to claims using stable IDs and opaque tokens. It never correlates users by email, name, phone number, or billing address.

Create the Growth Rail connection

Open Dashboard → Integrations → Auth, choose Logto, and create a Sandbox or Production connection. Copy the generated webhook endpoint URL — you will paste it into Logto in the next step.

Register the webhook in Logto

In Logto Console → Webhooks, add the copied endpoint and subscribe to PostRegister.

Return to Growth Rail and save the Logto webhook signing key. Growth Rail encrypts and stores it — the raw value is never returned by the API after saving.

Security: Never commit webhook secrets to source control or log them. If a secret is compromised, rotate it in both Logto and Growth Rail immediately.

Pass attribution data from your app

Pass the Logto user ID that appears as userId in the PostRegister payload. Growth Rail ignores broader User.Created data-mutation events.

// Use the stable Logto user ID, never an email address.
await GrowthRail.initAppUser(logtoUser.id);

Verify end-to-end in test mode

Complete a signup through Logto Experience and confirm one verified PostRegister outcome in Growth Rail.

Outcome	Meaning
Completed	Signup proof and SDK attribution token matched. The referral reward has been triggered.
Awaiting attribution	The webhook signature was valid, but the SDK claim has not arrived yet — or the stable user ID did not match a pending claim. The event is held; Growth Rail completes the referral when the claim arrives.
Ignored	The event was verified but no matching attribution claim exists and the hold window has expired, or the event type is out of scope.

Provider-specific notes

PostRegister covers registrations completed through the Experience API; Management API user creation is a different event family.
Logto signs the exact raw body with HMAC SHA-256, so proxies must not rewrite webhook content.