Carry signup attribution into the Stripe subscription

[paulocastellano]

Every account arrives with the UTM parameters that brought it and the onboarding answers it gave — persona, goals, referral source — and none of it reached Stripe. Revenue lived in one system and the campaign that produced it in another, so answering "which campaign is actually paying for itself" meant joining the two by hand on email.

This forwards the account owner's five UTMs plus persona, goals and referral_source as metadata on the Checkout session.

Subscription metadata, not session metadata

Cashier's withMetadata() writes into subscription_data.metadata during Checkout, so the values land on the Stripe Subscription, not the session.

That distinction matters: a Checkout session expires in 24 hours, while the subscription carries the attribution for as long as the customer does — visible on the subscription in the dashboard, and available to every report built on subscriptions. Attribution on the session would only ever be readable from the checkout.session.completed webhook, where we already know the account anyway.

Shaping the values for Stripe

Stripe metadata holds string key/value pairs, so two columns cannot go through as-is — passing either fails the request outright:

field	why	stored as
persona, referral_source	enum-cast, so the attribute is a BackedEnum object	?->value — agency, product_hunt
goals	JSON column, so the attribute is an array	comma-joined — grow_audience,save_time
utm_* (5)	plain strings	as-is

Comma-joining goals over goals_0 / goals_1 or a JSON blob keeps it readable in the Stripe dashboard and filterable.

array_filter drops the keys the user never filled in: an absent key reads the same in reporting, and Stripe treats an explicit null as a delete instruction. Every read is null-safe, so an account with no owner simply sends no metadata.

Scope

The ad click IDs sitting next to the UTMs on the users table (gclid, fbclid, li_fat_id, ttclid, rdt_cid, epik) are deliberately left out. Worth adding if we ever want to import conversions back into Google or Meta Ads, but that is a separate decision from campaign reporting.

Tests

StartSubscriptionCheckoutTest asserts the exact payload reaching withMetadata() — the full mapping in one case, and [] for an owner who filled in nothing.

Full suite green: 4062 passed.