Sync email to Stripe when user changes email address (#2432)

* Sync owner email to Stripe when changed

When an account owner changes their email address, update the
corresponding Stripe customer record via a background job.

Also handles ownership transfers: when a user becomes the account
owner, their email is synced to Stripe.

Responsibility chain:
- User::NotifiesAccountOfEmailChange triggers on owner identity change
  or when a user becomes owner
- Account::Billing#owner_email_changed enqueues sync job
- Account::SyncStripeCustomerEmailJob performs the update with
  polynomial backoff retries
- Account::Subscription#sync_customer_email_to_stripe calls Stripe API

* Address PR feedback: error handling and test coverage

- Handle Stripe::InvalidRequestError in sync_customer_email_to_stripe
  (mirrors cancel method behavior for deleted customers)
- Add test for deactivated owner (owner with nil identity)
- Add test for deleted Stripe customer scenario

saas/app/jobs/account/sync_stripe_customer_email_job.rb

@@ -0,0 +1,8 @@
+class Account::SyncStripeCustomerEmailJob < ApplicationJob
+  queue_as :default
+  retry_on Stripe::StripeError, wait: :polynomially_longer
+
+  def perform(subscription)
+    subscription.sync_customer_email_to_stripe
+  end
+end

saas/app/models/account/billing.rb

@@ -31,6 +31,10 @@ module Account::Billing
     reload_billing_waiver
   end
 
+  def owner_email_changed
+    Account::SyncStripeCustomerEmailJob.perform_later(subscription) if subscription
+  end
+
   private
     def active_subscription
       if comped?

saas/app/models/account/subscription.rb

@@ -47,4 +47,21 @@ class Account::Subscription < SaasRecord
     # Subscription already deleted/canceled in Stripe - treat as success
     Rails.logger.warn "Stripe subscription #{stripe_subscription_id} not found during cancel: #{e.message}"
   end
+
+  def sync_customer_email_to_stripe
+    if stripe_customer_id && (email = owner_email)
+      Stripe::Customer.update(stripe_customer_id, email: email)
+    end
+  rescue Stripe::InvalidRequestError => e
+    # Customer already deleted in Stripe - treat as success
+    Rails.logger.warn "Stripe customer #{stripe_customer_id} not found during email sync: #{e.message}"
+  end
+
+  private
+    # Account owner email for Stripe customer record. Returns nil when:
+    # - No owner exists (ownership being transferred, account in limbo)
+    # - Owner has no identity (deactivated user)
+    def owner_email
+      account.users.owner.first&.identity&.email_address
+    end
 end

saas/app/models/user/notifies_account_of_email_change.rb

@@ -0,0 +1,23 @@
+module User::NotifiesAccountOfEmailChange
+  extend ActiveSupport::Concern
+
+  included do
+    after_update :notify_account_of_owner_change, if: :account_owner_changed?
+  end
+
+  private
+    # Account owner changed when:
+    # - The current owner changed their email
+    # - A user just became the owner (ownership transfer)
+    def account_owner_changed?
+      owner? && identity && (saved_change_to_identity_id? || became_owner?)
+    end
+
+    def became_owner?
+      saved_change_to_role? && role_before_last_save != "owner"
+    end
+
+    def notify_account_of_owner_change
+      account.owner_email_changed
+    end
+end

saas/lib/fizzy/saas/engine.rb

@@ -133,6 +133,7 @@ module Fizzy
 
       config.to_prepare do
         ::Account.include Account::Billing, Account::Limited
+        ::User.include User::NotifiesAccountOfEmailChange
         ::Signup.prepend Fizzy::Saas::Signup
         CardsController.include(Card::LimitedCreation)
         Cards::PublishesController.include(Card::LimitedPublishing)

saas/test/models/account/billing_test.rb

@@ -68,4 +68,26 @@ class Account::BillingTest < ActiveSupport::TestCase
 
     account.incinerate
   end
+
+  test "owner_email_changed enqueues sync job when subscription exists" do
+    account = accounts(:"37s")
+    account.create_subscription!(
+      stripe_customer_id: "cus_test",
+      plan_key: "monthly_v1",
+      status: "active"
+    )
+
+    assert_enqueued_with(job: Account::SyncStripeCustomerEmailJob, args: [ account.subscription ]) do
+      account.owner_email_changed
+    end
+  end
+
+  test "owner_email_changed does nothing without subscription" do
+    account = accounts(:initech)
+    account.subscription&.destroy
+
+    assert_no_enqueued_jobs do
+      account.owner_email_changed
+    end
+  end
 end

saas/test/models/account/subscription_test.rb

@@ -117,4 +117,78 @@ class Account::SubscriptionTest < ActiveSupport::TestCase
       subscription.cancel
     end
   end
+
+  test "sync_customer_email_to_stripe updates Stripe customer with owner email" do
+    account = accounts(:"37s")
+    owner = account.users.find_by(role: :owner) || account.users.first.tap { |u| u.update!(role: :owner) }
+    subscription = account.create_subscription!(
+      stripe_customer_id: "cus_test",
+      plan_key: "monthly_v1",
+      status: "active"
+    )
+
+    Stripe::Customer.expects(:update).with("cus_test", email: owner.identity.email_address).once
+
+    subscription.sync_customer_email_to_stripe
+  end
+
+  test "sync_customer_email_to_stripe does nothing without stripe_customer_id" do
+    account = accounts(:"37s")
+    subscription = account.build_subscription(
+      stripe_customer_id: nil,
+      plan_key: "free_v1",
+      status: "active"
+    )
+
+    Stripe::Customer.expects(:update).never
+
+    subscription.sync_customer_email_to_stripe
+  end
+
+  test "sync_customer_email_to_stripe does nothing without owner" do
+    account = accounts(:"37s")
+    account.users.update_all(role: :member)
+    subscription = account.create_subscription!(
+      stripe_customer_id: "cus_test",
+      plan_key: "monthly_v1",
+      status: "active"
+    )
+
+    Stripe::Customer.expects(:update).never
+
+    subscription.sync_customer_email_to_stripe
+  end
+
+  test "sync_customer_email_to_stripe does nothing when owner has no identity" do
+    account = accounts(:"37s")
+    owner = account.users.find_by(role: :owner) || account.users.first.tap { |u| u.update!(role: :owner) }
+    owner.update_column(:identity_id, nil)
+    subscription = account.create_subscription!(
+      stripe_customer_id: "cus_test",
+      plan_key: "monthly_v1",
+      status: "active"
+    )
+
+    Stripe::Customer.expects(:update).never
+
+    subscription.sync_customer_email_to_stripe
+  end
+
+  test "sync_customer_email_to_stripe treats deleted customer as success" do
+    account = accounts(:"37s")
+    account.users.find_by(role: :owner) || account.users.first.tap { |u| u.update!(role: :owner) }
+    subscription = account.create_subscription!(
+      stripe_customer_id: "cus_deleted",
+      plan_key: "monthly_v1",
+      status: "active"
+    )
+
+    Stripe::Customer.stubs(:update).raises(
+      Stripe::InvalidRequestError.new("No such customer", {})
+    )
+
+    assert_nothing_raised do
+      subscription.sync_customer_email_to_stripe
+    end
+  end
 end

saas/test/models/user/notifies_account_of_email_change_test.rb

@@ -0,0 +1,51 @@
+require "test_helper"
+
+class User::NotifiesAccountOfEmailChangeTest < ActiveSupport::TestCase
+  setup do
+    @account = accounts(:"37s")
+    @owner = @account.users.find_by(role: :owner) || @account.users.first.tap { |u| u.update!(role: :owner) }
+    @member = @account.users.where.not(id: @owner.id).first || @account.users.create!(
+      name: "Member",
+      identity: Identity.create!(email_address: "member@example.com"),
+      role: :member
+    )
+  end
+
+  test "notifies account when owner changes email" do
+    @account.expects(:owner_email_changed).once
+
+    new_identity = Identity.create!(email_address: "new-owner@example.com")
+    @owner.update!(identity: new_identity)
+  end
+
+  test "does not notify account when non-owner changes email" do
+    @account.expects(:owner_email_changed).never
+
+    new_identity = Identity.create!(email_address: "new-member@example.com")
+    @member.update!(identity: new_identity)
+  end
+
+  test "does not notify account when owner is deactivated" do
+    @account.expects(:owner_email_changed).never
+
+    @owner.update!(identity: nil)
+  end
+
+  test "does not notify account when identity unchanged" do
+    @account.expects(:owner_email_changed).never
+
+    @owner.update!(name: "New Name")
+  end
+
+  test "notifies account when user becomes owner" do
+    @account.expects(:owner_email_changed).once
+
+    @member.update!(role: :owner)
+  end
+
+  test "does not notify account when owner becomes member" do
+    @account.expects(:owner_email_changed).never
+
+    @owner.update!(role: :member)
+  end
+end