[PM-40440] fix: Include Secrets Manager and storage in plan-change tax preview

src/Api/Models/Response/BillingCustomerDiscount.cs

@@ -57,6 +57,13 @@ public class BillingCustomerDiscount
     /// </summary>
     public IReadOnlyList<string>? AppliesTo { get; }
 
+    /// <summary>
+    /// True when this discount was surfaced from a price-migration schedule's Phase 2 coupon
+    /// rather than a genuine customer- or subscription-level discount. Lets clients distinguish
+    /// a deferred price-migration coupon from a real discount.
+    /// </summary>
+    public bool IsFromSchedule { get; }
+
     /// <summary>
     /// Creates a BillingCustomerDiscount from a SubscriptionInfo.BillingCustomerDiscount.
     /// </summary>
@@ -73,5 +80,6 @@ public BillingCustomerDiscount(SubscriptionInfo.BillingCustomerDiscount discount
         End = discount.End;
         DurationInMonths = discount.DurationInMonths;
         AppliesTo = discount.AppliesTo;
+        IsFromSchedule = discount.IsFromSchedule;
     }
 }

src/Core/Billing/Organizations/Commands/PreviewOrganizationTaxCommand.cs

@@ -249,42 +249,54 @@ public class PreviewOrganizationTaxCommand(
                     Quantity = quantity
                 });
 
-                var hasStorage =
-                    subscriptionItemsByPriceId.TryGetValue(newPlan.PasswordManager.StripeStoragePlanId,
-                        out var storage);
-
-                if (hasStorage && storage != null)
+                // Match existing storage by the CURRENT plan's id (as PM seats/SM do), then re-price at the
+                // new plan — storage ids can differ across the change (e.g. Families' personal-storage vs an
+                // org plan's shared storage). Guard: some plans have no storage add-on, so the id can be null.
+                if (!string.IsNullOrEmpty(currentPlan.PasswordManager.StripeStoragePlanId) &&
+                    !string.IsNullOrEmpty(newPlan.PasswordManager.StripeStoragePlanId))
                 {
-                    items.Add(new InvoiceSubscriptionDetailsItemOptions
+                    var hasStorage =
+                        subscriptionItemsByPriceId.TryGetValue(currentPlan.PasswordManager.StripeStoragePlanId,
+                            out var storage);
+
+                    if (hasStorage && storage != null)
                     {
-                        Price = newPlan.PasswordManager.StripeStoragePlanId,
-                        Quantity = storage.Quantity
-                    });
+                        items.Add(new InvoiceSubscriptionDetailsItemOptions
+                        {
+                            Price = newPlan.PasswordManager.StripeStoragePlanId,
+                            Quantity = storage.Quantity
+                        });
+                    }
                 }
 
-                var hasSecretsManagerSeats = subscriptionItemsByPriceId.TryGetValue(
-                    newPlan.SecretsManager.StripeSeatPlanId,
-                    out var secretsManagerSeats);
-
-                if (hasSecretsManagerSeats && secretsManagerSeats != null)
+                // Match existing SM items by the CURRENT plan's ids (as PM seats/storage do above), then re-price
+                // at the new plan. Guard: SecretsManager is null for Families/Free (PlanAdapter maps it to null).
+                if (currentPlan.SecretsManager != null && newPlan.SecretsManager != null)
                 {
-                    items.Add(new InvoiceSubscriptionDetailsItemOptions
-                    {
-                        Price = newPlan.SecretsManager.StripeSeatPlanId,
-                        Quantity = secretsManagerSeats.Quantity
-                    });
-
-                    var hasServiceAccounts =
-                        subscriptionItemsByPriceId.TryGetValue(newPlan.SecretsManager.StripeServiceAccountPlanId,
-                            out var serviceAccounts);
+                    var hasSecretsManagerSeats = subscriptionItemsByPriceId.TryGetValue(
+                        currentPlan.SecretsManager.StripeSeatPlanId,
+                        out var secretsManagerSeats);
 
-                    if (hasServiceAccounts && serviceAccounts != null)
+                    if (hasSecretsManagerSeats && secretsManagerSeats != null)
                     {
                         items.Add(new InvoiceSubscriptionDetailsItemOptions
                         {
-                            Price = newPlan.SecretsManager.StripeServiceAccountPlanId,
-                            Quantity = serviceAccounts.Quantity
+                            Price = newPlan.SecretsManager.StripeSeatPlanId,
+                            Quantity = secretsManagerSeats.Quantity
                         });
+
+                        var hasServiceAccounts =
+                            subscriptionItemsByPriceId.TryGetValue(currentPlan.SecretsManager.StripeServiceAccountPlanId,
+                                out var serviceAccounts);
+
+                        if (hasServiceAccounts && serviceAccounts != null)
+                        {
+                            items.Add(new InvoiceSubscriptionDetailsItemOptions
+                            {
+                                Price = newPlan.SecretsManager.StripeServiceAccountPlanId,
+                                Quantity = serviceAccounts.Quantity
+                            });
+                        }
                     }
                 }
 

src/Core/Billing/Services/Implementations/StripePaymentService.cs

@@ -815,6 +815,7 @@ private async Task ApplySchedulePhase2DataAsync(Subscription subscription, Subsc
             if (phase2Discount?.Coupon != null)
             {
                 subscriptionInfo.CustomerDiscount = new SubscriptionInfo.BillingCustomerDiscount(phase2Discount.Coupon);
+                subscriptionInfo.CustomerDiscount.IsFromSchedule = true;
             }
         }
         catch (StripeException ex)

src/Core/Models/Business/SubscriptionInfo.cs

@@ -119,6 +119,13 @@ public BillingCustomerDiscount(Coupon coupon)
         /// </para>
         /// </summary>
         public IReadOnlyList<string>? AppliesTo { get; set; }
+
+        /// <summary>
+        /// True when this discount was surfaced from a price-migration schedule's Phase 2 coupon
+        /// rather than a genuine customer- or subscription-level discount. Lets clients distinguish
+        /// a deferred price-migration coupon from a real discount. Defaults to false.
+        /// </summary>
+        public bool IsFromSchedule { get; set; }
     }
 
     public class BillingSubscription