fix: restrict individual plans to upgrade only (#1900)

Prevent users from creating a separate organisation for individual
plans. Only applies to users who have 1 personal organisation and are
subscribing to the "Individual" plan.

The reason for this change is to keep the layout in the "Personal" mode
which means it doesn't show a bunch of unusable "organisation" related
UI.

packages/trpc/server/billing/create-subscription.ts

@@ -12,7 +12,7 @@ import { ZCreateSubscriptionRequestSchema } from './create-subscription.types';
 export const createSubscriptionRoute = authenticatedProcedure
   .input(ZCreateSubscriptionRequestSchema)
   .mutation(async ({ ctx, input }) => {
-    const { organisationId, priceId } = input;
+    const { organisationId, priceId, isPersonalLayoutMode } = input;
 
     ctx.logger.info({
       input: {
@@ -70,10 +70,14 @@ export const createSubscriptionRoute = authenticatedProcedure
       });
     }
 
+    const returnUrl = isPersonalLayoutMode
+      ? `${NEXT_PUBLIC_WEBAPP_URL()}/settings/billing`
+      : `${NEXT_PUBLIC_WEBAPP_URL()}/o/${organisation.url}/settings/billing`;
+
     const redirectUrl = await createCheckoutSession({
       customerId,
       priceId,
-      returnUrl: `${NEXT_PUBLIC_WEBAPP_URL()}/o/${organisation.url}/settings/billing`,
+      returnUrl,
     });
 
     if (!redirectUrl) {

packages/trpc/server/billing/create-subscription.types.ts

@@ -3,4 +3,5 @@ import { z } from 'zod';
 export const ZCreateSubscriptionRequestSchema = z.object({
   organisationId: z.string().describe('The organisation to create the subscription for'),
   priceId: z.string().describe('The price to create the subscription for'),
+  isPersonalLayoutMode: z.boolean().optional(),
 });