feat(billing): add subscription and Stripe billing router

- Add stripeCustomerId column to users table
- Create Stripe client initialization (web/src/server/stripe.ts)
- Add billing service with getOrCreateCustomer, checkout/portal sessions,
  subscription management, invoice listing, and webhook event handling
- Create billing tRPC router with getSubscription, createCheckoutSession,
  createPortalSession, cancelSubscription, reactivateSubscription, listInvoices
- Add raw webhook endpoint at /api/stripe/webhook with signature verification
- Define Valibot schemas for all billing procedure inputs
- Wire billing router into root tRPC router
- Update schema tests for new column/index counts
- Write unit tests for billing service and router

web/src/server/api/routers/billing.ts

@@ -0,0 +1,100 @@
+import { TRPCError } from "@trpc/server";
+import { eq } from "drizzle-orm";
+import { wrap } from "@typeschema/valibot";
+import { createTRPCRouter, protectedProcedure } from "../utils";
+import {
+  CreateCheckoutSessionSchema,
+  CreatePortalSessionSchema,
+  CancelSubscriptionSchema,
+  ReactivateSubscriptionSchema,
+  ListInvoicesSchema,
+} from "../schemas/billing";
+import {
+  getOrCreateCustomer,
+  createCheckoutSession,
+  createPortalSession,
+  cancelSubscription,
+  reactivateSubscription,
+  listInvoices,
+} from "~/server/services/billing.service";
+import { db } from "~/server/db";
+import { subscriptions } from "~/server/db/schema/subscription";
+
+export const billingRouter = createTRPCRouter({
+  getSubscription: protectedProcedure.query(async ({ ctx }) => {
+    const sub = await db.query.subscriptions.findFirst({
+      where: eq(subscriptions.userId, ctx.user.id),
+    });
+    return sub ?? null;
+  }),
+
+  createCheckoutSession: protectedProcedure
+    .input(wrap(CreateCheckoutSessionSchema))
+    .mutation(async ({ ctx, input }) => {
+      const allowedPrices = [
+        process.env.STRIPE_PRICE_BASIC,
+        process.env.STRIPE_PRICE_PLUS,
+        process.env.STRIPE_PRICE_PREMIUM,
+      ].filter(Boolean);
+
+      if (!allowedPrices.includes(input.priceId)) {
+        throw new TRPCError({
+          code: "BAD_REQUEST",
+          message: "Invalid price ID",
+        });
+      }
+
+      return createCheckoutSession(
+        ctx.user.id,
+        ctx.user.email,
+        input.priceId,
+        input.successUrl,
+        input.cancelUrl,
+      );
+    }),
+
+  createPortalSession: protectedProcedure
+    .input(wrap(CreatePortalSessionSchema))
+    .mutation(async ({ ctx, input }) => {
+      const user = ctx.user;
+      const stripeCustomerId = user.stripeCustomerId;
+
+      if (!stripeCustomerId) {
+        throw new TRPCError({
+          code: "NOT_FOUND",
+          message: "No Stripe customer found",
+        });
+      }
+
+      return createPortalSession(stripeCustomerId, input.returnUrl);
+    }),
+
+  cancelSubscription: protectedProcedure
+    .input(wrap(CancelSubscriptionSchema))
+    .mutation(async ({ input }) => {
+      return cancelSubscription(input.subscriptionId);
+    }),
+
+  reactivateSubscription: protectedProcedure
+    .input(wrap(ReactivateSubscriptionSchema))
+    .mutation(async ({ input }) => {
+      return reactivateSubscription(input.subscriptionId);
+    }),
+
+  listInvoices: protectedProcedure
+    .input(wrap(ListInvoicesSchema))
+    .query(async ({ ctx, input }) => {
+      const user = ctx.user;
+      const stripeCustomerId = user.stripeCustomerId;
+
+      if (!stripeCustomerId) {
+        return { invoices: [], hasMore: false };
+      }
+
+      return listInvoices(
+        stripeCustomerId,
+        parseInt(input.limit ?? "10", 10),
+        input.startingAfter,
+      );
+    }),
+});