chore: import upstream snapshot with attribution

apps/sim/lib/billing/stripe-client.ts

@@ -0,0 +1,87 @@
+import { createLogger } from '@sim/logger'
+import Stripe from 'stripe'
+import { env } from '@/lib/core/config/env'
+
+const logger = createLogger('StripeClient')
+
+/**
+ * Check if Stripe credentials are valid
+ */
+export function hasValidStripeCredentials(): boolean {
+  return !!env.STRIPE_SECRET_KEY
+}
+
+/**
+ * Secure Stripe client singleton with initialization guard
+ */
+const createStripeClientSingleton = () => {
+  let stripeClient: Stripe | null = null
+  let isInitializing = false
+
+  return {
+    getInstance(): Stripe | null {
+      // If already initialized, return immediately
+      if (stripeClient) return stripeClient
+
+      // Prevent concurrent initialization attempts
+      if (isInitializing) {
+        logger.debug('Stripe client initialization already in progress')
+        return null
+      }
+
+      if (!hasValidStripeCredentials()) {
+        logger.warn('Stripe credentials not available - Stripe operations will be disabled')
+        return null
+      }
+
+      try {
+        isInitializing = true
+
+        stripeClient = new Stripe(env.STRIPE_SECRET_KEY || '', {
+          apiVersion: '2025-08-27.basil',
+        })
+
+        logger.info('Stripe client initialized successfully')
+        return stripeClient
+      } catch (error) {
+        logger.error('Failed to initialize Stripe client', { error })
+        stripeClient = null // Ensure cleanup on failure
+        return null
+      } finally {
+        isInitializing = false
+      }
+    },
+
+    // For testing purposes only - allows resetting the singleton
+    reset(): void {
+      stripeClient = null
+      isInitializing = false
+    },
+  }
+}
+
+const stripeClientSingleton = createStripeClientSingleton()
+
+/**
+ * Get the Stripe client instance
+ * @returns Stripe client or null if credentials are not available
+ */
+export function getStripeClient(): Stripe | null {
+  return stripeClientSingleton.getInstance()
+}
+
+/**
+ * Get the Stripe client instance, throwing an error if not available
+ * Use this when Stripe operations are required
+ */
+export function requireStripeClient(): Stripe {
+  const client = getStripeClient()
+
+  if (!client) {
+    throw new Error(
+      'Stripe client is not available. Set STRIPE_SECRET_KEY in your environment variables.'
+    )
+  }
+
+  return client
+}