fix(billing): real access-cutoff enforcement for over-limit tenants (#494)

app/[locale]/dashboard/admin/billing/billing-dashboard-client.tsx

@@ -50,6 +50,7 @@ interface BillingDashboardClientProps {
     }
     features: Record<string, unknown>
     transactionFeePercent: number
+    accessCutoffAt: string | null
   }
   paymentRequests: Array<{
     request_id: string
@@ -59,6 +60,7 @@ interface BillingDashboardClientProps {
     interval: string
     created_at: string
     proof_url?: string | null
+    request_type?: string
     platform_plans: { name: string; slug: string } | null
   }>
 }
@@ -99,8 +101,8 @@ export function BillingDashboardClient({ status, paymentRequests }: BillingDashb
       await requestManualRenewal()
       toast.success('Renewal request submitted')
       router.refresh()
-    } catch (e: any) {
-      toast.error(e.message)
+    } catch (e) {
+      toast.error(e instanceof Error ? e.message : 'Failed to submit renewal request')
     } finally {
       setRenewalLoading(false)
     }
@@ -125,8 +127,8 @@ export function BillingDashboardClient({ status, paymentRequests }: BillingDashb
       toast.success(t('cancelSuccess'))
       setCancelOpen(false)
       router.refresh()
-    } catch (e: any) {
-      toast.error(e.message || t('cancelError'))
+    } catch (e) {
+      toast.error(e instanceof Error ? e.message : t('cancelError'))
     } finally {
       setCancelLoading(false)
     }
@@ -140,8 +142,8 @@ export function BillingDashboardClient({ status, paymentRequests }: BillingDashb
       await uploadPaymentProof(requestId, formData)
       toast.success('Proof uploaded successfully')
       router.refresh()
-    } catch (e: any) {
-      toast.error(e.message)
+    } catch (e) {
+      toast.error(e instanceof Error ? e.message : 'Failed to upload proof')
       throw e // re-throw so ProofUpload shows error state
     } finally {
       setUploadingFor(null)
@@ -158,7 +160,7 @@ export function BillingDashboardClient({ status, paymentRequests }: BillingDashb
   const daysUntilEnd = periodEnd ? Math.ceil((periodEnd.getTime() - now.getTime()) / (1000 * 60 * 60 * 24)) : null
   const showRenewalSection = isManualSub && daysUntilEnd !== null && daysUntilEnd <= 30
   const hasPendingRenewal = paymentRequests.some(
-    (r) => (r as any).request_type === 'renewal' && !['confirmed', 'rejected', 'expired'].includes(r.status)
+    (r) => r.request_type === 'renewal' && !['confirmed', 'rejected', 'expired'].includes(r.status)
   )
   const cancelDateStr = (() => {
     const raw = status.subscription?.currentPeriodEnd || status.billingPeriodEnd
@@ -176,6 +178,7 @@ export function BillingDashboardClient({ status, paymentRequests }: BillingDashb
         upcomingPayment={status.upcomingPayment}
         usage={status.usage}
         transactionFeePercent={status.transactionFeePercent}
+        accessCutoffAt={status.accessCutoffAt}
         onManageClick={status.hasStripeCustomer ? handleManageBilling : undefined}
         onCancelClick={() => setCancelOpen(true)}
       />

app/actions/admin/billing.ts

@@ -5,6 +5,7 @@ import { createAdminClient } from '@/lib/supabase/admin'
 import {getCurrentTenantId, getCurrentUserId } from '@/lib/supabase/tenant'
 import { checkPlanLimits, formatPlanLimitError } from '@/lib/billing/plan-limits'
 import { classifyPlanChange } from '@/lib/billing/plan-change'
+import { reconcileAccessCutoff } from '@/lib/billing/access-cutoff'
 import { revalidatePath } from 'next/cache'
 
 async function verifyAdminAccess() {
@@ -39,7 +40,7 @@ export async function getSubscriptionStatus() {
   const [tenantResult, subscriptionResult, coursesCount, studentsCount] = await Promise.all([
     adminClient
       .from('tenants')
-      .select('plan, billing_status, billing_period_end, billing_email, stripe_customer_id')
+      .select('plan, billing_status, billing_period_end, billing_email, stripe_customer_id, access_cutoff_at')
       .eq('id', tenantId)
       .single(),
     adminClient
@@ -83,6 +84,7 @@ export async function getSubscriptionStatus() {
     billingPeriodEnd: tenant?.billing_period_end,
     billingEmail: tenant?.billing_email,
     hasStripeCustomer: !!tenant?.stripe_customer_id,
+    accessCutoffAt: tenant?.access_cutoff_at ?? null,
     subscription: subscription ? {
       status: subscription.status,
       paymentMethod: subscription.payment_method,
@@ -356,6 +358,10 @@ export async function confirmManualPayment(requestId: string) {
       updated_at: now.toISOString(),
     }, { onConflict: 'tenant_id' })
 
+  // Activation already passed the pre-flight limit check above, so this
+  // clears any cutoff scheduled from a prior over-limit period.
+  await reconcileAccessCutoff(adminClient, request.tenant_id)
+
   return { success: true }
 }
 
@@ -529,6 +535,10 @@ export async function changePlan(planId: string, interval: 'monthly' | 'yearly'
       { onConflict: 'tenant_id' }
     )
 
+  // Pre-flight check above already confirmed the new plan's limits are met,
+  // so this clears any cutoff scheduled from a prior over-limit period.
+  await reconcileAccessCutoff(adminClient, tenantId)
+
   revalidatePath('/dashboard/admin/billing')
   return { success: true, plan: ctx.plan.slug }
 }

app/api/cron/enforce-plan-limits/route.ts

@@ -0,0 +1,55 @@
+import { NextRequest, NextResponse } from 'next/server'
+import { createClient, type SupabaseClient } from '@supabase/supabase-js'
+import { reconcileAccessCutoff } from '@/lib/billing/access-cutoff'
+
+export const runtime = 'nodejs'
+
+/**
+ * Cron job: daily sweep reconciling access-cutoff state for every tenant (issue #494).
+ *
+ * `reconcileAccessCutoff()` is already called from event-driven sites —
+ * `downgradeTenantToFree()`, `changePlan()`, `confirmManualPayment()`, and
+ * `applyPortalPlanChange()` — but none of those fire for a tenant that simply
+ * grows over its own plan's limits organically (e.g. a free-plan school that
+ * accumulates students with no plan-change event at all). This cron closes
+ * that gap by walking every tenant once a day and reconciling
+ * `tenants.access_cutoff_at` against its current plan/usage, regardless of
+ * plan (a free-plan tenant needs this as much as a paid one).
+ *
+ * Secured by CRON_SECRET env var (set the same value in the cron scheduler).
+ */
+
+function getSupabaseAdmin(): SupabaseClient {
+  const url = process.env.NEXT_PUBLIC_SUPABASE_URL
+  const serviceKey = process.env.SUPABASE_SERVICE_ROLE_KEY
+  if (!url || !serviceKey) throw new Error('Supabase env vars not set')
+  return createClient(url, serviceKey)
+}
+
+export async function GET(req: NextRequest) {
+  const cronSecret = process.env.CRON_SECRET
+  const provided = req.headers.get('authorization')?.replace('Bearer ', '')
+  if (!cronSecret || provided !== cronSecret) {
+    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+  }
+
+  const supabase = getSupabaseAdmin()
+
+  const { data: tenants } = await supabase.from('tenants').select('id')
+
+  const result = { scheduled: 0, cleared: 0, none: 0, errors: 0 }
+
+  for (const tenant of tenants || []) {
+    try {
+      const decision = await reconcileAccessCutoff(supabase, tenant.id)
+      if (decision.action === 'schedule') result.scheduled++
+      else if (decision.action === 'clear') result.cleared++
+      else result.none++
+    } catch (err) {
+      console.error('enforce-plan-limits: reconcile failed for tenant', tenant.id, err)
+      result.errors++
+    }
+  }
+
+  return NextResponse.json({ success: true, ...result })
+}

app/api/cron/expire-platform-subscriptions/route.ts

@@ -4,6 +4,7 @@ import { sendEmail } from '@/lib/email/send'
 import { renewalReminderTemplate } from '@/lib/email/templates/renewal-reminder'
 import { planDowngradedTemplate } from '@/lib/email/templates/plan-downgraded'
 import { downgradeTenantToFree } from '@/lib/billing/downgrade-tenant'
+import { getTenantAdminEmails } from '@/lib/billing/tenant-admins'
 
 export const runtime = 'nodejs'
 
@@ -41,26 +42,6 @@ function getSupabaseAdmin(): SupabaseClient {
   return createClient(url, serviceKey)
 }
 
-/**
- * Resolve the active admin emails for a tenant. profiles has no email column,
- * so emails come from the auth admin API keyed by tenant_users membership.
- */
-async function getTenantAdminEmails(supabase: SupabaseClient, tenantId: string): Promise<string[]> {
-  const { data: adminUsers } = await supabase
-    .from('tenant_users')
-    .select('user_id')
-    .eq('tenant_id', tenantId)
-    .eq('role', 'admin')
-    .eq('status', 'active')
-
-  const emails: string[] = []
-  for (const admin of adminUsers || []) {
-    const { data: authUser } = await supabase.auth.admin.getUserById(admin.user_id)
-    if (authUser?.user?.email) emails.push(authUser.user.email)
-  }
-  return emails
-}
-
 // Email sends must never abort a transition; failures are logged and swallowed.
 async function safeEmail(emails: string[], template: { subject: string; html: string }): Promise<void> {
   for (const to of emails) {

components/admin/billing-overview.tsx

@@ -4,6 +4,7 @@ import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/com
 import { Badge } from '@/components/ui/badge'
 import { Button } from '@/components/ui/button'
 import { UsageMeter } from './usage-meter'
+import { LimitReachedBanner } from '@/components/shared/limit-reached-banner'
 import { IconCreditCard, IconCalendar, IconAlertTriangle, IconX } from '@tabler/icons-react'
 import Link from 'next/link'
 import { useTranslations } from 'next-intl'
@@ -33,6 +34,7 @@ interface BillingOverviewProps {
     students: { current: number; limit: number }
   }
   transactionFeePercent: number
+  accessCutoffAt: string | null
   onManageClick?: () => void
   onCancelClick?: () => void
 }
@@ -46,6 +48,7 @@ export function BillingOverview({
   upcomingPayment,
   usage,
   transactionFeePercent,
+  accessCutoffAt,
   onManageClick,
   onCancelClick,
 }: BillingOverviewProps) {
@@ -202,16 +205,32 @@ export function BillingOverview({
 
           <section aria-label={`${t('currentPlan')} usage`} className="border-t pt-5">
             <div className="grid gap-5 md:grid-cols-2">
-            <UsageMeter
-              label={t('courses')}
-              current={usage.courses.current}
-              limit={usage.courses.limit}
-            />
-            <UsageMeter
-              label={t('students')}
-              current={usage.students.current}
-              limit={usage.students.limit}
-            />
+            <div className="space-y-3">
+              <UsageMeter
+                label={t('courses')}
+                current={usage.courses.current}
+                limit={usage.courses.limit}
+              />
+              <LimitReachedBanner
+                resource="courses"
+                current={usage.courses.current}
+                limit={usage.courses.limit}
+                cutoffAt={accessCutoffAt}
+              />
+            </div>
+            <div className="space-y-3">
+              <UsageMeter
+                label={t('students')}
+                current={usage.students.current}
+                limit={usage.students.limit}
+              />
+              <LimitReachedBanner
+                resource="students"
+                current={usage.students.current}
+                limit={usage.students.limit}
+                cutoffAt={accessCutoffAt}
+              />
+            </div>
             </div>
           </section>
         </CardContent>

components/shared/limit-reached-banner.tsx

@@ -11,9 +11,10 @@ interface LimitReachedBannerProps {
   current: number
   limit: number          // -1 = unlimited
   className?: string
+  cutoffAt?: string | null
 }
 
-export function LimitReachedBanner({ resource, current, limit, className }: LimitReachedBannerProps) {
+export function LimitReachedBanner({ resource, current, limit, className, cutoffAt }: LimitReachedBannerProps) {
   const [dismissed, setDismissed] = useState(false)
 
   if (dismissed || limit === -1) return null
@@ -33,12 +34,19 @@ export function LimitReachedBanner({ resource, current, limit, className }: Limi
       className
     )}>
       <IconAlertTriangle className="h-5 w-5 shrink-0" />
-      <p className="flex-1 text-sm">
-        {isAtLimit
-          ? `You've reached your ${resource} limit (${limit}). Upgrade your plan to add more.`
-          : `You're using ${current} of ${limit} ${resource}. Consider upgrading for more capacity.`
-        }
-      </p>
+      <div className="flex-1 text-sm">
+        <p>
+          {isAtLimit
+            ? `You've reached your ${resource} limit (${limit}). Upgrade your plan to add more.`
+            : `You're using ${current} of ${limit} ${resource}. Consider upgrading for more capacity.`
+          }
+        </p>
+        {cutoffAt && (
+          <p className="font-semibold">
+            If this is not resolved by {new Date(cutoffAt).toLocaleDateString(undefined, { dateStyle: 'long' })}, all students will lose access to all courses.
+          </p>
+        )}
+      </div>
       <Link href="/dashboard/admin/billing/upgrade">
         <Button variant={isAtLimit ? 'destructive' : 'outline'} size="sm">
           Upgrade

docs/MONETIZATION.md

@@ -232,6 +232,17 @@ function MyComponent() {
 
 `app/actions/teacher/courses.ts` reads `platform_plans.limits.max_courses` from the database (not hardcoded). Returns `approaching: true` with `nextPlan` and `nextPlanPrice` when at 80%+ usage.
 
+The two sections above are **creation-time soft caps only** — they block a *new* student from joining or a *new* course from being created once a tenant is at its limit. Neither one does anything about students/courses that already exist when a tenant ends up over its plan's limit (e.g. after a downgrade, or by organically outgrowing its plan with no plan-change event). That gap was issue #494; it's closed by the mechanism below.
+
+### Post-Downgrade Access Enforcement (issue #494)
+
+`lib/billing/access-cutoff.ts` is the single place that decides and schedules `tenants.access_cutoff_at`:
+
+- Whenever a tenant's usage is checked, `countTenantUsage`/`computePlanLimitViolations` (`lib/billing/plan-limits.ts`) compare current course/active-student counts against the tenant's **current** plan limits. If either is over limit and no cutoff is already scheduled, `reconcileAccessCutoff()` schedules `access_cutoff_at` `ACCESS_CUTOFF_GRACE_DAYS` (14 days) out and emails the tenant's admins immediately via `accessCutoffWarningTemplate` (`lib/email/templates/access-cutoff-warning.ts`), naming the exact cutoff date and which limit(s) are exceeded. If usage drops back under the limit, the next reconciliation clears the scheduled cutoff automatically.
+- `reconcileAccessCutoff()` is called from every plan-state transition: `downgradeTenantToFree()` (both the Stripe `customer.subscription.deleted` webhook and the manual-transfer expiry cron), `changePlan()` and `confirmManualPayment()` in `app/actions/admin/billing.ts`, `applyPortalPlanChange()` (`lib/payments/platform-plan-change.ts`), and a daily cron `app/api/cron/enforce-plan-limits/route.ts` that sweeps every tenant to catch organic over-limit growth with no associated plan-change event.
+- Enforcement itself is in the database: once `access_cutoff_at` passes while the tenant is still over its plan's limits, `has_course_access()` (SQL function, migration `supabase/migrations/20260724130000_access_cutoff_enforcement.sql`) starts returning `false` for every student in that tenant — cutting off access tenant-wide, everywhere that function (or its TS counterpart `hasCourseAccess()`) gates access: lessons, exams, exercises, certificates, AI tutor chat. Access is restored automatically as soon as usage is back under the limit or the tenant upgrades.
+- This is a deliberate decision, not an oversight: with no production users yet, real enforcement was shipped directly rather than grandfathering pre-existing over-limit usage.
+
 ---
 
 ## Currency Support