Evidence note: Metrics in this note refer to repository tests or controlled scenarios unless a live production source is explicitly linked.

Educational platforms handle sensitive user progress, proprietary course curricula, and authenticated enrollment states. In client-side React/Next.js architectures, securing database access exclusively through backend endpoints often leads to authorization leaks or complex custom middleware.

For KaisLearnAI—a bilingual Arabic/English educational platform—I designed a zero-leak multi-tenant security architecture enforced directly at the database engine level via Supabase Row-Level Security (RLS).

The Security Invariant: Even if a malicious client attempts direct PostgreSQL queries using the public Supabase anon key, PostgreSQL natively blocks access to protected modules unless an authenticated JWT matching active enrollment records is cryptographically verified.

1. The Multi-Tenant RLS Policy Matrix

-- supabase/migrations/20260515_course_access_rls.sql

-- 1. Enable RLS on protected educational tables
ALTER TABLE public.course_modules ENABLE ROW LEVEL SECURITY;
ALTER TABLE public.user_progress ENABLE ROW LEVEL SECURITY;

-- 2. Course Modules: Viewable only if enrolled or module is marked free preview
CREATE POLICY "Allow module access to enrolled students"
ON public.course_modules
FOR SELECT
TO authenticated
USING (
  is_free_preview = true
  OR EXISTS (
    SELECT 1 FROM public.enrollments
    WHERE enrollments.user_id = auth.uid()
      AND enrollments.course_id = course_modules.course_id
      AND enrollments.status = 'active'
  )
);

-- 3. User Progress: Users can only view and update their own progress records
CREATE POLICY "Users control only own progress records"
ON public.user_progress
FOR ALL
TO authenticated
USING (user_id = auth.uid())
WITH CHECK (user_id = auth.uid());

Sources, Code & Further Reading