Backend API Integration for Lead Intake & Authentication System -- 2

Project Overview:
The project is a Next.js lending pre-qualification application built with TypeScript, Supabase Postgres, and Prisma. We need a developer to complete and secure the backend API integrations for lead intake and authentication.

Tech Stack:

Next.js (App Router) with TypeScript
Supabase Postgres (Prisma ORM)
NextAuth.js for authentication
Vercel deployment
Integration Tasks:

1. Lead Intake Webhook Integration
Complete the existing webhook endpoint at /api/webhooks/lead
Ensure HMAC signature verification is working correctly
Validate webhook payload with Zod schema
Implement proper idempotency handling (prevent duplicate leads)
Store leads in Supabase database via Prisma
Return appropriate HTTP responses (200/202/422/401)

2. Authentication System Setup
Complete NextAuth.js configuration (currently basic setup in /src/lib/auth)
Implement secure session management
Set up organization-based multi-tenant authentication
Create user login/logout functionality
Implement password reset flow
Add user invitation system for team members

3. TidyCal Webhook Integration
Secure the /api/webhooks/tidycal endpoint
Implement webhook signature verification or token-based auth
Parse booking data and store in database
Connect bookings to existing applications

Experience with Next.js 15 and TypeScript
Knowledge of NextAuth.js authentication
Experience with webhooks and API integrations
Familiarity with Supabase and Prisma ORM
Understanding of HMAC signature verification
Experience with API security best practices

Deliverables:
Working lead intake webhook with security
Complete authentication system with login/logout
Secure TidyCal webhook integration
API validation and error handling
Documentation for environment variables