WaterBottle: Delivery Management

WaterBottle is a full delivery management system for 20L water jug suppliers, covering three roles — Customer, Delivery staff, and Supplier Admin — from a single login-aware app on both iOS and Android. Customers see their live bottle and jug balance, request extra bottles or pickups, review delivery history by day/week/month/year, and pay outstanding balances by UPI or cash. Delivery staff get a route-based deliveries list with day-summary reporting, and Supplier Admins manage customers, staff, billing, and invoices — including WhatsApp handoff for sending invoices directly. Every business record is scoped to a tenant (supplier), with jar counts derived from an append-only ledger rather than stored directly, so balances can never drift out of sync with actual deliveries. Built on a NestJS + PostgreSQL + Redis backend behind a shared OpenAPI 3.1 contract, with a Next.js Super Admin web panel that can act as any supplier to manage their operations directly.