Contact person: Build a Full Petrol Pump Management Web App (Owner-Only WhatsApp, VIP Credit, Tanks/DIP, Variance, Employees, Expenses)

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Location: Guwahati, India

Budget: Recommended by industry experts

Time to start: As soon as possible

Project description:
"**Summary**
We need a **fully functional**, production-ready web app for a single petrol pump (with easy future expansion to multi-site). Simple English UI, mobile-friendly (PWA). Timezone **Asia/Kolkata (IST)**.

**Key Outcomes**

* Accurate **fuel stock** & **tank reconciliation** (DIP → liters), nozzle meter readings, price change log.
* Daily **sales** (liters/₹) with payment mix, **variance** vs physical DIP.
* **VIP Credit** customers billed monthly (SOA, aging). Non-VIP pay Cash/UPI/Card.
* **Employee** shifts, attendance, hours, shift settlements.
* **Expenses** (OpEx/CapEx), **daily net profit**.
* Nightly **WhatsApp DSR to owner only** (after last shift close), idempotent & reliable.
* Full **audit trail**, backups, and exports (PDF/CSV).

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## Modules & Features (Required)

**1) Masters & Setup**

* Products: Petrol (MS), Diesel (HSD), Lubes/AdBlue.
* Tanks: capacity + **strapping table** (DIP mm → liters).
* Dispensers/Nozzles: link each nozzle to a tank.
* Prices: **time-stamped** changes (midnight or anytime).
* Vendors (fuel/service); Sites (future multi-outlet ready).

**2) Daily Operations**

* **Shift Open/Close**: nozzle totalizers (open/close), tank DIP (mm), optional density/water.
* **Sales**: nozzle-wise liters & ₹; payment mode (Cash/UPI/Card/**Credit**).
* **POS for lubes** (SKU stock & billing).
* **Purchases/GRN**: supplier, invoice, liters, rate, charges → post to tank.
* **Cash Settlement**: expected vs counted; UPI/Card totals; deposit ref.

**3) Reconciliation & Variance**

* System closing = opening + purchases − sales.
* Physical closing from **DIP → liters**.
* Variance (L & %) with tolerance alerts; price change log.

**4) Customers (VIP Credit Only)**

* Mark customers as **VIP credit** with limit + monthly billing day (+ Dept/PO).
* Monthly **SOA PDF**, aging, receipts; non-VIP = no credit.

**5) Employees**

* Roster (assign attendants to nozzles), attendance in/out, working hours, OT, leaves.
* Shift productivity (L/hour), cash variance by user.
* Payroll inputs export.

**6) Expenses & Profit**

* Expenses: Service/Renovation/Food/Electricity/Misc; mode (Cash/UPI/Bank); **isCapex**.
* **Daily Gross Margin** (by effective buy cost), **OpEx**, **CapEx (separate)**, **Daily Net Profit**.

**7) Reports & Exports**

* **DSR**: product/nozzle sales (L/₹), payment mix, purchases, closing stock, variance, **expenses**, deposits, **net profit**.
* Tank stock ledger, DIP trend, price change log, purchase register.
* Customer ledger & monthly SOA, employee attendance/productivity.
* **PDF & CSV** exports everywhere relevant.

**8) WhatsApp (Owner-Only, Nightly)**

* Trigger **after last shift closes**; fallback provisional at cut-off if unclosed.
* Content: MS/HSD sales (L/₹), payment mix, purchases, closing stock, variance, expenses, deposits, alerts.
* **Idempotent** (no duplicates), retry/backoff on failure. Meta **WhatsApp Cloud API** (or BSP).

**9) Account, Audit & Safety**

* **Single Admin login** now (RBAC-ready for later).
* **Audit log** (who/when/before→after) for all edits/deletes.
* Shift **lock** after approval.
* Scheduled **daily backups**; IST everywhere.

---

## Tech Preferences (open to suggestions)

* **Frontend:** [login to view URL] (App Router) or ASP.NET Core + React; Tailwind + shadcn/ui; **PWA/offline**.
* **Backend:** Node.js (Next API/NestJS) or ASP.NET Core.
* **DB:** PostgreSQL (Prisma/EF Core), object storage for PDFs.
* **PDF:** Server-side (PDFKit/iText/QuestPDF).
* **WhatsApp:** Meta Business Cloud API (owner-only).
* **Deploy:** Docker; .env-based config.

---

## Data Model (minimum)

* products, price\_changes, tanks, **tank\_strapping(dip\_mm, liters)**, dispensers, nozzles
* shifts, meter\_readings, dips, sales, shift\_cash, purchases, expenses, employees, attendance
* customers(**is\_vip\_credit**, limit, billing\_day, gstin, dept/po), receipts
* audit\_log, report\_logs, whatsapp\_queue

---

## Deliverables

* Source code repo with instructions (README), schema/migrations, **seed data**.
* Working environment files (**.[login to view URL]**), Docker setup.
* **Automated nightly WhatsApp DSR** (owner only) with idempotency logs.
* PDF/CSV exports; backup script; error handling & toasts.
* Brief admin guide + 1h handover call/video.

---

## Acceptance Criteria

* Shift open/close with nozzle+DIP, correct **variance** & **closing stock**.
* Sales/expenses reflect on **Dashboard** and **DSR**; **Daily Net Profit** correct.
* Only **VIP** customers can be billed on credit; monthly **SOA PDF** generated.
* **WhatsApp DSR** reaches owner nightly (with provisional handling).
* All edits in **audit log**; shifts lock post-approval.
* Exports (PDF/CSV) and backup job run as documented.

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## What to include in your bid

* Tech stack choice & brief architecture (2–4 sentences).
* Similar work samples (inventory/fuel/retail/DSR/WhatsApp).
* Estimated timeline & cost (fixed or milestone-based).
* Any recommended enhancements (e.g., ATG/dispenser protocol integration).

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**Ready to start.** We’ll provide logos/branding, initial tank strapping CSVs, and sample day’s data." (client-provided description)