Mandinga

Separate pitch video (the video above this is demo)

🟢 Mandinga

Luck as the entry point. Wealth as the outcome.

Mandinga is a private, onchain saving protocol, inspired by Brazilian consórcios.

In Brazil, consórcios move more than 150 billion dollars per year. The idea is people commit to recurring payments, called quotas, and one person is chosen every month to receive the full pot. This repeats until everyone has had a turn winning the pot. It is one of the most successful financial coordination systems in the world, but it never became global.

Mandinga makes this model programmable, verifiable, and bankless.

Our MVP is a Chainlink VRF quota raffle because that is the most fair way to kickoff a future consórcio. And technically, a consórcio is a series of raffles with the same participants with extra steps

🐢 Why Mandinga?

Saving circles work because of social trust. But trust does not appear from nowhere.

We begin by using a provably fair draw where people buy quotas and Chainlink VRF selects a winner on-chain. This creates commitment, participation history, and a user base that is already financially engaged.

Our v2 is the consortium phase where each round selects a new winner and previous winners must keep paying until everyone receives their benefit.

So the raffle is not a separate idea. It is the v0.1 bootloader of a saving circle.

🐍 What It Does Today

• ✅ Live Dashboard
  dApp where you see the pot size, quotas sold, and time left 
• ✅ Quota based pooling
  Users buy quotas with ETH, your odds of winning are proportional to the quotas you buy
• ✅ Chainlink Verified Draw
  We use VRF to select the winner verifiably randomly on-chain.
• ✅ Winner claim and settlement
  Every 7th day the winner can claim the pot and finalizes the first rotation of a consortium

Consortium Logic Direction
In a consortium the draw happens each period until all members win. Past winners cannot win again and must continue buying quotas until the last person receives the benefit.

This equals a sequence of raffles with commitment rules. Our current MVP is only the first raffle, however.

🥗 Tech Overview

• Chainlink VRF v2.5 used for verifiable randomness and direct state mutation
• Arbitrum network for low cost high throughput
• Hardhat based development
• Solidity contracts
• Participation list is kept fully private using Fhenix

🌱 Roadmap: Work in Progress

• Consortium contract with sequential draws and mandatory payments
• Stylus SBT Ritual Receipt engine for participation reputation
• Orbit based isolated circles per community
• Privacy optional execution layer via Zama or Fhenix
• Liquid quotas, meaning you can cash out your participation at any point if someone else is willing to enter the circle in your place
• Stylus based on-chain SVG SBT receipts coming next

Hackathon Bounties
This project qualifies for:

Arbitrum

Mandinga is fully deployed on Arbitrum. Our protocol creates a new on-chain saving primitive that fits DeFi, payments and financial coordination use cases. We also set ourselves up to use Orbit later to isolate saving circles per community or geography.

Build Guidl / Scaffold-ETH

Mandinga is an approachable dApp for non traders. We care about real users saving together, not only developers optimizing yield. Our frontend is simple, emotional and accessible which fits Build Guidl goals: technical completeness plus UX effectiveness.

Chainlink

We use Chainlink VRF v2.5 inside the contract to mutate on-chain state. This is visible at RandomnessOracle.sol::fulfillRandomWords and then ConsortiumCore.sol::fulfillRandomness(uint256) which sets the winner. 

Fhenix 

Participant lists in saving circles are sensitive financial data. This list of participants is fully private using Fhenix. This aligns with Fhenix encrypted execution goals.

Github Repo

Frontend

Presentation
Pitch Video