Jokjipge (족집게)

Sybil-Resistant Prediction Markets

"예측하고, 증명하세요" — Predict and Prove It

Jokjipge is a prediction market platform where KYC verification ensures one person = one identity, preventing Sybil attacks and market manipulation that plague other prediction platforms.

The Problem

Traditional prediction markets suffer from critical vulnerabilities:

Problem	Impact
Sybil Attacks	One person creates multiple accounts to distort odds
Wash Trading	Fake volume attracts unsuspecting bettors
Whale Dominance	Wealthy actors manipulate markets unfairly
Bot Manipulation	Automated exploitation of pricing inefficiencies

The Solution

Jokjipge leverages VeryChat's KYC infrastructure to create fair prediction markets:

One Person, One Identity — KYC verification prevents multiple accounts
Position Limits — Maximum 100 VERY per user per market outcome
Transparent Participation — All bets recorded on-chain
Fair Pricing — AMM-based odds ensure consistent, mathematical pricing

Tech Stack

Layer	Technology
Smart Contracts	Solidity 0.8.26, Foundry
Frontend	Next.js 16, TypeScript, React 19
UI Components	shadcn/ui, Tailwind CSS
Authentication	VeryChat OAuth + WEPIN Wallet
Indexing	TheGraph (self-hosted)
Chains	VeryChain (mainnet)

Project Structure

jokjipge/
├── contracts/           # Solidity smart contracts (Foundry)
│   ├── src/             # Contract source files
│   ├── script/          # Deployment scripts
│   └── test/            # Contract tests
├── frontend/            # Next.js application
│   ├── app/             # Pages and API routes
│   ├── components/      # React components
│   ├── lib/             # Utilities, hooks, types
│   └── constants/       # Configuration
├── subgraph/            # TheGraph indexer
│   ├── src/mappings/    # Event handlers
│   └── schema.graphql   # Data schema
├── scripts/             # Market operation scripts
└── docs/                # Documentation

Smart Contracts

MarketFactory

Central factory for creating and managing prediction markets.

// Create a new market
createMarket(question, category, metadataUri, resolutionTime) → (marketId, marketAddress)

// Resolve a market (owner only)
resolveMarket(marketId, winningOutcome)

// Query markets
getMarket(marketId) → MarketInfo
getAllMarkets() → marketIds[]

PredictionMarket

Individual market contract handling bets, odds calculation, and payouts.

Key Features:

Binary outcomes (Yes/No)
Constant-product AMM for fair odds
Position limits (100 VERY max per user)
Proportional winner payouts

// Place a bet
placeBet(outcome) payable  // outcome: 0=No, 1=Yes

// Claim winnings after resolution
claimWinnings()

// Get current odds
getOdds() → (yesOdds, noOdds)

AMM Formula:

shares = (betAmount × otherShares) / (currentShares + betAmount)
odds = otherShares / (currentShares + otherShares)

Frontend Pages

Page	Route	Description
Market Browser	`/`	Browse, filter, and search markets
Market Detail	`/market/[id]`	View odds, place bets, claim winnings
My Bets	`/my-bets`	Track positions and P&L
Leaderboard	`/leaderboard`	Top predictors by ROI

Getting Started

Prerequisites

Node.js 18+
pnpm or npm
Foundry (for contracts)
Git

Installation

# Clone the repository
git clone https://github.com/CipherKuma/jokjipge.git
cd jokjipge

# Install frontend dependencies
cd frontend && npm install

# Install contract dependencies
cd ../contracts && forge install

# Install script dependencies
cd ../scripts && npm install

Environment Setup

Frontend (frontend/.env.local):

NEXT_PUBLIC_WALLETCONNECT_PROJECT_ID=your_project_id
NEXT_PUBLIC_APP_MODE=testnet
NEXT_PUBLIC_INDEXER_URL=http://localhost:8000/subgraphs/name/jokjipge

Contracts (contracts/.env):

PRIVATE_KEY=your_deployer_private_key

Scripts (scripts/.env):

PRIVATE_KEY=your_private_key

Running Locally

# Start the frontend
cd frontend && npm run dev

# Run contract tests
cd contracts && forge test

# Deploy contracts to testnet
cd contracts && make deploy-testnet

Deployed Contracts

Network	Chain ID	MarketFactory Address
VeryChain	4613	`0x581456618D817a834CBaFC26250c18DEaAC76025`

Market Operations

List All Markets

cd scripts && npm run list-markets

Create a Market

cd scripts && npm run create-market "<question>" "<category>" <days_until_resolution>

Categories: crypto, sports, entertainment, politics, gaming

Example:

npm run create-market "Will BTC hit 200k?" "crypto" 30

Resolve a Market

Using Foundry (recommended):

cd contracts && source .env
cast send 0x581456618D817a834CBaFC26250c18DEaAC76025 \
  "resolveMarket(uint256,uint8)" <market_id> <outcome> \
  --rpc-url https://rpc.verylabs.io \
  --private-key $PRIVATE_KEY --chain-id 4613

Outcome values: 0 = No wins, 1 = Yes wins

Subgraph

The subgraph indexes all on-chain events for efficient querying.

Entities

Market — Market details, pools, status
Bet — Individual bet records
User — User stats, positions, P&L
Position — Aggregated user positions per market

Deployment

Deploy to local graph-node:

cd subgraph
graph create --node http://localhost:8020/ jokjipge
graph deploy --node http://localhost:8020/ --ipfs http://localhost:5001 jokjipge

Market Mechanics

Position Limits (Anti-Sybil)

MAX_POSITION = 100 VERY per user per outcome

This prevents whale manipulation while allowing meaningful participation.

Odds Calculation

Using constant-product AMM:

yesOdds = totalNoShares / (totalYesShares + totalNoShares)
noOdds = totalYesShares / (totalYesShares + totalNoShares)

Payout Calculation

winnings = (userShares / totalWinningShares) × totalPool

Market Categories

Category	Examples
Crypto	Price predictions, protocol outcomes
Sports	K-League, KBO, international matches
Entertainment	K-drama ratings, music charts
Politics	Election outcomes, policy decisions
Gaming	Esports, game releases

Security

ReentrancyGuard — Prevents reentrancy attacks on claims
Position Limits — Contract-enforced 100 VERY max
Access Control — Only factory owner can resolve markets
KYC Verification — VeryChat ensures one identity per person

Architecture

┌─────────────────────────────────────────────────────────────┐
│                     Frontend (Next.js)                       │
│  Market Browser │ Trading UI │ Portfolio │ Leaderboard       │
└─────────────────────────────────────────────────────────────┘
                              │
                              ▼
┌───────────────────┬─────────────────┬───────────────────────┐
│   VeryChat Auth   │   WEPIN Wallet  │   VeryChain (EVM)     │
│   KYC Identity    │   Transactions  │   Smart Contracts     │
└───────────────────┴─────────────────┴───────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────┐
│                   TheGraph Subgraph                          │
│          Event Indexing │ GraphQL API │ Analytics            │
└─────────────────────────────────────────────────────────────┘

Contributing

Fork the repository
Create a feature branch (git checkout -b feature/amazing-feature)
Commit your changes (git commit -m 'feat: add amazing feature')
Push to the branch (git push origin feature/amazing-feature)
Open a Pull Request

Commit Convention

Use conventional commits:

feat: — New features
fix: — Bug fixes
refactor: — Code refactoring
docs: — Documentation updates
test: — Test additions/updates

License

This project is licensed under the MIT License.

Links

Repository: github.com/CipherKuma/jokjipge
VeryChain: verylabs.io
VeryChat: verychat.io

Name		Name	Last commit message	Last commit date
Latest commit History 56 Commits
.claude		.claude
contracts		contracts
docs		docs
frontend		frontend
scripts		scripts
subgraph		subgraph
.mcp.json		.mcp.json
CLAUDE.md		CLAUDE.md
PRD.md		PRD.md
README.md		README.md
SUBMISSION.md		SUBMISSION.md

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