Web3 Presale Contract Frontend Integration

We have an presale smart contract already deployed on testnet.
The frontend UI and wallet connection are already completed.

This job is frontend Web3 integration only.
No Solidity work, no redeployment.

Scope

• Integrate presale contract into existing React frontend
• Support ETH & USDT purchases
• Handle USDT approve → buy flow
• Display current stage, next stage, price, progress
• Read user data (claimable tokens, purchase status)
• Implement claim / claim + stake
• Proper transaction states and error handling

Tech

• React + TypeScript
• ethers.js or wagmi
• Contract ABI provided

Not Required

• No smart contract changes
• No backend
• No UI redesign

Requirements

Apply only if you have real presale frontend experience.

Please explain briefly how you would handle USDT approve → buy and multi-stage allocation.