BlockHarvest

A decentralised crop insurance platform built on the Solana blockchain. Farmers can register, pay premiums, and file claims — with all payments recorded immutably on-chain and farmer profiles stored in Supabase.

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Live Deployment: https://block-harvest-qk3j.vercel.app/

This is a Next.js project bootstrapped with create-next-app.

What it does

• Farmers connect their Phantom wallet and register with their name, crop type, and land size
• Premium payments (0.1 SOL) are transferred on-chain to a program vault and recorded immutably
• Claims are filed and approved by an admin wallet, releasing SOL back to the farmer
• Every transaction is publicly verifiable on Solana Explorer
• Farmer profile data is stored in Supabase for fast, flexible display

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Tech stack

Layer	Technology
Smart contract	Rust, Anchor 0.29.0
Blockchain	Solana Devnet
Frontend	Next.js 15, TypeScript, Tailwind CSS
Wallet	Phantom via Solana Wallet Adapter
Database	Supabase (PostgreSQL)
JS client	@coral-xyz/anchor 0.29.0, @solana/web3.js

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Project structure

blockHarvest/
└── block-harvest/
    ├── programs/
    │   └── block-harvest/
    │       └── src/
    │           └── lib.rs          # Anchor smart contract
    ├── app/                        # Next.js frontend
    │   ├── app/
    │   │   ├── layout.tsx          # Root layout
    │   │   ├── providers.tsx       # Wallet provider wrapper
    │   │   ├── page.tsx            # Landing + wallet connect
    │   │   ├── register/
    │   │   │   └── page.tsx        # Farmer registration form
    │   │   └── dashboard/
    │   │       └── page.tsx        # Farmer dashboard + pay premium
    │   └── lib/
    │       ├── anchor.ts           # Anchor client + PDA helpers
    │       └── supabase.ts         # Supabase client + types
    ├── Anchor.toml                 # Anchor config
    └── Cargo.toml                  # Rust workspace

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Smart contract

Program ID: C54J4haBjNNGYfV8ZENqvDRzvhX5ReeJPjyCVnySbdXj
Network: Solana Devnet
Framework: Anchor 0.29.0

Instructions

Instruction	Who can call	What it does
register_farmer	Any wallet	Creates a PDA account tied to the farmer's wallet
pay_premium	Registered farmer	Transfers 0.1 SOL to vault, marks premium_paid = true
file_claim	Admin only	Marks claim_filed = true on farmer's account
approve_claim	Admin only	Releases SOL from vault back to farmer's wallet

On-chain data (FarmerAccount PDA)

farmer            Pubkey    wallet address
premium_paid      bool      whether premium has been paid
premium_amount    u64       amount paid in lamports
payment_timestamp i64       unix timestamp of payment
claim_filed       bool      whether a claim has been filed
claim_approved    bool      whether the claim was approved
bump              u8        PDA bump seed

PDA derivation

Farmer PDA  →  seeds: ["farmer", wallet_address]
Vault PDA   →  seeds: ["vault"]

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Local setup

Prerequisites

• Rust 1.85+
• Solana CLI 3.x
• Node.js 20+
• Anchor CLI 0.29.0
• Phantom browser extension

1. Clone and install

git clone https://github.com/yourname/block-harvest.git
cd block-harvest

2. Set up Rust toolchain

rustup default stable
rustup update

3. Configure Solana for Devnet

solana config set --url devnet
solana-keygen new --outfile ~/.config/solana/id.json
# Get free SOL at https://faucet.solana.com

4. Build the smart contract

anchor build

5. Deploy to Devnet

anchor deploy --provider.cluster devnet

6. Set up the frontend

cd app
npm install

Create .env.local:

NEXT_PUBLIC_SUPABASE_URL=your_supabase_url
NEXT_PUBLIC_SUPABASE_ANON_KEY=your_supabase_anon_key
NEXT_PUBLIC_PROGRAM_ID=C54J4haBjNNGYfV8ZENqvDRzvhX5ReeJPjyCVnySbdXj
NEXT_PUBLIC_RPC_URL=https://api.devnet.solana.com

7. Set up Supabase

Run this in the Supabase SQL editor:

create table farmers (
  wallet_address text primary key,
  name           text not null,
  crop_type      text not null,
  land_size      numeric not null,
  created_at     timestamp with time zone default now()
);

alter table farmers disable row level security;

8. Run the frontend

npm run dev

Open http://localhost:3000

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User flow

1. Open app → connect Phantom wallet
2. First time? → redirected to /register
3. Fill in name, crop type, land size → submit
   - Creates on-chain PDA account
   - Saves profile to Supabase
4. Redirected to /dashboard
   - Profile loaded from Supabase
   - Payment status loaded from chain
5. Click "Pay Premium — 0.1 SOL"
   - Phantom prompts for approval
   - 0.1 SOL transferred to vault PDA
   - premium_paid = true stored on-chain
   - Transaction link shown (Solana Explorer)
6. Admin can file and approve claims
   - SOL released back to farmer wallet

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Verifying payments on-chain

Every premium payment produces a transaction signature. Paste it into:

https://explorer.solana.com/tx/<SIGNATURE>?cluster=devnet

You will see:

• The program that was called (block_harvest)
• The instruction (pay_premium)
• SOL transferred from farmer wallet to vault
• premium_paid = true written to the farmer's PDA account

This is the tamper-proof payment record — no database, no admin, no server can alter it.

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Known setup notes

• Anchor 0.29.0 is required for Rust and the JS client — do not mix versions
• The Solana platform tools ship their own Cargo; if you see edition2024 errors, delete ~/.cache/solana/ and let it re-download
• The pubkey!() macro is not available in Anchor 0.29.0 — admin is compared using .to_string()
• Wallet adapter components require a mounted guard in Next.js to avoid hydration errors

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Acknowledgements

Built as a college showcase project to demonstrate real-world use of the Solana blockchain for agricultural insurance use cases.