🌞 OnChainGM (Starknet - Cairo 1.0)

OnChainGM is a minimal and permissionless smart contract on Starknet that allows users to send an on-chain “GM” (Good Morning) message once every 24 hours using ERC-20 tokens (instead of ETH), with fees transferred to a designated recipient.

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🚀 Features

• ✅ Once per day GM enforcement (per address, 24h rule)
• 🪙 ERC-20 based fee (requires transfer_from and prior approval)
• 🏷️ Emits a clean OnChainGMEvent for UI tracking
• 🔐 Immutable fee config set at deployment

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🧾 Contract Info

Parameter	Value
Fee Token	0x0471...938d (custom ERC-20)
GM Fee	0.5 token (500000000000000000 u256)
Fee Recipient	0x077e...9a66
Cooldown Period	86400 seconds (24 hours)

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⚙️ Interface

The contract implements the following interface:

#[starknet::interface]
trait IOnchainGM<TContractState> {
    fn onChainGM(ref self: TContractState, value: u256);
    fn timeUntilNextGM(self: @TContractState, user: ContractAddress) -> u256;
    fn get_fee_recipient(self: @TContractState) -> ContractAddress;
    fn get_gm_fee(self: @TContractState) -> u256;
    fn get_last_GM_timestamp(self: @TContractState, address: ContractAddress) -> u256;
}

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🔐 How It Works

1. User must approve the contract to spend the GM fee amount on their behalf.
2. User calls onChainGM(value) where value == GM_FEE.
3. The contract checks:
   • Has 24 hours passed since last GM?
   • Is the value correct?
4. Transfers value tokens from the caller to the fee_recipient.
5. Records the timestamp and emits OnChainGMEvent.

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🪙 Fee Logic

• Token-based fee (ERC20::transfer_from)
• Caller must approve the contract beforehand
• If transfer fails, the call reverts with "Fee transfer failed"

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📦 Events

#[event]
enum Event {
    OnChainGMEvent: OnChainGMEvent,
}

struct OnChainGMEvent {
    sender: ContractAddress,
}

Used to track daily GM activity for frontends or indexers.

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🧪 Example Usage (Starknet CLI / SDK)

1. Approve the GM contract:

starknet invoke \
  --address <erc20_address> \
  --abi erc20_abi.json \
  --function approve \
  --inputs <onchaingm_contract_address> 500000000000000000

2. Send your GM:

starknet invoke \
  --address <onchaingm_contract_address> \
  --abi onchaingm_abi.json \
  --function onChainGM \
  --inputs 500000000000000000

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🧭 Deployment & Constants

Deployed version (for reference):

// Fee token
FEE_TOKEN = 0x04718f5a0fc34cc1af16a1cdee98ffb20c31f5cd61d6ab07201858f4287c938d

// Fee recipient
FEE_RECIPIENT = 0x077e6508cdd61b683fd3004bb2c2096229256f5e31e0d28ba0fb1a3748089a66

// GM Fee (0.5 token assuming 18 decimals)
GM_FEE = 500000000000000000

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📜 License

MIT License. Free to use, fork, and extend.

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📎 Reference Deployment

👉 Example contract:
Starkscan

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❤️ Support

Send your GM and show your support to the ecosystem 🌞