📘 Description

We need to implement a secure escrow smart contract in Cairo for Starknet that will act as a trustless intermediary for ERC20 token transactions. The contract should support multiple potential recipients for each order, with only one eventual winner receiving the funds. This will enable use cases like marketplace transactions, competition prizes, or conditional payments.

The contract should manage the complete lifecycle of an escrow order from creation through payment and completion/cancellation, while ensuring secure token transfers and proper state management.

✅ Acceptance Criteria

Order Management

• Contract must support creating orders with multiple potential recipients
• Each order must store:
  • Amount of tokens to be escrowed
  • List of potential recipient addresses
  • Current state (NotPaid, Paid, Completed, Cancelled)
• Order IDs should be unique and auto-incrementing

Token Handling

• Contract must safely interact with any ERC20 token
• Must validate sufficient token balance before transfers
• Must handle token transfer failures appropriately
• Must store escrowed tokens in the contract until completion

State Transitions

• Orders start in 'NotPaid' state
• Payment can only be made for 'NotPaid' orders
• Only paid orders can be completed
• Orders can be cancelled from any state
• Completion must transfer tokens to the designated winner

🌎 References

• Cairo Book
• OpenZeppelin Contracts
• Starknet Documentation
• ERC20 Standard