TheZapCoin

        loan.creation_time = Clock::get()?.unix_timestamp;        loan.repaid_amount = 0;        loan.status = LoanStatus::Active;        loan.bump = *ctx.bumps.get("loan").unwrap();         msg!("Loan created: {} tokens, {} days term", amount, term_days);        Ok(())    }     // Repay a loan with energy tokens    pub fn repay_loan_with_energy(        ctx: Context<RepayLoanWithEnergy>,        amount: u64,    ) -> Result<()> {        let loan = &mut ctx.accounts.loan;         // Ensure the loan is active        require!(loan.status == LoanStatus::Active, ErrorCode::LoanNotActive);         // Calculate the remaining amount to repay        let remaining_amount = loan.amount.checked_sub(loan.repaid_amount)            .ok_or(ErrorCode::ArithmeticOverflow)?;         // Ensure the repayment amount is not more than what's remaining

1. Line 85 loan.creation_time = Clock::get()?.unix_timestamp;: Reads on-chain time from the Clock sysvar.
2. Line 88 loan.bump = *ctx.bumps.get("loan").unwrap();: Uses the bump seed, the extra byte that pushes the derived address off the ed25519 curve.
3. Line 90 msg!("Loan created: {} tokens, {} days term", amount, term_days);: Logs to the program log, which is visible in explorers and the test output.
4. Line 102 require!(loan.status == LoanStatus::Active, ErrorCode::LoanNotActive);: An explicit validation that aborts the instruction with an error.
5. Line 105 let remaining_amount = loan.amount.checked_sub(loan.repaid_amount): Uses checked arithmetic so overflow fails instead of wrapping.

import {  Connection,  PublicKey,  Transaction,  SystemProgram,  Keypair,  sendAndConfirmTransaction,  ConfirmOptions,  LAMPORTS_PER_SOL} from '@solana/web3.js';import {  TOKEN_PROGRAM_ID,  getAssociatedTokenAddress,  createAssociatedTokenAccountInstruction,  getAccount,  createMint,  getMint,  mintTo,  transfer,  createTransferInstruction} from '@solana/spl-token';import { Program, AnchorProvider, web3, BN, Idl, setProvider } from '@project-serum/anchor';import idl from './zapcoin.json';

1. Line 7 sendAndConfirmTransaction,: Submits the signed transaction to the cluster.
2. Line 20 createTransferInstruction: An SPL token transfer through the Token Program.