How did it work before your optimization? Were there double charges?

Before my optimization, the system operated on a standard fund deduction algorithm that did not include additional checks for repeated operations. As a result, double deductions could occur in some cases, for example, due to resubmission of a transaction or communication failures.

After analysis, I implemented an idempotency mechanism — unique operation identifiers and a check for their presence before deduction. This helped eliminate double deductions and increased system reliability.

An example of simplified verification logic:

if (!transaction_processed(transaction_id)) {
    process_transaction(transaction_id);
} else {
    // transaction already processed, skip
}

This approach helps prevent duplication of operations in embedded systems.