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rust.idempotency_key

Correctness High

Detects non-idempotent operations without idempotency keys for safe retries.

Why It Matters

Missing idempotency keys:

Duplicate processing — Retries create duplicates
Data corruption — Multiple charges, orders
Inconsistent state — Lost updates on retry

Example

// ❌ Before (no idempotency key)
async fn create_payment(req: PaymentRequest) -> Payment {
    let payment = Payment::new(req.amount);
    db.insert(&payment).await?;
    payment
}

// ✅ After (with idempotency key)
async fn create_payment(
    idempotency_key: &str,
    req: PaymentRequest
) -> Result<Payment, Error> {
    // Check for existing payment with this key
    if let Some(existing) = db.find_by_idempotency_key(idempotency_key).await? {
        return Ok(existing);
    }

    let payment = Payment::new(req.amount, idempotency_key);
    db.insert(&payment).await?;
    Ok(payment)
}

What Unfault Detects

POST handlers without idempotency header
Payment/order creation without dedup key
State mutations without idempotency check

Auto-Fix

Unfault can add idempotency key parameter and lookup logic.