Vibe codingHardvc-g497

Subject Ai code reviewLevel Senior–Staff~20 minCommon in Databases & SQL interviewsIndustries Software development

Question

An AI wrote this Django funds-transfer view. It passes tests. In production, support finds accounts where money was debited but never credited, and a few double-credits. Explain both failure modes and fix them.

python

1def transfer(request):2    src = Account.objects.get(id=request.POST["src"])3    dst = Account.objects.get(id=request.POST["dst"])4    amount = Decimal(request.POST["amount"])5    src.balance -= amount6    src.save()7    notify_external_ledger(src, dst, amount)  # network call, can fail8    dst.balance += amount9    dst.save()10    return JsonResponse({"ok": True})

What a strong answer looks like

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