𝗧𝗵𝗲 𝗡𝘂𝗹𝗹 𝗜𝗻𝗽𝘂𝘁 𝗧𝗵𝗮𝘁 𝗕𝗿𝗼𝗸𝗲 𝗠𝘆 𝗣𝗿𝗼𝗱𝘂𝗰𝘁𝗶𝗼𝗻 𝗔𝗴𝗲𝗻𝘁

𝗧𝗵𝗲 𝗡𝘂𝗹𝗹 𝗜𝗻𝗽𝘂𝘁 𝗧𝗵𝗮𝘁 𝗕𝗿𝗼𝗸𝗲 𝗠𝘆 𝗣𝗿𝗼𝗱𝘂𝗰𝘁𝗶𝗼𝗻 𝗔𝗴𝗲𝗻𝘁

The demo ran perfectly for three weeks. Every test input worked. Every output went to the right place. I thought the system was reliable.

Then a supplier sent an email with an empty subject line.

The agent expected a string to extract an order reference. Instead, it received a null value. It did not crash. That would have been better. It generated a fake order reference that looked real. The downstream system processed it. Nobody noticed for four hours.

Demos use inputs you expect. Production uses inputs you do not expect.

I run the agent operation at aienterprise.dk. I saw the full trace. The prompt told the agent to extract the order reference from the subject line. This works if the subject line exists.

If the subject line is missing, a large language model fills the gap. It invents something that looks correct. This is not random noise. It is structured noise. It is dangerous because it looks right. You can catch a failure. You cannot easily catch a confident, wrong answer.

I did not retrain the model. I did not change the prompt. I added a guard before the model call.

Now, a simple check runs first. It asks: is the subject field present and non-empty? If the answer is no, the message goes to a hold queue for a human. The agent never sees the bad input.

This guard is twelve lines of code. It is the most important thing I built this year.

The pattern is simple. If an agent assumes structure, production will eventually send unstructured data. The fix is not a smarter model. The fix is a boundary. You need a check that routes bad input to a human instead of letting the model guess.

Reliability is the only feature. A demo shows an agent can do a task. Production shows an agent does the task at 3 AM on bad input. Only the second part matters to your customers.

My agent now processes 200 operations per day without issues. The hold queue triggers twice a week. A human reviews the odd data. I learn what production looks like.

If you build agents for high-risk categories under the EU AI Act, the deadline is December 2, 2027. This includes employment, biometrics, and education. A system that guesses on bad input will fail an audit. This guard is a compliance minimum.

Reliability is not a feature you add later.

மூலம்: https://dev.to/kimlike/the-null-input-that-broke-my-production-agent-and-what-fixed-it-1e77

விருப்பத்தேர்வு கற்றல் சமூகம்: https://t.me/GyaanSetuAi