We had a VCF deployment failure that would not yield. It had been open more than two weeks.
Nothing was hidden. The logs were there. The technical documentation was there. The knowledge base articles were there. Every one of those is different from anyone having the time to read all of it at once, in one sitting, while holding the whole thing in view. We are a team spread across India, the United States and China, and a two-week-old failure gets picked up and put down across a lot of handovers. Each of us had read a part of it well.
What eventually broke it loose was pointing an autonomous agent at the problem — Devin, running Claude Opus 4.8 — and letting it correlate the log errors against the documentation and the KBAs on its own. It came back with a root cause we could act on.
I want to be careful about the lesson here, because the obvious version of it is wrong and I have heard people repeat it confidently.
The agent was not smarter than the engineers on that call. It did not have an insight. Nobody had a flash of understanding that we had all somehow missed. What it had was patience across a corpus — a willingness to read every line of a large, boring haystack and keep all of it in view simultaneously. That is a genuinely different capability from expertise, and it happens to be precisely what a stuck triage is short of.
Human debugging degrades in a specific way. We are very good while the search space is small enough to hold in the head, and we degrade sharply once it is large and undifferentiated. That is the exact condition under which we give up and escalate to somebody more senior, who then degrades the same way against the same haystack, just later.
So the framing I would defend is not that AI replaces debugging. It is narrower and more useful: agents are good at the part of debugging that is mechanical and unrewarding to a person. Correlating. Cross-referencing. Not getting bored on page four hundred.
Two caveats I hold onto
It worked because the evidence existed and was reachable. An agent cannot infer a root cause from telemetry nobody collected. Most of the credit here belongs to the engineers who made the logs good and the documentation accurate, over years, for no immediate reward. The agent was the beneficiary of that discipline, not a substitute for it.
And you still have to verify the answer. A root cause is a claim. A confident wrong claim costs more than no claim at all, because it sends a team down a road with conviction. We could check this one against the system, and we did. If you cannot check it, you have not finished — you have just moved where the uncertainty lives.
There is a version of this story where the moral is that the tool is magic. That is not the story. The moral is that we had a class of work nobody wanted to do, we finally handed it to something that does not mind, and it turned out that was the whole blockage.