I am starting to think that AI fails most when used in a recursive loop, which is e.g. the case for software projects, research or long-form writing (books, papers): You start with a given state, give the AI a prompt to modify it, get a new state, then repeat. Each step introduces more AI generated data into the state of the system, which then again goes into the context for producing the next state. AIs pick up context probabilistically and they do not distinguish if data they operate on was produced by an AI or a human. I think how successful people are with AI depends on how much human steering they inject into the system at each step and how well represented their workflow was in the training data of the AI.

As a simple experiment, try giving AI a high level goal for your software and let it iterate on it by just repeatedly prompting it to continue, it will happily churn forever on the goal, turning the codebase into a useless spaghetti mess with very high probability, and growing it more and more without ever cutting anything back. That's what happens without human intervention regarding system state and manipulation. The main issues here are most prompts that are extremely underspecified ("fix the issue with the buttons on the main page") so AI will ingest context data it likely generated itself in a previous step and assumptions from its own training data, then act on that to produce a new state. Think of it like a random walk, the AI makes a small step in one random direction to achieve a goal, that brings the system to a new state which is now the basis for the next step, and so on. If there's no (or not enough) corrective action that pulls the system back to a known good reference state it will keep wandering in random directions.

That's the main issue, people have a hard time steering recursive, probabilistic systems, especially when they never look at the output of the system after each step and correct it. And let's be real, if you examine AI generated output in great detail after each iteration you're often better off writing the code yourself, so I would argue that the promised speed up of agentic development can only be realized if you stop inspecting every output of the system. And it seems we still haven't figured out how to specify the steering instructions that keep a system close to a given ideal state that allow unsupervised, recursive work on most codebases. I think some codebases are by themselves better suited for this as they provide a more rigid harness for AI development and exist in the training data (e.g. CRUD apps using RoR), whereas complex software that doesn't use rigid frameworks is at much higher risk of destruction by AI as there's no reference point in the training data that would hold the AI back from randomly walking to a garbage state.

And that's why people have such different views on agentic software development, some work on codebases that are better represented in the training data and so have great success using agentic tools on them, others work on software that isn't represented so well so AI does poorly on it. I don't think it's an issue with quality management, from my own experiments no amount of hand-written rules or system prompts will keep AI from destroying a codebase for which it doesn't have a strong idea how the code is supposed to look from its own training data in the first place. As another experiment, try giving AI strict rules about how to change code or introduce new features, it will always find a way around them or appropriate them in a maliciously funny way that you haven't anticipated. That's also an artefact of the training process, these systems aren't designed to say no or do nothing, they produce outputs to achieve goals and they will bend your rules to the greatest amount possible if it helps with goal fulfilment.