A narrow role, clean context, and timely resets
I would address overengineering not with another massive prompt, but with three simple constraints: a narrow role, a small active context, and a reset for a compromised session. The primary source here is not a company announcement or a model card, but a developer discussion provided for review. It has no date, so this is a practical analysis of observations rather than a breaking product update.
The first technique sounds almost too simple: assign the assistant the role of a strict minimalist. In the discussion, participants used wording that explicitly limited the goal to the smallest possible number of changed files and lines. This works better than a vague request such as do not overcomplicate things: the model receives a verifiable criterion for evaluating its proposed patch. One task, the simplest correct solution, and no related restructuring unless requested.
The second technique concerns long sessions. One participant notes that odd behavior usually begins once a large context has accumulated, even when rules are written in the prompt and in AGENTS.md. Their working approach is to start a session with a small, typical task, confirm that the assistant has adopted the right style, and then reuse that successful state for similar follow-up tasks and forks.
The third technique is stricter but clearer: when the assistant produces unsuitable edits, discard the changes and restart the task. Only the role, the task itself, and the key rules move into the new session. Asking the model to forget the past can be part of such a restart, but from an engineering perspective it is more reliable not to carry the old history forward. Otherwise, the noise remains noise, merely covered by a new instruction.
What this changes in day-to-day coding
The main takeaway is that reliability depends not only on the model you choose, but also on the session lifecycle. A short prompt sets boundaries, a small context reduces random assumptions, and a reset prevents a mistaken direction from becoming embedded in later answers.
This is especially noticeable during code cleanup. The goal is usually local, so an unexpected architectural overhaul makes review more expensive and obscures the original task. I would first check the diff size, the number of affected files, and whether any changes were made that the request never required. If the boundaries are violated again, continuing the conversation is often less useful than starting clean.
At the same time, the minimalist role is not a guarantee: the same discussion includes a complaint that the assistant ignores both the prompt and AGENTS.md. That means a prompt remains a soft constraint, while reverting, forking, and starting a new session become part of quality control. Reliability begins not with perfect wording, but with a willingness to discard corrupted context.