A system only one person understands is a liability
If only one developer can explain how your system works, you do not truly own it. This post argues that documentation is part of the deliverable, not an optional extra reserved for later.
Ask your developer a simple question: how does the login system work. If the only answer lives in their memory, you do not have documentation. You have a dependency on one person's continued availability, good health and goodwill.
Many small businesses discover this the hard way. A developer leaves, falls ill, or simply becomes unreachable, and the system keeps running until something breaks. Then nobody can explain why a certain function exists, why a particular workaround was chosen, or which server holds the database backup. The knowledge did not disappear because the code changed. It disappeared because it was never written down.
This is not a rare failure. It is the default outcome of any project where documentation is treated as optional, something to add later once there is time. There is never time later. The project ships, the next one starts, and the explanation stays in someone's head until it is needed and no longer available.
What documentation actually needs to cover
Good documentation is not a long manual nobody reads. It is a short, accurate record of the decisions that matter: how to deploy the system, where the credentials live, what each environment variable does and why the architecture looks the way it does rather than some simpler alternative. It should let a competent stranger, not just the original developer, keep the system running.
This matters more for small studios than large ones, not less. A large company can absorb the loss of one engineer because ten others share context. A small business working with a single developer or a small studio has no such buffer. If that relationship ends, whether by choice or by circumstance, the system needs to survive the transition intact.
A system that only one person can explain is not finished, however well it runs.
Why this should be part of the price, not an extra
At Yunaris, documentation is part of what you receive when a project is delivered, not a separate line item you negotiate for afterwards. You should own the record of how your own system works, in plain language, without needing to schedule a call to find out. That includes deployment steps, access details and a plain explanation of the architecture, handed to you alongside the working software.
Before you commission your next marketing site, web application or software product, ask the studio building it one question: what will you hand over besides the code. If the answer is vague, treat that as your first warning sign. Documentation you can read and act on, independent of any one person's memory, is not a courtesy. It is part of what you are actually paying for.