Since I worked as an architect some comments.

Architecture is fine for big, complex projects. Having everything planned out before keeps cost down, and ensures customer will not come with late changes. But if cost are expected to be low, and there's no customer, architecture is overkill. It's like making a movie without following the script line by line (watch Godard in Novelle Vague), or building it by yourself or by a non-architect. 2x faster, 10x cheaper. You immediately see an inflexible overarchitectured project.

You can do fine by restricting the agent with proper docs, proper tests and linters.