Construction contract before building permit?

When you buy a house "off the shelf," whether a solid or prefabricated house, the construction company usually submits the building application, right, or is that not the case?

You probably mean building a house with a construction company or general contractor and not buying a house from a property developer?!
Because if you buy a house, you don't have that whole issue.
As the builder, you submit the building application. It is prepared for you by the architect and you sign it.

I have the feeling that buying a plot of land for which there is no development plan always poses a risk.

No, not really.
As long as it is building land and a professional follows the known rules, he knows what roughly fits on it.
Look at the plot and look at the neighboring plots: usually it then becomes clear why a semi-detached house was planned there.
Counties and municipalities also have a minimum size for plots: often real division is not possible. Thus, one plans a semi-detached house with ideal division, etc.
If you find no reasons (insufficient size, poor dimensions, other restrictions according to Par 34 of the Building Code) then one could assume it can be divided.
I can well imagine that there is a plausible reason for the semi-detached house planning.

Regarding the contract: be careful that the general contractor does not later want money as an intermediary after the revocation period. You have used a service from him.

On 22.04. we signed the contract with Town & Country. On 23.04. an advertisement for a plot of land was published. The Town & Country representative made us aware of this. However, the plot still has to be divided. There is no development plan. There is an old but still valid preliminary building permit. However, this applies to a semi-detached house. We would like to build a detached single-family house after division. [...] Our idea was: to coordinate with the building authority next week whether a division and development with two single-family houses would be possible. Of course, this would only be a non-binding statement.

The validity of the preliminary building permit would, of course, expire with the division of the plot. A plot intended for a semi-detached house (i.e., a one-sided extension on the neighbor's boundary on the other side than that created by a division) would hardly be suitable for erecting a detached building. Sorry, somehow your story sounds very confused – a cadastral excerpt might help to understand it (I hope). A division of the plot also entails new setback areas. Does the "division" possibly mean that you want to divide a plot in depth?

The other half of the plot would be purchased by the Town & Country representative and then later developed with the second detached single-family house.

Believe that whoever wants to – he is probably not ashamed of any brazen joke at all.

When you buy a house "off the shelf," whether solid or prefabricated, the construction company usually files the building application, or is that not the case?

The answer "or is that not the case" is correct. Legally, the building application is filed by the builder; he only must use an authorized plan submitter (which can also be done through the construction company).

I have the feeling that buying a plot of land for which there is no development plan always involves a risk.

Basically, that is true again – however, you are the risk conjurer here, since you could actually realize the existing preliminary building permit (if you do not divide the plot beforehand).

Our idea was: to coordinate with the building authority next week whether a subdivision and development with two single-family houses would be possible. This would, of course, only be a non-binding statement.

P.S.: no, the building authority confirms or denies the divisibility just as bindingly as the preliminary building inquiry.

Thank you very much for the many constructive feedbacks!
The revocation was accepted and confirmed without any problems today.

, I found your feedback not very constructive but rather rude. Since you have worked so vigorously on my question, here is a classification or clarification for your peace of mind, in case my previous explanation was too vague:
The preliminary building inquiry was made many years ago and a semi-detached house was specifically requested from the city. The surrounding development consists exclusively of detached single-family houses. The plot size of over 1,000 m² (approx. 25*40) does allow for a different layout from a planning perspective. After a short phone call with the lady from the city, she also confirmed this—subject of course to further review.
The plot of over 1,000 m² could also be divided so that two single-family houses would fit. I do not understand in what way this is supposed to be "confused". Your preceding "sorry" is also not helpful.

I had assumed that I have to sign the building application. After all, I do want to build. But I would be presented with it ready for signature. My wording was somewhat amateurish, but if I knew my way around, I wouldn’t write in the forum.

I also don’t understand how I am invoking a risk. There is a plot without a development plan. An old preliminary building inquiry for your semi-detached house was approved. I want to deviate from this and obtain this information from the city. If it is not possible, then the plot simply won’t be purchased.

I am aware that a preliminary building inquiry is binding. My wording "non-binding" indicated that I wanted to obtain information in advance outside of a procedure that leads to an administrative act. The lady from the building authority also offered such an appointment on her own initiative.

@11ant, I found your feedback to be less constructive and rather rude. Since you tackled my question so energetically, here is a classification or clarification for your peace of mind, in case my previous presentation was too vague:

My contribution was as thorough and constructive as possible; unfortunately, you did not respond to my follow-up question. If my peace of mind could not endure that, on average, one ungrateful original poster appears per five thousand of my posts, then I would be in the wrong place here. Of course, I do not want to hold the readers collectively responsible for this rude reaction on your part and will therefore gladly continue to address your problem:

The plot of over 1,000 m² could also be divided in such a way that two single-family houses would have space. How this is supposed to be "confused" is not clear to me. Your prefixed "sorry" is also not helpful.

My regret is sincere. The confusion arises from the contradiction between the plot size and the building preliminary approval for a semi-detached house (and as said, this would be easy to clarify). If you prefer to strike the helping hand, that is unfortunate but cannot be changed by me. After all, there is a "professional risk" even in "volunteering" and hobby.

That I have to sign the building application, I had assumed. After all, I do want to build. But I would be presented with a signature-ready application. My wording was somewhat amateurish, but if I knew my way around, I would not be writing in the forum.

You will receive the signature-ready application from your architect if you commission one. From your general contractor's plan submitter, you will only receive such "necessary architectural services" against what I call a "deposit" (or more often alternatively after signing the construction contract). How the general contractor protects themselves here against freeloading planners varies.

I also do not understand in what way I am conjuring up a risk. There is a plot without a development plan. An old building preliminary inquiry for your semi-detached house was approved. I want to deviate from this and obtain this information from the city. If it does not work, the plot simply will not be bought. I am aware that a building preliminary inquiry is binding. My wording "non-binding" indicated that I wanted to obtain information in advance outside of a procedure that results in an administrative act.

In the current state (valid building preliminary approval, undivided plot), there is no risk of being able to carry out the approved building project even without a development plan—that does not require a development plan. You are the one conjuring the approval risk (by changing the subject of the application and/or dividing the plot, which is a significant basis of the building preliminary approval). What you inaccurately described as non-binding was the divisibility (which can be affirmed or denied as binding as the actual buildability).