Your concept will function, but be advised that your remaining space will be tighter than it is now with the open arch. Consider the scale of the window above carefully - borrowing light from each space is a good idea, and I see you have two different types of window above - one arch top, one palladian . . matching the other one you see in the living room but scaling up is probably a better option . . Good luck.

You can select the grid pattern for the doors, sidelights & transoms, but I recommend there are too many different arches in your home already. I would not add more.

Make sure you get the height of the doors right I'd extend some type of trim detail around the room extending the 2nd floor height. It breaks up the huge expanse of drywall.

That living room will be TINY.

I'm a big book lover and really appreciate building a library space. But first, practical questions:

Will it be an office used for full-time work at home and zoom calls that need privacy? How many people live in your home? Do you need the wall and pocket doors to shut out noise of kids? If the answer is no to these questions, I'd create the dining area space as a great office library and not add the wall and pocket doors.

Even with a transom window, your living room is going to feel like a grain silo - super tall and quite tight between the new wall and pony wall. (Could you remove the pony wall to open things up? You'd need to do the floors or place mismatched flooring with a large area rug to cover that strip.)

Before you make this big move, I'd string a line between the arch and hang drop cloths to create a fake wall. Live with it for weeks. Get a feel for the size of the two space.

Look at some inspiration pics for large rooms where one half is library office and the other is living space. You might be surprised at what you end up finding and liking that will not impede the scale of your home.

Thank you for all the suggestions. So much to think about. appreciate the help more than i can express in words.

Yes, librabry will be used as an office as well to work from home. Yes, I am on calls all day. We have 4 kids and they are homeschooled so it makes the noise that much greater. My husband has over 1K books and he is an avid reader which is why we want this library/office space.

We do plan on removing the pony wall as it serves no purpose. I will take your suggestion to look at other rooms where its all open concept..I just fear it will look messy for some reason if its all exposed.

Your house is a school, an office building, and a residence. I'd be putting up walls and doors too!

What about putting up a wall and using as the transome 2 of the square windows, as the same height as the square windows? It would add some nice repetition.

What are you doing about a door to the kitchen?

Are these pics from previous owners or is this your furniture and set up?

If I were to mimic the transome square windows from the adjasent wall would I make them small and spread a apart, or have one long triangle window?

The door to the kitchen is being closed off

The furniture is not mine, I will have a clean slate in this room.

Thank you to everyones comments and suggestions, the office has been completed.