Terrace door is not the same as a window, right?

That's exactly how I imagined it: flat threshold.
You didn't have any problems with rain tightness, right? At my request, an additional drainage channel will even be installed. Even though it obviously works well without it for you. That was a bit too risky for me. Nowadays, it hardly rains "normally" anymore. It's either bone dry or pouring rain.
I probably wouldn't have considered the mushroom pins in the low threshold either. I need to mention that to the floor layer.

Thanks to you all for the many helpful tips.

Nowadays there is hardly any "normal" rain anymore. Either bone dry or heavy downpour.

That is definitely nonsense. But one nasty heavy rain causing a living room flood every 10 years is enough to ruin your mood ;)

We have Premium 2.0 mushroom head locking on our Brömse windows also in the flat threshold.

I have to take a look at that at our place today. We also have the windows, doors, and the HSE from Brömse. A company from Magdeburg. ;)

Hi,

it looks like that for us too. :)