gludion

The problem is not the extra coincident nodes, but the fact that they are two closed curves.

Video_2023-12-11_182946.mp4    

There is another segment in your document that looks strikingly similar to the process of creating a spiral 🙂

 
Yes, there is an bug in the document that needs to be corrected. But since many operations depend on whether or not the curve is closed, this explicit indication of the curve type would help easier identification of the bug/incorrect curve type. In the given case, it is clear that Affinity "knows" that the curve is closed - and therefore does not offer a Join, but the user "does not know" - because it is not obvious from the shape of the curve.

If you are trying to create a spiral, you can try the new Spiral Tool.
https://affinity.help/designer2/English.lproj/pages/Tools/tools_spiral.html

@R C-R See image for a visual of @RM f/g insight.
 

bug fm insight.afdesign

When I open the bug.afdesign file the two curves are not expanded or arcs as in your bug2 file -- they are just simple open curves with one node at each end.
In fact, if I start from scratch & like the OP create two pie shapes, convert them to curves & delete all but a pair of different-sized arcs like in the original bug file, Join curves is not greyed out & works as expected.
I have included bug3.afdesign in which I created two new pie shapes, converted them to curves, removed the unneeded curve segments, & joined them. The history is included so you can see how I did that.
So I do not know why Join Curves does not work on the OP's curves. What am I missing?

They seem lines but they are not.
Have a look at the attachment.
bug2.afdesign

Uncheck

 
Inside this special layer

Hello,
I've a suggestion/wish for Affinity Designer but I'm not sure it's the right place for posting this (thx for moving the post here)
I've noticed that exporting SVG can sometimes result in a big file size (which is quite a paradox as vectors as supposed to be smaller). This is also the case in 1.7 beta.
Some reasons:
vector strokes with pressure are exported with a huge amount of points. However if I "expand stroke" before exporting, AD intelligently distribute an optimized amount of points and the resulting export is much smaller. However, the vector "spine" of the stroke is lost, and cannot be conveniently edited anymore. when exporting text as curves, each glyph data is duplicated if the glyph is used more than one symbols are duplicated if used more than once Some suggestions: could the SVG exporter:
perform "expand stroke" for pressure strokes, only for the SVG export? use <symbol> SVG tag to store AD symbols or glyph data and re-use the data using <use>, which result in smaller file size? Thanks

Hi Gludion,
Welcome to the Forums
Dragging a layer onto the thumbnail of another layer will make it mask that layer
I hope this helps
C

My post here includes a screenshot that demonstrates the difference between cropping (or masking) and clipping.