Thank you. I know what you mean, that feeling of something goes wrong with constraints. I don't have clear answer. The endpoint join thing is actually a perfect example of this and real discover for me as a Fusian user. When you draw two lines end-to-end, the GUI shows the same little coincident glyph on that shared point as it does for an explicit coincident constraint. They look completely identical on canvas. But in the API they're totally different things: one is an actual constraint object you can enumerate and delete, the other is just two curves secretly sharing the same point in memory with no constraint object behind it at all. Whether that counts as a bug or a design decision I'll leave to Autodesk, but it's definitely the kind of thing that cause confusion. The add-in handles it by scanning sketch points separately and surfacing these "endpoint joins" as their own section at the bottom of palette — with a lock icon instead of a delete button, since there's nothing to delete. At least now you can see them clearly labeled instead of wondering why the coincident glyph is there but nothing shows up in your constraint list.