Defocus is not honored for arc edges.

[iago-lito]

I think the blue and red lines should be almost overlapping in the following diagram, should they not?

#import "@preview/fletcher:0.5.4" as fl: node, edge

#set page(
  width: auto,
  height: auto,
  margin: 1mm,
)

#let line = (stroke: blue)
#let arc = (bend: 1deg, stroke: red)

#fl.diagram(
  node-stroke: .1em,

  node((0, 0), name: <O>,
    shape: rect,
    defocus: 1,
    [defocus: 1],
  ),

  node((-1, -1), name: <A>, []),
  node((-1,  1), name: <B>, []),
  node(( 1,  1), name: <C>, []),
  node(( 1, -1), name: <D>, []),

  // Defocus honored ❤️.
  edge(<A>, <O>, ..line),
  edge(<B>, <O>, ..line),
  edge(<C>, <O>, ..line),
  edge(<D>, <O>, ..line),

  // Defocus unhonored 💔.
  edge(<A>, <O>, ..arc),
  edge(<B>, <O>, ..arc),
  edge(<C>, <O>, ..arc),
  edge(<D>, <O>, ..arc),

)