Function draw_pin_stub 

pub fn draw_pin_stub(
    edge: Pos2,
    tip: Pos2,
    kind: PinDir,
    stroke: impl Into<RoleStroke>,
    painter: &Style<'_, impl Renderer>,
)

Draw a pin/port stub from edge (the outline’s outer face — see pin_stub_endpoints) out to tip, with an arrowhead flush against the shape so input and output pins read symmetrically:

• Input: apex on the edge, pointing into the shape.
• Output: base on the edge, pointing away (apex one length out).
• InOut: a plain line, no arrowhead.

The stub starts exactly at edge, so it butts against the outline instead of crossing into it; its bare remainder reaches tip, where routes connect.