solidcraft-smlib: SMLib's tangent draft corner meets lines at an edge (fork ccc56fd and docs)

Pinned at the fork's draft-corners head: a drafted rectangle (or any
line-line corner) has its walls meet at a corner edge under the tangent
rule as well, 6 faces rather than 14. A curvature refusal for a curve
that is neither a line nor an arc names that curve's start.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017itGh5fpMEousnZ91cYcVt

crates/smlib/SMLIB_REV

@@ -1 +1 @@
-815fe9f0f9b832bda08a584632178eb9db8af030
+04db68d0f62be428ab5bb325e33c9c7ddac25f68

crates/smlib/src/lib.rs

@@ -90,7 +90,7 @@ impl std::fmt::Display for Error {
                     sweeps::CornerRefusal::Apart => write!(f, "the draft's continued curves do not meet at the corner at {at}"),
                     sweeps::CornerRefusal::WallCloses => write!(f, "the draft closes the wall at {at} before the far end"),
                     sweeps::CornerRefusal::NotExact => {
-                        write!(f, "the draft cannot continue the walls at the corner at {at} exactly (only a line's or an arc's wall continues)")
+                        write!(f, "the draft cannot continue the walls exactly: the curve from {at} is neither a line nor an arc")
                     }
                 }
             }

crates/smlib/src/sweeps.rs

@@ -168,8 +168,9 @@ impl Brep {
     /// `draft` (radians) leans the walls: positive inward, negative outward; a drafted profile is
     /// one closed loop, its curves in order, and `direction` is its normal (either way round).
     /// `corner` closes a drafted profile's sharp corners; a corner it cannot close is
-    /// [`Error::Corner`] (or [`Error::NotExact`] where a curve there is neither a line nor an
-    /// arc, under [`DraftCorner::Curvature`]).
+    /// [`Error::Corner`] (with [`CornerRefusal::NotExact`] where, under
+    /// [`DraftCorner::Curvature`], a curve of a profile with a sharp corner is neither a line nor
+    /// an arc).
     pub fn extrude(profile: &[Curve], direction: [f64; 3], distance: f64, draft: f64, corner: DraftCorner, cap: bool) -> Result<Brep> {
         init()?;
         let l = List::of(profile)?;