diff --git a/crates/smlib/SMLIB_REV b/crates/smlib/SMLIB_REV
index c214fc77fe..a52a30d734 100644
--- a/crates/smlib/SMLIB_REV
+++ b/crates/smlib/SMLIB_REV
@@ -1 +1 @@
-1934b5799653dd205182456943bfb29beccaae92
+c46946993db8e757ed6f4cc1983ab277a7891b1d
diff --git a/crates/smlib/src/ffi/ops.rs b/crates/smlib/src/ffi/ops.rs
index f79977eade..248086e4b5 100644
--- a/crates/smlib/src/ffi/ops.rs
+++ b/crates/smlib/src/ffi/ops.rs
@@ -1,4 +1,4 @@
-//! The operations block of `capi/include/smlib.h` (`smlib_boolean`, `smlib_fillet`,
+//! The operations block of `capi/include/smlib.h` (`smlib_boolean`, `smlib_boolean2d`, `smlib_fillet`,
 //! `smlib_chamfer`, `smlib_blend`, `smlib_fillet_variable`, `smlib_chamfer_sides`, `smlib_shell`, `smlib_offset_faces`,
 //! `smlib_thicken`, `smlib_draft`, `smlib_merge_faces`, `smlib_brep_solid_count`, `smlib_imprint`; the fork's `capi/src/smlib_ops.cpp`), declared by
 //! hand. Part of the FFI boundary, like its parent: called only through
@@ -48,6 +48,7 @@ type PickFn = unsafe extern "C" fn(*const RawBrep, *const f64, i64, f64, f64, *m
 #[cfg(feature = "native")]
 unsafe extern "C" {
     fn smlib_boolean(a: *const RawBrep, b: *const RawBrep, op: i32, out: *mut *mut RawBrep) -> i32;
+    fn smlib_boolean2d(a: *const RawBrep, b: *const RawBrep, op: i32, out: *mut *mut RawBrep) -> i32;
     fn smlib_brep_solid_count(brep: *const RawBrep, out: *mut i64) -> i32;
     fn smlib_imprint(body: *const RawBrep, tool: *const RawBrep, out: *mut *mut RawBrep) -> i32;
     fn smlib_fillet(
@@ -148,6 +149,11 @@ pub fn boolean(a: &Handle, b: &Handle, op: i32) -> Result<Handle, i32> {
     new_brep(|out| unsafe { smlib_boolean(a.raw(), b.raw(), op, out) })
 }
 
+#[cfg(feature = "native")]
+pub fn boolean2d(a: &Handle, b: &Handle, op: i32) -> Result<Handle, i32> {
+    new_brep(|out| unsafe { smlib_boolean2d(a.raw(), b.raw(), op, out) })
+}
+
 #[cfg(feature = "native")]
 pub fn imprint(body: &Handle, tool: &Handle) -> Result<Handle, i32> {
     new_brep(|out| unsafe { smlib_imprint(body.raw(), tool.raw(), out) })
@@ -309,6 +315,11 @@ pub fn boolean(_: &Handle, _: &Handle, _: i32) -> Result<Handle, i32> {
     Err(NOT_BUILT)
 }
 
+#[cfg(not(feature = "native"))]
+pub fn boolean2d(_: &Handle, _: &Handle, _: i32) -> Result<Handle, i32> {
+    Err(NOT_BUILT)
+}
+
 #[cfg(not(feature = "native"))]
 pub fn imprint(_: &Handle, _: &Handle) -> Result<Handle, i32> {
     Err(NOT_BUILT)
diff --git a/crates/smlib/src/ffi/sweeps.rs b/crates/smlib/src/ffi/sweeps.rs
index 12d547b89a..d3b9476050 100644
--- a/crates/smlib/src/ffi/sweeps.rs
+++ b/crates/smlib/src/ffi/sweeps.rs
@@ -1,5 +1,5 @@
 //! The sweeps block of `capi/include/smlib.h` (`smlib_extrude`, `smlib_revolve`, `smlib_sweep`,
-//! `smlib_sweep_placed`, `smlib_loft`, `smlib_loft_to_point`, `smlib_screw_sweep`, `smlib_sweep_stations`; the fork's
+//! `smlib_sweep_placed`, `smlib_loft`, `smlib_loft_to_point`, `smlib_screw_sweep`, `smlib_sweep_stations`, `smlib_planar_faces`; the fork's
 //! `capi/src/smlib_sweeps.cpp`), declared by hand.
 //! Part of the FFI boundary, like its parent: called only through [`crate::sweeps`], which builds
 //! the curve lists.
@@ -54,6 +54,7 @@ impl<'a> List<'a> {
 
 #[cfg(feature = "native")]
 unsafe extern "C" {
+    fn smlib_planar_faces(kinds: *const i64, n_kinds: i64, reals: *const f64, n_reals: i64, out: *mut *mut RawBrep) -> i32;
     fn smlib_extrude(
         kinds: *const i64,
         n_kinds: i64,
@@ -147,6 +148,12 @@ fn raw(l: &List) -> Result<(*const i64, i64, *const f64, i64), i32> {
     Ok((l.kinds.as_ptr(), nk, l.reals.as_ptr(), nr))
 }
 
+#[cfg(feature = "native")]
+pub fn planar_faces(loops: &List) -> Result<Handle, i32> {
+    let (k, nk, r, nr) = raw(loops)?;
+    new_brep(|out| unsafe { smlib_planar_faces(k, nk, r, nr, out) })
+}
+
 #[cfg(feature = "native")]
 pub fn extrude(profile: &List, direction: &[f64; 3], distance: f64, draft: f64, cap: bool) -> Result<Handle, i32> {
     let (k, nk, r, nr) = raw(profile)?;
@@ -206,6 +213,11 @@ pub fn sweep_stations(profile: &List, maps: &[f64], ends: i32) -> Result<Handle,
     new_brep(|out| unsafe { smlib_sweep_stations(k, nk, r, nr, maps.as_ptr(), n, ends, out) })
 }
 
+#[cfg(not(feature = "native"))]
+pub fn planar_faces(_: &List) -> Result<Handle, i32> {
+    Err(NOT_BUILT)
+}
+
 #[cfg(not(feature = "native"))]
 pub fn extrude(_: &List, _: &[f64; 3], _: f64, _: f64, _: bool) -> Result<Handle, i32> {
     Err(NOT_BUILT)
diff --git a/crates/smlib/src/ops.rs b/crates/smlib/src/ops.rs
index 449d686a66..866d65b891 100644
--- a/crates/smlib/src/ops.rs
+++ b/crates/smlib/src/ops.rs
@@ -71,6 +71,23 @@ impl Brep {
         }
     }
 
+    /// `self` and `other`, sheets of planar faces on one plane ([`Brep::planar_faces`]), combined
+    /// as regions of that plane by `op`: `None` when the result is empty. The result's edges are
+    /// the inputs' own curves, split where they cross.
+    pub fn boolean2d(&self, other: &Brep, op: BooleanOp) -> Result<Option<Brep>> {
+        init()?;
+        let op = match op {
+            BooleanOp::Union => ffi::ops::BOOLEAN_UNION,
+            BooleanOp::Subtract => ffi::ops::BOOLEAN_SUBTRACT,
+            BooleanOp::Intersect => ffi::ops::BOOLEAN_INTERSECT,
+        };
+        match ffi::ops::boolean2d(&self.0, &other.0, op) {
+            Ok(h) => Ok(Some(Brep(h))),
+            Err(ffi::ERR_EMPTY) => Ok(None),
+            Err(s) => Err(error(s)),
+        }
+    }
+
     /// `self` with each face `tool` meets cut along the intersection, the pieces kept as faces of
     /// one body: `None` when the tool meets no face. Tagged operands give the pieces' history
     /// (each piece is a split of the face it was cut from).
diff --git a/crates/smlib/src/sweeps.rs b/crates/smlib/src/sweeps.rs
index cd082f0143..bc6e016b61 100644
--- a/crates/smlib/src/sweeps.rs
+++ b/crates/smlib/src/sweeps.rs
@@ -130,6 +130,14 @@ impl List {
 }
 
 impl Brep {
+    /// A sheet of planar faces bounded by `loops`: closed loops of curves in one plane, in any
+    /// order, nested as outer loops, their holes and islands in the holes.
+    pub fn planar_faces(loops: &[Curve]) -> Result<Brep> {
+        init()?;
+        let l = List::of(loops)?;
+        ffi::sweeps::planar_faces(&l.raw()).map(Brep).map_err(error)
+    }
+
     /// The planar `profile` extruded `distance` along the unit `direction` (square to its plane).
     /// `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).