ModelCraft foundation: workspace, quality gates, FE model, command engine, geometry boundary

A pure-Rust CAE modeling workspace following the SolidCraft conventions:
- modelcraft-model: nodes and elements by label with hostile-input validation
- modelcraft-geometry: SolidCraft's kernel (pinned git dependency) behind our own API;
  tessellation into a face-tagged boundary surface for volume meshing
- modelcraft-engine: CommandSpec registry, Session::execute with rollback and panic guard,
  scripts and a journal
- modelcraft-cli: list commands, run scripts
- xtask: layers (only geometry may use solidcraft-*), assets, licences, tests, wasm, ci
- AGENTS.md, architecture, ADR 0001 (libraries and licences), roadmap, CI

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

crates/geometry/src/lib.rs

@@ -0,0 +1,141 @@
+//! The geometry boundary.
+//!
+//! Meshing in ModelCraft starts from a triangulated boundary surface. This crate produces it:
+//! B-rep bodies come from SolidCraft's kernel (`solidcraft-kernel`, a pinned git dependency;
+//! plan/adr/0001-libraries.md) and leave it as a [`SurfaceMesh`] from SolidCraft's tessellator,
+//! with each triangle tagged by the B-rep face it lies on (for feature edges and for loads and
+//! boundary conditions on faces). No SolidCraft type appears in the public API, so the kernel can
+//! be replaced without touching the rest of the workspace. Only this crate may depend on
+//! `solidcraft-*` (`cargo xtask layers` enforces it).
+//!
+//! Lengths are millimetres.
+#![deny(clippy::unwrap_used, clippy::expect_used, clippy::panic, clippy::unimplemented, clippy::todo, clippy::unreachable)]
+#![forbid(unsafe_code)]
+
+use solidcraft_kernel::{Body, KernelError, guard};
+
+#[derive(Debug, Clone, PartialEq, thiserror::Error)]
+pub enum Error {
+    #[error("invalid input: {0}")]
+    Invalid(String),
+    #[error("the geometry operation failed: {0}")]
+    Failed(String),
+}
+
+pub type Result<T> = std::result::Result<T, Error>;
+
+impl From<KernelError> for Error {
+    fn from(e: KernelError) -> Self {
+        match e {
+            KernelError::Invalid(m) => Error::Invalid(m),
+            other => Error::Failed(other.to_string()),
+        }
+    }
+}
+
+/// A solid body.
+#[derive(Debug, Clone)]
+pub struct Shape {
+    pub name: String,
+    body: Body,
+}
+
+/// Mass properties and extent of a [`Shape`].
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct Measure {
+    pub volume: f64,
+    pub area: f64,
+    pub centroid: [f64; 3],
+    pub bbox_min: [f64; 3],
+    pub bbox_max: [f64; 3],
+    pub faces: usize,
+}
+
+/// A triangulated boundary surface: the input to volume meshing.
+#[derive(Debug, Clone, Default, PartialEq)]
+pub struct SurfaceMesh {
+    pub positions: Vec<[f64; 3]>,
+    /// Counter-clockwise seen from outside.
+    pub triangles: Vec<[u32; 3]>,
+    /// The B-rep face each triangle lies on.
+    pub tri_face: Vec<u32>,
+}
+
+fn xyz(v: solidcraft_geom::Vec3) -> [f64; 3] {
+    [v.x, v.y, v.z]
+}
+
+/// A box between two corners.
+pub fn block(a: [f64; 3], b: [f64; 3]) -> Result<Shape> {
+    let v = |p: [f64; 3]| solidcraft_geom::Vec3 { x: p[0], y: p[1], z: p[2] };
+    let body = guard("block", || solidcraft_kernel::box_solid(v(a), v(b)))?;
+    Ok(Shape { name: "Block".into(), body })
+}
+
+impl Shape {
+    pub fn measure(&self) -> Result<Measure> {
+        let m = guard("measure", || solidcraft_kernel::measure(&self.body))?;
+        Ok(Measure {
+            volume: m.volume,
+            area: m.area,
+            centroid: xyz(m.centroid),
+            bbox_min: xyz(m.bbox.min),
+            bbox_max: xyz(m.bbox.max),
+            faces: m.faces,
+        })
+    }
+
+    /// Triangulate the boundary within `tolerance` (chordal deviation, mm).
+    pub fn tessellate(&self, tolerance: f64) -> Result<SurfaceMesh> {
+        if !(tolerance > 0.0 && tolerance.is_finite()) {
+            return Err(Error::Invalid(format!("tessellation tolerance must be a positive number, got {tolerance}")));
+        }
+        let m = guard("tessellate", || self.body.tessellate(tolerance))?;
+        Ok(SurfaceMesh { positions: m.positions.into_iter().map(xyz).collect(), triangles: m.triangles, tri_face: m.tri_face })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn block_measures() {
+        let m = block([0., 0., 0.], [10., 20., 30.]).unwrap().measure().unwrap();
+        assert!((m.volume - 6000.0).abs() < 1e-6, "{}", m.volume);
+        assert!((m.area - 2200.0).abs() < 1e-6, "{}", m.area);
+        assert_eq!(m.faces, 6);
+        assert_eq!(m.bbox_max, [10., 20., 30.]);
+    }
+
+    #[test]
+    fn tessellation_covers_every_face_and_encloses_the_volume() {
+        let mesh = block([0., 0., 0.], [2., 3., 4.]).unwrap().tessellate(0.01).unwrap();
+        assert_eq!(mesh.triangles.len(), mesh.tri_face.len());
+        let mut faces: Vec<u32> = mesh.tri_face.clone();
+        faces.sort_unstable();
+        faces.dedup();
+        assert_eq!(faces.len(), 6);
+        // Divergence theorem: the outward-oriented triangles enclose the block's volume.
+        let p = |i: u32| mesh.positions[i as usize];
+        let six_v: f64 = mesh
+            .triangles
+            .iter()
+            .map(|t| {
+                let (a, b, c) = (p(t[0]), p(t[1]), p(t[2]));
+                a[0] * (b[1] * c[2] - b[2] * c[1]) - a[1] * (b[0] * c[2] - b[2] * c[0]) + a[2] * (b[0] * c[1] - b[1] * c[0])
+            })
+            .sum();
+        assert!((six_v / 6.0 - 24.0).abs() < 1e-9, "{}", six_v / 6.0);
+    }
+
+    #[test]
+    fn hostile_input_is_an_error() {
+        assert!(block([0.; 3], [0.; 3]).is_err());
+        assert!(block([0.; 3], [f64::NAN, 1., 1.]).is_err());
+        let b = block([0.; 3], [1.; 3]).unwrap();
+        for t in [0.0, -1.0, f64::NAN, f64::INFINITY] {
+            assert!(b.tessellate(t).is_err());
+        }
+    }
+}