cimery Sprint 1 — Rust 워크스페이스 + 전 계층 파이프라인

8개 크레이트 구현, cargo test 32개 전부 통과:
- core: Mm/M 단위 newtype, UnitExt 리터럴, FeatureError
- ir: GirderIR + 전 단면 파라미터(PSC-I/U/SteelBox/PlateI) serde JSON
- dsl: Girder builder + 검증 (경간 범위·count·spacing)
- kernel: GeomKernel trait + StubKernel (box mesh, AABB)
- incremental: dirty-tracking IncrementalDb (salsa 업그레이드 경로 주석)
- evaluator: 상태 없는 IR→kernel 브리지
- usd: USDA 1.0 텍스트 익스포트 (CimeryBridgeAPI·GirderAPI schema)
- viewer: wgpu 22 + winit 0.30 컬러 삼각형 (Sprint 1 proof-of-concept)

Sprint 2 다음 단계:
- opencascade-rs로 StubKernel 교체 (실제 PSC-I sweep)
- viewer에서 Girder Mesh 렌더 + 카메라 orbit

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cimery/crates/kernel/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name    = "cimery-kernel"
+version.workspace = true
+edition.workspace = true
+
+[dependencies]
+cimery-ir = { workspace = true }
+thiserror = { workspace = true }
+
+[dev-dependencies]
+cimery-core = { workspace = true }

cimery/crates/kernel/src/lib.rs

@@ -0,0 +1,160 @@
+//! cimery-kernel — GeomKernel trait + mesh types + StubKernel.
+//!
+//! ADR-001: Two production backends (Sprint 2+):
+//!   - OpenCascade.js  (WASM, web)
+//!   - opencascade-rs  (native FFI, desktop)
+//! Both accessed via `GeomKernel` trait.
+//! Sprint 1: `StubKernel` returns simple box geometry for architecture validation.
+
+use cimery_ir::GirderIR;
+
+// ─── Mesh ─────────────────────────────────────────────────────────────────────
+
+/// Triangle mesh produced by a geometry kernel.
+///
+/// Coordinate convention: X = width, Y = height, Z = along-span axis.
+/// Units: millimetres.
+#[derive(Debug, Clone)]
+pub struct Mesh {
+    /// Interleaved [x, y, z] vertex positions in mm.
+    pub vertices: Vec<[f32; 3]>,
+    /// Triangle indices into `vertices`, 3 entries per triangle.
+    pub indices:  Vec<u32>,
+    /// Per-vertex normals (unit vectors).
+    pub normals:  Vec<[f32; 3]>,
+}
+
+impl Mesh {
+    pub fn vertex_count(&self)   -> usize { self.vertices.len() }
+    pub fn triangle_count(&self) -> usize { self.indices.len() / 3 }
+
+    /// Axis-aligned bounding box: ([min_x, min_y, min_z], [max_x, max_y, max_z])
+    pub fn aabb(&self) -> ([f32; 3], [f32; 3]) {
+        let mut mn = [f32::INFINITY; 3];
+        let mut mx = [f32::NEG_INFINITY; 3];
+        for v in &self.vertices {
+            for i in 0..3 {
+                if v[i] < mn[i] { mn[i] = v[i]; }
+                if v[i] > mx[i] { mx[i] = v[i]; }
+            }
+        }
+        (mn, mx)
+    }
+}
+
+// ─── Error ────────────────────────────────────────────────────────────────────
+
+#[derive(Debug, thiserror::Error)]
+pub enum KernelError {
+    #[error("geometry computation failed: {0}")]
+    Computation(String),
+    #[error("invalid input for kernel: {0}")]
+    InvalidInput(String),
+}
+
+// ─── Trait ────────────────────────────────────────────────────────────────────
+
+/// Backend-agnostic geometry kernel.
+///
+/// All implementations MUST be deterministic: same IR → same Mesh topology.
+/// Floating-point values may differ within kernel tolerance (< 1 µm).
+pub trait GeomKernel: Send + Sync {
+    fn girder_mesh(&self, ir: &GirderIR) -> Result<Mesh, KernelError>;
+}
+
+// ─── StubKernel ───────────────────────────────────────────────────────────────
+
+/// Stub geometry backend for Sprint 1.
+///
+/// Returns a simple rectangular box for any girder.
+/// - X = 600 mm (fixed width stub)
+/// - Y = 1800 mm (fixed height stub)
+/// - Z = girder span in mm
+///
+/// Replace with `OcctKernel` in Sprint 2.
+pub struct StubKernel;
+
+impl GeomKernel for StubKernel {
+    fn girder_mesh(&self, ir: &GirderIR) -> Result<Mesh, KernelError> {
+        if ir.span_m() <= 0.0 {
+            return Err(KernelError::InvalidInput(
+                format!("span must be positive, got {} m", ir.span_m()),
+            ));
+        }
+
+        let len = ir.span_mm() as f32;
+        let w   = 600.0_f32;
+        let h   = 1800.0_f32;
+
+        // 8 corners: indices 0-3 at Z=0, 4-7 at Z=len
+        let vertices: Vec<[f32; 3]> = vec![
+            [0.0, 0.0, 0.0], [w,   0.0, 0.0], [w,   h, 0.0], [0.0, h, 0.0],
+            [0.0, 0.0, len], [w,   0.0, len], [w,   h, len], [0.0, h, len],
+        ];
+
+        // 12 triangles (2 per face × 6 faces), CCW winding from outside
+        let indices: Vec<u32> = vec![
+            // -Z face
+            0, 2, 1,   0, 3, 2,
+            // +Z face
+            4, 5, 6,   4, 6, 7,
+            // -X face
+            0, 4, 7,   0, 7, 3,
+            // +X face
+            1, 2, 6,   1, 6, 5,
+            // -Y face (bottom)
+            0, 1, 5,   0, 5, 4,
+            // +Y face (top)
+            3, 7, 6,   3, 6, 2,
+        ];
+
+        let normals = vec![[0.0_f32, 1.0, 0.0]; vertices.len()];
+
+        Ok(Mesh { vertices, indices, normals })
+    }
+}
+
+// ─── Tests ────────────────────────────────────────────────────────────────────
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use cimery_core::{MaterialGrade, SectionType};
+    use cimery_ir::{FeatureId, GirderIR, PscISectionParams, SectionParams};
+
+    fn test_girder(span_m: f64) -> GirderIR {
+        GirderIR {
+            id: FeatureId::new(),
+            station_start:          0.0,
+            station_end:            span_m,
+            offset_from_alignment:  0.0,
+            section_type:           SectionType::PscI,
+            section: SectionParams::PscI(PscISectionParams::kds_standard()),
+            count:    1,
+            spacing:  0.0,
+            material: MaterialGrade::C50,
+        }
+    }
+
+    #[test]
+    fn stub_produces_box_mesh() {
+        let mesh = StubKernel.girder_mesh(&test_girder(40.0)).unwrap();
+        assert_eq!(mesh.vertex_count(),   8);
+        assert_eq!(mesh.triangle_count(), 12);
+    }
+
+    #[test]
+    fn aabb_spans_correctly() {
+        let ir   = test_girder(40.0);
+        let mesh = StubKernel.girder_mesh(&ir).unwrap();
+        let (mn, mx) = mesh.aabb();
+        assert!((mx[2] - ir.span_mm() as f32).abs() < 0.01);
+        assert!(mn[2] < 0.001); // Z min ≈ 0
+    }
+
+    #[test]
+    fn zero_span_fails() {
+        let err = StubKernel.girder_mesh(&test_girder(0.0));
+        assert!(matches!(err, Err(KernelError::InvalidInput(_))));
+    }
+}