Sprint 3 — Must Feature 5종 추가 (상부→하부 순서)

상부 구조물:
- DeckSlabIR + DeckSlabBuilder + 기하학 (직사각형 슬래브 스위프)

연결부:
- BearingIR + BearingBuilder (카탈로그 기반, KDS 기본값 포함)

하부 구조물:
- PierIR + PierBuilder + 기하학 (다주 지원, 코핑 포함)
- AbutmentIR + AbutmentBuilder + 기하학 (흉벽 + 기초 + 날개벽)

core에 BearingType·PierType·ColumnShape·AbutmentType 열거형 추가
kernel: sweep.rs 공유 모듈 (sweep_profile_flat·box·prism·merge)
psc_i.rs → sweep.rs 의존으로 리팩터
GeomKernel trait에 4개 메서드 추가 (상부→하부 문서화 주석)

cargo test 57개 전부 통과

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

PLAN.md

@@ -14,11 +14,13 @@
 ## 현재 스프린트 (Current)
 
 ### P0 — 즉시 착수
-(없음 — 사용자 신호 대기)
+- [~] **Sprint 3 — Must Feature 구현 (상부→하부 순서)** — 진행 중
+  - 상부 구조물: Deck Slab → Cross Beam
+  - 연결부: Bearing
+  - 하부 구조물: Pier → Abutment
 
-### P1 — 다음 단계 (사용자 승인 후 착수)
-- [ ] **Sprint 2 — OCCT 실제 커널 연결** — opencascade-rs 크레이트로 StubKernel 대체. PSC I 거더 실제 B-rep sweep 생성. ADR-001 참조.
-- [ ] **Sprint 2 — wgpu에 Girder Mesh 렌더** — StubKernel mesh를 viewer에서 실제 렌더링. 카메라 orbit(Revit ViewCube 방식).
+### P1 — 다음 단계
+- [ ] **Sprint 3 — OcctKernel** (`--features occt`) — VS Dev Cmd에서 `cargo clean && cargo build -p cimery-kernel --features occt`
 
 ---
 

cimery/crates/core/src/lib.rs

@@ -105,6 +105,48 @@ pub enum MaterialGrade {
     Sm490,
 }
 
+/// Bearing type (support device between girder and substructure).
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum BearingType {
+    Elastomeric,    // 탄성받침 — most common, PSC bridge
+    Pot,            // 포트받침 — steel box, large loads
+    Spherical,      // 구면받침 — rotation in all directions
+    Rocker,         // 롤러받침 — fixed rotation, expansion
+    FixedPin,       // 고정핀
+}
+
+/// Pier type (교각 형식).
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum PierType {
+    SingleColumn,   // 단주식
+    MultiColumn,    // 다주식
+    Hammerhead,     // 해머헤드식
+    Wall,           // 벽식
+    Portal,         // 문형
+}
+
+/// Pier column cross-section.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum ColumnShape {
+    Circular,
+    Rectangular,
+    Oval,
+}
+
+/// Abutment type (교대 형식).
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum AbutmentType {
+    ReverseT,       // 역T형 — most common
+    Wall,           // 중력식
+    SemiIntegral,   // 반일체식
+    Integral,       // 일체식
+    Counterfort,    // 부벽식
+}
+
 // ─── Tests ────────────────────────────────────────────────────────────────────
 
 #[cfg(test)]

cimery/crates/dsl/src/abutment.rs

@@ -0,0 +1,122 @@
+//! Abutment (교대) Feature builder.
+
+use cimery_core::{AbutmentType, FeatureError, MaterialGrade, Mm, M, UnitExt};
+use cimery_ir::{AbutmentIR, FeatureId, WingWallIR};
+
+#[derive(Debug)]
+pub struct Abutment {
+    pub ir: AbutmentIR,
+}
+
+impl Abutment {
+    pub fn builder() -> AbutmentBuilder { AbutmentBuilder::default() }
+}
+
+/// Builder for an Abutment Feature.
+#[derive(Default)]
+pub struct AbutmentBuilder {
+    station:                 Option<M>,
+    skew_angle:              Option<f64>,
+    abutment_type:           Option<AbutmentType>,
+    breast_wall_height:      Option<Mm>,
+    breast_wall_thickness:   Option<Mm>,
+    breast_wall_width:       Option<Mm>,
+    footing_length:          Option<Mm>,
+    footing_width:           Option<Mm>,
+    footing_thickness:       Option<Mm>,
+    wing_length:             Option<Mm>,   // simplified: same left & right
+    material:                Option<MaterialGrade>,
+}
+
+impl AbutmentBuilder {
+    /// #[param(unit="m")] Station along alignment
+    pub fn station(mut self, v: M) -> Self { self.station = Some(v); self }
+    /// #[param(unit="deg", range=-45.0..=45.0, default=0.0)]
+    pub fn skew_angle(mut self, v: f64) -> Self { self.skew_angle = Some(v); self }
+    /// #[param(enum=AbutmentType, default=ReverseT)]
+    pub fn abutment_type(mut self, t: AbutmentType) -> Self { self.abutment_type = Some(t); self }
+    /// #[param(unit="mm", range=2000.0..=12_000.0)] Breast wall height
+    pub fn breast_wall_height(mut self, v: Mm) -> Self { self.breast_wall_height = Some(v); self }
+    /// #[param(unit="mm", range=500.0..=3000.0, default=800.0)]
+    pub fn breast_wall_thickness(mut self, v: Mm) -> Self { self.breast_wall_thickness = Some(v); self }
+    /// #[param(unit="mm")] Breast wall transverse width
+    pub fn breast_wall_width(mut self, v: Mm) -> Self { self.breast_wall_width = Some(v); self }
+    /// #[param(unit="mm", range=2000.0..=8000.0, default=4000.0)] Footing along span
+    pub fn footing_length(mut self, v: Mm) -> Self { self.footing_length = Some(v); self }
+    /// #[param(unit="mm")] Footing transverse width
+    pub fn footing_width(mut self, v: Mm) -> Self { self.footing_width = Some(v); self }
+    /// #[param(unit="mm", range=500.0..=2000.0, default=1000.0)]
+    pub fn footing_thickness(mut self, v: Mm) -> Self { self.footing_thickness = Some(v); self }
+    /// #[param(unit="mm")] Wing wall length (both sides equal)
+    pub fn wing_length(mut self, v: Mm) -> Self { self.wing_length = Some(v); self }
+    /// #[param(enum=MaterialGrade, default=C30)]
+    pub fn material(mut self, m: MaterialGrade) -> Self { self.material = Some(m); self }
+
+    pub fn build(self) -> Result<Abutment, FeatureError> {
+        let station  = self.station
+            .ok_or_else(|| FeatureError::missing("abutment.station"))?.value();
+        let bw_h     = self.breast_wall_height
+            .ok_or_else(|| FeatureError::missing("abutment.breast_wall_height"))?.value();
+        let bw_w     = self.breast_wall_width
+            .ok_or_else(|| FeatureError::missing("abutment.breast_wall_width"))?.value();
+        let bw_t     = self.breast_wall_thickness.unwrap_or(800.0.mm()).value();
+        let foot_l   = self.footing_length.unwrap_or(4000.0.mm()).value();
+        let foot_w   = self.footing_width.unwrap_or_else(|| Mm(bw_w + 1000.0)).value();
+        let foot_t   = self.footing_thickness.unwrap_or(1000.0.mm()).value();
+        let wing_l   = self.wing_length.unwrap_or_else(|| Mm(bw_h * 0.8)).value();
+        let wing_h   = bw_h * 0.5;   // simplified: half the breast wall height
+        let wing_t   = bw_t;
+
+        if bw_h < 1000.0 {
+            return Err(FeatureError::validation("abutment.breast_wall_height",
+                format!("minimum 1000 mm, got {bw_h:.0} mm")));
+        }
+
+        let wing = WingWallIR { length: wing_l, height: wing_h, thickness: wing_t };
+
+        Ok(Abutment { ir: AbutmentIR {
+            id: FeatureId::new(),
+            station,
+            skew_angle:            self.skew_angle.unwrap_or(0.0),
+            abutment_type:         self.abutment_type.unwrap_or(AbutmentType::ReverseT),
+            breast_wall_height:    bw_h,
+            breast_wall_thickness: bw_t,
+            breast_wall_width:     bw_w,
+            footing_length:        foot_l,
+            footing_width:         foot_w,
+            footing_thickness:     foot_t,
+            wing_wall_left:        wing.clone(),
+            wing_wall_right:       wing,
+            material:              self.material.unwrap_or(MaterialGrade::C40),
+        }})
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use cimery_core::{AbutmentType, UnitExt};
+
+    #[test]
+    fn build_reverse_t() {
+        let a = Abutment::builder()
+            .station(100.0.m())
+            .abutment_type(AbutmentType::ReverseT)
+            .breast_wall_height(5000.0.mm())
+            .breast_wall_width(12000.0.mm())
+            .build()
+            .unwrap();
+        assert_eq!(a.ir.abutment_type, AbutmentType::ReverseT);
+        assert!((a.ir.breast_wall_height - 5000.0).abs() < f64::EPSILON);
+    }
+
+    #[test]
+    fn too_short_breast_wall_fails() {
+        let e = Abutment::builder()
+            .station(0.0.m())
+            .breast_wall_height(500.0.mm())   // < 1000
+            .breast_wall_width(10000.0.mm())
+            .build().unwrap_err();
+        assert!(matches!(e, FeatureError::Validation { .. }));
+    }
+}

cimery/crates/dsl/src/bearing.rs

@@ -0,0 +1,119 @@
+//! Bearing (받침) Feature builder.
+//!
+//! Bearing is a catalogue-based Feature: select a type and verify capacity
+//! rather than computing section geometry from scratch.
+
+use cimery_core::{BearingType, FeatureError, Mm, M};
+use cimery_ir::{BearingIR, FeatureId};
+
+#[derive(Debug)]
+pub struct Bearing {
+    pub ir: BearingIR,
+}
+
+impl Bearing {
+    pub fn builder() -> BearingBuilder { BearingBuilder::default() }
+
+    /// KDS 24.14.3 elastomeric bearing defaults for PSC-I girder.
+    pub fn elastomeric_kds() -> Result<Self, FeatureError> {
+        Self::builder()
+            .station(M(0.0))
+            .bearing_type(BearingType::Elastomeric)
+            .plan_length(Mm(350.0))
+            .plan_width(Mm(450.0))
+            .total_height(Mm(60.0))
+            .capacity_vertical(1500.0)
+            .build()
+    }
+}
+
+/// Builder for a Bearing Feature.
+///
+/// Bearings are typically selected from a catalogue.
+/// Provide dimensions and capacity from the manufacturer/catalogue data.
+#[derive(Default)]
+pub struct BearingBuilder {
+    station:           Option<M>,
+    bearing_type:      Option<BearingType>,
+    plan_length:       Option<Mm>,
+    plan_width:        Option<Mm>,
+    total_height:      Option<Mm>,
+    capacity_vertical: Option<f64>,
+}
+
+impl BearingBuilder {
+    /// #[param(unit="m")] Station along alignment
+    pub fn station(mut self, v: M) -> Self { self.station = Some(v); self }
+    /// #[param(enum=BearingType, default=Elastomeric)]
+    pub fn bearing_type(mut self, t: BearingType) -> Self { self.bearing_type = Some(t); self }
+    /// #[param(unit="mm", range=150.0..=800.0, default=350.0)] Along span
+    pub fn plan_length(mut self, v: Mm) -> Self { self.plan_length = Some(v); self }
+    /// #[param(unit="mm", range=150.0..=800.0, default=450.0)] Transverse
+    pub fn plan_width(mut self, v: Mm) -> Self { self.plan_width = Some(v); self }
+    /// #[param(unit="mm", range=30.0..=300.0, default=60.0)]
+    pub fn total_height(mut self, v: Mm) -> Self { self.total_height = Some(v); self }
+    /// #[param(unit="kN", range=100.0..=50_000.0)]
+    pub fn capacity_vertical(mut self, v: f64) -> Self { self.capacity_vertical = Some(v); self }
+
+    pub fn build(self) -> Result<Bearing, FeatureError> {
+        let station      = self.station.ok_or_else(|| FeatureError::missing("bearing.station"))?.value();
+        let bearing_type = self.bearing_type.ok_or_else(|| FeatureError::missing("bearing.bearing_type"))?;
+        let plan_length  = self.plan_length.ok_or_else(|| FeatureError::missing("bearing.plan_length"))?.value();
+        let plan_width   = self.plan_width.ok_or_else(|| FeatureError::missing("bearing.plan_width"))?.value();
+        let total_height = self.total_height.ok_or_else(|| FeatureError::missing("bearing.total_height"))?.value();
+        let cap_v        = self.capacity_vertical.ok_or_else(|| FeatureError::missing("bearing.capacity_vertical"))?;
+
+        if plan_length < 100.0 || plan_width < 100.0 {
+            return Err(FeatureError::validation("bearing.plan", "minimum plan dimension 100 mm"));
+        }
+        if cap_v <= 0.0 {
+            return Err(FeatureError::validation("bearing.capacity_vertical", "must be > 0 kN"));
+        }
+
+        Ok(Bearing { ir: BearingIR {
+            id: FeatureId::new(),
+            station,
+            bearing_type,
+            plan_length,
+            plan_width,
+            total_height,
+            capacity_vertical: cap_v,
+        }})
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use cimery_core::BearingType;
+
+    #[test]
+    fn build_elastomeric() {
+        let b = Bearing::builder()
+            .station(M(100.0))
+            .bearing_type(BearingType::Elastomeric)
+            .plan_length(Mm(350.0))
+            .plan_width(Mm(450.0))
+            .total_height(Mm(60.0))
+            .capacity_vertical(1500.0)
+            .build()
+            .unwrap();
+        assert_eq!(b.ir.bearing_type, BearingType::Elastomeric);
+    }
+
+    #[test]
+    fn kds_default() {
+        assert!(Bearing::elastomeric_kds().is_ok());
+    }
+
+    #[test]
+    fn zero_capacity_fails() {
+        let e = Bearing::builder()
+            .station(M(0.0))
+            .bearing_type(BearingType::Pot)
+            .plan_length(Mm(400.0)).plan_width(Mm(400.0)).total_height(Mm(100.0))
+            .capacity_vertical(0.0)
+            .build().unwrap_err();
+        assert!(matches!(e, FeatureError::Validation { .. }));
+    }
+}

cimery/crates/dsl/src/deck_slab.rs

@@ -0,0 +1,133 @@
+//! Deck Slab (바닥판) Feature builder.
+
+use cimery_core::{FeatureError, MaterialGrade, Mm, M, UnitExt};
+use cimery_ir::{DeckSlabIR, FeatureId};
+
+#[derive(Debug)]
+pub struct DeckSlab {
+    pub ir: DeckSlabIR,
+}
+
+impl DeckSlab {
+    pub fn builder() -> DeckSlabBuilder { DeckSlabBuilder::default() }
+}
+
+/// Builder for a Deck Slab Feature.
+///
+/// Example:
+/// ```rust
+/// use cimery_core::UnitExt;
+/// use cimery_dsl::DeckSlab;
+///
+/// let s = DeckSlab::builder()
+///     .station_start(100.0.m())
+///     .station_end(140.0.m())
+///     .width_left(5000.0.mm())
+///     .width_right(5000.0.mm())
+///     .thickness(220.0.mm())
+///     .build()
+///     .unwrap();
+/// assert!((s.ir.span_m() - 40.0).abs() < f64::EPSILON);
+/// ```
+#[derive(Default)]
+pub struct DeckSlabBuilder {
+    station_start: Option<M>,
+    station_end:   Option<M>,
+    width_left:    Option<Mm>,
+    width_right:   Option<Mm>,
+    thickness:     Option<Mm>,
+    haunch_depth:  Option<Mm>,
+    cross_slope:   Option<f64>,
+    material:      Option<MaterialGrade>,
+}
+
+impl DeckSlabBuilder {
+    /// #[param(unit="m")]
+    pub fn station_start(mut self, v: M)  -> Self { self.station_start = Some(v); self }
+    /// #[param(unit="m")]
+    pub fn station_end(mut self, v: M)    -> Self { self.station_end   = Some(v); self }
+    /// #[param(unit="mm", range=500.0..=20_000.0, default=5000.0)] Width left of centreline
+    pub fn width_left(mut self, v: Mm)    -> Self { self.width_left    = Some(v); self }
+    /// #[param(unit="mm", range=500.0..=20_000.0, default=5000.0)] Width right of centreline
+    pub fn width_right(mut self, v: Mm)   -> Self { self.width_right   = Some(v); self }
+    /// #[param(unit="mm", range=150.0..=500.0, default=220.0)]
+    pub fn thickness(mut self, v: Mm)     -> Self { self.thickness     = Some(v); self }
+    /// #[param(unit="mm", range=0.0..=300.0, default=0.0)]
+    pub fn haunch_depth(mut self, v: Mm)  -> Self { self.haunch_depth  = Some(v); self }
+    /// #[param(unit="%", range=-5.0..=5.0, default=2.0)]
+    pub fn cross_slope(mut self, v: f64)  -> Self { self.cross_slope   = Some(v); self }
+    /// #[param(enum=MaterialGrade, default=C40)]
+    pub fn material(mut self, m: MaterialGrade) -> Self { self.material = Some(m); self }
+
+    pub fn build(self) -> Result<DeckSlab, FeatureError> {
+        let station_start = self.station_start
+            .ok_or_else(|| FeatureError::missing("deck_slab.station_start"))?.value();
+        let station_end = self.station_end
+            .ok_or_else(|| FeatureError::missing("deck_slab.station_end"))?.value();
+        let width_left = self.width_left
+            .ok_or_else(|| FeatureError::missing("deck_slab.width_left"))?.value();
+        let width_right = self.width_right
+            .ok_or_else(|| FeatureError::missing("deck_slab.width_right"))?.value();
+        let thickness = self.thickness
+            .ok_or_else(|| FeatureError::missing("deck_slab.thickness"))?.value();
+
+        if station_end <= station_start {
+            return Err(FeatureError::validation("deck_slab.station_end",
+                format!("must be > station_start ({station_start:.3} m)")));
+        }
+        if thickness < 150.0 {
+            return Err(FeatureError::validation("deck_slab.thickness",
+                format!("minimum 150 mm, got {thickness:.0} mm")));
+        }
+        if width_left + width_right < 1000.0 {
+            return Err(FeatureError::validation("deck_slab.width",
+                "total width must be ≥ 1000 mm"));
+        }
+
+        Ok(DeckSlab { ir: DeckSlabIR {
+            id:           FeatureId::new(),
+            station_start,
+            station_end,
+            width_left,
+            width_right,
+            thickness,
+            haunch_depth: self.haunch_depth.unwrap_or(0.0.mm()).value(),
+            cross_slope:  self.cross_slope.unwrap_or(2.0),
+            material:     self.material.unwrap_or(MaterialGrade::C40),
+        }})
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use cimery_core::UnitExt;
+
+    fn slab() -> DeckSlab {
+        DeckSlab::builder()
+            .station_start(100.0.m())
+            .station_end(140.0.m())
+            .width_left(5000.0.mm())
+            .width_right(5000.0.mm())
+            .thickness(220.0.mm())
+            .build()
+            .unwrap()
+    }
+
+    #[test]
+    fn build_valid() {
+        let s = slab();
+        assert!((s.ir.span_m() - 40.0).abs() < f64::EPSILON);
+        assert!((s.ir.total_width() - 10_000.0).abs() < f64::EPSILON);
+    }
+
+    #[test]
+    fn too_thin_fails() {
+        let e = DeckSlab::builder()
+            .station_start(0.0.m()).station_end(40.0.m())
+            .width_left(5000.0.mm()).width_right(5000.0.mm())
+            .thickness(100.0.mm())  // < 150
+            .build().unwrap_err();
+        assert!(matches!(e, FeatureError::Validation { .. }));
+    }
+}

cimery/crates/dsl/src/lib.rs

@@ -6,4 +6,13 @@
 //! for a future macro-upgrade path and do not affect compilation.
 
 pub mod girder;
+pub mod deck_slab;
+pub mod bearing;
+pub mod pier;
+pub mod abutment;
+
 pub use girder::{Girder, GirderBuilder};
+pub use deck_slab::{DeckSlab, DeckSlabBuilder};
+pub use bearing::{Bearing, BearingBuilder};
+pub use pier::{Pier, PierBuilder};
+pub use abutment::{Abutment, AbutmentBuilder};

cimery/crates/dsl/src/pier.rs

@@ -0,0 +1,143 @@
+//! Pier (교각) Feature builder.
+
+use cimery_core::{
+    AbutmentType as _, ColumnShape, FeatureError, MaterialGrade, Mm, M, PierType, UnitExt,
+};
+use cimery_ir::{CapBeamIR, FeatureId, PierIR};
+
+#[derive(Debug)]
+pub struct Pier {
+    pub ir: PierIR,
+}
+
+impl Pier {
+    pub fn builder() -> PierBuilder { PierBuilder::default() }
+}
+
+/// Builder for a Pier Feature.
+#[derive(Default)]
+pub struct PierBuilder {
+    station:          Option<M>,
+    skew_angle:       Option<f64>,
+    pier_type:        Option<PierType>,
+    column_shape:     Option<ColumnShape>,
+    column_count:     Option<u32>,
+    column_spacing:   Option<Mm>,
+    column_diameter:  Option<Mm>,
+    column_depth:     Option<Mm>,
+    column_height:    Option<Mm>,
+    cap_length:       Option<Mm>,
+    cap_width:        Option<Mm>,
+    cap_depth:        Option<Mm>,
+    material:         Option<MaterialGrade>,
+}
+
+impl PierBuilder {
+    /// #[param(unit="m")] Station along alignment
+    pub fn station(mut self, v: M) -> Self { self.station = Some(v); self }
+    /// #[param(unit="deg", range=-45.0..=45.0, default=0.0)]
+    pub fn skew_angle(mut self, v: f64) -> Self { self.skew_angle = Some(v); self }
+    /// #[param(enum=PierType, default=SingleColumn)]
+    pub fn pier_type(mut self, t: PierType) -> Self { self.pier_type = Some(t); self }
+    /// #[param(enum=ColumnShape, default=Circular)]
+    pub fn column_shape(mut self, s: ColumnShape) -> Self { self.column_shape = Some(s); self }
+    /// #[param(unit="count", range=1..=6, default=1)]
+    pub fn column_count(mut self, n: u32) -> Self { self.column_count = Some(n); self }
+    /// #[param(unit="mm", range=500.0..=5000.0, default=3000.0)] Column c/c spacing
+    pub fn column_spacing(mut self, v: Mm) -> Self { self.column_spacing = Some(v); self }
+    /// #[param(unit="mm", range=800.0..=5000.0, default=1500.0)] Diameter or width
+    pub fn column_diameter(mut self, v: Mm) -> Self { self.column_diameter = Some(v); self }
+    /// #[param(unit="mm", range=800.0..=5000.0, default=1500.0)] Depth (rectangular only)
+    pub fn column_depth(mut self, v: Mm) -> Self { self.column_depth = Some(v); self }
+    /// #[param(unit="mm", range=3000.0..=40_000.0)] Foundation top to cap soffit
+    pub fn column_height(mut self, v: Mm) -> Self { self.column_height = Some(v); self }
+    /// #[param(unit="mm")] Cap beam total transverse length
+    pub fn cap_length(mut self, v: Mm) -> Self { self.cap_length = Some(v); self }
+    /// #[param(unit="mm", range=800.0..=3000.0, default=1200.0)] Along span
+    pub fn cap_width(mut self, v: Mm) -> Self { self.cap_width = Some(v); self }
+    /// #[param(unit="mm", range=800.0..=3000.0, default=1500.0)]
+    pub fn cap_depth(mut self, v: Mm) -> Self { self.cap_depth = Some(v); self }
+    /// #[param(enum=MaterialGrade, default=C40)]
+    pub fn material(mut self, m: MaterialGrade) -> Self { self.material = Some(m); self }
+
+    pub fn build(self) -> Result<Pier, FeatureError> {
+        let station   = self.station.ok_or_else(|| FeatureError::missing("pier.station"))?.value();
+        let pier_type = self.pier_type.unwrap_or(PierType::SingleColumn);
+        let col_shape = self.column_shape.unwrap_or(ColumnShape::Circular);
+        let col_count = self.column_count.unwrap_or(1);
+        let col_dia   = self.column_diameter
+            .ok_or_else(|| FeatureError::missing("pier.column_diameter"))?.value();
+        let col_h     = self.column_height
+            .ok_or_else(|| FeatureError::missing("pier.column_height"))?.value();
+        let cap_w     = self.cap_width.unwrap_or(1200.0.mm()).value();
+        let cap_d     = self.cap_depth.unwrap_or(1500.0.mm()).value();
+        let cap_l     = self.cap_length.unwrap_or_else(|| {
+            let span = col_count as f64 * col_dia + 2.0 * 1000.0;
+            Mm(span)
+        }).value();
+
+        if col_dia < 500.0 {
+            return Err(FeatureError::validation("pier.column_diameter",
+                format!("minimum 500 mm, got {col_dia:.0} mm")));
+        }
+        if col_h < 2000.0 {
+            return Err(FeatureError::validation("pier.column_height",
+                format!("minimum 2000 mm, got {col_h:.0} mm")));
+        }
+        if col_count > 1 && self.column_spacing.is_none() {
+            return Err(FeatureError::missing("pier.column_spacing"));
+        }
+
+        Ok(Pier { ir: PierIR {
+            id:              FeatureId::new(),
+            station,
+            skew_angle:      self.skew_angle.unwrap_or(0.0),
+            pier_type,
+            column_shape:    col_shape,
+            column_count:    col_count,
+            column_spacing:  self.column_spacing.unwrap_or(0.0.mm()).value(),
+            column_diameter: col_dia,
+            column_depth:    self.column_depth.unwrap_or_else(|| Mm(col_dia)).value(),
+            column_height:   col_h,
+            cap_beam: CapBeamIR {
+                length:           cap_l,
+                width:            cap_w,
+                depth:            cap_d,
+                cantilever_left:  1000.0,
+                cantilever_right: 1000.0,
+            },
+            material: self.material.unwrap_or(MaterialGrade::C40),
+        }})
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use cimery_core::{ColumnShape, PierType, UnitExt};
+
+    #[test]
+    fn single_column_pier() {
+        let p = Pier::builder()
+            .station(100.0.m())
+            .pier_type(PierType::SingleColumn)
+            .column_shape(ColumnShape::Circular)
+            .column_diameter(1500.0.mm())
+            .column_height(8000.0.mm())
+            .build()
+            .unwrap();
+        assert_eq!(p.ir.column_count, 1);
+        assert!((p.ir.column_height - 8000.0).abs() < f64::EPSILON);
+    }
+
+    #[test]
+    fn multi_column_needs_spacing() {
+        let e = Pier::builder()
+            .station(100.0.m())
+            .column_count(3)
+            .column_diameter(1200.0.mm())
+            .column_height(8000.0.mm())
+            .build().unwrap_err();
+        assert!(matches!(e, FeatureError::MissingField { .. }));
+    }
+}

cimery/crates/ir/src/lib.rs

@@ -138,6 +138,112 @@ pub struct SteelPlateIParams {
     pub web_thickness:    f64,
 }
 
+// ─── Deck Slab IR ─────────────────────────────────────────────────────────────
+
+/// Fully-resolved Deck Slab (바닥판) specification.
+/// Structural dimensions in mm, alignment in m.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct DeckSlabIR {
+    pub id:                FeatureId,
+    pub station_start:     f64,   // m
+    pub station_end:       f64,   // m
+    /// Width left of alignment centreline [mm].
+    pub width_left:        f64,
+    /// Width right of alignment centreline [mm].
+    pub width_right:       f64,
+    /// Slab thickness [mm].
+    pub thickness:         f64,
+    /// Haunch depth over girder top flange [mm].
+    pub haunch_depth:      f64,
+    /// Cross-slope [%]. Positive = right side lower.
+    pub cross_slope:       f64,
+    pub material:          cimery_core::MaterialGrade,
+}
+
+impl DeckSlabIR {
+    pub fn span_m(&self)  -> f64 { self.station_end - self.station_start }
+    pub fn span_mm(&self) -> f64 { self.span_m() * 1_000.0 }
+    pub fn total_width(&self) -> f64 { self.width_left + self.width_right }
+}
+
+// ─── Bearing IR ───────────────────────────────────────────────────────────────
+
+/// Fully-resolved Bearing (받침) specification.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct BearingIR {
+    pub id:                  FeatureId,
+    pub station:             f64,   // m — position along alignment
+    pub bearing_type:        cimery_core::BearingType,
+    /// Dimension along span direction [mm].
+    pub plan_length:         f64,
+    /// Dimension transverse to span [mm].
+    pub plan_width:          f64,
+    pub total_height:        f64,   // mm
+    pub capacity_vertical:   f64,   // kN
+}
+
+// ─── Cap Beam IR ──────────────────────────────────────────────────────────────
+
+/// Pier cap beam (교각 코핑).
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct CapBeamIR {
+    pub length:            f64,   // mm — total along transverse
+    pub width:             f64,   // mm — along span
+    pub depth:             f64,   // mm — vertical
+    pub cantilever_left:   f64,   // mm — overhang beyond outermost column
+    pub cantilever_right:  f64,
+}
+
+// ─── Pier IR ──────────────────────────────────────────────────────────────────
+
+/// Fully-resolved Pier (교각) specification.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct PierIR {
+    pub id:              FeatureId,
+    pub station:         f64,   // m
+    pub skew_angle:      f64,   // degrees — deviation from normal
+    pub pier_type:       cimery_core::PierType,
+    pub column_shape:    cimery_core::ColumnShape,
+    pub column_count:    u32,
+    pub column_spacing:  f64,   // mm — centre-to-centre
+    /// Diameter (circular) or width (rectangular) [mm].
+    pub column_diameter: f64,
+    /// Depth for rectangular section [mm]; ignored for circular.
+    pub column_depth:    f64,
+    pub column_height:   f64,   // mm — footing top to cap beam soffit
+    pub cap_beam:        CapBeamIR,
+    pub material:        cimery_core::MaterialGrade,
+}
+
+// ─── Wing Wall IR ─────────────────────────────────────────────────────────────
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct WingWallIR {
+    pub length:    f64,   // mm — along wing wall axis
+    pub height:    f64,   // mm — at connection with breast wall
+    pub thickness: f64,   // mm
+}
+
+// ─── Abutment IR ──────────────────────────────────────────────────────────────
+
+/// Fully-resolved Abutment (교대) specification.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct AbutmentIR {
+    pub id:                      FeatureId,
+    pub station:                 f64,   // m
+    pub skew_angle:              f64,   // degrees
+    pub abutment_type:           cimery_core::AbutmentType,
+    pub breast_wall_height:      f64,   // mm
+    pub breast_wall_thickness:   f64,   // mm
+    pub breast_wall_width:       f64,   // mm — transverse
+    pub footing_length:          f64,   // mm — along span
+    pub footing_width:           f64,   // mm — transverse
+    pub footing_thickness:       f64,   // mm
+    pub wing_wall_left:          WingWallIR,
+    pub wing_wall_right:         WingWallIR,
+    pub material:                cimery_core::MaterialGrade,
+}
+
 // ─── Tests ────────────────────────────────────────────────────────────────────
 
 #[cfg(test)]

cimery/crates/kernel/Cargo.toml

@@ -10,6 +10,7 @@ edition.workspace = true
 occt = ["dep:opencascade"]
 
 [dependencies]
+cimery-core = { workspace = true }
 cimery-ir   = { workspace = true }
 thiserror   = { workspace = true }
 log         = { workspace = true }

cimery/crates/kernel/src/abutment.rs

@@ -0,0 +1,81 @@
+//! Abutment geometry — PureRustKernel.
+//! Breast wall + footing + wing walls (simplified rectangular shapes).
+
+use cimery_ir::AbutmentIR;
+use crate::{KernelError, Mesh, sweep};
+
+pub fn build_abutment_mesh(ir: &AbutmentIR) -> Result<Mesh, KernelError> {
+    if ir.breast_wall_height <= 0.0 {
+        return Err(KernelError::InvalidInput(
+            format!("breast_wall_height must be > 0, got {}", ir.breast_wall_height),
+        ));
+    }
+
+    let bw_h  = ir.breast_wall_height as f32;
+    let bw_t  = ir.breast_wall_thickness as f32;
+    let bw_w  = ir.breast_wall_width as f32;
+    let ft_l  = ir.footing_length as f32;
+    let ft_w  = ir.footing_width as f32;
+    let ft_t  = ir.footing_thickness as f32;
+
+    let mut parts: Vec<Mesh> = Vec::new();
+
+    // Breast wall: along transverse (Z), thickness along span (X), height (Y)
+    parts.push(sweep::centred_box(0.0, bw_h * 0.5, bw_t * 0.5, bw_h * 0.5, bw_w));
+
+    // Footing: below grade, spans along X (span direction)
+    {
+        let profile = vec![
+            [-ft_l * 0.5, -ft_t],
+            [ ft_l * 0.5, -ft_t],
+            [ ft_l * 0.5,  0.0 ],
+            [-ft_l * 0.5,  0.0 ],
+        ];
+        parts.push(sweep::sweep_profile_flat(&profile, ft_w));
+    }
+
+    // Wing walls (left and right)
+    for side in [&ir.wing_wall_left, &ir.wing_wall_right] {
+        let wl = side.length as f32;
+        let wh = side.height as f32;
+        let wt = side.thickness as f32;
+        // Simplified: vertical rectangle, oriented in XY, length along Z
+        parts.push(sweep::centred_box(0.0, wh * 0.5, wt * 0.5, wh * 0.5, wl));
+    }
+
+    Ok(sweep::merge_meshes(parts))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use cimery_core::{AbutmentType, MaterialGrade};
+    use cimery_ir::{AbutmentIR, FeatureId, WingWallIR};
+
+    fn test_ir() -> AbutmentIR {
+        let wing = WingWallIR { length: 4000.0, height: 3000.0, thickness: 500.0 };
+        AbutmentIR {
+            id: FeatureId::new(),
+            station: 0.0, skew_angle: 0.0,
+            abutment_type: AbutmentType::ReverseT,
+            breast_wall_height: 5000.0, breast_wall_thickness: 800.0,
+            breast_wall_width: 12000.0,
+            footing_length: 4000.0, footing_width: 13000.0, footing_thickness: 1000.0,
+            wing_wall_left: wing.clone(), wing_wall_right: wing,
+            material: MaterialGrade::C40,
+        }
+    }
+
+    #[test]
+    fn produces_mesh() {
+        let mesh = build_abutment_mesh(&test_ir()).unwrap();
+        assert!(mesh.triangle_count() > 0);
+    }
+
+    #[test]
+    fn zero_height_fails() {
+        let mut ir = test_ir();
+        ir.breast_wall_height = 0.0;
+        assert!(build_abutment_mesh(&ir).is_err());
+    }
+}

cimery/crates/kernel/src/bearing.rs

@@ -0,0 +1,35 @@
+//! Bearing geometry — PureRustKernel.
+
+use cimery_ir::BearingIR;
+use crate::{KernelError, Mesh, sweep};
+
+pub fn build_bearing_mesh(ir: &BearingIR) -> Result<Mesh, KernelError> {
+    if ir.plan_length <= 0.0 || ir.plan_width <= 0.0 || ir.total_height <= 0.0 {
+        return Err(KernelError::InvalidInput("bearing dimensions must be positive".into()));
+    }
+    // Centred box: plan_length × total_height × plan_width
+    // X = along span (plan_length), Y = height, Z = transverse (plan_width)
+    let l = ir.plan_length as f32;
+    let h = ir.total_height as f32;
+    let w = ir.plan_width as f32;
+    Ok(sweep::centred_box(-l/2.0, 0.0, l/2.0, h, w))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use cimery_core::BearingType;
+    use cimery_ir::{BearingIR, FeatureId};
+
+    #[test]
+    fn produces_mesh() {
+        let ir = BearingIR {
+            id: FeatureId::new(), station: 0.0,
+            bearing_type: BearingType::Elastomeric,
+            plan_length: 350.0, plan_width: 450.0,
+            total_height: 60.0, capacity_vertical: 1500.0,
+        };
+        let mesh = build_bearing_mesh(&ir).unwrap();
+        assert!(mesh.triangle_count() > 0);
+    }
+}

cimery/crates/kernel/src/deck_slab.rs

@@ -0,0 +1,50 @@
+//! Deck Slab geometry — PureRustKernel.
+
+use cimery_ir::DeckSlabIR;
+use crate::{KernelError, Mesh, sweep};
+
+pub fn build_deck_slab_mesh(ir: &DeckSlabIR) -> Result<Mesh, KernelError> {
+    if ir.span_mm() <= 0.0 {
+        return Err(KernelError::InvalidInput(
+            format!("span must be positive, got {} m", ir.span_m()),
+        ));
+    }
+    let w = ir.total_width() as f32;  // total width [mm]
+    let t = ir.thickness as f32;
+    let s = ir.span_mm() as f32;
+
+    // Simple rectangular slab: origin at (-width_left, 0, 0), top face at Y=0, soffit at Y=-t
+    let profile = vec![
+        [-(ir.width_left as f32),  0.0],
+        [ ir.width_right as f32,   0.0],
+        [ ir.width_right as f32,  -t  ],
+        [-(ir.width_left as f32), -t  ],
+    ];
+    let _ = w;  // calculated but slab profile already uses left/right
+    Ok(sweep::sweep_profile_flat(&profile, s))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use cimery_core::MaterialGrade;
+    use cimery_ir::{DeckSlabIR, FeatureId};
+
+    fn test_ir() -> DeckSlabIR {
+        DeckSlabIR {
+            id: FeatureId::new(),
+            station_start: 0.0, station_end: 40.0,
+            width_left: 5000.0, width_right: 5000.0,
+            thickness: 220.0, haunch_depth: 0.0, cross_slope: 2.0,
+            material: MaterialGrade::C40,
+        }
+    }
+
+    #[test]
+    fn produces_mesh() {
+        let mesh = build_deck_slab_mesh(&test_ir()).unwrap();
+        assert!(mesh.triangle_count() > 0);
+        let (_, mx) = mesh.aabb();
+        assert!((mx[2] - 40_000.0_f32).abs() < 1.0);
+    }
+}

cimery/crates/kernel/src/lib.rs

@@ -11,8 +11,15 @@
 //! Switch kernels by swapping the concrete type at the call site — no other changes.
 
 pub mod psc_i;
+pub mod sweep;
+pub mod deck_slab;
+pub mod bearing;
+pub mod pier;
+pub mod abutment;
 
-use cimery_ir::{GirderIR, SectionParams};
+use cimery_ir::{
+    AbutmentIR, BearingIR, DeckSlabIR, GirderIR, PierIR, SectionParams,
+};
 
 // ─── Mesh ─────────────────────────────────────────────────────────────────────
 
@@ -63,8 +70,16 @@ pub enum KernelError {
 /// Backend-agnostic geometry kernel.
 ///
 /// All implementations MUST be deterministic: same IR → same Mesh topology.
+/// Feature order matches bridge construction sequence: superstructure → substructure.
 pub trait GeomKernel: Send + Sync {
-    fn girder_mesh(&self, ir: &GirderIR) -> Result<Mesh, KernelError>;
+    // ── 상부 구조물 (Superstructure) ───────────────────────────────────────
+    fn girder_mesh(&self, ir: &GirderIR)       -> Result<Mesh, KernelError>;
+    fn deck_slab_mesh(&self, ir: &DeckSlabIR)  -> Result<Mesh, KernelError>;
+    // ── 연결부 (Interface) ─────────────────────────────────────────────────
+    fn bearing_mesh(&self, ir: &BearingIR)     -> Result<Mesh, KernelError>;
+    // ── 하부 구조물 (Substructure) ─────────────────────────────────────────
+    fn pier_mesh(&self, ir: &PierIR)           -> Result<Mesh, KernelError>;
+    fn abutment_mesh(&self, ir: &AbutmentIR)   -> Result<Mesh, KernelError>;
 }
 
 // ─── StubKernel ───────────────────────────────────────────────────────────────
@@ -76,6 +91,18 @@ pub trait GeomKernel: Send + Sync {
 pub struct StubKernel;
 
 impl GeomKernel for StubKernel {
+    fn deck_slab_mesh(&self, ir: &DeckSlabIR) -> Result<Mesh, KernelError> {
+        Ok(sweep::box_mesh(ir.total_width() as f32, ir.thickness as f32, ir.span_mm() as f32))
+    }
+    fn bearing_mesh(&self, ir: &BearingIR) -> Result<Mesh, KernelError> {
+        Ok(sweep::box_mesh(ir.plan_length as f32, ir.total_height as f32, ir.plan_width as f32))
+    }
+    fn pier_mesh(&self, ir: &PierIR) -> Result<Mesh, KernelError> {
+        Ok(sweep::box_mesh(ir.column_diameter as f32, ir.column_height as f32, ir.cap_beam.length as f32))
+    }
+    fn abutment_mesh(&self, ir: &AbutmentIR) -> Result<Mesh, KernelError> {
+        Ok(sweep::box_mesh(ir.breast_wall_thickness as f32, ir.breast_wall_height as f32, ir.breast_wall_width as f32))
+    }
     fn girder_mesh(&self, ir: &GirderIR) -> Result<Mesh, KernelError> {
         if ir.span_m() <= 0.0 {
             return Err(KernelError::InvalidInput(
@@ -114,6 +141,18 @@ impl GeomKernel for StubKernel {
 pub struct PureRustKernel;
 
 impl GeomKernel for PureRustKernel {
+    fn deck_slab_mesh(&self, ir: &DeckSlabIR) -> Result<Mesh, KernelError> {
+        deck_slab::build_deck_slab_mesh(ir)
+    }
+    fn bearing_mesh(&self, ir: &BearingIR) -> Result<Mesh, KernelError> {
+        bearing::build_bearing_mesh(ir)
+    }
+    fn pier_mesh(&self, ir: &PierIR) -> Result<Mesh, KernelError> {
+        pier::build_pier_mesh(ir)
+    }
+    fn abutment_mesh(&self, ir: &AbutmentIR) -> Result<Mesh, KernelError> {
+        abutment::build_abutment_mesh(ir)
+    }
     fn girder_mesh(&self, ir: &GirderIR) -> Result<Mesh, KernelError> {
         match &ir.section {
             SectionParams::PscI(p) => psc_i::build_psc_i_mesh(p, ir.span_mm()),

cimery/crates/kernel/src/pier.rs

@@ -0,0 +1,97 @@
+//! Pier geometry — PureRustKernel.
+//! Single-column: octagonal prism (≈ circle) + rectangular cap beam.
+//! Multi-column: N columns side-by-side + cap beam.
+
+use cimery_core::ColumnShape;
+use cimery_ir::PierIR;
+use crate::{KernelError, Mesh, sweep};
+
+pub fn build_pier_mesh(ir: &PierIR) -> Result<Mesh, KernelError> {
+    if ir.column_height <= 0.0 {
+        return Err(KernelError::InvalidInput(
+            format!("column_height must be > 0, got {}", ir.column_height),
+        ));
+    }
+
+    let col_h    = ir.column_height as f32;
+    let col_d    = ir.column_diameter as f32;
+    let col_dep  = ir.column_depth as f32;
+    let cap_l    = ir.cap_beam.length as f32;
+    let cap_w    = ir.cap_beam.width as f32;
+    let cap_d    = ir.cap_beam.depth as f32;
+    let count    = ir.column_count.max(1);
+    let spacing  = ir.column_spacing as f32;
+
+    let mut parts: Vec<Mesh> = Vec::new();
+
+    // Columns
+    for i in 0..count {
+        let cy = (i as f32 - (count as f32 - 1.0) * 0.5) * spacing;
+        let col = match ir.column_shape {
+            ColumnShape::Circular => {
+                // 12-sided polygon ≈ circle
+                sweep::polygon_prism(0.0, cy, col_d * 0.5, 12, col_h)
+            }
+            ColumnShape::Rectangular | ColumnShape::Oval => {
+                sweep::centred_box(0.0, cy, col_d * 0.5, col_dep * 0.5, col_h)
+            }
+        };
+        parts.push(col);
+    }
+
+    // Cap beam — centred in transverse, at top of columns
+    // Translate Y by column_height via profile offset
+    let cap = {
+        let profile = vec![
+            [-cap_w * 0.5,  col_h            ],
+            [ cap_w * 0.5,  col_h            ],
+            [ cap_w * 0.5,  col_h + cap_d    ],
+            [-cap_w * 0.5,  col_h + cap_d    ],
+        ];
+        sweep::sweep_profile_flat(&profile, cap_l)
+    };
+    parts.push(cap);
+
+    Ok(sweep::merge_meshes(parts))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use cimery_core::{ColumnShape, MaterialGrade, PierType};
+    use cimery_ir::{CapBeamIR, FeatureId, PierIR};
+
+    fn test_ir() -> PierIR {
+        PierIR {
+            id: FeatureId::new(),
+            station: 100.0, skew_angle: 0.0,
+            pier_type: PierType::SingleColumn,
+            column_shape: ColumnShape::Circular,
+            column_count: 1, column_spacing: 0.0,
+            column_diameter: 1500.0, column_depth: 1500.0,
+            column_height: 8000.0,
+            cap_beam: CapBeamIR {
+                length: 8000.0, width: 1200.0, depth: 1500.0,
+                cantilever_left: 1000.0, cantilever_right: 1000.0,
+            },
+            material: MaterialGrade::C40,
+        }
+    }
+
+    #[test]
+    fn single_column_pier() {
+        let mesh = build_pier_mesh(&test_ir()).unwrap();
+        // Basic: produces geometry
+        assert!(mesh.triangle_count() > 0);
+        assert!(mesh.vertex_count() > 0);
+        // Note: PureRustKernel sweeps column profile along Z (cross-section view).
+        // Proper 3D vertical pier geometry → OcctKernel (Sprint 3).
+    }
+
+    #[test]
+    fn zero_height_fails() {
+        let mut ir = test_ir();
+        ir.column_height = 0.0;
+        assert!(build_pier_mesh(&ir).is_err());
+    }
+}

cimery/crates/kernel/src/psc_i.rs

@@ -8,7 +8,7 @@
 //! (fillets, accurate haunches, proper mesh density).
 
 use cimery_ir::PscISectionParams;
-use crate::{KernelError, Mesh};
+use crate::{KernelError, Mesh, sweep};
 
 // ─── Public API ───────────────────────────────────────────────────────────────
 
@@ -25,7 +25,7 @@ pub fn build_psc_i_mesh(
         ));
     }
     let profile = psc_i_profile(p)?;
-    Ok(sweep_profile_flat(&profile, span_mm as f32))
+    Ok(sweep::sweep_profile_flat(&profile, span_mm as f32))
 }
 
 // ─── Profile ─────────────────────────────────────────────────────────────────
@@ -77,83 +77,7 @@ fn psc_i_profile(p: &PscISectionParams) -> Result<Vec<[f32; 2]>, KernelError> {
     ])
 }
 
-// ─── Sweep ────────────────────────────────────────────────────────────────────
-
-/// Sweep a closed polygon profile along Z, producing a closed solid.
-///
-/// Uses flat normals (no shared vertices between adjacent faces).
-/// Each triangle has 3 unique vertices with the same face normal.
-fn sweep_profile_flat(profile: &[[f32; 2]], span: f32) -> Mesh {
-    let n = profile.len();
-    let mut vertices: Vec<[f32; 3]> = Vec::new();
-    let mut normals:  Vec<[f32; 3]> = Vec::new();
-    let mut indices:  Vec<u32>      = Vec::new();
-
-    // Helper: push one triangle and record face normal
-    let mut push_tri = |v0: [f32; 3], v1: [f32; 3], v2: [f32; 3]| {
-        let normal = face_normal(v0, v1, v2);
-        for v in [v0, v1, v2] {
-            let idx = vertices.len() as u32;
-            vertices.push(v);
-            normals.push(normal);
-            indices.push(idx);
-        }
-    };
-
-    // ── Side faces: one quad (2 tris) per profile edge ─────────────────────
-    for i in 0..n {
-        let j  = (i + 1) % n;
-        let [x0, y0] = profile[i];
-        let [x1, y1] = profile[j];
-
-        let a = [x0, y0, 0.0];
-        let b = [x1, y1, 0.0];
-        let c = [x1, y1, span];
-        let d = [x0, y0, span];
-
-        push_tri(a, b, c);
-        push_tri(a, c, d);
-    }
-
-    // ── End caps: fan triangulation from centroid ──────────────────────────
-    let cx: f32 = profile.iter().map(|v| v[0]).sum::<f32>() / n as f32;
-    let cy: f32 = profile.iter().map(|v| v[1]).sum::<f32>() / n as f32;
-
-    // Front cap (Z = 0, normal = –Z). CCW from –Z: centre, then CW in XY.
-    let cen_front = [cx, cy, 0.0];
-    for i in 0..n {
-        let j = (i + 1) % n;
-        let a = [profile[i][0], profile[i][1], 0.0];
-        let b = [profile[j][0], profile[j][1], 0.0];
-        push_tri(cen_front, b, a);
-    }
-
-    // Back cap (Z = span, normal = +Z). CCW from +Z: centre, then CCW in XY.
-    let cen_back = [cx, cy, span];
-    for i in 0..n {
-        let j = (i + 1) % n;
-        let a = [profile[i][0], profile[i][1], span];
-        let b = [profile[j][0], profile[j][1], span];
-        push_tri(cen_back, a, b);
-    }
-
-    Mesh { vertices, normals, indices }
-}
-
-// ─── Math helpers ─────────────────────────────────────────────────────────────
-
-fn face_normal(a: [f32; 3], b: [f32; 3], c: [f32; 3]) -> [f32; 3] {
-    let ab = [b[0]-a[0], b[1]-a[1], b[2]-a[2]];
-    let ac = [c[0]-a[0], c[1]-a[1], c[2]-a[2]];
-    let n = [
-        ab[1]*ac[2] - ab[2]*ac[1],
-        ab[2]*ac[0] - ab[0]*ac[2],
-        ab[0]*ac[1] - ab[1]*ac[0],
-    ];
-    let len = (n[0]*n[0] + n[1]*n[1] + n[2]*n[2]).sqrt();
-    if len < 1e-10 { return [0.0, 1.0, 0.0]; }
-    [n[0]/len, n[1]/len, n[2]/len]
-}
+// Sweep and geometry helpers are in crate::sweep.
 
 // ─── Tests ────────────────────────────────────────────────────────────────────
 

cimery/crates/kernel/src/sweep.rs

@@ -0,0 +1,125 @@
+//! Shared geometry helpers for PureRustKernel feature modules.
+//! Cross-section sweep + face normal computation.
+
+use crate::Mesh;
+
+// ─── Normals ──────────────────────────────────────────────────────────────────
+
+/// Face normal of a CCW triangle (normalised).
+pub fn face_normal(a: [f32; 3], b: [f32; 3], c: [f32; 3]) -> [f32; 3] {
+    let ab = [b[0]-a[0], b[1]-a[1], b[2]-a[2]];
+    let ac = [c[0]-a[0], c[1]-a[1], c[2]-a[2]];
+    let n = [
+        ab[1]*ac[2] - ab[2]*ac[1],
+        ab[2]*ac[0] - ab[0]*ac[2],
+        ab[0]*ac[1] - ab[1]*ac[0],
+    ];
+    let len = (n[0]*n[0] + n[1]*n[1] + n[2]*n[2]).sqrt();
+    if len < 1e-10 { return [0.0, 1.0, 0.0]; }
+    [n[0]/len, n[1]/len, n[2]/len]
+}
+
+// ─── Sweep ────────────────────────────────────────────────────────────────────
+
+/// Sweep a closed polygon profile along Z from 0 to `span`.
+/// Uses flat normals (no shared vertices — faceted appearance).
+pub fn sweep_profile_flat(profile: &[[f32; 2]], span: f32) -> Mesh {
+    let n = profile.len();
+    let mut vertices: Vec<[f32; 3]> = Vec::new();
+    let mut normals:  Vec<[f32; 3]> = Vec::new();
+    let mut indices:  Vec<u32>      = Vec::new();
+
+    let mut push_tri = |v0: [f32;3], v1: [f32;3], v2: [f32;3]| {
+        let normal = face_normal(v0, v1, v2);
+        for v in [v0, v1, v2] {
+            indices.push(vertices.len() as u32);
+            vertices.push(v);
+            normals.push(normal);
+        }
+    };
+
+    // Side faces
+    for i in 0..n {
+        let j = (i + 1) % n;
+        let [x0, y0] = profile[i];
+        let [x1, y1] = profile[j];
+        let a = [x0, y0, 0.0];
+        let b = [x1, y1, 0.0];
+        let c = [x1, y1, span];
+        let d = [x0, y0, span];
+        push_tri(a, b, c);
+        push_tri(a, c, d);
+    }
+
+    // Caps
+    let cx: f32 = profile.iter().map(|v| v[0]).sum::<f32>() / n as f32;
+    let cy: f32 = profile.iter().map(|v| v[1]).sum::<f32>() / n as f32;
+
+    let cen_f = [cx, cy, 0.0];
+    for i in 0..n {
+        let j = (i+1)%n;
+        push_tri(cen_f, [profile[j][0],profile[j][1],0.0], [profile[i][0],profile[i][1],0.0]);
+    }
+    let cen_b = [cx, cy, span];
+    for i in 0..n {
+        let j = (i+1)%n;
+        push_tri(cen_b, [profile[i][0],profile[i][1],span], [profile[j][0],profile[j][1],span]);
+    }
+
+    Mesh { vertices, normals, indices }
+}
+
+// ─── Convenience shapes ───────────────────────────────────────────────────────
+
+/// Axis-aligned box: width × height × depth. Origin at (0,0,0).
+pub fn box_mesh(width: f32, height: f32, depth: f32) -> Mesh {
+    let w = width;
+    let h = height;
+    let d = depth;
+    let profile = vec![
+        [0.0, 0.0],
+        [w,   0.0],
+        [w,   h  ],
+        [0.0, h  ],
+    ];
+    sweep_profile_flat(&profile, d)
+}
+
+/// Centred rectangle in XY, swept along Z.
+/// Centre at (cx, cy), half-extents (hw, hh).
+pub fn centred_box(cx: f32, cy: f32, hw: f32, hh: f32, depth: f32) -> Mesh {
+    let profile = vec![
+        [cx - hw, cy - hh],
+        [cx + hw, cy - hh],
+        [cx + hw, cy + hh],
+        [cx - hw, cy + hh],
+    ];
+    sweep_profile_flat(&profile, depth)
+}
+
+/// Regular n-gon prism: approximates a cylinder.
+/// Centred at (cx, cy), swept along Z.
+pub fn polygon_prism(cx: f32, cy: f32, radius: f32, sides: u32, height: f32) -> Mesh {
+    let n = sides.max(3) as usize;
+    let profile: Vec<[f32; 2]> = (0..n).map(|i| {
+        let a = std::f32::consts::TAU * i as f32 / n as f32;
+        [cx + radius * a.cos(), cy + radius * a.sin()]
+    }).collect();
+    sweep_profile_flat(&profile, height)
+}
+
+// ─── Merge ────────────────────────────────────────────────────────────────────
+
+/// Concatenate multiple meshes into one.
+pub fn merge_meshes(meshes: Vec<Mesh>) -> Mesh {
+    let mut vertices: Vec<[f32; 3]> = Vec::new();
+    let mut normals:  Vec<[f32; 3]> = Vec::new();
+    let mut indices:  Vec<u32>      = Vec::new();
+    for m in meshes {
+        let base = vertices.len() as u32;
+        vertices.extend_from_slice(&m.vertices);
+        normals.extend_from_slice(&m.normals);
+        indices.extend(m.indices.iter().map(|i| i + base));
+    }
+    Mesh { vertices, normals, indices }
+}