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src/modules/home/modify/array.rs

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+// Array dropdown — ribbon definition + interactive commands.
+//
+// ARRAYRECT (AR):
+//   Rectangular array: row/column counts and spacing collected via text input.
+//   1. Row count → 2. Column count → 3. Row spacing → 4. Column spacing
+//   → Returns BatchCopy with a grid of Translate transforms.
+//
+// ARRAYPATH:
+//   Path array: copies placed at equal intervals along a curve/line.
+//   (pending geometry engine support — stub)
+//
+// ARRAYPOLAR:
+//   Polar array: copies rotated around a center point by a total angle.
+//   1. Center point → 2. Item count (text) → 3. Total angle in degrees (text)
+
+use acadrust::Handle;
+use glam::Vec3;
+
+use crate::command::{CadCommand, CmdResult, EntityTransform};
+use crate::modules::home::defaults;
+use crate::modules::IconKind;
+use crate::scene::wire_model::WireModel;
+
+// ── Dropdown constants ─────────────────────────────────────────────────────
+
+pub const DROPDOWN_ID: &str = "array_type";
+pub const ICON: IconKind = IconKind::Svg(include_bytes!("../../../../assets/icons/array_rect.svg"));
+
+pub const DROPDOWN_ITEMS: &[(&str, &str, IconKind)] = &[
+    (
+        "ARRAYRECT",
+        "Rectangular Array",
+        IconKind::Svg(include_bytes!("../../../../assets/icons/array_rect.svg")),
+    ),
+    (
+        "ARRAYPATH",
+        "Path Array",
+        IconKind::Svg(include_bytes!("../../../../assets/icons/array_path.svg")),
+    ),
+    (
+        "ARRAYPOLAR",
+        "Polar Array",
+        IconKind::Svg(include_bytes!("../../../../assets/icons/array_polar.svg")),
+    ),
+];
+
+// ── Rectangular Array ──────────────────────────────────────────────────────
+
+#[derive(Debug, Clone, Copy)]
+enum RectStep {
+    Rows,
+    Cols { rows: u32 },
+    RowSp { rows: u32, cols: u32 },
+    ColSp { rows: u32, cols: u32, row_sp: f32 },
+}
+
+pub struct ArrayRectCommand {
+    handles: Vec<Handle>,
+    wire_models: Vec<WireModel>,
+    step: RectStep,
+    default_rows: u32,
+    default_cols: u32,
+    default_row_sp: f32,
+    default_col_sp: f32,
+}
+
+impl ArrayRectCommand {
+    pub fn new(handles: Vec<Handle>, wire_models: Vec<WireModel>) -> Self {
+        Self {
+            handles,
+            wire_models,
+            step: RectStep::Rows,
+            default_rows: defaults::get_array_rows() as u32,
+            default_cols: defaults::get_array_cols() as u32,
+            default_row_sp: defaults::get_array_row_sp(),
+            default_col_sp: defaults::get_array_col_sp(),
+        }
+    }
+
+    fn build_transforms(rows: u32, cols: u32, row_sp: f32, col_sp: f32) -> Vec<EntityTransform> {
+        let mut t = Vec::new();
+        for r in 0..rows {
+            for c in 0..cols {
+                if r == 0 && c == 0 {
+                    continue;
+                }
+                t.push(EntityTransform::Translate(Vec3::new(
+                    col_sp * c as f32,
+                    row_sp * r as f32,
+                    0.0,
+                )));
+            }
+        }
+        t
+    }
+}
+
+impl CadCommand for ArrayRectCommand {
+    fn name(&self) -> &'static str {
+        "ARRAYRECT"
+    }
+
+    fn prompt(&self) -> String {
+        match self.step {
+            RectStep::Rows => format!("ARRAYRECT  Enter row count <{}>:", self.default_rows),
+            RectStep::Cols { rows } => format!(
+                "ARRAYRECT  Enter column count <{}>  [{rows} rows]:",
+                self.default_cols
+            ),
+            RectStep::RowSp { rows, cols } => format!(
+                "ARRAYRECT  Row spacing <{:.0}>  [{rows}×{cols}]:",
+                self.default_row_sp
+            ),
+            RectStep::ColSp { rows, cols, row_sp } => format!(
+                "ARRAYRECT  Column spacing <{:.0}>  [{rows}×{cols}, row={row_sp:.0}]:",
+                self.default_col_sp
+            ),
+        }
+    }
+
+    fn wants_text_input(&self) -> bool {
+        true
+    }
+
+    fn on_text_input(&mut self, text: &str) -> Option<CmdResult> {
+        let t = text.trim().replace(',', ".");
+        let t = t.as_str();
+        match self.step {
+            RectStep::Rows => {
+                let rows = if t.is_empty() {
+                    self.default_rows
+                } else {
+                    let v = t.parse::<u32>().unwrap_or(self.default_rows).max(1);
+                    defaults::set_array_rows(v as f32);
+                    self.default_rows = v;
+                    v
+                };
+                self.step = RectStep::Cols { rows };
+                None
+            }
+            RectStep::Cols { rows } => {
+                let cols = if t.is_empty() {
+                    self.default_cols
+                } else {
+                    let v = t.parse::<u32>().unwrap_or(self.default_cols).max(1);
+                    defaults::set_array_cols(v as f32);
+                    self.default_cols = v;
+                    v
+                };
+                self.step = RectStep::RowSp { rows, cols };
+                None
+            }
+            RectStep::RowSp { rows, cols } => {
+                let row_sp = if t.is_empty() {
+                    self.default_row_sp
+                } else {
+                    let v = t.parse::<f32>().unwrap_or(self.default_row_sp);
+                    defaults::set_array_row_sp(v);
+                    self.default_row_sp = v;
+                    v
+                };
+                self.step = RectStep::ColSp { rows, cols, row_sp };
+                None
+            }
+            RectStep::ColSp { rows, cols, row_sp } => {
+                let col_sp = if t.is_empty() {
+                    self.default_col_sp
+                } else {
+                    let v = t.parse::<f32>().unwrap_or(self.default_col_sp);
+                    defaults::set_array_col_sp(v);
+                    v
+                };
+                Some(CmdResult::BatchCopy(
+                    self.handles.clone(),
+                    Self::build_transforms(rows, cols, row_sp, col_sp),
+                ))
+            }
+        }
+    }
+
+    fn on_preview_wires(&mut self, _pt: Vec3) -> Vec<WireModel> {
+        let (rows, cols, row_sp, col_sp) = match self.step {
+            RectStep::Rows => (
+                self.default_rows,
+                self.default_cols,
+                self.default_row_sp,
+                self.default_col_sp,
+            ),
+            RectStep::Cols { rows } => (
+                rows,
+                self.default_cols,
+                self.default_row_sp,
+                self.default_col_sp,
+            ),
+            RectStep::RowSp { rows, cols } => {
+                (rows, cols, self.default_row_sp, self.default_col_sp)
+            }
+            RectStep::ColSp { rows, cols, row_sp } => (rows, cols, row_sp, self.default_col_sp),
+        };
+        Self::build_transforms(rows, cols, row_sp, col_sp)
+            .iter()
+            .flat_map(|t| {
+                if let EntityTransform::Translate(delta) = t {
+                    self.wire_models
+                        .iter()
+                        .map(|w| w.translated(*delta))
+                        .collect::<Vec<_>>()
+                } else {
+                    vec![]
+                }
+            })
+            .collect()
+    }
+
+    fn on_point(&mut self, _pt: Vec3) -> CmdResult {
+        CmdResult::NeedPoint
+    }
+
+    fn on_enter(&mut self) -> CmdResult {
+        // Enter with empty input = use default for current step
+        self.on_text_input("").map_or(CmdResult::NeedPoint, |r| r)
+    }
+
+    fn on_escape(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+}
+
+// ── Polar Array ────────────────────────────────────────────────────────────
+
+enum PolarStep {
+    Center,
+    Count { center: Vec3 },
+    Angle { center: Vec3, count: u32 },
+}
+
+pub struct ArrayPolarCommand {
+    handles: Vec<Handle>,
+    wire_models: Vec<WireModel>,
+    step: PolarStep,
+    default_count: u32,
+    default_angle: f32,
+}
+
+impl ArrayPolarCommand {
+    pub fn new(handles: Vec<Handle>, wire_models: Vec<WireModel>) -> Self {
+        Self {
+            handles,
+            wire_models,
+            step: PolarStep::Center,
+            default_count: defaults::get_array_p_count() as u32,
+            default_angle: defaults::get_array_p_angle(),
+        }
+    }
+}
+
+impl CadCommand for ArrayPolarCommand {
+    fn name(&self) -> &'static str {
+        "ARRAYPOLAR"
+    }
+
+    fn prompt(&self) -> String {
+        match &self.step {
+            PolarStep::Center => format!(
+                "ARRAYPOLAR  Specify center point  [{} objects]:",
+                self.handles.len()
+            ),
+            PolarStep::Count { .. } => {
+                format!("ARRAYPOLAR  Enter item count <{}>:", self.default_count)
+            }
+            PolarStep::Angle { count, .. } => format!(
+                "ARRAYPOLAR  Enter total angle in degrees <{:.0}>  [{count} items]:",
+                self.default_angle
+            ),
+        }
+    }
+
+    fn wants_text_input(&self) -> bool {
+        matches!(self.step, PolarStep::Count { .. } | PolarStep::Angle { .. })
+    }
+
+    fn on_text_input(&mut self, text: &str) -> Option<CmdResult> {
+        let t = text.trim().replace(',', ".");
+        let t = t.as_str();
+        match &self.step {
+            PolarStep::Count { center } => {
+                let center = *center;
+                let count = if t.is_empty() {
+                    self.default_count
+                } else {
+                    let v = t.parse::<u32>().unwrap_or(self.default_count).max(2);
+                    defaults::set_array_p_count(v as f32);
+                    self.default_count = v;
+                    v
+                };
+                self.step = PolarStep::Angle { center, count };
+                None
+            }
+            PolarStep::Angle { center, count } => {
+                let center = *center;
+                let count = *count;
+                let total_deg = if t.is_empty() {
+                    self.default_angle
+                } else {
+                    let v = t.parse::<f32>().unwrap_or(self.default_angle);
+                    defaults::set_array_p_angle(v);
+                    v
+                };
+                let step_rad = total_deg.to_radians() / count as f32;
+                let transforms = (1..count)
+                    .map(|n| EntityTransform::Rotate {
+                        center,
+                        angle_rad: step_rad * n as f32,
+                    })
+                    .collect();
+                Some(CmdResult::BatchCopy(self.handles.clone(), transforms))
+            }
+            _ => None,
+        }
+    }
+
+    fn on_preview_wires(&mut self, pt: Vec3) -> Vec<WireModel> {
+        let (center, count, total_deg) = match &self.step {
+            PolarStep::Center => (pt, self.default_count, self.default_angle),
+            PolarStep::Count { center } => (*center, self.default_count, self.default_angle),
+            PolarStep::Angle { center, count } => (*center, *count, self.default_angle),
+        };
+        let step_rad = total_deg.to_radians() / count as f32;
+        let mut out: Vec<WireModel> = (1..count)
+            .flat_map(|n| {
+                let angle_rad = step_rad * n as f32;
+                self.wire_models
+                    .iter()
+                    .map(move |w| w.rotated(center, angle_rad))
+            })
+            .collect();
+        // Rubber-band from center to cursor while picking the center point.
+        if matches!(self.step, PolarStep::Center) {
+            out.push(WireModel::solid(
+                "rubber_band".into(),
+                vec![[center.x, center.y, center.z], [pt.x, pt.y, pt.z]],
+                WireModel::CYAN,
+                false,
+            ));
+        }
+        out
+    }
+
+    fn on_point(&mut self, pt: Vec3) -> CmdResult {
+        if let PolarStep::Center = self.step {
+            self.step = PolarStep::Count { center: pt };
+        }
+        CmdResult::NeedPoint
+    }
+
+    fn on_enter(&mut self) -> CmdResult {
+        self.on_text_input("").map_or(CmdResult::NeedPoint, |r| r)
+    }
+
+    fn on_escape(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+}
+
+// ── Path Array ─────────────────────────────────────────────────────────────
+//
+// ARRAYPATH:
+//   Copies selected objects at equal arc-length intervals along a path entity.
+//   1. Select path entity (Line, Arc, Circle, LwPolyline)
+//   2. Enter item count (total, including the original at the path start)
+//   → Returns BatchCopy with Translate transforms derived from path samples.
+
+use acadrust::EntityType;
+use std::f32::consts::TAU as FTAU;
+
+// ── Path geometry helpers ──────────────────────────────────────────────────
+
+/// Tessellate an LwPolyline.
+fn lw_dense_pts(p: &acadrust::entities::LwPolyline) -> Vec<Vec3> {
+    let z = p.elevation as f32;
+    let verts = &p.vertices;
+    if verts.is_empty() {
+        return vec![];
+    }
+    let n = verts.len();
+    let segs = if p.is_closed { n } else { n.saturating_sub(1) };
+    let mut out: Vec<Vec3> = vec![];
+
+    for i in 0..segs {
+        let v0 = &verts[i];
+        let v1 = &verts[(i + 1) % n];
+        let x0 = v0.location.x as f32;
+        let y0 = v0.location.y as f32;
+        let x1 = v1.location.x as f32;
+        let y1 = v1.location.y as f32;
+
+        if out.is_empty() {
+            out.push(Vec3::new(x0, y0, z));
+        }
+
+        let bulge = v0.bulge as f32;
+        if bulge.abs() < 1e-9 {
+            out.push(Vec3::new(x1, y1, z));
+        } else {
+            let dx = x1 - x0;
+            let dy = y1 - y0;
+            let d = (dx * dx + dy * dy).sqrt();
+            if d < 1e-9 {
+                out.push(Vec3::new(x1, y1, z));
+                continue;
+            }
+            let angle = 4.0 * bulge.atan();
+            let r = (d * 0.5) / (angle * 0.5).sin().abs();
+            let mx = (x0 + x1) * 0.5;
+            let my = (y0 + y1) * 0.5;
+            let inv = 1.0 / d;
+            let (px, py) = (-dy * inv, dx * inv);
+            let sign = if bulge > 0.0 { 1.0f32 } else { -1.0 };
+            let h_val = r - (r * r - d * d * 0.25).max(0.0).sqrt();
+            let (cx, cy) = (mx - sign * px * (r - h_val), my - sign * py * (r - h_val));
+            let a0 = (y0 - cy).atan2(x0 - cx);
+            let a1 = (y1 - cy).atan2(x1 - cx);
+            // Signed span: CCW for bulge > 0, CW (negative) for bulge < 0.
+            let span = if bulge > 0.0 {
+                let s = a1 - a0;
+                if s <= 0.0 {
+                    s + FTAU
+                } else {
+                    s
+                }
+            } else {
+                let s = a1 - a0;
+                if s >= 0.0 {
+                    s - FTAU
+                } else {
+                    s
+                }
+            };
+            let steps = ((r * span.abs() / 2.0).ceil() as usize).clamp(4, 64);
+            for j in 1..=steps {
+                let ang = a0 + span * (j as f32 / steps as f32);
+                out.push(Vec3::new(cx + r * ang.cos(), cy + r * ang.sin(), z));
+            }
+        }
+    }
+    out
+}
+
+/// Walk `pts` (ordered) and return `count` points at equal arc-length spacing.
+fn subsample_equidistant(pts: &[Vec3], count: usize) -> Vec<Vec3> {
+    if count == 0 {
+        return vec![];
+    }
+    if pts.len() < 2 {
+        return vec![pts.first().copied().unwrap_or(Vec3::ZERO); count];
+    }
+
+    let mut cum = vec![0.0f32; pts.len()];
+    for i in 1..pts.len() {
+        cum[i] = cum[i - 1] + pts[i].distance(pts[i - 1]);
+    }
+    let total = *cum.last().unwrap();
+    if total < 1e-9 {
+        return vec![pts[0]; count];
+    }
+
+    let mut out = Vec::with_capacity(count);
+    let mut seg = 0usize;
+    for i in 0..count {
+        let target = if count > 1 {
+            total * i as f32 / (count - 1) as f32
+        } else {
+            0.0
+        };
+        while seg + 2 < pts.len() && cum[seg + 1] < target - 1e-9 {
+            seg += 1;
+        }
+        let seg_len = cum[seg + 1] - cum[seg];
+        let t = if seg_len > 1e-9 {
+            (target - cum[seg]) / seg_len
+        } else {
+            0.0
+        };
+        out.push(pts[seg].lerp(pts[seg + 1], t.clamp(0.0, 1.0)));
+    }
+    out
+}
+
+// ── State machine ──────────────────────────────────────────────────────────
+
+enum PathStep {
+    SelectPath,
+    Count { path_entity: EntityType },
+}
+
+pub struct ArrayPathCommand {
+    handles: Vec<Handle>,
+    wire_models: Vec<WireModel>,
+    all_entities: Vec<EntityType>,
+    step: PathStep,
+    default_count: u32,
+}
+
+impl ArrayPathCommand {
+    pub fn new(
+        handles: Vec<Handle>,
+        wire_models: Vec<WireModel>,
+        all_entities: Vec<EntityType>,
+    ) -> Self {
+        Self {
+            handles,
+            wire_models,
+            all_entities,
+            step: PathStep::SelectPath,
+            default_count: defaults::get_array_path_count() as u32,
+        }
+    }
+
+    /// Sample `count` evenly-spaced points along `entity`.
+    fn sample_path(entity: &EntityType, count: usize) -> Vec<Vec3> {
+        if count == 0 {
+            return vec![];
+        }
+        let fn_norm = |x: f32| -> f32 { ((x % FTAU) + FTAU) % FTAU };
+        match entity {
+            EntityType::Line(l) => {
+                let p0 = Vec3::new(l.start.x as f32, l.start.y as f32, 0.0);
+                let p1 = Vec3::new(l.end.x as f32, l.end.y as f32, 0.0);
+                let d = (count - 1).max(1) as f32;
+                (0..count).map(|i| p0.lerp(p1, i as f32 / d)).collect()
+            }
+            EntityType::Arc(a) => {
+                let (cx, cy, r) = (a.center.x as f32, a.center.y as f32, a.radius as f32);
+                let a0 = a.start_angle.to_radians() as f32;
+                let a1 = a.end_angle.to_radians() as f32;
+                let span = {
+                    let s = fn_norm(a1) - fn_norm(a0);
+                    if s <= 0.0 {
+                        s + FTAU
+                    } else {
+                        s
+                    }
+                };
+                let d = (count - 1).max(1) as f32;
+                (0..count)
+                    .map(|i| {
+                        let ang = fn_norm(a0) + span * (i as f32 / d);
+                        Vec3::new(cx + r * ang.cos(), cy + r * ang.sin(), 0.0)
+                    })
+                    .collect()
+            }
+            EntityType::Circle(c) => {
+                let (cx, cy, r) = (c.center.x as f32, c.center.y as f32, c.radius as f32);
+                (0..count)
+                    .map(|i| {
+                        let ang = i as f32 / count as f32 * FTAU;
+                        Vec3::new(cx + r * ang.cos(), cy + r * ang.sin(), 0.0)
+                    })
+                    .collect()
+            }
+            EntityType::LwPolyline(p) => subsample_equidistant(&lw_dense_pts(p), count),
+            _ => vec![Vec3::ZERO; count],
+        }
+    }
+
+    /// Build Translate transforms: delta from pts[0] to each subsequent point.
+    fn build_transforms(pts: &[Vec3]) -> Vec<EntityTransform> {
+        if pts.len() < 2 {
+            return vec![];
+        }
+        let origin = pts[0];
+        pts[1..]
+            .iter()
+            .map(|&p| EntityTransform::Translate(p - origin))
+            .collect()
+    }
+}
+
+impl CadCommand for ArrayPathCommand {
+    fn name(&self) -> &'static str {
+        "ARRAYPATH"
+    }
+
+    fn prompt(&self) -> String {
+        match &self.step {
+            PathStep::SelectPath => format!(
+                "ARRAYPATH  Select path entity  [{} objects]:",
+                self.handles.len()
+            ),
+            PathStep::Count { .. } => {
+                format!("ARRAYPATH  Enter item count <{}>:", self.default_count)
+            }
+        }
+    }
+
+    fn needs_entity_pick(&self) -> bool {
+        matches!(self.step, PathStep::SelectPath)
+    }
+
+    fn wants_text_input(&self) -> bool {
+        matches!(self.step, PathStep::Count { .. })
+    }
+
+    fn on_entity_pick(&mut self, handle: Handle, _pt: Vec3) -> CmdResult {
+        if handle.is_null() || self.handles.contains(&handle) {
+            return CmdResult::NeedPoint;
+        }
+        if let Some(entity) = self
+            .all_entities
+            .iter()
+            .find(|e| e.common().handle == handle)
+            .cloned()
+        {
+            self.step = PathStep::Count {
+                path_entity: entity,
+            };
+        }
+        CmdResult::NeedPoint
+    }
+
+    fn on_hover_entity(&mut self, handle: Handle, _pt: Vec3) -> Vec<WireModel> {
+        if handle.is_null() || self.handles.contains(&handle) {
+            return vec![];
+        }
+        if !matches!(self.step, PathStep::SelectPath) {
+            return vec![];
+        }
+        if let Some(entity) = self
+            .all_entities
+            .iter()
+            .find(|e| e.common().handle == handle)
+        {
+            let pts = Self::sample_path(entity, 64);
+            if pts.len() >= 2 {
+                return vec![WireModel::solid(
+                    "arraypath_hover".into(),
+                    pts.iter().map(|p| [p.x, p.y, p.z]).collect(),
+                    WireModel::CYAN,
+                    false,
+                )];
+            }
+        }
+        vec![]
+    }
+
+    fn on_text_input(&mut self, text: &str) -> Option<CmdResult> {
+        let PathStep::Count { path_entity } = &self.step else {
+            return None;
+        };
+        let t = text.trim().replace(',', ".");
+        let count = if t.is_empty() {
+            self.default_count
+        } else {
+            let v = t.parse::<u32>().unwrap_or(self.default_count).max(2);
+            defaults::set_array_path_count(v as f32);
+            self.default_count = v;
+            v
+        };
+        let pts = Self::sample_path(path_entity, count as usize);
+        let transforms = Self::build_transforms(&pts);
+        if transforms.is_empty() {
+            return Some(CmdResult::Cancel);
+        }
+        Some(CmdResult::BatchCopy(self.handles.clone(), transforms))
+    }
+
+    fn on_preview_wires(&mut self, _pt: Vec3) -> Vec<WireModel> {
+        let PathStep::Count { path_entity } = &self.step else {
+            return vec![];
+        };
+        let pts = Self::sample_path(path_entity, self.default_count as usize);
+        let transforms = Self::build_transforms(&pts);
+        transforms
+            .iter()
+            .flat_map(|t| {
+                if let EntityTransform::Translate(delta) = t {
+                    self.wire_models
+                        .iter()
+                        .map(|w| w.translated(*delta))
+                        .collect::<Vec<_>>()
+                } else {
+                    vec![]
+                }
+            })
+            .collect()
+    }
+
+    fn on_point(&mut self, _pt: Vec3) -> CmdResult {
+        CmdResult::NeedPoint
+    }
+
+    fn on_enter(&mut self) -> CmdResult {
+        self.on_text_input("").map_or(CmdResult::NeedPoint, |r| r)
+    }
+
+    fn on_escape(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+}

src/modules/home/modify/copy.rs

@@ -0,0 +1,108 @@
+// Copy tool — ribbon definition + interactive command.
+//
+// Command:  COPY (CO)
+//   Requires at least one entity selected before starting.
+//   Step 1: pick base point
+//   Step 2+: each click makes another copy at (click - base); Enter to finish.
+
+use acadrust::Handle;
+use glam::Vec3;
+
+use crate::command::{CadCommand, CmdResult, EntityTransform};
+use crate::modules::{IconKind, ModuleEvent, ToolDef};
+use crate::scene::wire_model::WireModel;
+
+// ── Ribbon definition ──────────────────────────────────────────────────────
+
+pub fn tool() -> ToolDef {
+    ToolDef {
+        id: "COPY",
+        label: "Copy",
+        icon: IconKind::Svg(include_bytes!("../../../../assets/icons/copy.svg")),
+        event: ModuleEvent::Command("COPY".to_string()),
+    }
+}
+
+// ── Command implementation ─────────────────────────────────────────────────
+
+enum Step {
+    Base,
+    Placing(Vec3),
+}
+
+pub struct CopyCommand {
+    handles: Vec<Handle>,
+    wire_models: Vec<WireModel>,
+    step: Step,
+    count: usize,
+}
+
+impl CopyCommand {
+    pub fn new(handles: Vec<Handle>, wire_models: Vec<WireModel>) -> Self {
+        Self {
+            handles,
+            wire_models,
+            step: Step::Base,
+            count: 0,
+        }
+    }
+}
+
+impl CadCommand for CopyCommand {
+    fn name(&self) -> &'static str {
+        "COPY"
+    }
+
+    fn prompt(&self) -> String {
+        match &self.step {
+            Step::Base => format!(
+                "COPY  Specify base point  [{} objects]:",
+                self.handles.len()
+            ),
+            Step::Placing(base) => format!(
+                "COPY  Specify destination  [{} copies so far | Enter=done | base {:.3},{:.3}]:",
+                self.count, base.x, base.y
+            ),
+        }
+    }
+
+    fn on_point(&mut self, pt: Vec3) -> CmdResult {
+        match &self.step {
+            Step::Base => {
+                self.step = Step::Placing(pt);
+                CmdResult::NeedPoint
+            }
+            Step::Placing(base) => {
+                let delta = pt - *base;
+                self.count += 1;
+                CmdResult::CopySelected(self.handles.clone(), EntityTransform::Translate(delta))
+            }
+        }
+    }
+
+    fn on_enter(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+    fn on_escape(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+
+    fn on_preview_wires(&mut self, pt: Vec3) -> Vec<WireModel> {
+        let Step::Placing(base) = &self.step else {
+            return vec![];
+        };
+        let delta = pt - *base;
+        let mut out: Vec<WireModel> = self
+            .wire_models
+            .iter()
+            .map(|w| w.translated(delta))
+            .collect();
+        out.push(WireModel::solid(
+            "rubber_band".into(),
+            vec![[base.x, base.y, base.z], [pt.x, pt.y, pt.z]],
+            WireModel::CYAN,
+            false,
+        ));
+        out
+    }
+}

src/modules/home/modify/delete.rs

@@ -0,0 +1,15 @@
+// Delete tool — ribbon definition.
+//
+// Fires the ERASE command (same as pressing Delete key or typing ERASE/E).
+// Shown as "Delete" in the ribbon so the label matches familiar terminology.
+
+use crate::modules::{IconKind, ModuleEvent, ToolDef};
+
+pub fn tool() -> ToolDef {
+    ToolDef {
+        id: "ERASE",
+        label: "Delete",
+        icon: IconKind::Svg(include_bytes!("../../../../assets/icons/erase.svg")),
+        event: ModuleEvent::Command("ERASE".to_string()),
+    }
+}

src/modules/home/modify/explode.rs

@@ -0,0 +1,226 @@
+// Explode tool — ribbon definition + command implementation.
+//
+// Command:  EXPLODE (X)
+//   EXPLODE: Breaks compound objects into their constituent simple entities.
+//
+//   Supported:
+//     LwPolyline → Lines (straight segments) + Arcs (bulge segments)
+//
+//   Unsupported entity types are skipped silently.
+
+use std::f64::consts::TAU;
+
+use acadrust::entities::EntityCommon;
+use acadrust::entities::{Arc as ArcEnt, Circle as CircleEnt, Line as LineEnt, LwPolyline};
+use acadrust::types::Vector3;
+use acadrust::{CadDocument, EntityType, Handle};
+
+use crate::command::{CadCommand, CmdResult};
+use crate::modules::{IconKind, ModuleEvent, ToolDef};
+use glam::Vec3;
+
+// ── Ribbon definition ──────────────────────────────────────────────────────
+
+pub fn tool() -> ToolDef {
+    ToolDef {
+        id: "EXPLODE",
+        label: "Explode",
+        icon: IconKind::Svg(include_bytes!("../../../../assets/icons/explode.svg")),
+        event: ModuleEvent::Command("EXPLODE".to_string()),
+    }
+}
+
+// ── Geometry helpers ────────────────────────────────────────────────────────
+
+/// Decompose an entity into its constituent simple entities.
+/// Returns an empty vec if the entity cannot be exploded.
+pub fn explode_entity(entity: &EntityType, document: &CadDocument) -> Vec<EntityType> {
+    match entity {
+        EntityType::LwPolyline(p) => explode_lwpolyline(p),
+        EntityType::Insert(ins) => ins
+            .explode_from_document(document)
+            .into_iter()
+            .map(normalize_insert_entity)
+            .collect(),
+        _ => vec![],
+    }
+}
+
+pub fn normalize_insert_entity(mut entity: EntityType) -> EntityType {
+    match &mut entity {
+        EntityType::Arc(arc) => {
+            arc.start_angle = arc.start_angle.to_degrees();
+            arc.end_angle = arc.end_angle.to_degrees();
+        }
+        EntityType::Ellipse(ell) => {
+            let major_len = ell.major_axis_length();
+            let full_span = {
+                let mut span = ell.end_parameter - ell.start_parameter;
+                if span < 0.0 {
+                    span += std::f64::consts::TAU;
+                }
+                (span - std::f64::consts::TAU).abs() < 1e-6
+            };
+            if (ell.minor_axis_ratio - 1.0).abs() < 1e-6 && full_span {
+                let mut circle = CircleEnt::new();
+                circle.common = ell.common.clone();
+                circle.center = ell.center;
+                circle.radius = major_len;
+                circle.normal = ell.normal;
+                entity = EntityType::Circle(circle);
+            }
+        }
+        _ => {}
+    }
+
+    entity.common_mut().handle = Handle::NULL;
+    entity.common_mut().owner_handle = Handle::NULL;
+    entity
+}
+
+pub fn normalize_entity_for_block(mut entity: EntityType) -> EntityType {
+    if let EntityType::Arc(arc) = &mut entity {
+        arc.start_angle = arc.start_angle.to_radians();
+        arc.end_angle = arc.end_angle.to_radians();
+    }
+    entity
+}
+
+fn explode_lwpolyline(p: &LwPolyline) -> Vec<EntityType> {
+    let n = p.vertices.len();
+    if n < 2 {
+        return vec![];
+    }
+
+    let elevation = p.elevation;
+    let n_segs = if p.is_closed { n } else { n - 1 };
+
+    let mut result = Vec::new();
+    for i in 0..n_segs {
+        let v0 = &p.vertices[i];
+        let v1 = &p.vertices[(i + 1) % n];
+
+        let p0 = [v0.location.x, v0.location.y];
+        let p1 = [v1.location.x, v1.location.y];
+
+        if v0.bulge.abs() < 1e-10 {
+            // Straight segment → Line
+            let mut common = p.common.clone();
+            common.handle = Handle::NULL;
+            let line = LineEnt {
+                common,
+                start: Vector3::new(p0[0], p0[1], elevation),
+                end: Vector3::new(p1[0], p1[1], elevation),
+                ..LineEnt::new()
+            };
+            result.push(EntityType::Line(line));
+        } else {
+            // Arc segment from bulge
+            if let Some(arc) = bulge_to_arc(p0, p1, v0.bulge, elevation, &p.common) {
+                result.push(arc);
+            }
+        }
+    }
+    result
+}
+
+/// Convert a polyline bulge segment to an Arc entity.
+///   Arc angles are measured from the +X axis.
+fn bulge_to_arc(
+    p0: [f64; 2],
+    p1: [f64; 2],
+    bulge: f64,
+    elevation: f64,
+    common_src: &EntityCommon,
+) -> Option<EntityType> {
+    let chord_x = p1[0] - p0[0];
+    let chord_y = p1[1] - p0[1];
+    let chord_len = (chord_x * chord_x + chord_y * chord_y).sqrt();
+    if chord_len < 1e-12 {
+        return None;
+    }
+
+    // Included angle = 4 * atan(bulge)
+    let b = bulge;
+    let b2 = b * b;
+
+    // Radius: r = chord * (1 + b²) / (4 * |b|)
+    let r = chord_len * (1.0 + b2) / (4.0 * b.abs());
+
+    // Perpendicular distance from midpoint to center:
+    // d = r * cos(theta/2), where cos(theta/2) = (1 - b²) / (1 + b²)
+    let d = r * (1.0 - b2) / (1.0 + b2);
+
+    // Midpoint
+    let mx = (p0[0] + p1[0]) * 0.5;
+    let my = (p0[1] + p1[1]) * 0.5;
+
+    // Left-perpendicular direction (rotate chord 90° CCW)
+    let perp_x = -chord_y / chord_len;
+    let perp_y = chord_x / chord_len;
+
+    // Positive bulge → center is to the left of chord direction (CCW arc)
+    let sign = b.signum();
+    let cx = mx + sign * d * perp_x;
+    let cy = my + sign * d * perp_y;
+
+    // Angles from center to p0 and p1
+    let a0_rad = (p0[1] - cy).atan2(p0[0] - cx);
+    let a1_rad = (p1[1] - cy).atan2(p1[0] - cx);
+
+    // acadrust arcs are always CCW: positive bulge → CCW from p0 to p1
+    // Negative bulge → CW from p0 to p1 = CCW from p1 to p0
+    let (start_deg, end_deg) = if b > 0.0 {
+        (norm_deg(a0_rad.to_degrees()), norm_deg(a1_rad.to_degrees()))
+    } else {
+        (norm_deg(a1_rad.to_degrees()), norm_deg(a0_rad.to_degrees()))
+    };
+
+    let mut common = common_src.clone();
+    common.handle = Handle::NULL;
+
+    let arc = ArcEnt {
+        common,
+        center: Vector3::new(cx, cy, elevation),
+        radius: r,
+        start_angle: start_deg,
+        end_angle: end_deg,
+        ..ArcEnt::new()
+    };
+    Some(EntityType::Arc(arc))
+}
+
+fn norm_deg(a: f64) -> f64 {
+    let t = TAU.to_degrees();
+    ((a % t) + t) % t
+}
+
+// ── Command stub (kept for future interactive selection mode) ───────────────
+
+pub struct ExplodeCommand;
+
+impl ExplodeCommand {
+    #[allow(dead_code)]
+    pub fn new() -> Self {
+        Self
+    }
+}
+
+impl CadCommand for ExplodeCommand {
+    fn name(&self) -> &'static str {
+        "EXPLODE"
+    }
+    fn prompt(&self) -> String {
+        "EXPLODE  Select objects to explode:".into()
+    }
+
+    fn on_point(&mut self, _pt: Vec3) -> CmdResult {
+        CmdResult::Cancel
+    }
+    fn on_enter(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+    fn on_escape(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+}

src/modules/home/modify/extend.rs

@@ -0,0 +1 @@
+// Extend — dispatch handled by trim.rs dropdown. This file exists for module resolution.

src/modules/home/modify/fillet.rs

@@ -0,0 +1,830 @@
+// Fillet / Chamfer — ribbon definitions + full command implementations.
+//
+// FILLET (F):
+//   Pick two lines. Command finds their intersection, computes a tangent arc
+//   of radius R, trims both lines to the tangent points, and inserts the arc.
+//   R=0 just extends/trims both lines to the exact intersection (sharp corner).
+//
+// CHAMFER (CHA):
+//   Pick two lines. Command finds their intersection, backs off dist1 along
+//   line 1 and dist2 along line 2, trims, and inserts a straight chamfer line.
+
+use acadrust::entities::{Arc as ArcEnt, Line as LineEnt};
+use acadrust::types::Vector3;
+use acadrust::{EntityType, Handle};
+use glam::Vec3;
+
+use crate::command::{CadCommand, CmdResult};
+use crate::modules::home::defaults;
+use crate::modules::IconKind;
+use crate::scene::wire_model::WireModel;
+
+// ── Dropdown constants ─────────────────────────────────────────────────────
+
+pub const DROPDOWN_ID: &str = "fillet_chamfer";
+pub const ICON: IconKind = IconKind::Svg(include_bytes!("../../../../assets/icons/fillet.svg"));
+
+pub const DROPDOWN_ITEMS: &[(&str, &str, IconKind)] = &[
+    (
+        "FILLET",
+        "Fillet",
+        IconKind::Svg(include_bytes!("../../../../assets/icons/fillet.svg")),
+    ),
+    (
+        "CHAMFER",
+        "Chamfer",
+        IconKind::Svg(include_bytes!("../../../../assets/icons/chamfer.svg")),
+    ),
+];
+
+// ══════════════════════════════════════════════════════════════════════════
+// Geometry
+// ══════════════════════════════════════════════════════════════════════════
+
+/// Intersect two infinite lines. Returns (t on L1, u on L2).
+fn ll(
+    ax: f64,
+    ay: f64,
+    dx: f64,
+    dy: f64,
+    cx: f64,
+    cy: f64,
+    ex: f64,
+    ey: f64,
+) -> Option<(f64, f64)> {
+    let det = dx * ey - dy * ex;
+    if det.abs() < 1e-10 {
+        return None;
+    }
+    let t = ((cx - ax) * ey - (cy - ay) * ex) / det;
+    let u = ((cx - ax) * dy - (cy - ay) * dx) / det;
+    Some((t, u))
+}
+
+/// Extract coords and unit direction for a Line entity.
+fn line_geom(l: &LineEnt) -> ([f64; 2], [f64; 2], [f64; 2], f64) {
+    let p1 = [l.start.x, l.start.y];
+    let p2 = [l.end.x, l.end.y];
+    let dx = p2[0] - p1[0];
+    let dy = p2[1] - p1[1];
+    let len = (dx * dx + dy * dy).sqrt().max(1e-12);
+    (p1, p2, [dx / len, dy / len], len)
+}
+
+/// Project click onto line, returning t ∈ ℝ.
+fn project_click(click: [f64; 2], p1: [f64; 2], unit: [f64; 2]) -> f64 {
+    (click[0] - p1[0]) * unit[0] + (click[1] - p1[1]) * unit[1]
+}
+
+// ── Fillet ─────────────────────────────────────────────────────────────────
+
+/// Compute fillet: trim l1/l2 and insert a tangent arc of `radius`.
+/// Returns (trimmed_l1, trimmed_l2, fillet_arc).
+fn compute_fillet(
+    l1: &LineEnt,
+    click1: [f64; 2],
+    l2: &LineEnt,
+    click2: [f64; 2],
+    radius: f64,
+) -> Option<(EntityType, EntityType, Option<EntityType>)> {
+    let (p1, _p2, u1, _len1) = line_geom(l1);
+    let (p3, _p4, u2, _len2) = line_geom(l2);
+
+    // Intersection of infinite lines
+    let (t_p, u_p) = ll(p1[0], p1[1], u1[0], u1[1], p3[0], p3[1], u2[0], u2[1])?;
+
+    // Intersection point
+    let px = p1[0] + t_p * u1[0];
+    let py = p1[1] + t_p * u1[1];
+
+    // Direction from P toward each click (the "keep" side)
+    let s1 = project_click(click1, [px, py], u1); // positive = along u1
+    let s2 = project_click(click2, [px, py], u2);
+    let dir1 = if s1 >= 0.0 {
+        [u1[0], u1[1]]
+    } else {
+        [-u1[0], -u1[1]]
+    };
+    let dir2 = if s2 >= 0.0 {
+        [u2[0], u2[1]]
+    } else {
+        [-u2[0], -u2[1]]
+    };
+
+    // Angle between the two keep-directions
+    let cos_a = (dir1[0] * dir2[0] + dir1[1] * dir2[1]).clamp(-1.0, 1.0);
+    let angle = cos_a.acos();
+
+    // Lines are parallel / anti-parallel
+    if angle < 1e-6 || (angle - std::f64::consts::PI).abs() < 1e-6 {
+        return None;
+    }
+
+    let half = angle / 2.0;
+    let z = l1.start.z;
+
+    if radius < 1e-9 {
+        // r = 0: just extend/trim both lines to the intersection
+        let (new_l1, new_l2) = trim_to_point(l1, t_p, p1, u1, l2, u_p, p3, u2)?;
+        return Some((EntityType::Line(new_l1), EntityType::Line(new_l2), None));
+    }
+
+    // Distance from P to tangent points
+    let d = radius / half.tan();
+
+    // Tangent points
+    let t1 = [px + d * dir1[0], py + d * dir1[1]];
+    let t2 = [px + d * dir2[0], py + d * dir2[1]];
+
+    // Arc center: along bisector of dir1+dir2, distance = r / sin(half)
+    let bx = dir1[0] + dir2[0];
+    let by = dir1[1] + dir2[1];
+    let blen = (bx * bx + by * by).sqrt();
+    if blen < 1e-10 {
+        return None;
+    }
+    let arc_dist = radius / half.sin();
+    let arc_cx = px + arc_dist * bx / blen;
+    let arc_cy = py + arc_dist * by / blen;
+
+    // Arc angles in degrees
+    let a_start_deg = (t1[1] - arc_cy).atan2(t1[0] - arc_cx).to_degrees();
+    let a_end_deg = (t2[1] - arc_cy).atan2(t2[0] - arc_cx).to_degrees();
+
+    // Pick CCW direction that fills the concave corner
+    let cross = dir1[0] * dir2[1] - dir1[1] * dir2[0];
+    let (start_deg, end_deg) = if cross <= 0.0 {
+        (a_start_deg, a_end_deg)
+    } else {
+        (a_end_deg, a_start_deg)
+    };
+
+    // Trim l1 to T1 and l2 to T2
+    let new_l1 = trim_to_xy(l1, t_p, t1, dir1, p1, u1)?;
+    let new_l2 = trim_to_xy(l2, u_p, t2, dir2, p3, u2)?;
+
+    // Build arc entity
+    let mut arc = ArcEnt::new();
+    arc.common = l1.common.clone();
+    arc.common.handle = Handle::NULL;
+    arc.center = Vector3::new(arc_cx, arc_cy, z);
+    arc.radius = radius;
+    arc.start_angle = start_deg;
+    arc.end_angle = end_deg;
+
+    Some((
+        EntityType::Line(new_l1),
+        EntityType::Line(new_l2),
+        Some(EntityType::Arc(arc)),
+    ))
+}
+
+/// Trim a line's parameter to an intersection t on the same side as dir (keep side).
+fn trim_to_xy(
+    orig: &LineEnt,
+    t_isect: f64,
+    tangent: [f64; 2],
+    dir: [f64; 2],
+    p1: [f64; 2],
+    unit: [f64; 2],
+) -> Option<LineEnt> {
+    let z = orig.start.z;
+    let mut l = orig.clone();
+    l.common.handle = Handle::NULL;
+
+    // t_tangent: parameter of the tangent point along the line from start
+    let t_tan = (tangent[0] - p1[0]) * unit[0] + (tangent[1] - p1[1]) * unit[1];
+
+    // dir is positive along unit → we keep the portion BEYOND t_tan in that direction
+    // dir positive: keep from t_tan to +∞ (i.e. set start to tangent point)
+    // dir negative: keep from -∞ to t_tan (i.e. set end to tangent point)
+    let len = {
+        let dx = orig.end.x - orig.start.x;
+        let dy = orig.end.y - orig.start.y;
+        (dx * dx + dy * dy).sqrt().max(1e-12)
+    };
+    let dot = dir[0] * unit[0] + dir[1] * unit[1]; // +1 or -1
+
+    if dot > 0.0 {
+        // keep from tangent to end → move start to tangent point
+        l.start = Vector3::new(tangent[0], tangent[1], z);
+    } else {
+        // keep from start to tangent → move end to tangent point
+        l.end = Vector3::new(tangent[0], tangent[1], z);
+    }
+    let _ = (t_isect, len, t_tan); // used implicitly via `dot`
+    Some(l)
+}
+
+/// Trim both lines exactly to their intersection point (r=0 case).
+fn trim_to_point(
+    l1: &LineEnt,
+    t_p: f64,
+    p1: [f64; 2],
+    u1: [f64; 2],
+    l2: &LineEnt,
+    u_p: f64,
+    _p3: [f64; 2],
+    _u2: [f64; 2],
+) -> Option<(LineEnt, LineEnt)> {
+    let px = p1[0] + t_p * u1[0];
+    let py = p1[1] + t_p * u1[1];
+    let z1 = l1.start.z;
+    let z2 = l2.start.z;
+
+    // For l1: if t_p is past the midpoint, keep start…P; else keep P…end
+    // We use the same "which end is P closer to" logic
+    let mut ll1 = l1.clone();
+    ll1.common.handle = Handle::NULL;
+    let mut ll2 = l2.clone();
+    ll2.common.handle = Handle::NULL;
+
+    if t_p >= 0.0 {
+        ll1.end = Vector3::new(px, py, z1);
+    } else {
+        ll1.start = Vector3::new(px, py, z1);
+    }
+
+    if u_p >= 0.0 {
+        ll2.end = Vector3::new(px, py, z2);
+    } else {
+        ll2.start = Vector3::new(px, py, z2);
+    }
+
+    Some((ll1, ll2))
+}
+
+// ── Point-generation helpers ──────────────────────────────────────────────
+
+fn line_pts(l: &LineEnt) -> Vec<[f32; 3]> {
+    vec![
+        [l.start.x as f32, l.start.y as f32, l.start.z as f32],
+        [l.end.x as f32, l.end.y as f32, l.end.z as f32],
+    ]
+}
+
+fn arc_pts(cx: f64, cy: f64, r: f64, a0_deg: f64, a1_deg: f64, y: f64) -> Vec<[f32; 3]> {
+    use std::f64::consts::TAU;
+    let fn_norm = |a: f64| -> f64 { ((a % TAU) + TAU) % TAU };
+    let a0 = a0_deg.to_radians();
+    let a1 = a1_deg.to_radians();
+    let span = {
+        let s = fn_norm(a1) - fn_norm(a0);
+        if s <= 0.0 {
+            s + TAU
+        } else {
+            s
+        }
+    };
+    let steps = (span.abs() * 20.0).ceil().max(4.0) as usize;
+    (0..=steps)
+        .map(|i| {
+            let ang = fn_norm(a0) + span * (i as f64 / steps as f64);
+            [
+                (cx + r * ang.cos()) as f32,
+                y as f32,
+                (cy + r * ang.sin()) as f32,
+            ]
+        })
+        .collect()
+}
+
+fn entity_pts(e: &EntityType) -> Vec<[f32; 3]> {
+    match e {
+        EntityType::Line(l) => line_pts(l),
+        EntityType::Arc(a) => arc_pts(
+            a.center.x,
+            a.center.y,
+            a.radius,
+            a.start_angle,
+            a.end_angle,
+            a.center.y,
+        ),
+        _ => vec![],
+    }
+}
+
+// ── Chamfer ────────────────────────────────────────────────────────────────
+
+/// Compute chamfer: trim l1 by dist1 from intersection, l2 by dist2, add chamfer line.
+fn compute_chamfer(
+    l1: &LineEnt,
+    click1: [f64; 2],
+    dist1: f64,
+    l2: &LineEnt,
+    click2: [f64; 2],
+    dist2: f64,
+) -> Option<(EntityType, EntityType, EntityType)> {
+    let (p1, _, u1, _) = line_geom(l1);
+    let (p3, _, u2, _) = line_geom(l2);
+
+    let (t_p, u_p) = ll(p1[0], p1[1], u1[0], u1[1], p3[0], p3[1], u2[0], u2[1])?;
+
+    let px = p1[0] + t_p * u1[0];
+    let py = p1[1] + t_p * u1[1];
+    let z = l1.start.z;
+
+    let s1 = project_click(click1, [px, py], u1);
+    let s2 = project_click(click2, [px, py], u2);
+    let dir1 = if s1 >= 0.0 {
+        [u1[0], u1[1]]
+    } else {
+        [-u1[0], -u1[1]]
+    };
+    let dir2 = if s2 >= 0.0 {
+        [u2[0], u2[1]]
+    } else {
+        [-u2[0], -u2[1]]
+    };
+
+    // Chamfer points: back off dist from P along keep-direction
+    let c1 = [px + dist1 * dir1[0], py + dist1 * dir1[1]];
+    let c2 = [px + dist2 * dir2[0], py + dist2 * dir2[1]];
+
+    // Trim l1 to c1 and l2 to c2
+    let new_l1 = trim_to_xy(l1, t_p, c1, dir1, p1, u1)?;
+    let new_l2 = trim_to_xy(l2, u_p, c2, dir2, p3, u2)?;
+
+    // Chamfer line
+    let mut cline = l1.clone();
+    cline.common.handle = Handle::NULL;
+    cline.start = Vector3::new(c1[0], c1[1], z);
+    cline.end = Vector3::new(c2[0], c2[1], z);
+
+    Some((
+        EntityType::Line(new_l1),
+        EntityType::Line(new_l2),
+        EntityType::Line(cline),
+    ))
+}
+
+// ══════════════════════════════════════════════════════════════════════════
+// FilletCommand
+// ══════════════════════════════════════════════════════════════════════════
+
+enum FilletStep {
+    First,
+    Second {
+        h1: Handle,
+        l1: LineEnt,
+        click1: [f64; 2],
+    },
+}
+
+pub struct FilletCommand {
+    radius: f64,
+    step: FilletStep,
+    all_entities: Vec<EntityType>,
+}
+
+impl FilletCommand {
+    pub fn new(radius: f32, all_entities: Vec<EntityType>) -> Self {
+        Self {
+            radius: radius as f64,
+            step: FilletStep::First,
+            all_entities,
+        }
+    }
+}
+
+impl CadCommand for FilletCommand {
+    fn name(&self) -> &'static str {
+        "FILLET"
+    }
+
+    fn prompt(&self) -> String {
+        match &self.step {
+            FilletStep::First => format!(
+                "FILLET  Select first line  [R={:.4} | type R <val> to change]:",
+                self.radius
+            ),
+            FilletStep::Second { .. } => {
+                format!("FILLET  Select second line  [R={:.4}]:", self.radius)
+            }
+        }
+    }
+
+    fn wants_text_input(&self) -> bool {
+        matches!(self.step, FilletStep::First)
+    }
+
+    fn on_text_input(&mut self, text: &str) -> Option<CmdResult> {
+        let t = text.trim();
+        let body = if t.to_uppercase().starts_with('R') {
+            t[1..].trim()
+        } else {
+            t
+        };
+        if let Ok(v) = body.replace(',', ".").parse::<f64>() {
+            if v >= 0.0 {
+                self.radius = v;
+                defaults::set_fillet_radius(v as f32);
+            }
+        }
+        None
+    }
+
+    fn needs_entity_pick(&self) -> bool {
+        true
+    }
+
+    fn on_entity_pick(&mut self, handle: Handle, pt: Vec3) -> CmdResult {
+        if handle.is_null() {
+            return CmdResult::NeedPoint;
+        }
+        let click = [pt.x as f64, pt.y as f64];
+
+        match &self.step {
+            FilletStep::First => {
+                // Must be a line
+                let l1 = self
+                    .all_entities
+                    .iter()
+                    .find(|e| e.common().handle == handle)
+                    .and_then(|e| {
+                        if let EntityType::Line(l) = e {
+                            Some(l.clone())
+                        } else {
+                            None
+                        }
+                    });
+                if let Some(l) = l1 {
+                    self.step = FilletStep::Second {
+                        h1: handle,
+                        l1: l,
+                        click1: click,
+                    };
+                    CmdResult::NeedPoint
+                } else {
+                    CmdResult::NeedPoint // not a line — ignore
+                }
+            }
+            FilletStep::Second { h1, l1, click1 } => {
+                let h1 = *h1;
+                let l1 = l1.clone();
+                let click1 = *click1;
+                if handle == h1 {
+                    return CmdResult::NeedPoint;
+                }
+
+                let l2 = self
+                    .all_entities
+                    .iter()
+                    .find(|e| e.common().handle == handle)
+                    .and_then(|e| {
+                        if let EntityType::Line(l) = e {
+                            Some(l.clone())
+                        } else {
+                            None
+                        }
+                    });
+
+                if let Some(l2) = l2 {
+                    match compute_fillet(&l1, click1, &l2, click, self.radius) {
+                        Some((new_l1, new_l2, maybe_arc)) => {
+                            let mut additions = vec![];
+                            if let Some(arc) = maybe_arc {
+                                additions.push(arc);
+                            }
+                            CmdResult::ReplaceMany(
+                                vec![(h1, vec![new_l1]), (handle, vec![new_l2])],
+                                additions,
+                            )
+                        }
+                        None => {
+                            // Could not compute fillet (parallel lines, etc.)
+                            CmdResult::NeedPoint
+                        }
+                    }
+                } else {
+                    CmdResult::NeedPoint
+                }
+            }
+        }
+    }
+
+    fn on_hover_entity(&mut self, handle: Handle, pt: Vec3) -> Vec<WireModel> {
+        if handle.is_null() {
+            return vec![];
+        }
+        let click = [pt.x as f64, pt.y as f64];
+
+        match &self.step {
+            FilletStep::First => {
+                // Highlight hovered line in cyan
+                let pts = self
+                    .all_entities
+                    .iter()
+                    .find(|e| e.common().handle == handle)
+                    .and_then(|e| {
+                        if let EntityType::Line(l) = e {
+                            Some(line_pts(l))
+                        } else {
+                            None
+                        }
+                    });
+                if let Some(pts) = pts {
+                    vec![WireModel::solid(
+                        "fillet_hover".into(),
+                        pts,
+                        WireModel::CYAN,
+                        false,
+                    )]
+                } else {
+                    vec![]
+                }
+            }
+            FilletStep::Second { l1, click1, .. } => {
+                let l1 = l1.clone();
+                let click1 = *click1;
+                if handle.is_null() {
+                    return vec![];
+                }
+                let l2 = self
+                    .all_entities
+                    .iter()
+                    .find(|e| e.common().handle == handle)
+                    .and_then(|e| {
+                        if let EntityType::Line(l) = e {
+                            Some(l.clone())
+                        } else {
+                            None
+                        }
+                    });
+                if let Some(l2) = l2 {
+                    if let Some((new_l1, new_l2, maybe_arc)) =
+                        compute_fillet(&l1, click1, &l2, click, self.radius)
+                    {
+                        let mut out = vec![
+                            WireModel::solid(
+                                "fillet_l1".into(),
+                                entity_pts(&new_l1),
+                                WireModel::CYAN,
+                                false,
+                            ),
+                            WireModel::solid(
+                                "fillet_l2".into(),
+                                entity_pts(&new_l2),
+                                WireModel::CYAN,
+                                false,
+                            ),
+                        ];
+                        if let Some(arc) = maybe_arc {
+                            out.push(WireModel::solid(
+                                "fillet_arc".into(),
+                                entity_pts(&arc),
+                                WireModel::CYAN,
+                                false,
+                            ));
+                        }
+                        return out;
+                    }
+                }
+                vec![]
+            }
+        }
+    }
+
+    fn on_point(&mut self, _pt: Vec3) -> CmdResult {
+        CmdResult::NeedPoint
+    }
+    fn on_enter(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+    fn on_escape(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+}
+
+// ══════════════════════════════════════════════════════════════════════════
+// ChamferCommand
+// ══════════════════════════════════════════════════════════════════════════
+
+enum ChamferStep {
+    First,
+    Second {
+        h1: Handle,
+        l1: LineEnt,
+        click1: [f64; 2],
+    },
+}
+
+pub struct ChamferCommand {
+    dist1: f64,
+    dist2: f64,
+    step: ChamferStep,
+    all_entities: Vec<EntityType>,
+}
+
+impl ChamferCommand {
+    pub fn new(dist: f32, all_entities: Vec<EntityType>) -> Self {
+        Self {
+            dist1: dist as f64,
+            dist2: defaults::get_chamfer_dist2() as f64,
+            step: ChamferStep::First,
+            all_entities,
+        }
+    }
+}
+
+impl CadCommand for ChamferCommand {
+    fn name(&self) -> &'static str {
+        "CHAMFER"
+    }
+
+    fn prompt(&self) -> String {
+        match &self.step {
+            ChamferStep::First => format!(
+                "CHAMFER  Select first line  [D1={:.4} D2={:.4} | type D <d1> <d2>]:",
+                self.dist1, self.dist2
+            ),
+            ChamferStep::Second { .. } => format!(
+                "CHAMFER  Select second line  [D1={:.4} D2={:.4}]:",
+                self.dist1, self.dist2
+            ),
+        }
+    }
+
+    fn wants_text_input(&self) -> bool {
+        matches!(self.step, ChamferStep::First)
+    }
+
+    fn on_text_input(&mut self, text: &str) -> Option<CmdResult> {
+        let t = text.trim();
+        let body = if t.to_uppercase().starts_with('D') {
+            t[1..].trim()
+        } else {
+            t
+        };
+        let parts: Vec<f64> = body
+            .split_whitespace()
+            .filter_map(|s| s.replace(',', ".").parse::<f64>().ok())
+            .collect();
+        if let Some(&v) = parts.first() {
+            self.dist1 = v.max(0.0);
+            defaults::set_chamfer_dist1(self.dist1 as f32);
+        }
+        if let Some(&v) = parts.get(1) {
+            self.dist2 = v.max(0.0);
+            defaults::set_chamfer_dist2(self.dist2 as f32);
+        } else if parts.len() == 1 {
+            self.dist2 = self.dist1;
+            defaults::set_chamfer_dist2(self.dist2 as f32);
+        }
+        None
+    }
+
+    fn needs_entity_pick(&self) -> bool {
+        true
+    }
+
+    fn on_entity_pick(&mut self, handle: Handle, pt: Vec3) -> CmdResult {
+        if handle.is_null() {
+            return CmdResult::NeedPoint;
+        }
+        let click = [pt.x as f64, pt.y as f64];
+
+        match &self.step {
+            ChamferStep::First => {
+                let l1 = self
+                    .all_entities
+                    .iter()
+                    .find(|e| e.common().handle == handle)
+                    .and_then(|e| {
+                        if let EntityType::Line(l) = e {
+                            Some(l.clone())
+                        } else {
+                            None
+                        }
+                    });
+                if let Some(l) = l1 {
+                    self.step = ChamferStep::Second {
+                        h1: handle,
+                        l1: l,
+                        click1: click,
+                    };
+                    CmdResult::NeedPoint
+                } else {
+                    CmdResult::NeedPoint
+                }
+            }
+            ChamferStep::Second { h1, l1, click1 } => {
+                let h1 = *h1;
+                let l1 = l1.clone();
+                let click1 = *click1;
+                if handle == h1 {
+                    return CmdResult::NeedPoint;
+                }
+
+                let l2 = self
+                    .all_entities
+                    .iter()
+                    .find(|e| e.common().handle == handle)
+                    .and_then(|e| {
+                        if let EntityType::Line(l) = e {
+                            Some(l.clone())
+                        } else {
+                            None
+                        }
+                    });
+
+                if let Some(l2) = l2 {
+                    match compute_chamfer(&l1, click1, self.dist1, &l2, click, self.dist2) {
+                        Some((new_l1, new_l2, chamfer_line)) => CmdResult::ReplaceMany(
+                            vec![(h1, vec![new_l1]), (handle, vec![new_l2])],
+                            vec![chamfer_line],
+                        ),
+                        None => CmdResult::NeedPoint,
+                    }
+                } else {
+                    CmdResult::NeedPoint
+                }
+            }
+        }
+    }
+
+    fn on_hover_entity(&mut self, handle: Handle, pt: Vec3) -> Vec<WireModel> {
+        if handle.is_null() {
+            return vec![];
+        }
+        let click = [pt.x as f64, pt.y as f64];
+
+        match &self.step {
+            ChamferStep::First => {
+                let pts = self
+                    .all_entities
+                    .iter()
+                    .find(|e| e.common().handle == handle)
+                    .and_then(|e| {
+                        if let EntityType::Line(l) = e {
+                            Some(line_pts(l))
+                        } else {
+                            None
+                        }
+                    });
+                if let Some(pts) = pts {
+                    vec![WireModel::solid(
+                        "chamfer_hover".into(),
+                        pts,
+                        WireModel::CYAN,
+                        false,
+                    )]
+                } else {
+                    vec![]
+                }
+            }
+            ChamferStep::Second { l1, click1, .. } => {
+                let l1 = l1.clone();
+                let click1 = *click1;
+                let l2 = self
+                    .all_entities
+                    .iter()
+                    .find(|e| e.common().handle == handle)
+                    .and_then(|e| {
+                        if let EntityType::Line(l) = e {
+                            Some(l.clone())
+                        } else {
+                            None
+                        }
+                    });
+                if let Some(l2) = l2 {
+                    if let Some((new_l1, new_l2, cline)) =
+                        compute_chamfer(&l1, click1, self.dist1, &l2, click, self.dist2)
+                    {
+                        return vec![
+                            WireModel::solid(
+                                "chamfer_l1".into(),
+                                entity_pts(&new_l1),
+                                WireModel::CYAN,
+                                false,
+                            ),
+                            WireModel::solid(
+                                "chamfer_l2".into(),
+                                entity_pts(&new_l2),
+                                WireModel::CYAN,
+                                false,
+                            ),
+                            WireModel::solid(
+                                "chamfer_line".into(),
+                                entity_pts(&cline),
+                                WireModel::CYAN,
+                                false,
+                            ),
+                        ];
+                    }
+                }
+                vec![]
+            }
+        }
+    }
+
+    fn on_point(&mut self, _pt: Vec3) -> CmdResult {
+        CmdResult::NeedPoint
+    }
+    fn on_enter(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+    fn on_escape(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+}

src/modules/home/modify/group.rs

@@ -0,0 +1,12 @@
+// Group tool — ribbon definition.
+
+use crate::modules::{IconKind, ModuleEvent, ToolDef};
+
+pub fn tool() -> ToolDef {
+    ToolDef {
+        id: "GROUP",
+        label: "Group",
+        icon: IconKind::Svg(include_bytes!("../../../../assets/icons/group.svg")),
+        event: ModuleEvent::Command("GROUP".to_string()),
+    }
+}

src/modules/home/modify/mirror.rs

@@ -0,0 +1,106 @@
+// Mirror tool — ribbon definition + interactive command.
+//
+// Command:  MIRROR (MI)
+//   Requires at least one entity selected.
+//   Step 1: pick first mirror-line point
+//   Step 2: pick second mirror-line point → mirrors
+
+use acadrust::Handle;
+use glam::Vec3;
+
+use crate::command::{CadCommand, CmdResult, EntityTransform};
+use crate::modules::{IconKind, ModuleEvent, ToolDef};
+use crate::scene::wire_model::WireModel;
+
+pub fn tool() -> ToolDef {
+    ToolDef {
+        id: "MIRROR",
+        label: "Mirror",
+        icon: IconKind::Svg(include_bytes!("../../../../assets/icons/mirror.svg")),
+        event: ModuleEvent::Command("MIRROR".to_string()),
+    }
+}
+
+enum Step {
+    P1,
+    P2(Vec3),
+}
+
+pub struct MirrorCommand {
+    handles: Vec<Handle>,
+    wire_models: Vec<WireModel>,
+    step: Step,
+}
+
+impl MirrorCommand {
+    pub fn new(handles: Vec<Handle>, wire_models: Vec<WireModel>) -> Self {
+        Self {
+            handles,
+            wire_models,
+            step: Step::P1,
+        }
+    }
+}
+
+impl CadCommand for MirrorCommand {
+    fn name(&self) -> &'static str {
+        "MIRROR"
+    }
+
+    fn prompt(&self) -> String {
+        match &self.step {
+            Step::P1 => format!(
+                "MIRROR  Specify first mirror-line point  [{} objects]:",
+                self.handles.len()
+            ),
+            Step::P2(p1) => format!(
+                "MIRROR  Specify second point  [p1={:.2},{:.2}]:",
+                p1.x, p1.y
+            ),
+        }
+    }
+
+    fn on_point(&mut self, pt: Vec3) -> CmdResult {
+        match &self.step {
+            Step::P1 => {
+                self.step = Step::P2(pt);
+                CmdResult::NeedPoint
+            }
+            Step::P2(p1) => {
+                let p1 = *p1;
+                CmdResult::TransformSelected(
+                    self.handles.clone(),
+                    EntityTransform::Mirror { p1, p2: pt },
+                )
+            }
+        }
+    }
+
+    fn on_enter(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+    fn on_escape(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+
+    fn on_preview_wires(&mut self, pt: Vec3) -> Vec<WireModel> {
+        let Step::P2(p1) = &self.step else {
+            return vec![];
+        };
+        let p1 = *p1;
+        // Mirrored ghosts of all selected objects.
+        let mut out: Vec<WireModel> = self
+            .wire_models
+            .iter()
+            .map(|w| w.mirrored(p1, pt))
+            .collect();
+        // Mirror-axis line (rubber-band).
+        out.push(WireModel::solid(
+            "rubber_band".into(),
+            vec![[p1.x, p1.y, p1.z], [pt.x, pt.y, pt.z]],
+            WireModel::CYAN,
+            false,
+        ));
+        out
+    }
+}

src/modules/home/modify/mod.rs

@@ -0,0 +1,15 @@
+pub mod array;
+pub mod copy;
+pub mod delete;
+pub mod explode;
+mod extend;
+pub mod fillet;
+pub mod group;
+pub mod mirror;
+pub mod offset;
+pub mod rotate;
+pub mod scale;
+pub mod stretch;
+pub mod translate;
+pub mod trim;
+pub mod ungroup;

src/modules/home/modify/offset.rs

@@ -0,0 +1,573 @@
+// Offset tool — ribbon definition + interactive command.
+//
+// Command:  OFFSET (O)
+//   OFFSET: Creates a parallel copy of an object (line, arc, circle,
+//   or lwpolyline) at a specified distance on the chosen side.
+//
+//   Steps:
+//     1. Text input: "Specify offset distance <last>:" → enter float or Enter for default
+//     2. Pick object to offset (Line, Arc, Circle, LwPolyline)
+//     3. Pick a point on the side to offset toward
+
+use std::f64::consts::TAU;
+
+use acadrust::entities::LwVertex;
+use acadrust::entities::{Arc as ArcEnt, Circle as CircleEnt, Line as LineEnt, LwPolyline};
+use acadrust::{EntityType, Handle};
+use glam::Vec3;
+
+use crate::command::{CadCommand, CmdResult};
+use crate::modules::home::defaults;
+use crate::modules::{IconKind, ModuleEvent, ToolDef};
+use crate::scene::wire_model::WireModel;
+
+// ── Ribbon definition ──────────────────────────────────────────────────────
+
+pub fn tool() -> ToolDef {
+    ToolDef {
+        id: "OFFSET",
+        label: "Offset",
+        icon: IconKind::Svg(include_bytes!("../../../../assets/icons/offset.svg")),
+        event: ModuleEvent::Command("OFFSET".to_string()),
+    }
+}
+
+// ── Geometry helpers ────────────────────────────────────────────────────────
+
+/// Infinite-line intersection in 2D.  Returns the point or None if parallel.
+fn isect_lines(p0: [f64; 2], p1: [f64; 2], q0: [f64; 2], q1: [f64; 2]) -> Option<[f64; 2]> {
+    let dx = p1[0] - p0[0];
+    let dy = p1[1] - p0[1];
+    let ex = q1[0] - q0[0];
+    let ey = q1[1] - q0[1];
+    let det = dx * ey - dy * ex;
+    if det.abs() < 1e-10 {
+        return None;
+    }
+    let t = ((q0[0] - p0[0]) * ey - (q0[1] - p0[1]) * ex) / det;
+    Some([p0[0] + t * dx, p0[1] + t * dy])
+}
+
+fn norm_rad(a: f64) -> f64 {
+    ((a % TAU) + TAU) % TAU
+}
+
+// ── Line offset ────────────────────────────────────────────────────────────
+
+fn offset_line(l: &LineEnt, dist: f64, side_pt: Vec3) -> Option<EntityType> {
+    let dx = l.end.x - l.start.x;
+    let dy = l.end.y - l.start.y;
+    let len = (dx * dx + dy * dy).sqrt();
+    if len < 1e-12 {
+        return None;
+    }
+
+    let nx = -dy / len; // left-perpendicular
+    let ny = dx / len;
+
+    let vx = side_pt.x as f64 - l.start.x;
+    let vy = side_pt.y as f64 - l.start.y;
+    let cross = dx * vy - dy * vx;
+    let sign = if cross >= 0.0 { 1.0 } else { -1.0 };
+
+    let ox = sign * nx * dist;
+    let oy = sign * ny * dist;
+
+    let mut new_l = l.clone();
+    new_l.common.handle = Handle::NULL;
+    new_l.start.x += ox;
+    new_l.start.y += oy;
+    new_l.end.x += ox;
+    new_l.end.y += oy;
+    Some(EntityType::Line(new_l))
+}
+
+// ── Circle offset ──────────────────────────────────────────────────────────
+
+fn offset_circle(c: &CircleEnt, dist: f64, side_pt: Vec3) -> Option<EntityType> {
+    let px = side_pt.x as f64;
+    let py = side_pt.y as f64;
+    let dc = ((px - c.center.x).powi(2) + (py - c.center.y).powi(2)).sqrt();
+
+    let new_r = if dc < c.radius {
+        c.radius - dist
+    } else {
+        c.radius + dist
+    };
+    if new_r <= 1e-9 {
+        return None;
+    }
+
+    let mut new_c = c.clone();
+    new_c.common.handle = Handle::NULL;
+    new_c.radius = new_r;
+    Some(EntityType::Circle(new_c))
+}
+
+// ── Arc offset ─────────────────────────────────────────────────────────────
+
+fn offset_arc(a: &ArcEnt, dist: f64, side_pt: Vec3) -> Option<EntityType> {
+    let px = side_pt.x as f64;
+    let py = side_pt.y as f64;
+    let dc = ((px - a.center.x).powi(2) + (py - a.center.y).powi(2)).sqrt();
+
+    let new_r = if dc < a.radius {
+        a.radius - dist
+    } else {
+        a.radius + dist
+    };
+    if new_r <= 1e-9 {
+        return None;
+    }
+
+    let mut new_a = a.clone();
+    new_a.common.handle = Handle::NULL;
+    new_a.radius = new_r;
+    Some(EntityType::Arc(new_a))
+}
+
+// ── LwPolyline offset ──────────────────────────────────────────────────────
+//
+// Algorithm:
+//   1. Offset every segment by `dist` in the direction perpendicular to it
+//      (sign is determined once from the first non-degenerate segment + side_pt).
+//   2. Reconnect adjacent offset segments:
+//      - Open: first / last vertex use the raw offset endpoints;
+//        interior vertices are the intersection of adjacent offset segments.
+//      - Closed: every vertex is the intersection of the previous and next
+//        offset segments.
+//   3. Bulge values are preserved from the original vertices (arc segments
+//      keep the same angle; the radius changes implicitly via the new chord
+//      length — a minor approximation acceptable for modest offsets).
+
+fn offset_lwpolyline(p: &LwPolyline, dist: f64, side_pt: Vec3) -> Option<EntityType> {
+    let n = p.vertices.len();
+    if n < 2 {
+        return None;
+    }
+
+    let n_segs = if p.is_closed { n } else { n - 1 };
+
+    // Determine offset sign from the first non-degenerate segment.
+    let sign: f64 = (0..n_segs).find_map(|i| {
+        let v0 = &p.vertices[i];
+        let v1 = &p.vertices[(i + 1) % n];
+        let dx = v1.location.x - v0.location.x;
+        let dy = v1.location.y - v0.location.y;
+        let len = (dx * dx + dy * dy).sqrt();
+        if len < 1e-12 {
+            return None;
+        }
+        let vx = side_pt.x as f64 - v0.location.x;
+        let vy = side_pt.y as f64 - v0.location.y;
+        let cross = dx * vy - dy * vx;
+        Some(if cross >= 0.0 { 1.0 } else { -1.0 })
+    })?;
+
+    // Offset each segment.  A segment may be degenerate (zero length) → None.
+    struct OffSeg {
+        p0: [f64; 2],
+        p1: [f64; 2],
+    }
+
+    let segs: Vec<Option<OffSeg>> = (0..n_segs)
+        .map(|i| {
+            let v0 = &p.vertices[i];
+            let v1 = &p.vertices[(i + 1) % n];
+            let dx = v1.location.x - v0.location.x;
+            let dy = v1.location.y - v0.location.y;
+            let len = (dx * dx + dy * dy).sqrt();
+            if len < 1e-12 {
+                return None;
+            }
+            let ox = sign * (-dy / len) * dist;
+            let oy = sign * (dx / len) * dist;
+            Some(OffSeg {
+                p0: [v0.location.x + ox, v0.location.y + oy],
+                p1: [v1.location.x + ox, v1.location.y + oy],
+            })
+        })
+        .collect();
+
+    let m = segs.len();
+
+    // Helper: corner vertex from the intersection of two consecutive offset segments.
+    let corner = |prev: &OffSeg, curr: &OffSeg| -> [f64; 2] {
+        isect_lines(prev.p0, prev.p1, curr.p0, curr.p1).unwrap_or([
+            (prev.p1[0] + curr.p0[0]) * 0.5,
+            (prev.p1[1] + curr.p0[1]) * 0.5,
+        ])
+    };
+
+    let mut new_verts: Vec<LwVertex> = Vec::new();
+
+    if p.is_closed {
+        for i in 0..m {
+            let prev_idx = (i + m - 1) % m;
+            let prev = match &segs[prev_idx] {
+                Some(s) => s,
+                None => continue,
+            };
+            let curr = match &segs[i] {
+                Some(s) => s,
+                None => continue,
+            };
+            let pt = corner(prev, curr);
+            let mut v = LwVertex::from_coords(pt[0], pt[1]);
+            v.bulge = p.vertices[i].bulge;
+            new_verts.push(v);
+        }
+    } else {
+        // First vertex
+        if let Some(s) = &segs[0] {
+            let mut v = LwVertex::from_coords(s.p0[0], s.p0[1]);
+            v.bulge = p.vertices[0].bulge;
+            new_verts.push(v);
+        }
+        // Interior vertices
+        for i in 1..m {
+            let prev = match &segs[i - 1] {
+                Some(s) => s,
+                None => continue,
+            };
+            let curr = match &segs[i] {
+                Some(s) => s,
+                None => continue,
+            };
+            let pt = corner(prev, curr);
+            let mut v = LwVertex::from_coords(pt[0], pt[1]);
+            v.bulge = p.vertices[i].bulge;
+            new_verts.push(v);
+        }
+        // Last vertex
+        if let Some(s) = &segs[m - 1] {
+            new_verts.push(LwVertex::from_coords(s.p1[0], s.p1[1]));
+        }
+    }
+
+    if new_verts.len() < 2 {
+        return None;
+    }
+
+    let mut new_p = p.clone();
+    new_p.common.handle = Handle::NULL;
+    new_p.vertices = new_verts;
+    Some(EntityType::LwPolyline(new_p))
+}
+
+// ── Dispatch ───────────────────────────────────────────────────────────────
+
+fn compute_offset(entity: &EntityType, dist: f64, side_pt: Vec3) -> Option<EntityType> {
+    match entity {
+        EntityType::Line(l) => offset_line(l, dist, side_pt),
+        EntityType::Circle(c) => offset_circle(c, dist, side_pt),
+        EntityType::Arc(a) => offset_arc(a, dist, side_pt),
+        EntityType::LwPolyline(p) => offset_lwpolyline(p, dist, side_pt),
+        _ => None,
+    }
+}
+
+// ── Wire preview points ─────────────────────────────────────────────────────
+
+fn entity_wire_pts(e: &EntityType) -> Vec<[f32; 3]> {
+    match e {
+        EntityType::Line(l) => vec![
+            [l.start.x as f32, l.start.y as f32, l.start.z as f32],
+            [l.end.x as f32, l.end.y as f32, l.end.z as f32],
+        ],
+        EntityType::Circle(c) => {
+            let steps = 64usize;
+            (0..=steps)
+                .map(|i| {
+                    let a = TAU * i as f64 / steps as f64;
+                    [
+                        (c.center.x + c.radius * a.cos()) as f32,
+                        (c.center.y + c.radius * a.sin()) as f32,
+                        c.center.z as f32,
+                    ]
+                })
+                .collect()
+        }
+        EntityType::Arc(a) => {
+            let a0 = norm_rad(a.start_angle.to_radians());
+            let a1 = norm_rad(a.end_angle.to_radians());
+            let span = {
+                let s = a1 - a0;
+                if s <= 0.0 {
+                    s + TAU
+                } else {
+                    s
+                }
+            };
+            let steps = ((span.abs() * 20.0).ceil() as usize).max(4);
+            (0..=steps)
+                .map(|i| {
+                    let ang = a0 + span * (i as f64 / steps as f64);
+                    [
+                        (a.center.x + a.radius * ang.cos()) as f32,
+                        (a.center.y + a.radius * ang.sin()) as f32,
+                        a.center.z as f32,
+                    ]
+                })
+                .collect()
+        }
+        EntityType::LwPolyline(p) => lwpolyline_pts(p),
+        _ => vec![],
+    }
+}
+
+/// Tessellate a LwPolyline into wire points (straight segments + arc bulges).
+fn lwpolyline_pts(p: &LwPolyline) -> Vec<[f32; 3]> {
+    let n = p.vertices.len();
+    if n < 2 {
+        return vec![];
+    }
+    let z = p.elevation as f32;
+    let n_segs = if p.is_closed { n } else { n - 1 };
+    let mut pts: Vec<[f32; 3]> = Vec::new();
+
+    for i in 0..n_segs {
+        let v0 = &p.vertices[i];
+        let v1 = &p.vertices[(i + 1) % n];
+        let x0 = v0.location.x;
+        let y0 = v0.location.y;
+        let x1 = v1.location.x;
+        let y1 = v1.location.y;
+
+        if pts.is_empty() {
+            pts.push([x0 as f32, y0 as f32, z]);
+        }
+
+        if v0.bulge.abs() < 1e-10 {
+            pts.push([x1 as f32, y1 as f32, z]);
+        } else {
+            // Arc from bulge
+            let b = v0.bulge;
+            let chord_x = x1 - x0;
+            let chord_y = y1 - y0;
+            let chord_len = (chord_x * chord_x + chord_y * chord_y).sqrt();
+            if chord_len < 1e-12 {
+                pts.push([x1 as f32, y1 as f32, z]);
+                continue;
+            }
+
+            let b2 = b * b;
+            let r = chord_len * (1.0 + b2) / (4.0 * b.abs());
+            let d = r * (1.0 - b2) / (1.0 + b2);
+            let mx = (x0 + x1) * 0.5;
+            let my = (y0 + y1) * 0.5;
+            let perp_x = -chord_y / chord_len;
+            let perp_y = chord_x / chord_len;
+            let sign = b.signum();
+            let cx = mx + sign * d * perp_x;
+            let cy = my + sign * d * perp_y;
+
+            let a0 = norm_rad((y0 - cy).atan2(x0 - cx));
+            let a1 = norm_rad((y1 - cy).atan2(x1 - cx));
+            let span = if b > 0.0 {
+                let s = a1 - a0;
+                if s <= 0.0 {
+                    s + TAU
+                } else {
+                    s
+                }
+            } else {
+                let s = a0 - a1;
+                if s <= 0.0 {
+                    s + TAU
+                } else {
+                    s
+                }
+            };
+            let steps = ((span.abs() * 20.0).ceil() as usize).max(4);
+            for j in 1..=steps {
+                let t = j as f64 / steps as f64;
+                let ang = if b > 0.0 {
+                    a0 + span * t
+                } else {
+                    a0 - span * t
+                };
+                pts.push([(cx + r * ang.cos()) as f32, (cy + r * ang.sin()) as f32, z]);
+            }
+        }
+    }
+
+    if p.is_closed {
+        if let Some(&first) = pts.first() {
+            pts.push(first);
+        }
+    }
+    pts
+}
+
+// ── Command implementation ─────────────────────────────────────────────────
+
+enum Step {
+    Distance,
+    SelectObject {
+        dist: f64,
+    },
+    PickSide {
+        dist: f64,
+        #[allow(dead_code)]
+        handle: Handle,
+        entity: EntityType,
+    },
+}
+
+pub struct OffsetCommand {
+    default_dist: f64,
+    step: Step,
+    all_entities: Vec<EntityType>,
+}
+
+impl OffsetCommand {
+    pub fn new(last_dist: f32, all_entities: Vec<EntityType>) -> Self {
+        Self {
+            default_dist: last_dist as f64,
+            step: Step::Distance,
+            all_entities,
+        }
+    }
+}
+
+impl CadCommand for OffsetCommand {
+    fn name(&self) -> &'static str {
+        "OFFSET"
+    }
+
+    fn prompt(&self) -> String {
+        match &self.step {
+            Step::Distance => format!(
+                "OFFSET  Specify offset distance <{:.4}>:",
+                self.default_dist
+            ),
+            Step::SelectObject { dist } => {
+                format!("OFFSET  Select object to offset  [dist={dist:.4}]:")
+            }
+            Step::PickSide { dist, .. } => {
+                format!("OFFSET  Specify side to offset  [dist={dist:.4}]:")
+            }
+        }
+    }
+
+    fn wants_text_input(&self) -> bool {
+        matches!(self.step, Step::Distance)
+    }
+
+    fn on_text_input(&mut self, text: &str) -> Option<CmdResult> {
+        if let Step::Distance = self.step {
+            let dist = if text.trim().is_empty() {
+                self.default_dist
+            } else {
+                text.trim()
+                    .replace(',', ".")
+                    .parse::<f64>()
+                    .unwrap_or(self.default_dist)
+                    .abs()
+                    .max(1e-9)
+            };
+            defaults::set_offset_dist(dist as f32);
+            self.default_dist = dist;
+            self.step = Step::SelectObject { dist };
+        }
+        None
+    }
+
+    fn needs_entity_pick(&self) -> bool {
+        matches!(self.step, Step::SelectObject { .. })
+    }
+
+    fn on_entity_pick(&mut self, handle: Handle, _pt: Vec3) -> CmdResult {
+        if handle.is_null() {
+            return CmdResult::NeedPoint;
+        }
+
+        let dist = match &self.step {
+            Step::SelectObject { dist } => *dist,
+            _ => return CmdResult::NeedPoint,
+        };
+
+        let entity = self
+            .all_entities
+            .iter()
+            .find(|e| e.common().handle == handle)
+            .cloned();
+
+        match entity {
+            Some(e @ EntityType::Line(_))
+            | Some(e @ EntityType::Circle(_))
+            | Some(e @ EntityType::Arc(_))
+            | Some(e @ EntityType::LwPolyline(_)) => {
+                self.step = Step::PickSide {
+                    dist,
+                    handle,
+                    entity: e,
+                };
+                CmdResult::NeedPoint
+            }
+            _ => CmdResult::NeedPoint,
+        }
+    }
+
+    fn on_hover_entity(&mut self, handle: Handle, _pt: Vec3) -> Vec<WireModel> {
+        if handle.is_null() {
+            return vec![];
+        }
+        if let Some(entity) = self
+            .all_entities
+            .iter()
+            .find(|e| e.common().handle == handle)
+        {
+            let pts = entity_wire_pts(entity);
+            if !pts.is_empty() {
+                return vec![WireModel::solid(
+                    "offset_hover".into(),
+                    pts,
+                    WireModel::CYAN,
+                    false,
+                )];
+            }
+        }
+        vec![]
+    }
+
+    fn on_point(&mut self, pt: Vec3) -> CmdResult {
+        let (dist, entity) = match &self.step {
+            Step::PickSide { dist, entity, .. } => (*dist, entity.clone()),
+            _ => return CmdResult::NeedPoint,
+        };
+
+        match compute_offset(&entity, dist, pt) {
+            Some(new_entity) => CmdResult::CommitAndExit(new_entity),
+            None => CmdResult::NeedPoint,
+        }
+    }
+
+    fn on_preview_wires(&mut self, pt: Vec3) -> Vec<WireModel> {
+        let (dist, entity) = match &self.step {
+            Step::PickSide { dist, entity, .. } => (*dist, entity.clone()),
+            _ => return vec![],
+        };
+
+        if let Some(result) = compute_offset(&entity, dist, pt) {
+            let pts = entity_wire_pts(&result);
+            if !pts.is_empty() {
+                return vec![WireModel::solid(
+                    "offset_preview".into(),
+                    pts,
+                    WireModel::CYAN,
+                    false,
+                )];
+            }
+        }
+        vec![]
+    }
+
+    fn on_enter(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+    fn on_escape(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+}

src/modules/home/modify/rotate.rs

@@ -0,0 +1,190 @@
+// Rotate tool — ribbon definition + interactive command.
+//
+// Command:  ROTATE (RO)
+//   Requires at least one entity selected before starting.
+//   Step 1: pick rotation center
+//   Step 2: pick reference point (defines the 0° direction)
+//   Step 3: pick destination point → rotates by (dest_angle - ref_angle)
+
+use acadrust::Handle;
+use glam::Vec3;
+
+use crate::command::{CadCommand, CmdResult, EntityTransform};
+use crate::modules::home::defaults;
+use crate::modules::{IconKind, ModuleEvent, ToolDef};
+use crate::scene::wire_model::WireModel;
+
+// ── Ribbon definition ──────────────────────────────────────────────────────
+
+pub fn tool() -> ToolDef {
+    ToolDef {
+        id: "ROTATE",
+        label: "Rotate",
+        icon: IconKind::Svg(include_bytes!("../../../../assets/icons/rotate.svg")),
+        event: ModuleEvent::Command("ROTATE".to_string()),
+    }
+}
+
+// ── Command implementation ─────────────────────────────────────────────────
+
+enum Step {
+    Center,
+    RefPoint { center: Vec3 },
+    Angle { center: Vec3, ref_angle: f32 },
+}
+
+pub struct RotateCommand {
+    handles: Vec<Handle>,
+    wire_models: Vec<WireModel>,
+    step: Step,
+    default_angle: f32, // degrees
+}
+
+impl RotateCommand {
+    pub fn new(handles: Vec<Handle>, wire_models: Vec<WireModel>) -> Self {
+        Self {
+            handles,
+            wire_models,
+            step: Step::Center,
+            default_angle: defaults::get_rotate_angle(),
+        }
+    }
+}
+
+impl CadCommand for RotateCommand {
+    fn name(&self) -> &'static str {
+        "ROTATE"
+    }
+
+    fn prompt(&self) -> String {
+        match &self.step {
+            Step::Center => format!(
+                "ROTATE  Specify rotation center  [{} objects]:",
+                self.handles.len()
+            ),
+            Step::RefPoint { .. } => {
+                "ROTATE  Specify reference point  (or skip: type angle directly):".into()
+            }
+            Step::Angle { ref_angle, .. } => format!(
+                "ROTATE  Specify destination or type angle in degrees  <{:.4}>  [ref={:.1}°]:",
+                self.default_angle,
+                ref_angle.to_degrees()
+            ),
+        }
+    }
+
+    fn on_point(&mut self, pt: Vec3) -> CmdResult {
+        match &self.step {
+            Step::Center => {
+                self.step = Step::RefPoint { center: pt };
+                CmdResult::NeedPoint
+            }
+            Step::RefPoint { center } => {
+                let center = *center;
+                let ref_angle = (pt.y - center.y).atan2(pt.x - center.x);
+                self.step = Step::Angle { center, ref_angle };
+                CmdResult::NeedPoint
+            }
+            Step::Angle { center, ref_angle } => {
+                let center = *center;
+                let ref_angle = *ref_angle;
+                let dest_angle = (pt.y - center.y).atan2(pt.x - center.x);
+                let delta = dest_angle - ref_angle;
+                defaults::set_rotate_angle(delta.to_degrees());
+                self.default_angle = delta.to_degrees();
+                CmdResult::TransformSelected(
+                    self.handles.clone(),
+                    EntityTransform::Rotate {
+                        center,
+                        angle_rad: delta,
+                    },
+                )
+            }
+        }
+    }
+
+    fn on_enter(&mut self) -> CmdResult {
+        // At Angle step: Enter uses the stored default angle.
+        if let Step::Angle { center, .. } = &self.step {
+            let center = *center;
+            let angle_rad = self.default_angle.to_radians();
+            return CmdResult::TransformSelected(
+                self.handles.clone(),
+                EntityTransform::Rotate { center, angle_rad },
+            );
+        }
+        CmdResult::Cancel
+    }
+    fn on_escape(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+
+    fn on_text_input(&mut self, text: &str) -> Option<CmdResult> {
+        if let Step::Angle { center, .. } = &self.step {
+            let deg: f32 = text.trim().replace(',', ".").parse().ok()?;
+            let center = *center;
+            defaults::set_rotate_angle(deg);
+            return Some(CmdResult::TransformSelected(
+                self.handles.clone(),
+                EntityTransform::Rotate {
+                    center,
+                    angle_rad: deg.to_radians(),
+                },
+            ));
+        }
+        None
+    }
+
+    fn on_preview_wires(&mut self, pt: Vec3) -> Vec<WireModel> {
+        let (center, ref_angle) = match &self.step {
+            Step::Angle { center, ref_angle } => (*center, *ref_angle),
+            Step::RefPoint { center } => {
+                // Show a reference line from center to cursor only.
+                return vec![WireModel::solid(
+                    "rubber_band".into(),
+                    vec![[center.x, center.y, center.z], [pt.x, pt.y, pt.z]],
+                    WireModel::CYAN,
+                    false,
+                )];
+            }
+            _ => return vec![],
+        };
+        let dest_angle = (pt.y - center.y).atan2(pt.x - center.x);
+        let angle_rad = dest_angle - ref_angle;
+        // Object ghosts rotated to new angle.
+        let mut out: Vec<WireModel> = self
+            .wire_models
+            .iter()
+            .map(|w| w.rotated(center, angle_rad))
+            .collect();
+        // Arc rubber-band showing the rotation sweep.
+        let r = center.distance(pt).max(0.3);
+        let mut end = dest_angle;
+        if end < ref_angle {
+            end += std::f32::consts::TAU;
+        }
+        let span = end - ref_angle;
+        let segs = ((span.abs() / std::f32::consts::TAU) * 48.0)
+            .ceil()
+            .max(4.0) as u32;
+        let mut arc_pts: Vec<[f32; 3]> = (0..=segs)
+            .map(|i| {
+                let a = ref_angle + span * (i as f32 / segs as f32);
+                [center.x + r * a.cos(), center.y + r * a.sin(), center.z]
+            })
+            .collect();
+        arc_pts.push([center.x, center.y, center.z]);
+        arc_pts.push([
+            center.x + r * ref_angle.cos(),
+            center.y + r * ref_angle.sin(),
+            center.z,
+        ]);
+        out.push(WireModel::solid(
+            "rubber_band".into(),
+            arc_pts,
+            WireModel::CYAN,
+            false,
+        ));
+        out
+    }
+}

src/modules/home/modify/scale.rs

@@ -0,0 +1,167 @@
+// Scale tool — ribbon definition + interactive command.
+//
+// Command:  SCALE (SC)
+//   Requires at least one entity selected.
+//   Step 1: pick base (scale center)
+//   Step 2: pick reference point  (defines reference distance)
+//   Step 3: pick new point        (new distance = scale factor * objects)
+
+use acadrust::Handle;
+use glam::Vec3;
+
+use crate::command::{CadCommand, CmdResult, EntityTransform};
+use crate::modules::home::defaults;
+use crate::modules::{IconKind, ModuleEvent, ToolDef};
+use crate::scene::wire_model::WireModel;
+
+#[allow(dead_code)]
+pub fn tool() -> ToolDef {
+    ToolDef {
+        id: "SCALE",
+        label: "Scale",
+        icon: IconKind::Svg(include_bytes!("../../../../assets/icons/scale.svg")),
+        event: ModuleEvent::Command("SCALE".to_string()),
+    }
+}
+
+enum Step {
+    Base,
+    Ref { base: Vec3 },
+    New { base: Vec3, ref_dist: f32 },
+}
+
+pub struct ScaleCommand {
+    handles: Vec<Handle>,
+    wire_models: Vec<WireModel>,
+    step: Step,
+    default_factor: f32,
+}
+
+impl ScaleCommand {
+    pub fn new(handles: Vec<Handle>, wire_models: Vec<WireModel>) -> Self {
+        Self {
+            handles,
+            wire_models,
+            step: Step::Base,
+            default_factor: defaults::get_scale_factor(),
+        }
+    }
+}
+
+impl CadCommand for ScaleCommand {
+    fn name(&self) -> &'static str {
+        "SCALE"
+    }
+
+    fn prompt(&self) -> String {
+        match &self.step {
+            Step::Base => format!(
+                "SCALE  Specify base point  [{} objects]:",
+                self.handles.len()
+            ),
+            Step::Ref { .. } => {
+                "SCALE  Specify reference point  (or type scale factor directly):".into()
+            }
+            Step::New { ref_dist, .. } => format!(
+                "SCALE  Specify new point or type scale factor  <{:.4}>  [ref={:.3}]:",
+                self.default_factor, ref_dist
+            ),
+        }
+    }
+
+    fn on_point(&mut self, pt: Vec3) -> CmdResult {
+        match &self.step {
+            Step::Base => {
+                self.step = Step::Ref { base: pt };
+                CmdResult::NeedPoint
+            }
+            Step::Ref { base } => {
+                let base = *base;
+                let ref_dist = base.distance(pt).max(1e-6);
+                self.step = Step::New { base, ref_dist };
+                CmdResult::NeedPoint
+            }
+            Step::New { base, ref_dist } => {
+                let base = *base;
+                let new_dist = base.distance(pt).max(1e-6);
+                let factor = new_dist / *ref_dist;
+                defaults::set_scale_factor(factor);
+                CmdResult::TransformSelected(
+                    self.handles.clone(),
+                    EntityTransform::Scale {
+                        center: base,
+                        factor,
+                    },
+                )
+            }
+        }
+    }
+
+    fn on_enter(&mut self) -> CmdResult {
+        // At New-point step: Enter uses the stored default factor applied from base.
+        if let Step::New { base, .. } = &self.step {
+            let base = *base;
+            let factor = self.default_factor;
+            return CmdResult::TransformSelected(
+                self.handles.clone(),
+                EntityTransform::Scale {
+                    center: base,
+                    factor,
+                },
+            );
+        }
+        CmdResult::Cancel
+    }
+    fn on_escape(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+
+    fn on_text_input(&mut self, text: &str) -> Option<CmdResult> {
+        if let Step::New { base, .. } | Step::Ref { base } = &self.step {
+            let factor: f32 = text.trim().replace(',', ".").parse().ok()?;
+            if factor > 0.0 {
+                let base = *base;
+                defaults::set_scale_factor(factor);
+                return Some(CmdResult::TransformSelected(
+                    self.handles.clone(),
+                    EntityTransform::Scale {
+                        center: base,
+                        factor,
+                    },
+                ));
+            }
+        }
+        None
+    }
+
+    fn on_preview_wires(&mut self, pt: Vec3) -> Vec<WireModel> {
+        let (base, factor) = match &self.step {
+            Step::Ref { base } => {
+                // Reference pick: just show rubber-band line, no scale yet.
+                return vec![WireModel::solid(
+                    "rubber_band".into(),
+                    vec![[base.x, base.y, base.z], [pt.x, pt.y, pt.z]],
+                    WireModel::CYAN,
+                    false,
+                )];
+            }
+            Step::New { base, ref_dist } => {
+                let f = base.distance(pt).max(1e-6) / ref_dist;
+                (*base, f)
+            }
+            _ => return vec![],
+        };
+        let mut out: Vec<WireModel> = self
+            .wire_models
+            .iter()
+            .map(|w| w.scaled(base, factor))
+            .collect();
+        out.push(WireModel::solid(
+            "rubber_band".into(),
+            vec![[base.x, base.y, base.z], [pt.x, pt.y, pt.z]],
+            WireModel::CYAN,
+            false,
+        ));
+        out
+    }
+}

src/modules/home/modify/stretch.rs

@@ -0,0 +1,109 @@
+// Stretch tool — ribbon definition + interactive command.
+//
+// Command:  STRETCH (SS)
+//   STRETCH: Moves endpoints/vertices that lie within a crossing
+//   window while leaving the rest of the object fixed.
+//   Simplified implementation: works like MOVE on the full selected set
+//   because we don't yet have a crossing-window selector in the viewport.
+//   Step 1: pick base point
+//   Step 2: pick new point → translates all selected entities by (new - base)
+
+use acadrust::Handle;
+use glam::Vec3;
+
+use crate::command::{CadCommand, CmdResult, EntityTransform};
+use crate::modules::{IconKind, ModuleEvent, ToolDef};
+use crate::scene::wire_model::WireModel;
+
+// ── Ribbon definition ──────────────────────────────────────────────────────
+
+pub fn tool() -> ToolDef {
+    ToolDef {
+        id: "STRETCH",
+        label: "Stretch",
+        icon: IconKind::Svg(include_bytes!("../../../../assets/icons/stretch.svg")),
+        event: ModuleEvent::Command("STRETCH".to_string()),
+    }
+}
+
+// ── Command implementation ─────────────────────────────────────────────────
+
+enum Step {
+    Base,
+    Target(Vec3),
+}
+
+pub struct StretchCommand {
+    handles: Vec<Handle>,
+    step: Step,
+}
+
+impl StretchCommand {
+    pub fn new(handles: Vec<Handle>) -> Self {
+        Self {
+            handles,
+            step: Step::Base,
+        }
+    }
+}
+
+impl CadCommand for StretchCommand {
+    fn name(&self) -> &'static str {
+        "STRETCH"
+    }
+
+    fn prompt(&self) -> String {
+        match &self.step {
+            Step::Base => format!(
+                "STRETCH  Specify base point  [{} objects]:",
+                self.handles.len()
+            ),
+            Step::Target(base) => format!(
+                "STRETCH  Specify new point  [base {:.3},{:.3}]:",
+                base.x, base.y
+            ),
+        }
+    }
+
+    fn on_point(&mut self, pt: Vec3) -> CmdResult {
+        match &self.step {
+            Step::Base => {
+                self.step = Step::Target(pt);
+                CmdResult::NeedPoint
+            }
+            Step::Target(base) => {
+                let delta = pt - *base;
+                CmdResult::TransformSelected(
+                    self.handles.clone(),
+                    EntityTransform::Translate(delta),
+                )
+            }
+        }
+    }
+
+    fn on_enter(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+    fn on_escape(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+
+    fn on_mouse_move(&mut self, pt: Vec3) -> Option<WireModel> {
+        if let Step::Target(base) = &self.step {
+            Some(WireModel {
+                name: "rubber_band".into(),
+                points: vec![[base.x, base.y, base.z], [pt.x, pt.y, pt.z]],
+                color: WireModel::CYAN,
+                selected: false,
+                pattern_length: 0.0,
+                pattern: [0.0; 8],
+                line_weight_px: 1.0,
+                snap_pts: vec![],
+                tangent_geoms: vec![],
+                key_vertices: vec![],
+            })
+        } else {
+            None
+        }
+    }
+}

src/modules/home/modify/translate.rs

@@ -0,0 +1,109 @@
+// Move tool — ribbon definition + interactive command.
+//
+// Command:  MOVE (M)
+//   Requires at least one entity selected before starting.
+//   Step 1: pick base point
+//   Step 2: pick destination → translates all selected entities by (dest - base)
+
+use acadrust::Handle;
+use glam::Vec3;
+
+use crate::command::{CadCommand, CmdResult, EntityTransform};
+use crate::modules::{IconKind, ModuleEvent, ToolDef};
+use crate::scene::wire_model::WireModel;
+
+// ── Ribbon definition ──────────────────────────────────────────────────────
+
+pub fn tool() -> ToolDef {
+    ToolDef {
+        id: "MOVE",
+        label: "Move",
+        icon: IconKind::Svg(include_bytes!("../../../../assets/icons/move.svg")),
+        event: ModuleEvent::Command("MOVE".to_string()),
+    }
+}
+
+// ── Command implementation ─────────────────────────────────────────────────
+
+enum Step {
+    Base,
+    Target(Vec3),
+}
+
+pub struct MoveCommand {
+    handles: Vec<Handle>,
+    wire_models: Vec<WireModel>,
+    step: Step,
+}
+
+impl MoveCommand {
+    pub fn new(handles: Vec<Handle>, wire_models: Vec<WireModel>) -> Self {
+        Self {
+            handles,
+            wire_models,
+            step: Step::Base,
+        }
+    }
+}
+
+impl CadCommand for MoveCommand {
+    fn name(&self) -> &'static str {
+        "MOVE"
+    }
+
+    fn prompt(&self) -> String {
+        match &self.step {
+            Step::Base => format!(
+                "MOVE  Specify base point  [{} objects]:",
+                self.handles.len()
+            ),
+            Step::Target(base) => format!(
+                "MOVE  Specify destination  [base {:.3},{:.3}]:",
+                base.x, base.y
+            ),
+        }
+    }
+
+    fn on_point(&mut self, pt: Vec3) -> CmdResult {
+        match &self.step {
+            Step::Base => {
+                self.step = Step::Target(pt);
+                CmdResult::NeedPoint
+            }
+            Step::Target(base) => {
+                let delta = pt - *base;
+                CmdResult::TransformSelected(
+                    self.handles.clone(),
+                    EntityTransform::Translate(delta),
+                )
+            }
+        }
+    }
+
+    fn on_enter(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+    fn on_escape(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+
+    fn on_preview_wires(&mut self, pt: Vec3) -> Vec<WireModel> {
+        let Step::Target(base) = &self.step else {
+            return vec![];
+        };
+        let delta = pt - *base;
+        // Translated ghost of each selected object + rubber-band line.
+        let mut out: Vec<WireModel> = self
+            .wire_models
+            .iter()
+            .map(|w| w.translated(delta))
+            .collect();
+        out.push(WireModel::solid(
+            "rubber_band".into(),
+            vec![[base.x, base.y, base.z], [pt.x, pt.y, pt.z]],
+            WireModel::CYAN,
+            false,
+        ));
+        out
+    }
+}

src/modules/home/modify/trim.rs

@@ -0,0 +1,883 @@
+// Trim / Extend — ribbon definitions + full command implementations.
+//
+// TRIM  (TR): Click the segment you want to remove. The command finds all
+//             intersections of that entity with every other entity and trims
+//             out the clicked interval. Stays active — click more segments,
+//             press Enter to finish.
+//
+// EXTEND (EX): Click near one end of an entity.  The command extends that
+//              endpoint to the nearest intersecting boundary. Stays active.
+
+use std::f64::consts::TAU;
+
+use acadrust::entities::{Arc as ArcEnt, Line as LineEnt};
+use acadrust::types::Vector3;
+use acadrust::{EntityType, Handle};
+use glam::Vec3;
+
+use crate::command::{CadCommand, CmdResult};
+use crate::modules::IconKind;
+use crate::scene::wire_model::WireModel;
+
+// ── Dropdown constants ─────────────────────────────────────────────────────
+
+pub const DROPDOWN_ID: &str = "trim_extend";
+pub const ICON: IconKind = IconKind::Svg(include_bytes!("../../../../assets/icons/trim.svg"));
+
+pub const DROPDOWN_ITEMS: &[(&str, &str, IconKind)] = &[
+    (
+        "TRIM",
+        "Trim",
+        IconKind::Svg(include_bytes!("../../../../assets/icons/trim.svg")),
+    ),
+    (
+        "EXTEND",
+        "Extend",
+        IconKind::Svg(include_bytes!("../../../../assets/icons/extend.svg")),
+    ),
+];
+
+// ══════════════════════════════════════════════════════════════════════════
+// Geometry helpers
+// ══════════════════════════════════════════════════════════════════════════
+
+/// Normalize angle to [0, 2π).
+fn norm(a: f64) -> f64 {
+    ((a % TAU) + TAU) % TAU
+}
+
+/// Is angle `a` within the arc from `s` to `e` (CCW, radians)?
+fn in_arc(a: f64, s: f64, e: f64) -> bool {
+    let (a, s, e) = (norm(a), norm(s), norm(e));
+    if (e - s).abs() < 1e-9 || (e - s - TAU).abs() < 1e-9 {
+        return true;
+    }
+    if s <= e {
+        a >= s - 1e-9 && a <= e + 1e-9
+    } else {
+        a >= s - 1e-9 || a <= e + 1e-9
+    }
+}
+
+/// Parametric t ∈ [0,1] on arc (a0→a1 CCW) for angle `a`.
+fn arc_t(a: f64, a0: f64, a1: f64) -> f64 {
+    let span = {
+        let s = norm(a1) - norm(a0);
+        if s <= 0.0 {
+            s + TAU
+        } else {
+            s
+        }
+    };
+    let da = {
+        let d = norm(a) - norm(a0);
+        if d < 0.0 {
+            d + TAU
+        } else {
+            d
+        }
+    };
+    (da / span).clamp(0.0, 1.0)
+}
+
+/// Intersect infinite lines (p+t·d) and (q+u·e). Returns (t, u).
+fn ll(
+    px: f64,
+    py: f64,
+    dx: f64,
+    dy: f64,
+    qx: f64,
+    qy: f64,
+    ex: f64,
+    ey: f64,
+) -> Option<(f64, f64)> {
+    let det = dx * ey - dy * ex;
+    if det.abs() < 1e-10 {
+        return None;
+    }
+    let t = ((qx - px) * ey - (qy - py) * ex) / det;
+    let u = ((qx - px) * dy - (qy - py) * dx) / det;
+    Some((t, u))
+}
+
+/// Intersect infinite line (p+t·d) with circle (cx,cy,r). Returns t values.
+fn lc(px: f64, py: f64, dx: f64, dy: f64, cx: f64, cy: f64, r: f64) -> Vec<f64> {
+    let fx = px - cx;
+    let fy = py - cy;
+    let a = dx * dx + dy * dy;
+    let b = 2.0 * (fx * dx + fy * dy);
+    let c = fx * fx + fy * fy - r * r;
+    let disc = b * b - 4.0 * a * c;
+    if disc < 0.0 {
+        return vec![];
+    }
+    let sq = disc.sqrt();
+    if disc < 1e-14 {
+        vec![(-b) / (2.0 * a)]
+    } else {
+        vec![(-b - sq) / (2.0 * a), (-b + sq) / (2.0 * a)]
+    }
+}
+
+/// Circle-circle intersection: angles on circle 1 where they meet.
+fn cc_angles(cx1: f64, cy1: f64, r1: f64, cx2: f64, cy2: f64, r2: f64) -> Vec<f64> {
+    let d = ((cx2 - cx1).powi(2) + (cy2 - cy1).powi(2)).sqrt();
+    if d < 1e-9 || d > r1 + r2 + 1e-9 || d < (r1 - r2).abs() - 1e-9 {
+        return vec![];
+    }
+    let a = (r1 * r1 - r2 * r2 + d * d) / (2.0 * d);
+    let h2 = r1 * r1 - a * a;
+    if h2 < 0.0 {
+        return vec![];
+    }
+    let h = h2.sqrt();
+    let mx = cx1 + a * (cx2 - cx1) / d;
+    let my = cy1 + a * (cy2 - cy1) / d;
+    let px = h * (cy2 - cy1) / d;
+    let py = -h * (cx2 - cx1) / d;
+    let a1 = ((my + py) - cy1).atan2((mx + px) - cx1);
+    let a2 = ((my - py) - cy1).atan2((mx - px) - cx1);
+    if h < 1e-9 {
+        vec![a1]
+    } else {
+        vec![a1, a2]
+    }
+}
+
+// ── Boundary geometry ─────────────────────────────────────────────────────
+
+enum Geo {
+    Line {
+        handle: Handle,
+        p1: [f64; 2],
+        p2: [f64; 2],
+    },
+    Arc {
+        handle: Handle,
+        cx: f64,
+        cy: f64,
+        r: f64,
+        a0: f64,
+        a1: f64,
+    },
+    Circle {
+        handle: Handle,
+        cx: f64,
+        cy: f64,
+        r: f64,
+    },
+}
+
+fn build_geos(entities: &[EntityType]) -> Vec<Geo> {
+    entities
+        .iter()
+        .filter_map(|e| {
+            let h = e.common().handle;
+            match e {
+                EntityType::Line(l) => Some(Geo::Line {
+                    handle: h,
+                    p1: [l.start.x, l.start.y],
+                    p2: [l.end.x, l.end.y],
+                }),
+                EntityType::Arc(a) => Some(Geo::Arc {
+                    handle: h,
+                    cx: a.center.x,
+                    cy: a.center.y,
+                    r: a.radius,
+                    a0: a.start_angle.to_radians(),
+                    a1: a.end_angle.to_radians(),
+                }),
+                EntityType::Circle(c) => Some(Geo::Circle {
+                    handle: h,
+                    cx: c.center.x,
+                    cy: c.center.y,
+                    r: c.radius,
+                }),
+                _ => None,
+            }
+        })
+        .collect()
+}
+
+// ── Intersection helpers ──────────────────────────────────────────────────
+
+/// Sorted, deduped t-params ∈ [0,1] where LINE segment (ax,ay)→(bx,by) intersects boundaries.
+fn line_seg_ts(ax: f64, ay: f64, bx: f64, by: f64, target: Handle, geos: &[Geo]) -> Vec<f64> {
+    let (dx, dy) = (bx - ax, by - ay);
+    let mut ts = vec![];
+    for geo in geos {
+        match geo {
+            Geo::Line { handle, p1, p2 } => {
+                if *handle == target {
+                    continue;
+                }
+                let (ex, ey) = (p2[0] - p1[0], p2[1] - p1[1]);
+                if let Some((t, u)) = ll(ax, ay, dx, dy, p1[0], p1[1], ex, ey) {
+                    if (-1e-9..=1.0 + 1e-9).contains(&u) && (-1e-9..=1.0 + 1e-9).contains(&t) {
+                        ts.push(t.clamp(0.0, 1.0));
+                    }
+                }
+            }
+            Geo::Arc {
+                handle,
+                cx,
+                cy,
+                r,
+                a0,
+                a1,
+            } => {
+                if *handle == target {
+                    continue;
+                }
+                for t in lc(ax, ay, dx, dy, *cx, *cy, *r) {
+                    if !(-1e-9..=1.0 + 1e-9).contains(&t) {
+                        continue;
+                    }
+                    let ix = ax + t * dx;
+                    let iy = ay + t * dy;
+                    if in_arc((iy - cy).atan2(ix - cx), *a0, *a1) {
+                        ts.push(t.clamp(0.0, 1.0));
+                    }
+                }
+            }
+            Geo::Circle { handle, cx, cy, r } => {
+                if *handle == target {
+                    continue;
+                }
+                for t in lc(ax, ay, dx, dy, *cx, *cy, *r) {
+                    if (-1e-9..=1.0 + 1e-9).contains(&t) {
+                        ts.push(t.clamp(0.0, 1.0));
+                    }
+                }
+            }
+        }
+    }
+    ts.sort_by(|a, b| a.partial_cmp(b).unwrap());
+    ts.dedup_by(|a, b| (*a - *b).abs() < 1e-6);
+    ts
+}
+
+/// Sorted, deduped t-params ∈ [0,1] where ARC (cx,cy,r,a0→a1) intersects boundaries.
+fn arc_seg_ts(
+    cx: f64,
+    cy: f64,
+    r: f64,
+    a0: f64,
+    a1: f64,
+    target: Handle,
+    geos: &[Geo],
+) -> Vec<f64> {
+    let mut ts = vec![];
+    for geo in geos {
+        let angles: Vec<f64> = match geo {
+            Geo::Line { handle, p1, p2 } => {
+                if *handle == target {
+                    continue;
+                }
+                let (dx, dy) = (p2[0] - p1[0], p2[1] - p1[1]);
+                lc(p1[0], p1[1], dx, dy, cx, cy, r)
+                    .into_iter()
+                    .filter(|&u| (-1e-9..=1.0 + 1e-9).contains(&u))
+                    .map(|u| (p1[1] + u * dy - cy).atan2(p1[0] + u * dx - cx))
+                    .collect()
+            }
+            Geo::Arc {
+                handle,
+                cx: cx2,
+                cy: cy2,
+                r: r2,
+                a0: a02,
+                a1: a12,
+            } => {
+                if *handle == target {
+                    continue;
+                }
+                cc_angles(cx, cy, r, *cx2, *cy2, *r2)
+                    .into_iter()
+                    .filter(|&a| in_arc(a, *a02, *a12))
+                    .collect()
+            }
+            Geo::Circle {
+                handle,
+                cx: cx2,
+                cy: cy2,
+                r: r2,
+            } => {
+                if *handle == target {
+                    continue;
+                }
+                cc_angles(cx, cy, r, *cx2, *cy2, *r2)
+            }
+        };
+        for a in angles {
+            if in_arc(a, a0, a1) {
+                ts.push(arc_t(a, a0, a1));
+            }
+        }
+    }
+    ts.sort_by(|a, b| a.partial_cmp(b).unwrap());
+    ts.dedup_by(|a, b| (*a - *b).abs() < 1e-6);
+    ts
+}
+
+// ── Trim helpers ──────────────────────────────────────────────────────────
+
+/// Remove the t-interval containing `t_click` from sorted ts.  Returns surviving pieces.
+fn trim_intervals(ts: &[f64], t_click: f64) -> Vec<(f64, f64)> {
+    let mut bounds = vec![0.0f64];
+    bounds.extend_from_slice(ts);
+    bounds.push(1.0);
+    bounds.dedup_by(|a, b| (*a - *b).abs() < 1e-6);
+
+    let remove = bounds
+        .windows(2)
+        .position(|w| t_click >= w[0] - 1e-6 && t_click <= w[1] + 1e-6);
+
+    bounds
+        .windows(2)
+        .enumerate()
+        .filter(|(idx, _)| Some(*idx) != remove)
+        .filter(|(_, w)| (w[1] - w[0]) > 1e-6)
+        .map(|(_, w)| (w[0], w[1]))
+        .collect()
+}
+
+fn lerp2(p1: [f64; 2], p2: [f64; 2], t: f64) -> [f64; 2] {
+    [p1[0] + t * (p2[0] - p1[0]), p1[1] + t * (p2[1] - p1[1])]
+}
+
+/// Trim a Line entity. Returns the surviving line segments.
+fn trim_line(orig: &LineEnt, ts: &[f64], t_click: f64) -> Vec<EntityType> {
+    let p1 = [orig.start.x, orig.start.y];
+    let p2 = [orig.end.x, orig.end.y];
+    let z = orig.start.z;
+    trim_intervals(ts, t_click)
+        .into_iter()
+        .filter_map(|(ta, tb)| {
+            let a = lerp2(p1, p2, ta);
+            let b = lerp2(p1, p2, tb);
+            if (b[0] - a[0]).hypot(b[1] - a[1]) < 1e-6 {
+                return None;
+            }
+            let mut l = orig.clone();
+            l.common.handle = Handle::NULL;
+            l.start = Vector3::new(a[0], a[1], z);
+            l.end = Vector3::new(b[0], b[1], z);
+            Some(EntityType::Line(l))
+        })
+        .collect()
+}
+
+/// Trim an Arc entity. Returns the surviving arc segments.
+fn trim_arc(orig: &ArcEnt, ts: &[f64], t_click: f64) -> Vec<EntityType> {
+    let a0 = orig.start_angle.to_radians();
+    let a1 = orig.end_angle.to_radians();
+    let span = {
+        let s = norm(a1) - norm(a0);
+        if s <= 0.0 {
+            s + TAU
+        } else {
+            s
+        }
+    };
+    let angle_at = |t: f64| norm(a0) + span * t;
+
+    trim_intervals(ts, t_click)
+        .into_iter()
+        .filter_map(|(ta, tb)| {
+            if (tb - ta).abs() < 1e-6 {
+                return None;
+            }
+            let mut a = orig.clone();
+            a.common.handle = Handle::NULL;
+            a.start_angle = angle_at(ta).to_degrees();
+            a.end_angle = angle_at(tb).to_degrees();
+            Some(EntityType::Arc(a))
+        })
+        .collect()
+}
+
+// ── Extend helper ─────────────────────────────────────────────────────────
+
+/// Extend a Line to the nearest boundary on the extended side.
+/// t_click < 0.5 → extend start (look for t < 0); t_click ≥ 0.5 → extend end (t > 1).
+fn extend_line(orig: &LineEnt, t_click: f64, geos: &[Geo]) -> Option<EntityType> {
+    let ax = orig.start.x;
+    let ay = orig.start.y;
+    let bx = orig.end.x;
+    let by = orig.end.y;
+    let (dx, dy) = (bx - ax, by - ay);
+    let target = orig.common.handle;
+    let extend_end = t_click >= 0.5;
+
+    let mut best_t = if extend_end {
+        f64::INFINITY
+    } else {
+        f64::NEG_INFINITY
+    };
+
+    for geo in geos {
+        match geo {
+            Geo::Line { handle, p1, p2 } => {
+                if *handle == target {
+                    continue;
+                }
+                let (ex, ey) = (p2[0] - p1[0], p2[1] - p1[1]);
+                if let Some((t, u)) = ll(ax, ay, dx, dy, p1[0], p1[1], ex, ey) {
+                    if !(-1e-9..=1.0 + 1e-9).contains(&u) {
+                        continue;
+                    }
+                    if extend_end && t > 1.0 + 1e-6 && t < best_t {
+                        best_t = t;
+                    }
+                    if !extend_end && t < -1e-6 && t > best_t {
+                        best_t = t;
+                    }
+                }
+            }
+            Geo::Arc {
+                handle,
+                cx,
+                cy,
+                r,
+                a0,
+                a1,
+            } => {
+                if *handle == target {
+                    continue;
+                }
+                for t in lc(ax, ay, dx, dy, *cx, *cy, *r) {
+                    let ix = ax + t * dx;
+                    let iy = ay + t * dy;
+                    if !in_arc((iy - cy).atan2(ix - cx), *a0, *a1) {
+                        continue;
+                    }
+                    if extend_end && t > 1.0 + 1e-6 && t < best_t {
+                        best_t = t;
+                    }
+                    if !extend_end && t < -1e-6 && t > best_t {
+                        best_t = t;
+                    }
+                }
+            }
+            Geo::Circle { handle, cx, cy, r } => {
+                if *handle == target {
+                    continue;
+                }
+                for t in lc(ax, ay, dx, dy, *cx, *cy, *r) {
+                    if extend_end && t > 1.0 + 1e-6 && t < best_t {
+                        best_t = t;
+                    }
+                    if !extend_end && t < -1e-6 && t > best_t {
+                        best_t = t;
+                    }
+                }
+            }
+        }
+    }
+
+    if !best_t.is_finite() {
+        return None;
+    }
+    let mut line = orig.clone();
+    line.common.handle = Handle::NULL;
+    let new_x = ax + best_t * dx;
+    let new_y = ay + best_t * dy;
+    if extend_end {
+        line.end = Vector3::new(new_x, new_y, orig.end.z);
+    } else {
+        line.start = Vector3::new(new_x, new_y, orig.start.z);
+    }
+    Some(EntityType::Line(line))
+}
+
+// ── Point-generation helpers ──────────────────────────────────────────────
+
+const DIM_RED: [f32; 4] = [1.0, 0.3, 0.3, 0.6];
+
+fn line_pts(l: &LineEnt) -> Vec<[f32; 3]> {
+    vec![
+        [l.start.x as f32, l.start.y as f32, l.start.z as f32],
+        [l.end.x as f32, l.end.y as f32, l.end.z as f32],
+    ]
+}
+
+fn arc_pts(cx: f64, cy: f64, r: f64, a0: f64, a1: f64, y: f64) -> Vec<[f32; 3]> {
+    let span = {
+        let s = norm(a1) - norm(a0);
+        if s <= 0.0 {
+            s + TAU
+        } else {
+            s
+        }
+    };
+    let steps = (span.abs() * 20.0).ceil().max(4.0) as usize;
+    (0..=steps)
+        .map(|i| {
+            let ang = norm(a0) + span * (i as f64 / steps as f64);
+            [
+                (cx + r * ang.cos()) as f32,
+                y as f32,
+                (cy + r * ang.sin()) as f32,
+            ]
+        })
+        .collect()
+}
+
+fn entity_pts(e: &EntityType) -> Vec<[f32; 3]> {
+    match e {
+        EntityType::Line(l) => line_pts(l),
+        EntityType::Arc(a) => arc_pts(
+            a.center.x,
+            a.center.y,
+            a.radius,
+            a.start_angle.to_radians(),
+            a.end_angle.to_radians(),
+            a.center.y,
+        ),
+        _ => vec![],
+    }
+}
+
+// ══════════════════════════════════════════════════════════════════════════
+// TrimCommand
+// ══════════════════════════════════════════════════════════════════════════
+
+pub struct TrimCommand {
+    all_entities: Vec<EntityType>,
+    geos: Vec<Geo>,
+}
+
+impl TrimCommand {
+    pub fn new(all_entities: Vec<EntityType>) -> Self {
+        let geos = build_geos(&all_entities);
+        Self { all_entities, geos }
+    }
+}
+
+impl CadCommand for TrimCommand {
+    fn name(&self) -> &'static str {
+        "TRIM"
+    }
+
+    fn prompt(&self) -> String {
+        "TRIM  Click segment to remove  [Enter=done]:".into()
+    }
+
+    fn needs_entity_pick(&self) -> bool {
+        true
+    }
+
+    fn on_entity_pick(&mut self, handle: Handle, pt: Vec3) -> CmdResult {
+        if handle.is_null() {
+            return CmdResult::NeedPoint;
+        }
+
+        let entity = self
+            .all_entities
+            .iter()
+            .find(|e| e.common().handle == handle);
+
+        let result: Option<Vec<EntityType>> = match entity {
+            Some(EntityType::Line(l)) => {
+                let ax = l.start.x;
+                let ay = l.start.y;
+                let bx = l.end.x;
+                let by = l.end.y;
+                let ts = line_seg_ts(ax, ay, bx, by, handle, &self.geos);
+                if ts.is_empty() {
+                    return CmdResult::NeedPoint;
+                }
+                let dx = bx - ax;
+                let dy = by - ay;
+                let len2 = dx * dx + dy * dy;
+                let t_click = if len2 > 1e-12 {
+                    ((pt.x as f64 - ax) * dx + (pt.y as f64 - ay) * dy) / len2
+                } else {
+                    0.5
+                };
+                Some(trim_line(l, &ts, t_click))
+            }
+            Some(EntityType::Arc(a)) => {
+                let cx = a.center.x;
+                let cy = a.center.y;
+                let a0 = a.start_angle.to_radians();
+                let a1 = a.end_angle.to_radians();
+                let ts = arc_seg_ts(cx, cy, a.radius, a0, a1, handle, &self.geos);
+                if ts.is_empty() {
+                    return CmdResult::NeedPoint;
+                }
+                let click_angle = (pt.y as f64 - cy).atan2(pt.x as f64 - cx);
+                let t_click = arc_t(click_angle, a0, a1);
+                Some(trim_arc(a, &ts, t_click))
+            }
+            _ => None,
+        };
+
+        if let Some(new_entities) = result {
+            // Snapshot is updated in on_entity_replaced once we know the real handles.
+            // Pre-stage: remove old entry now so geos exclude it immediately.
+            if let Some(pos) = self
+                .all_entities
+                .iter()
+                .position(|e| e.common().handle == handle)
+            {
+                self.all_entities.remove(pos);
+                // Add pieces with NULL handles as geometry-only placeholders.
+                self.all_entities.extend(new_entities.clone());
+                self.geos = build_geos(&self.all_entities);
+            }
+            CmdResult::ReplaceEntity(handle, new_entities)
+        } else {
+            self.command_line_hint();
+            CmdResult::NeedPoint
+        }
+    }
+
+    fn on_entity_replaced(&mut self, _old: Handle, new_handles: &[acadrust::Handle]) {
+        // The last new_handles.len() entries in all_entities are the trimmed pieces
+        // that were appended with NULL handles. Assign their real document handles.
+        let start = self.all_entities.len().saturating_sub(new_handles.len());
+        for (e, &h) in self.all_entities[start..]
+            .iter_mut()
+            .zip(new_handles.iter())
+        {
+            match e {
+                EntityType::Line(l) => l.common.handle = h,
+                EntityType::Arc(a) => a.common.handle = h,
+                _ => {}
+            }
+        }
+        self.geos = build_geos(&self.all_entities);
+    }
+
+    fn on_hover_entity(&mut self, handle: Handle, pt: Vec3) -> Vec<WireModel> {
+        if handle.is_null() {
+            return vec![];
+        }
+
+        let entity = self
+            .all_entities
+            .iter()
+            .find(|e| e.common().handle == handle);
+
+        match entity {
+            Some(EntityType::Line(l)) => {
+                let ax = l.start.x;
+                let ay = l.start.y;
+                let bx = l.end.x;
+                let by = l.end.y;
+                let ts = line_seg_ts(ax, ay, bx, by, handle, &self.geos);
+                if ts.is_empty() {
+                    return vec![];
+                }
+                let dx = bx - ax;
+                let dy = by - ay;
+                let len2 = dx * dx + dy * dy;
+                let t_click = if len2 > 1e-12 {
+                    ((pt.x as f64 - ax) * dx + (pt.y as f64 - ay) * dy) / len2
+                } else {
+                    0.5
+                };
+                let survivors = trim_line(l, &ts, t_click);
+                let p1 = [l.start.x as f32, l.start.y as f32, l.start.y as f32];
+                let p2 = [l.end.x as f32, l.end.y as f32, l.end.y as f32];
+                let removed = WireModel::solid("trim_rm".into(), vec![p1, p2], DIM_RED, false);
+                let mut out = vec![removed];
+                for (i, e) in survivors.iter().enumerate() {
+                    let pts = entity_pts(e);
+                    out.push(WireModel::solid(
+                        format!("trim_keep_{i}"),
+                        pts,
+                        WireModel::CYAN,
+                        false,
+                    ));
+                }
+                out
+            }
+            Some(EntityType::Arc(a)) => {
+                let cx = a.center.x;
+                let cy = a.center.y;
+                let a0 = a.start_angle.to_radians();
+                let a1 = a.end_angle.to_radians();
+                let ts = arc_seg_ts(cx, cy, a.radius, a0, a1, handle, &self.geos);
+                if ts.is_empty() {
+                    return vec![];
+                }
+                let click_angle = (pt.y as f64 - cy).atan2(pt.x as f64 - cx);
+                let t_click = arc_t(click_angle, a0, a1);
+                let survivors = trim_arc(a, &ts, t_click);
+                let orig_pts = arc_pts(cx, cy, a.radius, a0, a1, a.center.y);
+                let removed = WireModel::solid("trim_rm".into(), orig_pts, DIM_RED, false);
+                let mut out = vec![removed];
+                for (i, e) in survivors.iter().enumerate() {
+                    let pts = entity_pts(e);
+                    out.push(WireModel::solid(
+                        format!("trim_keep_{i}"),
+                        pts,
+                        WireModel::CYAN,
+                        false,
+                    ));
+                }
+                out
+            }
+            _ => vec![],
+        }
+    }
+
+    fn on_point(&mut self, _pt: Vec3) -> CmdResult {
+        CmdResult::NeedPoint
+    }
+    fn on_enter(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+    fn on_escape(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+}
+
+impl TrimCommand {
+    fn command_line_hint(&self) {}
+}
+
+// ══════════════════════════════════════════════════════════════════════════
+// ExtendCommand
+// ══════════════════════════════════════════════════════════════════════════
+
+pub struct ExtendCommand {
+    all_entities: Vec<EntityType>,
+    geos: Vec<Geo>,
+    /// (old_handle, new_entity_with_updated_geometry) — set in on_entity_pick,
+    /// consumed in on_entity_replaced to patch the snapshot with both new handle + geometry.
+    pending_replace: Option<(Handle, EntityType)>,
+}
+
+impl ExtendCommand {
+    pub fn new(all_entities: Vec<EntityType>) -> Self {
+        let geos = build_geos(&all_entities);
+        Self {
+            all_entities,
+            geos,
+            pending_replace: None,
+        }
+    }
+}
+
+impl CadCommand for ExtendCommand {
+    fn name(&self) -> &'static str {
+        "EXTEND"
+    }
+
+    fn prompt(&self) -> String {
+        "EXTEND  Click near end of object to extend  [Enter=done]:".into()
+    }
+
+    fn needs_entity_pick(&self) -> bool {
+        true
+    }
+
+    fn on_entity_pick(&mut self, handle: Handle, pt: Vec3) -> CmdResult {
+        if handle.is_null() {
+            return CmdResult::NeedPoint;
+        }
+
+        let entity = self
+            .all_entities
+            .iter()
+            .find(|e| e.common().handle == handle);
+
+        let result: Option<EntityType> = match entity {
+            Some(EntityType::Line(l)) => {
+                let ax = l.start.x;
+                let ay = l.start.y;
+                let bx = l.end.x;
+                let by = l.end.y;
+                let dx = bx - ax;
+                let dy = by - ay;
+                let len2 = dx * dx + dy * dy;
+                let t_click = if len2 > 1e-12 {
+                    ((pt.x as f64 - ax) * dx + (pt.y as f64 - ay) * dy) / len2
+                } else {
+                    0.5
+                };
+                extend_line(l, t_click, &self.geos)
+            }
+            _ => None,
+        };
+
+        if let Some(new_entity) = result {
+            // Save the extended entity so on_entity_replaced can patch the snapshot
+            // with both the new geometry and the real document handle.
+            self.pending_replace = Some((handle, new_entity.clone()));
+            CmdResult::ReplaceEntity(handle, vec![new_entity])
+        } else {
+            CmdResult::NeedPoint
+        }
+    }
+
+    fn on_entity_replaced(&mut self, old: Handle, new_handles: &[acadrust::Handle]) {
+        if let (Some(&new_handle), Some((pending_old, mut new_entity))) =
+            (new_handles.first(), self.pending_replace.take())
+        {
+            if pending_old == old {
+                // Update the snapshot entry: replace geometry + assign real handle.
+                if let EntityType::Line(l) = &mut new_entity {
+                    l.common.handle = new_handle;
+                }
+                if let Some(pos) = self
+                    .all_entities
+                    .iter()
+                    .position(|e| e.common().handle == old)
+                {
+                    self.all_entities[pos] = new_entity;
+                }
+                self.geos = build_geos(&self.all_entities);
+            }
+        }
+    }
+
+    fn on_hover_entity(&mut self, handle: Handle, pt: Vec3) -> Vec<WireModel> {
+        if handle.is_null() {
+            return vec![];
+        }
+
+        let entity = self
+            .all_entities
+            .iter()
+            .find(|e| e.common().handle == handle);
+        if let Some(EntityType::Line(l)) = entity {
+            let ax = l.start.x;
+            let ay = l.start.y;
+            let bx = l.end.x;
+            let by = l.end.y;
+            let dx = bx - ax;
+            let dy = by - ay;
+            let len2 = dx * dx + dy * dy;
+            let t_click = if len2 > 1e-12 {
+                ((pt.x as f64 - ax) * dx + (pt.y as f64 - ay) * dy) / len2
+            } else {
+                0.5
+            };
+            if let Some(extended) = extend_line(l, t_click, &self.geos) {
+                let pts = entity_pts(&extended);
+                return vec![WireModel::solid(
+                    "extend_prev".into(),
+                    pts,
+                    WireModel::CYAN,
+                    false,
+                )];
+            }
+        }
+        vec![]
+    }
+
+    fn on_point(&mut self, _pt: Vec3) -> CmdResult {
+        CmdResult::NeedPoint
+    }
+    fn on_enter(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+    fn on_escape(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+}

src/modules/home/modify/ungroup.rs

@@ -0,0 +1,12 @@
+// Ungroup tool — ribbon definition.
+
+use crate::modules::{IconKind, ModuleEvent, ToolDef};
+
+pub fn tool() -> ToolDef {
+    ToolDef {
+        id: "UNGROUP",
+        label: "Ungroup",
+        icon: IconKind::Svg(include_bytes!("../../../../assets/icons/ungroup.svg")),
+        event: ModuleEvent::Command("UNGROUP".to_string()),
+    }
+}