Toolbar drop-downs highlight the row under the pointer and the keyboard focus (#288)

A panel drop-down's command rows are full-width rows that take the theme's hover background
(icon, label and shortcut on it) when hovered or focused. Up/Down move the focus through the
enabled rows, Enter starts the command, Escape closes the drop-down. Rows publish
`dropdown:<id>` and the highlighted one `dropdown_hot:<id>`; scenario s46 checks pointer and
keyboard highlight.

Fixes #288

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01RjGw4gA5ZvKrU8MQP6sBgT

AGENTS.md

@@ -2,10 +2,9 @@
 
 SolidCraft is a clean-room, open-source, pure-Rust parametric 3D CAD application:
 sketches with a constraint solver, a parametric timeline of features, a B-rep
-kernel, and a desktop UI that agents can drive. Siblings with the same conventions live next to
-it in `storytold/`: `cadcraft` (AutoCAD-style, the closest relative), `photocraft`, `vectorcraft`,
-`gridcraft`, `designcraft`, `wordcraft`, `deckcraft`, `soundcraft`. Repos don't share code; when
-code is adapted from a sibling (MIT OR Apache-2.0) it is noted in ATTRIBUTION.md.
+kernel, and a desktop UI that agents can drive. Projects published by
+[storytold](https://github.com/storytold) can serve as references for implementation conventions.
+Any code adapted from other projects (MIT OR Apache-2.0) is noted in ATTRIBUTION.md.
 
 ## Product name and compatibility
 SolidCraft is the displayed product name; `solidcraft` is the repository name. Keep existing

ATTRIBUTION.md

@@ -55,7 +55,7 @@ Generated-in-code assets are original and have no file to list:
 |---|---|---|---|
 | vendor/truck-meshalgo | truck-meshalgo 0.4.0, https://github.com/ricosjp/truck (RICOS Co. Ltd.) | Apache-2.0 | meshing: parameter searches kept inside the surface domain (vendor/README.md) |
 | vendor/truck-stepio | truck-stepio 0.3.0, https://github.com/ricosjp/truck (RICOS Co. Ltd.) | Apache-2.0 | STEP writer: intersection-curve surfaces written at unique ids (vendor/README.md) |
-| vendor/truck-shapeops | truck-shapeops 0.4.0, https://github.com/ricosjp/truck (RICOS Co. Ltd.) | Apache-2.0 | robust meshing and nearest-parameter fallback in booleans; trace macro (vendor/README.md) |
+| vendor/truck-shapeops | truck-shapeops 0.4.0, https://github.com/ricosjp/truck (RICOS Co. Ltd.) | Apache-2.0 | robust meshing and nearest-parameter fallback in booleans; degenerate intersection-curve rejection; trace macro (vendor/README.md) |
 | vendor/matext4cgmath | matext4cgmath 0.1.0, https://github.com/ricosjp/matext4cgmath (RICOS Co. Ltd.) | Apache-2.0 | root refinement stops after 100 Newton steps (vendor/README.md) |
 
 ## Vendored renderer compatibility fix

CLAUDE.md

@@ -2,10 +2,9 @@
 
 SolidCraft is a clean-room, open-source, pure-Rust parametric 3D CAD application:
 sketches with a constraint solver, a parametric timeline of features, a B-rep
-kernel, and a desktop UI that agents can drive. Siblings with the same conventions live next to
-it in `storytold/`: `cadcraft` (AutoCAD-style, the closest relative), `photocraft`, `vectorcraft`,
-`gridcraft`, `designcraft`, `wordcraft`, `deckcraft`, `soundcraft`. Repos don't share code; when
-code is adapted from a sibling (MIT OR Apache-2.0) it is noted in ATTRIBUTION.md.
+kernel, and a desktop UI that agents can drive. Projects published by
+[storytold](https://github.com/storytold) can serve as references for implementation conventions.
+Any code adapted from other projects (MIT OR Apache-2.0) is noted in ATTRIBUTION.md.
 
 ## Product name and compatibility
 SolidCraft is the displayed product name; `solidcraft` is the repository name. Keep existing

Cargo.lock

@@ -3290,13 +3290,14 @@ dependencies = [
 
 [[package]]
 name = "solvecraft"
-version = "0.3.1"
+version = "0.3.2"
 dependencies = [
  "eframe",
  "egui",
  "embed-resource",
  "hidapi",
  "log",
+ "quick-xml 0.38.4",
  "rfd",
  "serde_json",
  "solvecraft-engine",
@@ -3306,7 +3307,7 @@ dependencies = [
 
 [[package]]
 name = "solvecraft-cli"
-version = "0.3.1"
+version = "0.3.2"
 dependencies = [
  "serde_json",
  "solvecraft-engine",
@@ -3315,7 +3316,7 @@ dependencies = [
 
 [[package]]
 name = "solvecraft-doc"
-version = "0.3.1"
+version = "0.3.2"
 dependencies = [
  "log",
  "serde",
@@ -3330,7 +3331,7 @@ dependencies = [
 
 [[package]]
 name = "solvecraft-engine"
-version = "0.3.1"
+version = "0.3.2"
 dependencies = [
  "log",
  "serde",
@@ -3346,7 +3347,7 @@ dependencies = [
 
 [[package]]
 name = "solvecraft-geom"
-version = "0.3.1"
+version = "0.3.2"
 dependencies = [
  "serde",
  "serde_json",
@@ -3354,7 +3355,7 @@ dependencies = [
 
 [[package]]
 name = "solvecraft-io"
-version = "0.3.1"
+version = "0.3.2"
 dependencies = [
  "quick-xml 0.38.4",
  "solvecraft-doc",
@@ -3366,7 +3367,7 @@ dependencies = [
 
 [[package]]
 name = "solvecraft-kernel"
-version = "0.3.1"
+version = "0.3.2"
 dependencies = [
  "log",
  "serde",
@@ -3381,7 +3382,7 @@ dependencies = [
 
 [[package]]
 name = "solvecraft-mcp"
-version = "0.3.1"
+version = "0.3.2"
 dependencies = [
  "serde_json",
  "solvecraft-engine",
@@ -3389,7 +3390,7 @@ dependencies = [
 
 [[package]]
 name = "solvecraft-render"
-version = "0.3.1"
+version = "0.3.2"
 dependencies = [
  "image",
  "serde",
@@ -3399,7 +3400,7 @@ dependencies = [
 
 [[package]]
 name = "solvecraft-sketch"
-version = "0.3.1"
+version = "0.3.2"
 dependencies = [
  "serde",
  "serde_json",
@@ -3410,7 +3411,7 @@ dependencies = [
 
 [[package]]
 name = "solvecraft-ui-egui"
-version = "0.3.1"
+version = "0.3.2"
 dependencies = [
  "egui",
  "egui-wgpu",
@@ -3425,7 +3426,7 @@ dependencies = [
 
 [[package]]
 name = "solvecraft-web"
-version = "0.3.1"
+version = "0.3.2"
 dependencies = [
  "eframe",
  "egui",
@@ -4848,7 +4849,7 @@ checksum = "e450f9b2ed1dff33c94c12589a87338689467b9c4f5d8a5710bd09a847d2c8a7"
 
 [[package]]
 name = "xtask"
-version = "0.3.1"
+version = "0.3.2"
 dependencies = [
  "serde_json",
 ]

Cargo.toml

@@ -5,7 +5,7 @@ members = ["crates/*", "apps/*", "xtask"]
 exclude = ["vendor"]
 
 [workspace.package]
-version = "0.3.1"
+version = "0.3.2"
 edition = "2024"
 license = "MIT OR Apache-2.0"
 rust-version = "1.95"

README.md

@@ -4,7 +4,7 @@
 
 Sketch, constrain, and build solids with a parametric feature timeline. Change a dimension
 and watch your model rebuild. Run it on your desktop, in your browser, or let AI agents
-model through the built-in MCP server. Part of the storytold "craft" family.
+model through the built-in MCP server.
 
 ![SolidCraft: draw a rounded electronics enclosure, sketch its USB port directly on a face, add four mounting bosses and resize it through Parameters](docs/screenshots/enclosure-demo-0.2.1.gif)
 

ROADMAP.md

@@ -67,6 +67,9 @@ headline counts in-scope tabs only and lists the deferred ones separately.
   Type a value and press Enter to commit one undo step; rejected values remain editable and
   cancellation leaves the sketch unchanged. Fit keeps geometry clear of the Sketch Palette
   and navigation controls, including enlarged displays and nested pending placements.
+- Curvature and Polygon constraints accept complete preselected operands. Fix/Unfix
+  consumes complete point/curve selections consistently; mixed or ambiguous selections
+  retain the picking workflow. Rejected constraints preserve selection and undo history.
 - Contextual error reporting: a **Create Issue** action beside feature errors opens a
   reviewable GitHub issue draft with the error, operation settings, build diagnostics and
   useful reproduction context. The draft is editable, with optional capture of the actual
@@ -289,7 +292,29 @@ headline counts in-scope tabs only and lists the deferred ones separately.
   continuous collision detection; local thin walls and small details remain limitations.
   See [contact-set limits and recovery](docs/contact-sets.md).
 
+## Document-opening performance
+
+- Cold rebuild profiling separates parsing, geometry, placement, display meshing and
+  thumbnails. Straight-line closest-point projection and exact curved-surface evaluation
+  reuse reduce repeated work without relaxing geometry checks. Three alternating optimized
+  benchmark runs reduce median rebuild time by 26% on the public sensor enclosure and 22%
+  on a local case assembly; shape measurements and topology match the original build.
+  See [performance measurements](docs/perf.md). Further cold Boolean and import costs remain.
+- Prepared assembly geometry survives selection and view changes while real geometry and
+  placement changes invalidate it. A Pi assembly edge-selection probe drops from 9.24 s to
+  0.57 s; initial opening is unchanged. Actual Windows desktop profiling measures 15.87 s
+  median opening, with 82% spent rebuilding geometry; halving full opening remains open.
+
 ## Kernel
 
+- Boolean intersection-curve construction refuses point-only, collapsed and non-finite
+  polylines without panicking. Direct constructor regressions retain valid open endpoints
+  and closed spherical intersections; the original interactive trigger remains unidentified.
+- Shell of a stepped, joined planar body no longer creates horizontal subdivisions across
+  continuous walls. Fresh axis-aligned Cut walls are stitched using their exact construction
+  support and shared topology, preserving real steps and intentional boundaries. The local
+  reported case returns from 86 to 49 faces with unchanged material and bounds; regressions
+  cover stepped stock, STEP round trips and saved projections from removed pieces.
+
 truck (Apache-2.0) behind our own `kernel` crate, with our own blend operation and boolean
 retry/validation; see `plan/adr/0001-geometry-kernel.md` (local) — summary in README.

apps/solvecraft/Cargo.toml

@@ -21,6 +21,7 @@ rfd = { workspace = true }
 
 [target.'cfg(target_os = "windows")'.dependencies]
 hidapi = { version = "2.6.7", default-features = false, features = ["windows-native"] }
+quick-xml = { workspace = true }
 
 [target.'cfg(all(unix, not(target_os = "macos")))'.dependencies]
 winit = { version = "0.30", default-features = false, features = ["x11"] }

apps/solvecraft/src/space_mouse.rs

@@ -6,11 +6,14 @@ use std::time::{Duration, Instant};
 
 use egui::Context;
 use hidapi::{DeviceInfo, HidApi};
+use quick_xml::Reader;
+use quick_xml::events::Event;
 use solvecraft_engine::render::Camera;
 use solvecraft_ui_egui::SolveApp;
 
 const STALE_AFTER: Duration = Duration::from_millis(150);
 const RETRY_AFTER: Duration = Duration::from_secs(2);
+const MAX_PROFILE_BYTES: u64 = 1024 * 1024;
 
 #[derive(Clone, Copy, Debug, Default, PartialEq)]
 struct Axes {
@@ -18,6 +21,172 @@ struct Axes {
     rotation: [i16; 3],
 }
 
+#[derive(Clone, Copy, Debug, PartialEq)]
+struct AxisRule {
+    output: usize,
+    enabled: bool,
+    reversed: bool,
+    scale: f64,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+struct DriverMapping {
+    axes: [AxisRule; 6],
+    overall_scale: f64,
+}
+
+impl Default for DriverMapping {
+    fn default() -> Self {
+        Self { axes: std::array::from_fn(|output| AxisRule { output, enabled: true, reversed: false, scale: 1.0 }), overall_scale: 1.0 }
+    }
+}
+
+#[derive(Clone, Copy, Debug, Default, PartialEq)]
+struct Motion {
+    translation: [f64; 3],
+    rotation: [f64; 3],
+}
+
+impl DriverMapping {
+    fn apply(self, axes: Axes) -> Motion {
+        let raw = [
+            normalized(axes.translation[0]),
+            normalized(axes.translation[1]),
+            normalized(axes.translation[2]),
+            normalized(axes.rotation[0]),
+            normalized(axes.rotation[1]),
+            normalized(axes.rotation[2]),
+        ];
+        let mut logical = [0.0; 6];
+        for (input, rule) in self.axes.iter().enumerate() {
+            if rule.enabled {
+                let sign = if rule.reversed { -1.0 } else { 1.0 };
+                logical[rule.output] = raw[input] * sign * rule.scale * self.overall_scale;
+            }
+        }
+        Motion { translation: [logical[0], logical[1], logical[2]], rotation: [logical[3], logical[4], logical[5]] }
+    }
+}
+
+#[derive(Clone, Copy, Debug, Default)]
+struct ProfileAxis {
+    input: Option<usize>,
+    output: Option<usize>,
+    enabled: bool,
+    reversed: bool,
+    scale: f64,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+enum ProfilePart {
+    Input,
+    Output,
+}
+
+fn axis_index(name: &str) -> Option<usize> {
+    match name.trim() {
+        "HIDMultiAxis_X" => Some(0),
+        "HIDMultiAxis_Y" => Some(1),
+        "HIDMultiAxis_Z" => Some(2),
+        "HIDMultiAxis_Rx" => Some(3),
+        "HIDMultiAxis_Ry" => Some(4),
+        "HIDMultiAxis_Rz" => Some(5),
+        _ => None,
+    }
+}
+
+/// 3DxWare stores the active KMJ application's axis selection, swapping, inversion and speed in
+/// `%APPDATA%/3Dconnexion/3DxWare/Cfg/<app>-KMJ.xml`. Direct HID reads bypass the driver, so apply
+/// that profile explicitly when it exists. Unknown or incomplete fields retain the raw HID axis.
+fn parse_driver_mapping(xml: &[u8]) -> Option<DriverMapping> {
+    let mut reader = Reader::from_reader(xml);
+    reader.config_mut().trim_text(true);
+    let mut buf = Vec::new();
+    let mut mapping = DriverMapping::default();
+    let mut axis: Option<ProfileAxis> = None;
+    let mut part = None;
+    let mut field = Vec::new();
+    let mut found = false;
+    loop {
+        match reader.read_event_into(&mut buf).ok()? {
+            Event::Start(start) => match start.local_name().as_ref() {
+                b"Axis" => axis = Some(ProfileAxis { enabled: true, scale: 1.0, ..Default::default() }),
+                b"Input" => part = Some(ProfilePart::Input),
+                b"Output" => part = Some(ProfilePart::Output),
+                name @ (b"ActionID" | b"Enabled" | b"Reversed" | b"Scale" | b"OverallScale") => field = name.to_vec(),
+                _ => {}
+            },
+            Event::Text(text) => {
+                let value = String::from_utf8_lossy(text.as_ref());
+                match field.as_slice() {
+                    b"ActionID" => {
+                        if let Some(current) = axis.as_mut() {
+                            match part {
+                                Some(ProfilePart::Input) => current.input = axis_index(&value),
+                                Some(ProfilePart::Output) => current.output = axis_index(&value),
+                                None => {}
+                            }
+                        }
+                    }
+                    b"Enabled" => {
+                        if let Some(current) = axis.as_mut() {
+                            current.enabled = value.trim().eq_ignore_ascii_case("true");
+                        }
+                    }
+                    b"Reversed" => {
+                        if part == Some(ProfilePart::Output)
+                            && let Some(current) = axis.as_mut()
+                        {
+                            current.reversed = value.trim().eq_ignore_ascii_case("true");
+                        }
+                    }
+                    b"Scale" => {
+                        if part == Some(ProfilePart::Output)
+                            && let Some(scale) = value.trim().parse::<f64>().ok().filter(|scale| scale.is_finite())
+                            && let Some(current) = axis.as_mut()
+                        {
+                            current.scale = scale.clamp(0.0, 10.0);
+                        }
+                    }
+                    b"OverallScale" => {
+                        if let Some(scale) = value.trim().parse::<f64>().ok().filter(|scale| scale.is_finite()) {
+                            mapping.overall_scale = scale.clamp(0.0, 10.0);
+                        }
+                    }
+                    _ => {}
+                }
+            }
+            Event::End(end) => match end.local_name().as_ref() {
+                b"Axis" => {
+                    if let Some(current) = axis.take()
+                        && let (Some(input), Some(output)) = (current.input, current.output)
+                    {
+                        mapping.axes[input] = AxisRule { output, enabled: current.enabled, reversed: current.reversed, scale: current.scale };
+                        found = true;
+                    }
+                }
+                b"Input" | b"Output" => part = None,
+                b"ActionID" | b"Enabled" | b"Reversed" | b"Scale" | b"OverallScale" => field.clear(),
+                _ => {}
+            },
+            Event::Eof => break,
+            _ => {}
+        }
+        buf.clear();
+    }
+    found.then_some(mapping)
+}
+
+fn load_driver_mapping() -> Option<DriverMapping> {
+    let profile = std::path::PathBuf::from(std::env::var_os("APPDATA")?).join("3Dconnexion").join("3DxWare").join("Cfg").join("solvecraft-KMJ.xml");
+    if std::fs::metadata(&profile).ok()?.len() > MAX_PROFILE_BYTES {
+        log::warn!("3D mouse: ignoring oversized 3DxWare profile {}", profile.display());
+        return None;
+    }
+    let xml = std::fs::read(&profile).ok()?;
+    parse_driver_mapping(&xml)
+}
+
 #[derive(Clone, Copy)]
 struct Reading {
     axes: Axes,
@@ -107,6 +276,8 @@ fn reader(ctx: Context, shared: Arc<Mutex<Reading>>) {
 pub struct SpaceMouse {
     shared: Arc<Mutex<Reading>>,
     last_frame: Instant,
+    driver_mapping: DriverMapping,
+    mapping_checked_at: Instant,
 }
 
 impl SpaceMouse {
@@ -118,13 +289,21 @@ impl SpaceMouse {
         if let Err(error) = std::thread::Builder::new().name("solvecraft-3d-mouse".into()).spawn(move || reader(worker_ctx, worker_state)) {
             log::warn!("3D mouse: reader could not start: {error}");
         }
-        Self { shared, last_frame: now }
+        Self { shared, last_frame: now, driver_mapping: load_driver_mapping().unwrap_or_default(), mapping_checked_at: now }
     }
 
     pub fn tick(&mut self, app: &mut SolveApp, ctx: &Context) {
         let now = Instant::now();
         let seconds = now.duration_since(self.last_frame).as_secs_f64().min(0.05);
         self.last_frame = now;
+        if now.duration_since(self.mapping_checked_at) >= RETRY_AFTER {
+            let updated = load_driver_mapping().unwrap_or_default();
+            if updated != self.driver_mapping {
+                log::info!("3D mouse: applying updated 3DxWare axis profile");
+                self.driver_mapping = updated;
+            }
+            self.mapping_checked_at = now;
+        }
         if !app.preferences.space_mouse_enabled || app.home.open {
             return;
         }
@@ -141,7 +320,14 @@ impl SpaceMouse {
         }
         app.begin_external_navigation();
         let height = app.viewport.rect.map_or(600.0, |rect| f64::from(rect.height().max(1.0)));
-        navigate(&mut app.cam, axes, seconds * speed.clamp(0.1, 5.0), height, app.session.active_sketch.is_some());
+        navigate(
+            &mut app.cam,
+            self.driver_mapping.apply(axes),
+            seconds * speed.clamp(0.1, 5.0),
+            height,
+            app.session.active_sketch.is_some(),
+            app.preferences.zoom_reverse,
+        );
         ctx.request_repaint_after(Duration::from_millis(16));
     }
 }
@@ -153,15 +339,21 @@ fn normalized(value: i16) -> f64 {
     if v.abs() <= 20.0 { 0.0 } else { v.signum() * ((v.abs() - 20.0) / 330.0).min(1.0) }
 }
 
-fn navigate(cam: &mut Camera, axes: Axes, seconds: f64, height: f64, sketch: bool) {
+fn navigate(cam: &mut Camera, motion: Motion, seconds: f64, height: f64, sketch: bool, reverse_zoom: bool) {
     if !(seconds > 0.0) || !seconds.is_finite() {
         return;
     }
-    let [x, y, z] = axes.translation.map(normalized);
-    let [rx, ry, rz] = axes.rotation.map(normalized);
-    cam.pan(x * height * 0.6 * seconds, -y * height * 0.6 * seconds, height);
-    cam.zoom_at((-z * 1.5 * seconds).exp(), None);
+    let [x, y, z] = motion.translation;
+    let [rx, ry, rz] = motion.rotation;
+    // Logical 3DxWare coordinates are X = left/right, Y = zoom and Z = up/down. The user's
+    // profile above can swap the physical forward/back and up/down axes before they reach here.
+    cam.pan(x * height * 0.6 * seconds, z * height * 0.6 * seconds, height);
+    let zoom_sign = if reverse_zoom { -1.0 } else { 1.0 };
+    cam.zoom_at((-y * zoom_sign * 1.5 * seconds).exp(), None);
     if !sketch {
+        // These are logical 3DxWare coordinates after the profile mapping above: Rx is Tilt,
+        // Ry is Roll and Rz is Spin. The KMJ profile swaps physical Ry/Rz for the selected
+        // navigation mode, so swapping them again here would make Roll behave like Spin.
         cam.orbit(ry * 250.0 * seconds, rx * 250.0 * seconds);
         cam.roll_by(rz * 2.0 * seconds);
     }
@@ -171,6 +363,10 @@ fn navigate(cam: &mut Camera, axes: Axes, seconds: f64, height: f64, sketch: boo
 mod tests {
     use super::*;
 
+    fn raw(axes: Axes) -> Motion {
+        DriverMapping::default().apply(axes)
+    }
+
     #[test]
     fn decodes_separate_reports_without_stale_motion_or_padding_interference() {
         let now = Instant::now();
@@ -192,15 +388,102 @@ mod tests {
     fn six_axes_move_the_camera_and_sketches_keep_their_orientation() {
         let mut cam = Camera::default();
         let before = cam;
-        navigate(&mut cam, Axes { translation: [350, 350, 350], rotation: [350, 350, 350] }, 0.02, 600.0, false);
+        navigate(&mut cam, raw(Axes { translation: [350, 350, 350], rotation: [350, 350, 350] }), 0.02, 600.0, false, false);
         assert_ne!(cam.target, before.target);
         assert!(cam.distance < before.distance);
         assert_ne!(cam.yaw, before.yaw);
         assert_ne!(cam.pitch, before.pitch);
         assert_ne!(cam.roll, before.roll);
         let orientation = (cam.yaw, cam.pitch, cam.roll);
-        navigate(&mut cam, Axes { translation: [350, 0, 0], rotation: [350, 350, 350] }, 0.02, 600.0, true);
+        navigate(&mut cam, raw(Axes { translation: [350, 0, 0], rotation: [350, 350, 350] }), 0.02, 600.0, true, false);
         assert_eq!((cam.yaw, cam.pitch, cam.roll), orientation);
         assert!(cam.is_valid());
     }
+
+    #[test]
+    fn individual_axes_have_physical_spacemouse_meaning() {
+        let before = Camera::default();
+
+        let mut slide = before;
+        navigate(&mut slide, raw(Axes { translation: [350, 0, 0], rotation: [0; 3] }), 0.02, 600.0, false, false);
+        assert_ne!(slide.target, before.target);
+        assert_eq!(slide.distance, before.distance);
+
+        let mut push = before;
+        navigate(&mut push, raw(Axes { translation: [0, 350, 0], rotation: [0; 3] }), 0.02, 600.0, false, false);
+        assert_eq!(push.target, before.target);
+        assert!(push.distance < before.distance);
+
+        let mut lift = before;
+        navigate(&mut lift, raw(Axes { translation: [0, 0, 350], rotation: [0; 3] }), 0.02, 600.0, false, false);
+        assert_ne!(lift.target, before.target);
+        assert_eq!(lift.distance, before.distance);
+
+        let mut tilt = before;
+        navigate(&mut tilt, raw(Axes { translation: [0; 3], rotation: [350, 0, 0] }), 0.02, 600.0, false, false);
+        assert_eq!((tilt.yaw, tilt.roll), (before.yaw, before.roll));
+        assert_ne!(tilt.pitch, before.pitch);
+
+        let mut roll = before;
+        navigate(&mut roll, raw(Axes { translation: [0; 3], rotation: [0, 350, 0] }), 0.02, 600.0, false, false);
+        assert_eq!((roll.pitch, roll.roll), (before.pitch, before.roll));
+        assert_ne!(roll.yaw, before.yaw);
+
+        let mut twist = before;
+        navigate(&mut twist, raw(Axes { translation: [0; 3], rotation: [0, 0, 350] }), 0.02, 600.0, false, false);
+        assert_eq!((twist.yaw, twist.pitch), (before.yaw, before.pitch));
+        assert_ne!(twist.roll, before.roll);
+    }
+
+    #[test]
+    fn reverse_zoom_setting_applies_to_spacemouse() {
+        let before = Camera::default();
+        let motion = raw(Axes { translation: [0, 350, 0], rotation: [0; 3] });
+        let mut normal = before;
+        navigate(&mut normal, motion, 0.02, 600.0, false, false);
+        let mut reversed = before;
+        navigate(&mut reversed, motion, 0.02, 600.0, false, true);
+        assert!(normal.distance < before.distance);
+        assert!(reversed.distance > before.distance);
+    }
+
+    #[test]
+    fn applies_3dxware_axis_swaps_and_reversals() {
+        let profile = br#"
+            <AppCfg><Devices><Device><AxisBank>
+              <Axis><Enabled>true</Enabled><Input><ActionID>HIDMultiAxis_X</ActionID></Input><Output><ActionID>HIDMultiAxis_X</ActionID><Reversed>false</Reversed></Output></Axis>
+              <Axis><Enabled>true</Enabled><Input><ActionID>HIDMultiAxis_Y</ActionID></Input><Output><ActionID>HIDMultiAxis_Z</ActionID><Reversed>false</Reversed></Output></Axis>
+              <Axis><Enabled>true</Enabled><Input><ActionID>HIDMultiAxis_Z</ActionID></Input><Output><ActionID>HIDMultiAxis_Y</ActionID><Reversed>true</Reversed></Output></Axis>
+              <Axis><Enabled>true</Enabled><Input><ActionID>HIDMultiAxis_Rx</ActionID></Input><Output><ActionID>HIDMultiAxis_Rx</ActionID><Reversed>false</Reversed></Output></Axis>
+              <Axis><Enabled>true</Enabled><Input><ActionID>HIDMultiAxis_Ry</ActionID></Input><Output><ActionID>HIDMultiAxis_Rz</ActionID><Reversed>false</Reversed></Output></Axis>
+              <Axis><Enabled>true</Enabled><Input><ActionID>HIDMultiAxis_Rz</ActionID></Input><Output><ActionID>HIDMultiAxis_Ry</ActionID><Reversed>true</Reversed></Output></Axis>
+            </AxisBank></Device></Devices></AppCfg>
+        "#;
+        let mapping = parse_driver_mapping(profile).expect("valid 3DxWare profile");
+        let motion = mapping.apply(Axes { translation: [350, 0, 350], rotation: [350, 0, 350] });
+        assert_eq!(motion.translation, [1.0, -1.0, 0.0]);
+        assert_eq!(motion.rotation, [1.0, -1.0, 0.0]);
+    }
+
+    #[test]
+    fn mapped_roll_and_spin_reach_distinct_camera_rotations() {
+        let profile = br#"
+            <AppCfg><Devices><Device><AxisBank>
+              <Axis><Enabled>true</Enabled><Input><ActionID>HIDMultiAxis_Ry</ActionID></Input><Output><ActionID>HIDMultiAxis_Rz</ActionID><Reversed>false</Reversed></Output></Axis>
+              <Axis><Enabled>true</Enabled><Input><ActionID>HIDMultiAxis_Rz</ActionID></Input><Output><ActionID>HIDMultiAxis_Ry</ActionID><Reversed>true</Reversed></Output></Axis>
+            </AxisBank></Device></Devices></AppCfg>
+        "#;
+        let mapping = parse_driver_mapping(profile).expect("valid 3DxWare profile");
+        let before = Camera::default();
+
+        let mut physical_roll = before;
+        navigate(&mut physical_roll, mapping.apply(Axes { translation: [0; 3], rotation: [0, 350, 0] }), 0.02, 600.0, false, false);
+        assert_eq!((physical_roll.yaw, physical_roll.pitch), (before.yaw, before.pitch));
+        assert_ne!(physical_roll.roll, before.roll);
+
+        let mut physical_spin = before;
+        navigate(&mut physical_spin, mapping.apply(Axes { translation: [0; 3], rotation: [0, 0, 350] }), 0.02, 600.0, false, false);
+        assert_ne!(physical_spin.yaw, before.yaw);
+        assert_eq!((physical_spin.pitch, physical_spin.roll), (before.pitch, before.roll));
+    }
 }

crates/doc/src/config_shell_tests.rs

@@ -457,3 +457,124 @@ fn saved_curved_strip_projection_is_lost_after_exact_wall_coalescence() {
         }
     }
 }
+
+#[test]
+fn saved_stepped_tab_cut_piece_projection_is_lost_without_expanding_material() {
+    use solvecraft_kernel::{BoolOp, FacePaint, Paint};
+    use solvecraft_sketch::{LinkKind, LinkSource, Sketch};
+    let mut doc = Document::new("public stepped tab case");
+    doc.set_param("length", "40", Some("mm"), None).unwrap();
+    doc.set_param("wall", "2", Some("mm"), None).unwrap();
+    for (name, kind) in [
+        ("Case", json!({"type":"box","corner":[0,0,0],"length":"length","width":"30","height":"20"})),
+        ("Tab", json!({"type":"box","corner":["length",10,12],"length":"8","width":"10","height":"8"})),
+    ] {
+        let id = doc.add_feature(serde_json::from_value(kind).unwrap(), Some(name)).unwrap();
+        doc.feature_mut(id).unwrap().body_names = vec![name.into()];
+    }
+    doc.add_feature(
+        FeatureKind::Combine { target: "Case".into(), tools: vec!["Tab".into()], operation: crate::Operation::Join, keep_tools: false },
+        None,
+    )
+    .unwrap();
+    let tool = doc
+        .add_feature(
+            serde_json::from_value(
+                json!({"type":"box","corner":["wall","wall","wall"],"length":"length-2*wall","width":"30-2*wall","height":"22-wall"}),
+            )
+            .unwrap(),
+            Some("Pocket tool"),
+        )
+        .unwrap();
+    doc.feature_mut(tool).unwrap().body_names = vec!["Pocket tool".into()];
+    let cut = doc
+        .add_feature(
+            FeatureKind::Combine { target: "Case".into(), tools: vec!["Pocket tool".into()], operation: crate::Operation::Cut, keep_tools: false },
+            Some("Pocket"),
+        )
+        .unwrap();
+    let mut model = Model::new();
+    model.evaluate(&doc);
+    assert!(model.results.iter().all(|r| r.error.is_none()), "{:?}", model.results);
+    let before = model.state_before(cut);
+    // A real per-face paint control preserves the former slab construction;
+    // no historical names or geometry are fabricated.
+    let old_stock = before
+        .body("Case")
+        .unwrap()
+        .body
+        .clone()
+        .with_paint(Some(Paint { opacity: 1., faces: vec![FacePaint { face: 0, color: [1., 0., 0.], opacity: 1. }] }));
+    let old_cut = solvecraft_kernel::boolean(&old_stock, &before.body("Pocket tool").unwrap().body, BoolOp::Cut).unwrap().unwrap();
+    let mut old_body = ModelBody::new("Case".into(), old_cut, cut);
+    old_body.names = crate::naming::NameCell::new(Some(std::sync::Arc::new(crate::naming::NamingOrigin {
+        feature: doc.feature(cut).unwrap().clone(),
+        before,
+        depth: 1,
+        mats: vec![],
+    })));
+    let at = Vec3::new(0., 15., 1.);
+    let former = crate::naming::face_name_at_body(&old_body, at).unwrap();
+    assert_ne!(former, crate::naming::strip_piece(&former), "actual former bounded wall patch has a full piece name");
+    let index = crate::naming::face_on_body(&old_body, &former, at).unwrap().0;
+    let mut old_state = crate::ModelState::default();
+    old_state.bodies.push(old_body);
+    let plane = solvecraft_geom::Plane::YZ;
+    let resolved = crate::project::resolve_face_indices(&old_state, &plane, LinkKind::Project, "Case", &[index]).unwrap();
+    let current_state = model.state();
+    let current = current_state.body("Case").unwrap();
+    let stem = crate::naming::strip_piece(&former);
+    let current_names = crate::naming::face_names(current);
+    let merged = current_names.iter().position(|name| name == stem).unwrap();
+    assert!(current.body.face_was_coalesced(merged), "new exact generated-wall construction supplies the loss-only witness");
+    assert!(!current_names.contains(&former));
+    let mut sketch = Sketch::new();
+    sketch.add_link(LinkKind::Project, LinkSource::Face { body: "Case".into(), at }, &resolved.geom).unwrap();
+    sketch.links[0].face_name = Some(former);
+    let original = sketch.clone();
+    let captured = original.points.iter().filter(|p| p.link.is_some()).map(|p| p.pos).collect::<Vec<_>>();
+    assert_eq!(captured.len(), 4);
+    assert!(captured.iter().all(|p| (p.x == 10. || p.x == 20.) && (p.y == 0. || p.y == 20.)));
+    let sk = doc.add_feature(FeatureKind::Sketch { plane: PlaneRef::Custom { plane }, sketch }, Some("Saved wall patch")).unwrap();
+    let material = doc
+        .add_feature(
+            FeatureKind::Extrude {
+                sketch: sk,
+                profiles: crate::ProfileSel::All,
+                extent: serde_json::from_value(json!({"distance":"1"})).unwrap(),
+                operation: crate::Operation::NewBody,
+                targets: vec![],
+            },
+            Some("Saved band stock"),
+        )
+        .unwrap();
+    for (length, wall) in [(40., 2.), (50., 3.)] {
+        doc.set_param("length", &length.to_string(), Some("mm"), None).unwrap();
+        doc.set_param("wall", &wall.to_string(), Some("mm"), None).unwrap();
+        model.evaluate(&doc);
+        let reopened = crate::format::read(&doc.to_json()).unwrap();
+        let mut cold = Model::new();
+        cold.evaluate(&reopened);
+        for current in [&model, &cold] {
+            let result = current.results.iter().find(|r| r.id == sk).unwrap();
+            assert!(result.error.is_none(), "{result:?}");
+            assert!(result.warning.as_deref().is_some_and(|w| w.contains("no longer exists; last geometry retained")), "{result:?}");
+            let state = current.state();
+            let saved = state.sketch(sk).unwrap();
+            assert!(saved.sketch.links[0].lost);
+            assert_eq!(saved.sketch.points, original.points);
+            assert_eq!(saved.sketch.curves, original.curves);
+            let stock = state.bodies.iter().find(|b| b.feature == material).unwrap();
+            assert!(
+                (solvecraft_kernel::measure(&stock.body).unwrap().volume - 200.).abs() < 1e-7,
+                "saved10x20 patch must not become30x20 wall; actualvolume={}, bounds={:?}, originalpoints={:?}",
+                solvecraft_kernel::measure(&stock.body).unwrap().volume,
+                stock.mesh().bounds(),
+                original.points
+            );
+            let case = state.body("Case").unwrap();
+            let expected = length * 30. * 20. + 8. * 10. * 8. - (length - 2. * wall) * (30. - 2. * wall) * (20. - wall);
+            assert!((solvecraft_kernel::measure(&case.body).unwrap().volume - expected).abs() < 1e-6);
+        }
+    }
+}

crates/doc/src/eval.rs

@@ -3436,9 +3436,18 @@ pub fn world_state(doc: &Document, st: &ModelState) -> ModelState {
             let name = doc.world_body_name(st, &b.name, comp, &path);
             // A body moved in from another component keeps its place (its offset).
             let bm = doc.model_body_offset(b).map(|o| crate::mat_mul(&m, o)).unwrap_or(m);
-            let body =
-                if crate::is_identity(&bm) { b.body.clone() } else { kernel::transform_matrix(&b.body, bm).unwrap_or_else(|_| b.body.clone()) };
-            let mut placed = ModelBody::new(name, body, b.feature);
+            // Identical geometry also shares its display mesh cell with the definition.
+            // A changed placement keeps a distinct mesh, at that placement's coordinates.
+            let mut placed = if crate::is_identity(&bm) {
+                let mut placed = b.clone();
+                placed.name = name;
+                placed
+            } else {
+                let body = kernel::transform_matrix(&b.body, bm).unwrap_or_else(|_| b.body.clone());
+                ModelBody::new(name, body, b.feature)
+            };
+            // World states keep their previous display-only evaluation-key semantics.
+            placed.key = 0;
             placed.source_name = Some(b.definition_name().to_string());
             placed.source_transform = crate::mat_mul(&bm, &b.source_transform);
             placed.component = comp;
@@ -3481,6 +3490,87 @@ pub fn world_state(doc: &Document, st: &ModelState) -> ModelState {
     out
 }
 
+#[cfg(test)]
+mod world_placement_cache_tests {
+    use super::*;
+
+    #[test]
+    fn placed_real_feature_retains_names_from_its_original_feature_context() {
+        let mut doc = Document::new("authored names");
+        let component = doc.add_component(Some("Part"), 0).unwrap();
+        let feature = doc
+            .add_feature(
+                FeatureKind::Box {
+                    corner: crate::point_expr(Vec3::ZERO),
+                    length: "2 mm".into(),
+                    width: "3 mm".into(),
+                    height: "4 mm".into(),
+                    operation: crate::Operation::NewBody,
+                },
+                Some("AuthoredBox"),
+            )
+            .unwrap();
+        doc.feature_mut(feature).unwrap().component = component;
+        let matrix = crate::rigid(Vec3::new(15., -2., 8.), Vec3::ZERO, Vec3::X, 0.7);
+        doc.occurrences.iter_mut().find(|o| o.component == component).unwrap().transform = matrix;
+        let mut model = Model::default();
+        model.evaluate(&doc);
+        let state = model.state();
+        let source = &state.bodies[0];
+        assert!(source.names.origin.is_some());
+        assert!(source.mesh.get().is_none());
+        let world = world_state(&doc, &state);
+        assert!(source.mesh.get().is_some(), "source naming is prepared before adoption, as before");
+        let names = crate::naming::face_names(&world.bodies[0]);
+        assert!(Arc::ptr_eq(&names, &crate::naming::face_names(source)));
+        assert!(names.iter().all(|name| name.starts_with(&format!("F{feature}:"))));
+        let local = source.mesh();
+        let placed = world.bodies[0].mesh();
+        assert_eq!(local.tri_face, placed.tri_face);
+        let mapped: Vec<_> = local.positions.iter().map(|p| crate::apply_point(&matrix, *p)).collect();
+        assert!(mapped.iter().all(|p| placed.positions.iter().any(|q| p.dist(*q) < 1e-8)));
+        assert!(placed.positions.iter().all(|p| mapped.iter().any(|q| p.dist(*q) < 1e-8)));
+    }
+
+    #[test]
+    fn identity_shares_mesh_but_rotated_instances_keep_distinct_physical_coordinates_and_source_names() {
+        let mut doc = Document::new("placements");
+        let component = doc.add_component(Some("Part"), 0).unwrap();
+        doc.body_components.insert("Block".into(), component);
+        let matrix = crate::rigid(Vec3::new(10., 20., 0.), Vec3::ZERO, Vec3::Z, std::f64::consts::FRAC_PI_2);
+        let second = doc.add_occurrence(component, 0, matrix).unwrap();
+        let mut state = ModelState::default();
+        state.bodies.push(ModelBody::new("Block".into(), kernel::box_solid(Vec3::ZERO, Vec3::new(2., 3., 4.)).unwrap(), 1));
+        state.bodies[0].key = 1234;
+        let source = &state.bodies[0];
+        let world = world_state(&doc, &state);
+        assert_eq!(world.bodies.len(), 2);
+        let first = world.body("Block").unwrap();
+        let second_name = doc.world_body_name(&state, "Block", component, &[second]);
+        let placed = world.body(&second_name).unwrap();
+        assert!(source.mesh.get().is_some(), "persistent source names stay prepared before adoption");
+        assert!(Arc::ptr_eq(&source.mesh, &first.mesh), "unchanged geometry must retain the shared display mesh cell");
+        assert_eq!(first.key, 0);
+        assert_eq!(placed.key, 0);
+        assert!(!Arc::ptr_eq(&source.mesh, &placed.mesh), "a transformed mesh cannot be reused without mapping coordinates");
+        assert_eq!(first.source_name.as_deref(), Some("Block"));
+        assert_eq!(placed.source_name.as_deref(), Some("Block"));
+        assert_eq!(placed.source_transform, matrix);
+        assert_eq!(doc.model_body_component(placed), component);
+        let bounds = placed.mesh().bounds();
+        assert!(bounds.min.dist(Vec3::new(7., 20., 0.)) < 1e-9);
+        assert!(bounds.max.dist(Vec3::new(10., 22., 4.)) < 1e-9);
+        let names = crate::naming::face_names(source);
+        assert!(Arc::ptr_eq(&names, &crate::naming::face_names(first)));
+        assert!(Arc::ptr_eq(&names, &crate::naming::face_names(placed)));
+        let original_mesh = source.mesh();
+        assert!(Arc::ptr_eq(&original_mesh, &first.mesh()));
+        let again = world_state(&doc, &state);
+        assert!(Arc::ptr_eq(&original_mesh, &again.body("Block").unwrap().mesh()));
+        assert!(Arc::ptr_eq(&names, &crate::naming::face_names(again.body(&second_name).unwrap())));
+    }
+}
+
 #[cfg(test)]
 mod chain_tests {
     use super::*;

crates/engine/src/lib.rs

@@ -150,6 +150,28 @@ pub struct Preview {
     pub after: Arc<ModelState>,
 }
 
+/// Prepared world geometry depends on design/model identity and placement context, not
+/// selection or the view revision. Retained Arcs prevent pointer reuse after a design closes.
+#[derive(Clone)]
+struct WorldCache {
+    doc: Arc<Document>,
+    model: Arc<solvecraft_doc::ModelState>,
+    pending_moves: std::collections::BTreeMap<u64, solvecraft_doc::Mat>,
+    active_component: u64,
+    active_occurrence_path: Option<Vec<u64>>,
+    world: Arc<solvecraft_doc::ModelState>,
+}
+
+impl WorldCache {
+    fn matches(&self, session: &Session, model: &Arc<solvecraft_doc::ModelState>) -> bool {
+        Arc::ptr_eq(&self.doc, &session.doc)
+            && Arc::ptr_eq(&self.model, model)
+            && self.pending_moves == session.pending_moves
+            && self.active_component == session.active_component
+            && self.active_occurrence_path == session.active_occurrence_path
+    }
+}
+
 /// An editing session on one design.
 pub struct Session {
     pub doc: Arc<Document>,
@@ -173,7 +195,7 @@ pub struct Session {
     pub active_occurrence_path: Option<Vec<u64>>,
     /// Occurrence moves not captured yet (Capture Position keeps them, a recompute drops them).
     pub pending_moves: std::collections::BTreeMap<u64, solvecraft_doc::Mat>,
-    world_cache: std::sync::Mutex<Option<(u64, Arc<solvecraft_doc::ModelState>)>>,
+    world_cache: std::sync::Mutex<Option<WorldCache>>,
     occurrence_visibility_cache: std::sync::Mutex<Option<occurrences::VisibilityCache>>,
     /// Features copied with `timeline.copy` (pasted by `timeline.paste`).
     pub clipboard: Vec<solvecraft_doc::Feature>,
@@ -308,10 +330,10 @@ impl Session {
             return st;
         }
         if let Ok(c) = self.world_cache.lock()
-            && let Some((rev, w)) = c.as_ref()
-            && *rev == self.revision
+            && let Some(cached) = c.as_ref()
+            && cached.matches(self, &st)
         {
-            return w.clone();
+            return cached.world.clone();
         }
         let mut w = if self.pending_moves.is_empty() {
             solvecraft_doc::world_state(&self.doc, &st)
@@ -350,7 +372,14 @@ impl Session {
         }
         let w = Arc::new(w);
         if let Ok(mut c) = self.world_cache.lock() {
-            *c = Some((self.revision, w.clone()));
+            *c = Some(WorldCache {
+                doc: self.doc.clone(),
+                model: st,
+                pending_moves: self.pending_moves.clone(),
+                active_component: self.active_component,
+                active_occurrence_path: self.active_occurrence_path.clone(),
+                world: w.clone(),
+            });
         }
         w
     }
@@ -503,7 +532,7 @@ impl Session {
             active_component: self.active_component,
             active_occurrence_path: self.active_occurrence_path.clone(),
             pending_moves: self.pending_moves.clone(),
-            world_cache: Default::default(),
+            world_cache: std::sync::Mutex::new(self.world_cache.lock().ok().and_then(|cache| cache.clone())),
             occurrence_visibility_cache: Default::default(),
             clipboard: self.clipboard.clone(),
             section: None,
@@ -519,12 +548,6 @@ impl Session {
     pub fn invalidate_view(&mut self, previous_revision: u64) {
         let old = self.revision;
         self.revision = old.max(previous_revision) + 1;
-        if let Ok(mut cache) = self.world_cache.lock()
-            && let Some((revision, _)) = cache.as_mut()
-            && *revision == old
-        {
-            *revision = self.revision;
-        }
     }
 
     /// Commit commands evaluated on a scratch copy without losing this session's file,
@@ -651,3 +674,5 @@ mod split_face_tests;
 mod tests;
 #[cfg(test)]
 mod thread_tests;
+#[cfg(test)]
+mod world_placement_cache_tests;

crates/engine/src/world_placement_cache_tests.rs

@@ -0,0 +1,177 @@
+//! Placement-cache changes must retain physical picking, pending positions and named joints.
+use crate::{Session, geom::Vec3};
+use serde_json::{Value, json};
+use std::sync::Arc;
+
+fn run(session: &mut Session, command: &str, params: Value) -> Value {
+    session.execute(command, &params).unwrap_or_else(|error| panic!("{command}: {error}"))
+}
+
+#[test]
+fn world_placement_cache_preserves_pending_picks_materials_scratch_and_named_joint_frames() {
+    let mut session = Session::default();
+    let created = run(&mut session, "component.create", json!({"name":"Part"}));
+    let component = created["component"].as_u64().unwrap();
+    let first = created["occurrence"].as_u64().unwrap();
+    run(&mut session, "solid.box", json!({"length":2,"width":3,"height":4,"body_name":"Block","operation":"new"}));
+    run(&mut session, "material.assign", json!({"bodies":["Block"],"material":"Brass"}));
+    let second = run(&mut session, "occurrence.copy", json!({"occurrence":first}))["occurrence"].as_u64().unwrap();
+    run(&mut session, "occurrence.move", json!({"occurrence":second,"translate":[10,20,0],"axis":[0,0,1],"angle":"90 deg","capture":false}));
+    let pending = session.pending_moves.clone();
+    let path = vec![second];
+    let placement = session.occurrence_placement(&path).unwrap();
+    let name = placement.bodies[0].world.clone();
+    let world = session.world_state();
+    assert!(Arc::ptr_eq(&world, &session.world_state()));
+    let source_state = session.model.state();
+    let source = source_state.body("Block").unwrap();
+    let placed = world.body(&name).unwrap();
+    assert_eq!(placed.source_name.as_deref(), Some("Block"));
+    assert_eq!(placed.component, component);
+    let bounds = placed.mesh().bounds();
+    assert!(bounds.min.dist(Vec3::new(7., 20., 0.)) < 1e-9);
+    assert!(bounds.max.dist(Vec3::new(10., 22., 4.)) < 1e-9);
+    assert_eq!(session.doc.model_body_look(placed), session.doc.model_body_look(source));
+    let source_names = crate::doc::naming::face_names(source);
+    assert_eq!(source_names, crate::doc::naming::face_names(placed));
+    let pick = Vec3::new(8.5, 21., 4.);
+    let top = placed.body.faces(0.001).unwrap().into_iter().find(|face| face.plane_normal.is_some_and(|n| n.z > 0.99)).unwrap().index;
+    run(&mut session, "select.set", json!({"items":[{"type":"face","body":name,"index":top,"point":[pick.x,pick.y,pick.z]}]}));
+    assert!(matches!(&session.selection[0], crate::Sel::Face { body, index, .. } if body == &name && *index == top));
+    assert!(Arc::ptr_eq(&world, &session.world_state()), "selection changes must not discard prepared placements");
+    let scratch = session.scratch();
+    assert_eq!(scratch.pending_moves, pending);
+    let scratch_world = scratch.world_state();
+    assert!(Arc::ptr_eq(&world, &scratch_world));
+    let scratch_body = scratch_world.body(&name).unwrap();
+    assert!(scratch_body.mesh().bounds().min.dist(bounds.min) < 1e-9);
+    assert_eq!(crate::doc::naming::face_names(scratch_body), source_names);
+    run(&mut session, "component.capture_position", json!({}));
+    run(&mut session, "joint.origin", json!({"name":"Top joint","occurrence":second,"face":[pick.x,pick.y,pick.z]}));
+    let joint = session.doc.assembly.origins[0].origin.clone();
+    let local_frame = crate::doc::joints::resolve_origin(&session.doc, &session.model.state(), &joint).unwrap();
+    let before_joint = crate::doc::mat_mul(&crate::doc::joints::occurrence_world(&session.doc, second), &local_frame);
+    assert!(crate::doc::apply_point(&before_joint, Vec3::ZERO).dist(pick) < 1e-9);
+    run(&mut session, "occurrence.move", json!({"occurrence":second,"translate":[5,0,0],"capture":true}));
+    let moved = session.world_state();
+    assert!(!Arc::ptr_eq(&world, &moved), "a changed transform must invalidate placed meshes");
+    assert!(moved.body(&name).unwrap().mesh().bounds().min.dist(bounds.min + Vec3::new(5., 0., 0.)) < 1e-9);
+    assert!(world.body(&name).unwrap().mesh().bounds().min.dist(bounds.min) < 1e-9, "prior snapshots must remain immutable");
+    assert_eq!(crate::doc::naming::face_names(moved.body(&name).unwrap()), source_names);
+    let local_frame = crate::doc::joints::resolve_origin(&session.doc, &session.model.state(), &joint).unwrap();
+    let after_joint = crate::doc::mat_mul(&crate::doc::joints::occurrence_world(&session.doc, second), &local_frame);
+    assert!(crate::doc::apply_point(&after_joint, Vec3::ZERO).dist(pick + Vec3::new(5., 0., 0.)) < 1e-9);
+    let reopened = Session::new(crate::doc::Document::from_json(&session.doc.to_json()).unwrap());
+    assert!(reopened.world_state().body(&name).unwrap().mesh().bounds().min.dist(bounds.min + Vec3::new(5., 0., 0.)) < 1e-9);
+    assert_eq!(reopened.model.results.iter().filter(|r| r.error.is_some()).count(), 0);
+}
+
+#[test]
+fn selection_visibility_section_and_view_revisions_reuse_world_geometry() {
+    let mut session = Session::default();
+    run(&mut session, "component.create", json!({"name":"Part"}));
+    run(&mut session, "solid.box", json!({"length":2,"width":3,"height":4,"body_name":"Block","operation":"new"}));
+    let world = session.world_state();
+    let revision = session.revision;
+    run(&mut session, "select.set", json!({"items":[{"type":"body","name":"Block"}]}));
+    assert!(session.revision > revision);
+    assert!(Arc::ptr_eq(&world, &session.world_state()));
+    run(&mut session, "select.clear", json!({}));
+    assert!(Arc::ptr_eq(&world, &session.world_state()));
+    run(&mut session, "browser.visibility", json!({"items":["Block"],"visible":false}));
+    assert!(!session.body_visible("Block"));
+    assert!(Arc::ptr_eq(&world, &session.world_state()));
+    run(&mut session, "inspect.section", json!({"plane":{"origin":[0,0,2],"normal":[0,0,1]}}));
+    assert!(session.section.is_some());
+    assert!(Arc::ptr_eq(&world, &session.world_state()));
+    session.invalidate_view(session.revision + 10);
+    assert!(Arc::ptr_eq(&world, &session.world_state()));
+    assert!(Arc::ptr_eq(&world, &session.scratch().world_state()));
+}
+
+#[test]
+fn world_cache_requires_exact_design_model_pending_and_author_context() {
+    let mut session = Session::default();
+    let created = run(&mut session, "component.create", json!({"name":"Part"}));
+    let component = created["component"].as_u64().unwrap();
+    let first = created["occurrence"].as_u64().unwrap();
+    run(&mut session, "solid.box", json!({"length":2,"width":3,"height":4,"body_name":"Block","operation":"new"}));
+    let sketch = run(&mut session, "sketch.create", json!({"plane":"XY"}))["sketch"].as_u64().unwrap();
+    run(&mut session, "sketch.finish", json!({}));
+    let second = run(&mut session, "occurrence.copy", json!({"occurrence":first}))["occurrence"].as_u64().unwrap();
+    let initial = session.world_state();
+    run(&mut session, "occurrence.move", json!({"occurrence":second,"translate":[10,20,0],"capture":false}));
+    let pending = session.world_state();
+    assert!(!Arc::ptr_eq(&initial, &pending));
+    let name = session.occurrence_placement(&[second]).unwrap().bodies[0].world.clone();
+    assert!(pending.body(&name).unwrap().mesh().bounds().min.dist(Vec3::new(10., 20., 0.)) < 1e-9);
+    run(&mut session, "component.activate", json!({"component":component,"occurrence":second,"path":[second]}));
+    let authored = session.world_state();
+    assert!(!Arc::ptr_eq(&pending, &authored));
+    assert!(authored.sketch(sketch).unwrap().plane.origin.dist(Vec3::new(10., 20., 0.)) < 1e-9);
+    let mut scratch = session.scratch();
+    assert!(Arc::ptr_eq(&authored, &scratch.world_state()));
+    scratch.active_occurrence_path = Some(vec![first]);
+    let scratch_world = scratch.world_state();
+    assert!(!Arc::ptr_eq(&authored, &scratch_world));
+    assert!(scratch_world.sketch(sketch).unwrap().plane.origin.dist(Vec3::ZERO) < 1e-9);
+    assert!(Arc::ptr_eq(&authored, &session.world_state()), "scratch context must not replace the source cache");
+    run(&mut session, "appearance.assign", json!({"bodies":["Block"],"color":"#ff0000"}));
+    let painted = session.world_state();
+    assert!(!Arc::ptr_eq(&authored, &painted));
+    assert_ne!(session.doc.model_body_look(painted.body("Block").unwrap()), None);
+    run(&mut session, "edit.undo", json!({}));
+    let undone = session.world_state();
+    assert!(!Arc::ptr_eq(&painted, &undone));
+    run(&mut session, "edit.redo", json!({}));
+    let redone = session.world_state();
+    assert!(!Arc::ptr_eq(&undone, &redone));
+    assert!(session.doc.model_body_look(redone.body("Block").unwrap()).is_some());
+    let before_edit = session.world_state();
+    run(&mut session, "solid.box", json!({"length":5,"width":6,"height":7,"body_name":"Other","operation":"new"}));
+    let edited = session.world_state();
+    assert!(!Arc::ptr_eq(&before_edit, &edited));
+    assert!(edited.body("Other").is_some());
+    session.doc = Arc::new(crate::doc::Document::from_json(&session.doc.to_json()).unwrap());
+    let replaced = session.world_state();
+    assert!(!Arc::ptr_eq(&edited, &replaced), "equal contents in a different document cannot share the cache key");
+    session.model = crate::doc::Model::default();
+    session.model.evaluate(&session.doc);
+    assert!(!Arc::ptr_eq(&replaced, &session.world_state()), "a new evaluated model must invalidate even when the document Arc is unchanged");
+}
+
+#[test]
+fn adopted_scratch_keeps_its_warm_geometry_and_history_stages_invalidate_it() {
+    let mut session = Session::default();
+    run(&mut session, "component.create", json!({"name":"Part"}));
+    run(&mut session, "solid.box", json!({"length":2,"width":3,"height":4,"body_name":"Block","operation":"new"}));
+    let source = session.world_state();
+    let source_json = session.doc.to_json();
+    let mut scratch = session.scratch();
+    run(&mut scratch, "solid.box", json!({"length":5,"width":6,"height":7,"body_name":"Draft","operation":"new"}));
+    let warmed = scratch.world_state();
+    assert!(!Arc::ptr_eq(&source, &warmed));
+    assert_eq!(session.doc.to_json(), source_json);
+    assert!(Arc::ptr_eq(&source, &session.world_state()));
+    assert!(source.body("Draft").is_none());
+    let feature = warmed.body("Draft").unwrap().feature;
+    session.accept_computed(scratch);
+    assert!(Arc::ptr_eq(&warmed, &session.world_state()), "adoption/view revision must retain the worker's prepared geometry");
+    session.invalidate_view(session.revision + 20);
+    assert!(Arc::ptr_eq(&warmed, &session.world_state()));
+    run(&mut session, "timeline.rollback", json!({"position":1}));
+    let rolled = session.world_state();
+    assert!(!Arc::ptr_eq(&warmed, &rolled));
+    assert!(rolled.body("Block").is_some());
+    assert!(rolled.body("Draft").is_none());
+    run(&mut session, "timeline.rollback", json!({}));
+    let restored = session.world_state();
+    assert!(!Arc::ptr_eq(&rolled, &restored));
+    assert!(restored.body("Draft").is_some());
+    run(&mut session, "timeline.suppress", json!({"feature":feature,"suppressed":true}));
+    let suppressed = session.world_state();
+    assert!(!Arc::ptr_eq(&restored, &suppressed));
+    assert!(suppressed.body("Draft").is_none());
+    run(&mut session, "timeline.suppress", json!({"feature":feature,"suppressed":false}));
+    assert!(session.world_state().body("Draft").is_some());
+}

crates/geom/src/profile.rs

@@ -244,8 +244,24 @@ impl Seg2 {
             }
         }
     }
-    /// Parameter of the point of the segment closest to `p` (sampling, then Newton).
+    /// Parameter of the closest point: exact projection for lines,
+    /// sampling followed by Newton for the remaining curves.
     pub fn closest_param(&self, p: Vec2) -> f64 {
+        let finite = |p: Vec2| p.x.is_finite() && p.y.is_finite();
+        match *self {
+            Seg2::Line { a, b } if finite(a) && finite(b) && finite(p) => {
+                let d = b - a;
+                if a == b {
+                    return 0.0;
+                }
+                let denominator = d.len2();
+                let t = (p - a).dot(d) / denominator;
+                if denominator > 0.0 && denominator.is_finite() && t.is_finite() {
+                    return t.clamp(0.0, 1.0);
+                }
+            }
+            _ => {}
+        }
         let n = 64;
         let mut t =
             (0..=n).map(|i| i as f64 / n as f64).min_by(|x, y| self.point_at(*x).dist(p).total_cmp(&self.point_at(*y).dist(p))).unwrap_or(0.0);
@@ -540,6 +556,76 @@ impl Region2 {
 mod tests {
     use super::*;
 
+    #[test]
+    fn closest_line_projection_and_degeneracy() {
+        let line = Seg2::Line { a: Vec2::new(-3.0, 4.0), b: Vec2::new(7.0, 4.0) };
+        for (p, t) in [(Vec2::new(-9.0, 20.0), 0.0), (Vec2::new(2.0, -5.0), 0.5), (Vec2::new(15.0, 4.0), 1.0)] {
+            assert_eq!(line.closest_param(p), t);
+            assert_eq!(line.reversed().closest_param(p), 1.0 - t);
+        }
+        let a = Vec2::new(1e100, -1e100);
+        let b = a + Vec2::new(1e90, 2e90);
+        let large = Seg2::Line { a, b };
+        assert!((large.closest_param(a.lerp(b, 0.5)) - 0.5).abs() < 1e-6);
+        assert_eq!(Seg2::Line { a, b: a }.closest_param(Vec2::ZERO), 0.0);
+        let tiny = Seg2::Line { a: Vec2::ZERO, b: Vec2::new(1e-12, 0.0) };
+        assert_eq!(tiny.closest_param(Vec2::new(0.5e-12, 1.0)), 0.5);
+        for line in [line, line.reversed(), tiny] {
+            for k in 0..53 {
+                let p = Vec2::new((k * 17 % 37) as f64 - 18.0, (k * 31 % 29) as f64 - 14.0);
+                let closest = line.point_at(line.closest_param(p)).dist(p);
+                let dense = (0..=8192).map(|i| line.point_at(i as f64 / 8192.0).dist(p)).fold(f64::INFINITY, f64::min);
+                assert!(closest <= dense + 1e-12);
+            }
+        }
+    }
+
+    fn sampled_closest(s: &Seg2, p: Vec2) -> f64 {
+        let mut t = (0..=64).map(|i| i as f64 / 64.0).min_by(|x, y| s.point_at(*x).dist(p).total_cmp(&s.point_at(*y).dist(p))).unwrap_or(0.0);
+        for _ in 0..30 {
+            let (q, d) = (s.point_at(t), s.derivative(t));
+            let (d2, h) = ((s.derivative((t + 1e-6).min(1.0)) - s.derivative((t - 1e-6).max(0.0))) / 2e-6, q - p);
+            let df = d.dot(d) + h.dot(d2);
+            if df.abs() < 1e-300 {
+                break;
+            }
+            let nt = (t - h.dot(d) / df).clamp(0.0, 1.0);
+            if (nt - t).abs() < 1e-14 {
+                t = nt;
+                break;
+            }
+            t = nt;
+        }
+        t
+    }
+
+    #[test]
+    fn closest_projection_preserves_clearance_tolerance_and_generic_fallback() {
+        use std::f64::consts::TAU;
+        let curves = [
+            Seg2::Line { a: Vec2::new(-4.0, 7.0), b: Vec2::new(3.0, -2.0) },
+            Seg2::Arc { center: Vec2::new(3.0, -2.0), radius: 6.0, start: 5.9, sweep: 1.3 },
+            Seg2::Arc { center: Vec2::ZERO, radius: 2.0, start: 0.2, sweep: -TAU },
+            Seg2::Arc { center: Vec2::ZERO, radius: 2.0, start: 0.0, sweep: TAU },
+            Seg2::Arc { center: Vec2::ZERO, radius: 2.0, start: 0.0, sweep: 0.0 },
+            Seg2::Arc { center: Vec2::ZERO, radius: 2.0, start: 0.0, sweep: 1e-12 },
+            Seg2::Cubic { p0: Vec2::ZERO, p1: Vec2::new(2.0, 7.0), p2: Vec2::new(6.0, -3.0), p3: Vec2::new(8.0, 4.0) },
+        ];
+        for (i, s) in curves.iter().enumerate() {
+            for k in 0..101 {
+                let p = Vec2::new((k * 17 % 37) as f64 - 18.0, (k * 31 % 29) as f64 - 14.0);
+                let old = sampled_closest(s, p);
+                let new = s.closest_param(p);
+                if i > 0 {
+                    assert_eq!(new.to_bits(), old.to_bits());
+                }
+                assert!(s.point_at(new).dist(p) <= s.point_at(old).dist(p) + 1e-10);
+                let on_curve = s.point_at(k as f64 / 100.0);
+                assert!(s.point_at(s.closest_param(on_curve)).dist(on_curve) < 1e-9);
+            }
+        }
+    }
+
     #[test]
     fn triangulated_area() {
         let sq = Loop2::polygon(&[Vec2::new(0.0, 0.0), Vec2::new(10.0, 0.0), Vec2::new(10.0, 8.0), Vec2::new(5.0, 3.0), Vec2::new(0.0, 8.0)]);

crates/kernel/src/body.rs

@@ -33,6 +33,8 @@ pub struct Body {
     pub(crate) splits: Option<std::sync::Arc<Vec<Vec<Vec3>>>>,
     /// Exact construction/import source identities, in this body's face order.
     pub(crate) face_sources: Option<std::sync::Arc<Vec<Option<FaceSource>>>>,
+    /// Sticky transient veto: authored face boundaries must survive later rebuilds.
+    pub(crate) regularization_protected: bool,
 }
 
 #[derive(Clone, Debug, PartialEq)]
@@ -120,6 +122,11 @@ fn mesh_shells(solid: &Solid, tol: f64) -> Vec<MeshedShell> {
 /// `None` when nothing needs splitting or the parameters don't match the surface.
 #[allow(clippy::type_complexity)]
 fn refined(pm: &PolygonMesh, surf: &mt::Surface, tol: f64) -> Option<Vec<[(Vec3, Vec3); 3]>> {
+    refined_with_cache(pm, surf, tol, true)
+}
+
+#[allow(clippy::type_complexity)]
+fn refined_with_cache(pm: &PolygonMesh, surf: &mt::Surface, tol: f64, memoize: bool) -> Option<Vec<[(Vec3, Vec3); 3]>> {
     use mt::{ParametricSurface, ParametricSurface3D};
     let (pos, uvs, nor) = (pm.positions(), pm.uv_coords(), pm.normals());
     if uvs.is_empty() {
@@ -148,6 +155,15 @@ fn refined(pm: &PolygonMesh, surf: &mt::Surface, tol: f64) -> Option<Vec<[(Vec3,
     // Edges on the face's boundary are shared with the next face: never split them.
     let k = |x: &V| ((x.1.0 * 1e9).round() as i64, (x.1.1 * 1e9).round() as i64);
     let ek = |a: &V, b: &V| if k(a) < k(b) { (k(a), k(b)) } else { (k(b), k(a)) };
+    // Only exact finite values identify reusable evaluations. In particular,
+    // the rounded UV keys used for boundary incidence cannot identify a point
+    // whose derivatives or midpoint may be reused.
+    let vertex_key = |v: &V| {
+        let values = [v.0.x, v.0.y, v.0.z, v.1.0, v.1.1, v.2.x, v.2.y, v.2.z];
+        values.iter().all(|x| x.is_finite()).then(|| values.map(f64::to_bits))
+    };
+    let cache_limit = cap * 3;
+    let mut singular_cache = std::collections::HashMap::<(u64, u64), bool>::new();
     let mut changed = false;
     for _ in 0..4 {
         let mut uses: std::collections::HashMap<((i64, i64), (i64, i64)), u32> = std::collections::HashMap::new();
@@ -156,34 +172,60 @@ fn refined(pm: &PolygonMesh, surf: &mt::Surface, tol: f64) -> Option<Vec<[(Vec3,
                 *uses.entry(e).or_default() += 1;
             }
         }
-        let at = |a: &V, b: &V| -> Option<V> {
-            if uses.get(&ek(a, b)).copied().unwrap_or(0) < 2 {
-                return None;
+        let mut edge_cache = std::collections::HashMap::<([u64; 8], [u64; 8]), Option<V>>::new();
+        let mut at = |a: &V, b: &V| -> Option<V> {
+            let key = if memoize { vertex_key(a).zip(vertex_key(b)).map(|(a, b)| if a < b { (a, b) } else { (b, a) }) } else { None };
+            if let Some(key) = key
+                && let Some(value) = edge_cache.get(&key)
+            {
+                return *value;
             }
-            // Not at a degenerate point (a cone's apex: its parameters there are arbitrary).
-            let singular = |x: &V| {
-                let (du, dv) = (surf.uder(x.1.0, x.1.1), surf.vder(x.1.0, x.1.1));
-                let c = du.cross(dv);
-                c.x * c.x + c.y * c.y + c.z * c.z
-                    <= 1e-12 * (du.x * du.x + du.y * du.y + du.z * du.z + dv.x * dv.x + dv.y * dv.y + dv.z * dv.z).powi(2) + 1e-300
+            let mut calculate = || -> Option<V> {
+                if uses.get(&ek(a, b)).copied().unwrap_or(0) < 2 {
+                    return None;
+                }
+                // Not at a degenerate point (a cone's apex: its parameters there are arbitrary).
+                let mut singular = |x: &V| {
+                    let key = (x.1.0.to_bits(), x.1.1.to_bits());
+                    let cacheable = memoize && x.1.0.is_finite() && x.1.1.is_finite();
+                    if cacheable && let Some(value) = singular_cache.get(&key) {
+                        return *value;
+                    }
+                    let (du, dv) = (surf.uder(x.1.0, x.1.1), surf.vder(x.1.0, x.1.1));
+                    let c = du.cross(dv);
+                    let value = c.x * c.x + c.y * c.y + c.z * c.z
+                        <= 1e-12 * (du.x * du.x + du.y * du.y + du.z * du.z + dv.x * dv.x + dv.y * dv.y + dv.z * dv.z).powi(2) + 1e-300;
+                    if cacheable && singular_cache.len() < cache_limit {
+                        singular_cache.insert(key, value);
+                    }
+                    value
+                };
+                if singular(a) || singular(b) {
+                    return None;
+                }
+                let (u, v) = ((a.1.0 + b.1.0) / 2.0, (a.1.1 + b.1.1) / 2.0);
+                let q = from_p3(surf.subs(u, v));
+                // Within tolerance, or so far off that the parameters wrapped (a seam).
+                let sag = q.dist((a.0 + b.0) * 0.5);
+                if sag <= tol || sag >= 0.5 * a.0.dist(b.0) {
+                    return None;
+                }
+                let n = surf.normal(u, v);
+                let mut n = Vec3::new(n.x, n.y, n.z);
+                // Keep the mesh's normal side.
+                if n.dot(a.2 + b.2) < 0.0 {
+                    n = -n;
+                }
+                Some((q, (u, v), n))
             };
-            if singular(a) || singular(b) {
-                return None;
+            let value = calculate();
+            if let Some(key) = key
+                && edge_cache.len() < cache_limit
+                && value.is_none_or(|v| vertex_key(&v).is_some())
+            {
+                edge_cache.insert(key, value);
             }
-            let (u, v) = ((a.1.0 + b.1.0) / 2.0, (a.1.1 + b.1.1) / 2.0);
-            let q = from_p3(surf.subs(u, v));
-            // Within tolerance, or so far off that the parameters wrapped (a seam).
-            let sag = q.dist((a.0 + b.0) * 0.5);
-            if sag <= tol || sag >= 0.5 * a.0.dist(b.0) {
-                return None;
-            }
-            let n = surf.normal(u, v);
-            let mut n = Vec3::new(n.x, n.y, n.z);
-            // Keep the mesh's normal side.
-            if n.dot(a.2 + b.2) < 0.0 {
-                n = -n;
-            }
-            Some((q, (u, v), n))
+            value
         };
         let mut next = Vec::with_capacity(tris.len());
         let mut any = false;
@@ -320,6 +362,7 @@ impl Body {
             && self.paint == other.paint
             && self.splits == other.splits
             && self.face_sources == other.face_sources
+            && self.regularization_protected == other.regularization_protected
     }
 
     pub(crate) fn new(solid: Solid) -> Result<Body> {
@@ -358,9 +401,15 @@ impl Body {
             paint: None,
             splits: None,
             face_sources: None,
+            regularization_protected: false,
         })
     }
 
+    pub(crate) fn inherit_regularization_protection(mut self, input: &Body) -> Self {
+        self.regularization_protected |= input.regularization_protected;
+        self
+    }
+
     pub fn face_sources(&self) -> Option<&[Option<FaceSource>]> {
         self.face_sources.as_deref().map(Vec::as_slice)
     }
@@ -588,6 +637,7 @@ impl Body {
     /// The same body with the lines its faces were split along on purpose.
     pub fn with_split_lines(mut self, s: Option<std::sync::Arc<Vec<Vec<Vec3>>>>) -> Body {
         self.splits = s.filter(|l| !l.is_empty());
+        self.regularization_protected |= self.splits.is_some();
         self
     }
 
@@ -612,6 +662,7 @@ impl Body {
             })
             .filter(|p| p.opacity < 1.0 || !p.faces.is_empty())
             .map(std::sync::Arc::new);
+        self.regularization_protected |= self.paint().is_some_and(|paint| !paint.faces.is_empty());
         self
     }
 
@@ -658,11 +709,15 @@ impl Body {
                 let flip = !face.orientation();
                 let base = u32::try_from(out.positions.len()).unwrap_or(u32::MAX);
                 // Curved faces: split triangles that cut through the surface.
-                if refine
-                    && let Some(sf) = solid_faces.get(fi)
-                    && !matches!(sf.surface(), mt::Surface::Plane(_))
-                    && let Some(tris) = refined(&pm, &sf.surface(), tol)
-                {
+                let refinement = if refine {
+                    solid_faces.get(fi).and_then(|sf| {
+                        let surface = sf.surface();
+                        if matches!(surface, mt::Surface::Plane(_)) { None } else { refined(&pm, &surface, tol) }
+                    })
+                } else {
+                    None
+                };
+                if let Some(tris) = refinement {
                     let fid = u32::try_from(fi).unwrap_or(u32::MAX);
                     for t in tris {
                         let mut idx = [0u32; 3];
@@ -1019,7 +1074,7 @@ impl Body {
                             })
                             .collect()
                     });
-                    Ok(result.with_face_sources(sources.map(std::sync::Arc::new)))
+                    Ok(result.with_face_sources(sources.map(std::sync::Arc::new)).inherit_regularization_protection(self))
                 })
                 .collect()
         })
@@ -1029,3 +1084,11 @@ impl Body {
 #[cfg(test)]
 #[path = "body_lump_tests.rs"]
 mod lump_tests;
+
+#[cfg(test)]
+#[path = "refine_cache_tests.rs"]
+mod refine_cache_tests;
+
+#[cfg(test)]
+#[path = "regularization_protection_tests.rs"]
+mod regularization_protection_tests;

crates/kernel/src/intersection_curve_tests.rs

@@ -0,0 +1,60 @@
+//! Regressions against the actual patched truck constructor, run by workspace CI.
+use truck_meshalgo::prelude::PolylineCurve;
+use truck_modeling::{BoundedCurve, ParametricCurve, Plane, Point3, Sphere};
+use truck_shapeops::IntersectionCurveWithParameters;
+
+fn planes() -> (Plane, Plane) {
+    let o = Point3::new(0.0, 0.0, 0.0);
+    (Plane::new(o, Point3::new(1.0, 0.0, 0.0), Point3::new(0.0, 1.0, 0.0)), Plane::new(o, Point3::new(1.0, 0.0, 0.0), Point3::new(0.0, 0.0, 1.0)))
+}
+
+#[test]
+fn degenerate_intersection_polylines_return_none_without_panicking() {
+    let origin = Point3::new(0.0, 0.0, 0.0);
+    for points in [
+        vec![],
+        vec![origin],
+        vec![origin, origin],
+        vec![origin; 3],
+        vec![origin, Point3::new(f64::NAN, 0.0, 0.0)],
+        vec![origin, Point3::new(f64::INFINITY, 0.0, 0.0)],
+    ] {
+        let (a, b) = planes();
+        let result = std::panic::catch_unwind(|| IntersectionCurveWithParameters::try_new(a, b, PolylineCurve(points.clone()), 0.01));
+        assert!(result.is_ok(), "constructor panicked for {points:?}");
+        assert!(result.unwrap().is_none(), "collapsed input must not create a curve: {points:?}");
+    }
+}
+
+#[test]
+fn closed_intersection_retains_the_closure_and_spherical_supports() {
+    let a = Sphere::new(Point3::new(0.0, 0.0, 1.0), 2.0_f64.sqrt());
+    let b = Sphere::new(Point3::new(0.0, 0.0, -1.0), 2.0_f64.sqrt());
+    let poly = PolylineCurve(vec![
+        Point3::new(1.0, 0.0, 0.0),
+        Point3::new(0.0, 1.0, 0.0),
+        Point3::new(-1.0, 0.0, 0.0),
+        Point3::new(0.0, -1.0, 0.0),
+        Point3::new(1.0, 0.0, 0.0),
+    ]);
+    let curve = IntersectionCurveWithParameters::try_new(a, b, poly, 0.01).unwrap();
+    let (lo, hi) = curve.range_tuple();
+    assert_eq!(curve.subs(lo), curve.subs(hi));
+    for i in 0..=40 {
+        let p = curve.subs(lo + (hi - lo) * i as f64 / 40.0);
+        assert!(p.z.abs() < 1e-8, "{p:?}");
+        assert!(((p.x * p.x + p.y * p.y).sqrt() - 1.0).abs() <= 0.01, "{p:?}");
+    }
+}
+
+#[test]
+fn open_intersection_keeps_endpoints_on_both_planes() {
+    let (a, b) = planes();
+    let start = Point3::new(1.0, 0.0, 0.0);
+    let end = Point3::new(3.0, 0.0, 0.0);
+    let curve = IntersectionCurveWithParameters::try_new(a, b, PolylineCurve(vec![start, end]), 0.01).unwrap();
+    let (lo, hi) = curve.range_tuple();
+    assert_eq!(curve.subs(lo), start);
+    assert_eq!(curve.subs(hi), end);
+    assert_eq!(curve.subs((lo + hi) / 2.0), Point3::new(2.0, 0.0, 0.0));
+}

crates/kernel/src/lib.rs

@@ -30,6 +30,8 @@ mod heal;
 mod helix;
 mod iges_in;
 mod iges_out;
+#[cfg(test)]
+mod intersection_curve_tests;
 mod lip;
 mod loopblend;
 mod measure;

crates/kernel/src/meshbody.rs

@@ -109,6 +109,7 @@ pub fn mesh_body(positions: &[Vec3], triangles: &[[u32; 3]]) -> Result<Body> {
         paint: None,
         splits: None,
         face_sources: None,
+        regularization_protected: false,
     })
 }
 
@@ -201,6 +202,7 @@ impl Body {
             paint: self.paint.clone(),
             splits: self.splits.clone(),
             face_sources: None,
+            regularization_protected: self.regularization_protected,
         })
     }
 }

crates/kernel/src/ops.rs

@@ -221,6 +221,7 @@ pub fn boolean(a: &Body, b: &Body, op: BoolOp) -> Result<Option<Body>> {
             )),
         };
     }
+    r = r.map(|result| result.map(|body| body.inherit_regularization_protection(a).inherit_regularization_protection(b)));
     if matches!(op, BoolOp::Cut | BoolOp::Union) {
         r = r.and_then(|result| result.map(|body| body.with_preserved_boolean_planar_sources(a, b, op == BoolOp::Cut)).transpose());
     }
@@ -538,7 +539,11 @@ pub(crate) fn join_pieces(pieces: Vec<Body>) -> Result<Option<Body>> {
         _ => {
             let shells: Vec<mt::Shell> = pieces.iter().flat_map(|p| p.solid.boundaries().clone()).collect();
             let solid = guard("pieces", || Solid::try_new(shells).map_err(|e| KernelError::Failed(e.to_string())))?;
-            Body::new(solid).map(Some)
+            let protected = pieces.iter().any(|piece| piece.regularization_protected);
+            Body::new(solid).map(|mut body| {
+                body.regularization_protected = protected;
+                Some(body)
+            })
         }
     }
 }
@@ -558,8 +563,9 @@ pub fn transform_matrix(body: &Body, m: [[f64; 4]; 4]) -> Result<Body> {
         );
         // An affine placement retains face order and appearance metadata.
         let sources = body.transformed_sources(m)?;
-        Body::new(placed_topology(&body.solid, mat)?)
-            .map(|placed| placed.with_color(body.color()).with_paint(body.paint().cloned()).with_face_sources(sources))
+        Body::new(placed_topology(&body.solid, mat)?).map(|placed| {
+            placed.with_color(body.color()).with_paint(body.paint().cloned()).with_face_sources(sources).inherit_regularization_protection(body)
+        })
     })
 }
 

crates/kernel/src/planar_regularize.rs

@@ -117,6 +117,36 @@ fn merged_face(faces: &[&mt::Face], members: &[usize], plane: Plane, eligible: &
 
 impl Body {
     pub(crate) fn regularize_certified_planar_faces(self) -> Result<Self> {
+        self.regularize_planar_faces(false)
+    }
+
+    /// Only newly produced Cut walls call this path. The temporary planes carry
+    /// construction support, never persistent ancestor/source-role authority.
+    pub(crate) fn regularize_generated_planar_faces(self) -> Result<Self> {
+        let body = self.regularize_planar_faces(true)?;
+        let sources = body.face_sources().map(|sources| {
+            sources
+                .iter()
+                .map(|source| {
+                    let mut source = source.clone();
+                    if let Some(super::FaceSource::ExtrudeSide { plane, coalesced, .. }) = &mut source {
+                        if plane.is_some() && !*coalesced {
+                            source = None;
+                        } else {
+                            *plane = None;
+                        }
+                    }
+                    source
+                })
+                .collect()
+        });
+        Ok(body.with_face_sources(sources.map(Arc::new)))
+    }
+
+    fn regularize_planar_faces(self, generated: bool) -> Result<Self> {
+        if self.regularization_protected {
+            return Ok(self);
+        }
         let Some(sources) = self.face_sources() else { return Ok(self) };
         if sources.len() > 16_384 || self.paint().is_some_and(|p| !p.faces.is_empty()) {
             return Ok(self);
@@ -148,7 +178,16 @@ impl Body {
                 .zip(sources)
                 .map(|(f, s)| {
                     s.as_ref()
-                        .and_then(super::planar_sources::certified_plane)
+                        .and_then(|source| {
+                            if generated {
+                                match source {
+                                    super::FaceSource::ExtrudeSide { segment: solvecraft_geom::Seg2::Line { .. }, plane: Some(p), .. } => Some(*p),
+                                    _ => None,
+                                }
+                            } else {
+                                super::planar_sources::certified_plane(source)
+                            }
+                        })
                         .filter(|p| super::planar_sources::actual_plane(f).is_some_and(|actual| super::planar_sources::same_support(p, &actual)))
                 })
                 .collect();
@@ -179,7 +218,7 @@ impl Body {
                 };
                 let Some(left) = identity.checked_sub(cost) else { return Ok(None) };
                 identity = left;
-                if sa != sb {
+                if !generated && sa != sb {
                     continue;
                 }
                 let Some(cost) = split_points.checked_mul(6).and_then(|n| n.checked_add(1)) else { return Ok(None) };
@@ -235,7 +274,14 @@ impl Body {
                         let Some(left) = metadata.checked_sub(cost) else { return Ok(None) };
                         metadata = left;
                     }
-                    output_sources.push(source.cloned());
+                    let mut source = source.cloned();
+                    if generated
+                        && replacements.contains_key(&leader)
+                        && let Some(super::FaceSource::ExtrudeSide { coalesced, .. }) = &mut source
+                    {
+                        *coalesced = true;
+                    }
+                    output_sources.push(source);
                     offset += 1;
                 }
                 shells.push(mt::Shell::from(output));

crates/kernel/src/planar_sources.rs

@@ -114,13 +114,15 @@ impl Body {
     /// Retain exact shell roles, and construction roles for Cut, only on unchanged
     /// supports without a competing coplanar tool. No imported or fitted role is inferred.
     pub(crate) fn with_preserved_boolean_planar_sources(self, input: &Body, tool: &Body, constructed: bool) -> Result<Self> {
+        let self_ = self.inherit_regularization_protection(input).inherit_regularization_protection(tool);
         if !input.face_sources().is_some_and(|sources| sources.iter().flatten().any(|s| boolean_source(s, constructed))) {
-            return Ok(self);
+            return Ok(self_);
         }
-        self.map_planar_sources(input, None, Some(tool), &[], constructed)
+        self_.map_planar_sources(input, None, Some(tool), &[], constructed)
     }
 
     fn map_planar_sources(mut self, input: &Body, shell: Option<f64>, blocker: Option<&Body>, open: &[Vec3], constructed: bool) -> Result<Self> {
+        self.regularization_protected |= input.regularization_protected;
         let Some(sources) = input.face_sources() else { return Ok(self) };
         if input.solid.face_iter().count() > 16_384
             || self.solid.face_iter().count() > 16_384

crates/kernel/src/polyhedron.rs

@@ -342,7 +342,15 @@ pub fn round_all_edges(b: &Body, r: f64) -> Result<Body> {
 /// by the thickness (open faces outward, past the body) keeping the body's topology, which
 /// gives the cavity; the shell is the body minus the cavity.
 fn shell_planar(b: &Body, open: &[Vec3], thickness: f64) -> Result<Body> {
-    let healed = Body::new(crate::heal::heal_keep(b.deep_copy(), b.size(), b.split_keep()))?;
+    // Face paint and authored splits are construction boundaries. Retain their
+    // eligibility veto through the temporary body used for the cavity Cut.
+    // Paint indices stay in source order by avoiding healing in that case.
+    let solid = if b.paint().is_some_and(|paint| !paint.faces.is_empty()) {
+        b.deep_copy()
+    } else {
+        crate::heal::heal_keep(b.deep_copy(), b.size(), b.split_keep())
+    };
+    let healed = Body::new(solid)?.with_paint(b.paint().cloned()).with_split_lines(b.split_lines().cloned()).inherit_regularization_protection(b);
     let size = healed.size();
     let mesh = healed.tessellate((size * 1e-3).max(1e-3))?;
     // Faces to open: the face of the triangle nearest each point.

crates/kernel/src/prism.rs

@@ -848,6 +848,16 @@ fn sew_connected_sections(plane: &Plane, d: Vec3, levels: &[f64], slabs: &[Vec<R
     }
     let mut faces: Vec<FaceSpec> = Vec::new();
     let mut sources = Vec::new();
+    let frame_is_orthonormal = plane.origin.is_finite()
+        && plane.x.is_finite()
+        && plane.y.is_finite()
+        && d.is_finite()
+        && (plane.x.len2() - 1.).abs() <= 64. * f64::EPSILON
+        && (plane.y.len2() - 1.).abs() <= 64. * f64::EPSILON
+        && (d.len2() - 1.).abs() <= 64. * f64::EPSILON
+        && plane.x.dot(plane.y).abs() <= 64. * f64::EPSILON
+        && plane.x.dot(d).abs() <= 64. * f64::EPSILON
+        && plane.y.dot(d).abs() <= 64. * f64::EPSILON;
     for (first, end, sg) in runs {
         let (z0, z1) = (levels[first], levels[end]);
         let (a, b) = (sg.start(), sg.end());
@@ -868,7 +878,28 @@ fn sew_connected_sections(plane: &Plane, d: Vec3, levels: &[f64], slabs: &[Vec<R
             _ => SurfSpec::Plane,
         };
         faces.push(FaceSpec { loops: vec![lp3], surface, probe: Some((at(sg.point_at(0.5), (z0 + z1) / 2.0), outward)) });
-        sources.push((end > first + 1).then_some(crate::FaceSource::ExtrudeSide { segment: sg, plane: None, coalesced: true }));
+        // Axis-aligned generated lines have a common oriented support frame
+        // independent of axial stations or along-line endpoint interpolation.
+        let generated_plane = if coalesce
+            && frame_is_orthonormal
+            && let Seg2::Line { a, b } = sg
+        {
+            let (origin, x) = if a.y == b.y && a.x != b.x {
+                (at(Vec2::new(0., a.y), 0.), plane.x * (b.x - a.x).signum())
+            } else if a.x == b.x && a.y != b.y {
+                (at(Vec2::new(a.x, 0.), 0.), plane.y * (b.y - a.y).signum())
+            } else {
+                (Vec3::ZERO, Vec3::ZERO)
+            };
+            (origin.is_finite() && x.len2() > 0.).then_some(Plane { origin, x, y: d })
+        } else {
+            None
+        };
+        sources.push((generated_plane.is_some() || end > first + 1).then_some(crate::FaceSource::ExtrudeSide {
+            segment: sg,
+            plane: generated_plane,
+            coalesced: end > first + 1,
+        }));
     }
     for (z, up, rs) in &caps {
         for r in rs {
@@ -885,7 +916,11 @@ fn sew_connected_sections(plane: &Plane, d: Vec3, levels: &[f64], slabs: &[Vec<R
             sources.push(None);
         }
     }
-    Some(crate::sew::sew_touching_with_sources(&faces, &sources))
+    Some(crate::sew::sew_touching_with_sources(&faces, &sources).and_then(
+        |body| {
+            if coalesce { body.regularize_generated_planar_faces() } else { Ok(body) }
+        },
+    ))
 }
 
 fn simple_prism_boolean(a: &Body, b: &Body, op: BoolOp) -> Option<Result<Option<Body>>> {
@@ -1109,6 +1144,8 @@ fn stack_boolean(a: &Body, b: &Body, op: BoolOp) -> Option<Result<Option<Body>>>
         &slabs,
         tol,
         op == BoolOp::Cut
+            && !a.regularization_protected
+            && !b.regularization_protected
             && a.split_keep().is_empty()
             && b.split_keep().is_empty()
             && a.paint().is_none_or(|p| p.faces.is_empty())
@@ -1216,6 +1253,62 @@ mod planar_tests {
         assert_eq!(crate::step_export(&[&tool], "tool").unwrap(), before_tool);
         assert_eq!(crate::step_export(&[&roof], "roof").unwrap(), before_roof);
     }
+    fn stepped_tab_stock() -> Body {
+        let stock = crate::box_solid(Vec3::new(-20., -15., 0.), Vec3::new(20., 15., 24.)).unwrap();
+        let tab = crate::box_solid(Vec3::new(-12., -25., 8.), Vec3::new(-4., -15., 16.)).unwrap();
+        crate::boolean(&stock, &tab, BoolOp::Union).unwrap().unwrap()
+    }
+
+    fn coplanar_joins(body: &Body) -> usize {
+        let faces: Vec<_> = body.solid.face_iter().collect();
+        let mut adjacency = std::collections::HashMap::<_, Vec<usize>>::new();
+        for (i, face) in faces.iter().enumerate() {
+            for edge in face.edge_iter() {
+                adjacency.entry(edge.id()).or_default().push(i);
+            }
+        }
+        adjacency
+            .values()
+            .filter(|faces| {
+                let [a, b] = faces.as_slice() else { return false };
+                let (Some(pa), Some(pb)) = (body.planar_face(*a), body.planar_face(*b)) else { return false };
+                let (na, nb) = (pa.normal(), pb.normal());
+                na.dot(nb) > 1. - 1e-12 && (pb.origin - pa.origin).dot(na).abs() < 1e-10
+            })
+            .count()
+    }
+
+    #[test]
+    fn shell_of_joined_stepped_tabs_has_no_artificial_planar_stations() {
+        let stock = stepped_tab_stock();
+        let snapshot = crate::step_export(&[&stock], "unchanged stock").unwrap();
+        assert_eq!(coplanar_joins(&stock), 0);
+        let shell = crate::shell(&stock, &[Vec3::new(0., 0., 24.)], 1.).unwrap();
+        assert_eq!(coplanar_joins(&shell), 0, "Shell must not add internal edges across continuous planar walls");
+        assert!(shell.validity().is_empty());
+        let mesh = shell.tessellate(1e-5).unwrap();
+        let expected = 40. * 30. * 24. + 8. * 10. * 8. - (38. * 28. * 23. + 6. * 10. * 6.);
+        assert!((mesh.measure().volume - expected).abs() < 1e-6);
+        for (point, material) in [
+            (Vec3::new(0., 0., 0.5), true),
+            (Vec3::new(0., 0., 10.), false),
+            (Vec3::new(0., -14.5, 10.), true),
+            (Vec3::new(19.5, 0., 10.), true),
+            (Vec3::new(-8., -24.5, 12.), true),
+            (Vec3::new(-8., -20., 12.), false),
+            (Vec3::new(0., -18., 9.), false),
+        ] {
+            assert_eq!(mesh.contains(point), material, "wrong material at {point:?}");
+        }
+        let step = crate::step_export(&[&shell], "stepped tab shell").unwrap();
+        let reopened = crate::step_import(&step).unwrap();
+        let body = &reopened.bodies[0].body;
+        assert_eq!(body.face_count(), shell.face_count());
+        assert_eq!(coplanar_joins(body), 0);
+        assert!((body.tessellate(1e-5).unwrap().measure().volume - expected).abs() < 1e-6);
+        assert_eq!(crate::step_export(&[&stock], "unchanged stock").unwrap(), snapshot);
+    }
+
     #[test]
     fn contiguous_analytic_walls_remove_faces_but_retain_vertical_stations() {
         for curved in [false, true] {

crates/kernel/src/refine_cache_tests.rs

@@ -0,0 +1,53 @@
+use super::*;
+
+fn bits(v: Vec3) -> [u64; 3] {
+    [v.x.to_bits(), v.y.to_bits(), v.z.to_bits()]
+}
+
+fn check_body(body: &Body) -> usize {
+    let meshes = mesh_shells(&body.solid, 0.5);
+    let mut changed = 0;
+    for (face, meshed) in body.solid.face_iter().zip(meshes.iter().flat_map(|shell| shell.face_iter())) {
+        let Some(mesh) = meshed.surface() else { continue };
+        let surface = face.surface();
+        let cached = refined_with_cache(&mesh, &surface, 0.002, true);
+        let original = refined_with_cache(&mesh, &surface, 0.002, false);
+        match (cached, original) {
+            (None, None) => {}
+            (Some(cached), Some(original)) => {
+                changed += 1;
+                assert_eq!(cached.len(), original.len(), "triangle count/winding must not change");
+                for (cached, original) in cached.into_iter().zip(original) {
+                    for ((point, normal), (old_point, old_normal)) in cached.into_iter().zip(original) {
+                        assert_eq!(bits(point), bits(old_point), "every refined coordinate must remain bit-identical");
+                        assert_eq!(bits(normal), bits(old_normal), "every refined normal must remain bit-identical");
+                    }
+                }
+            }
+            _ => panic!("memoization changed the refine/no-refine decision"),
+        }
+    }
+    changed
+}
+
+#[test]
+fn exact_refinement_cache_preserves_periodic_seams_and_normals() {
+    let cylinder = crate::cylinder(Vec3::ZERO, Vec3::Z, 15., 8.).unwrap();
+    let torus = crate::torus(Vec3::ZERO, 18., 4.).unwrap();
+    assert!(check_body(&cylinder) > 0, "the fixture must actually refine");
+    assert!(check_body(&torus) > 0, "the periodic fixture must actually refine");
+}
+
+#[test]
+fn exact_refinement_cache_preserves_singular_poles_and_placed_surfaces() {
+    let sphere = crate::sphere(Vec3::ZERO, 12.).unwrap();
+    assert!(check_body(&sphere) > 0, "the polar fixture must actually refine");
+    let placed = crate::transform(&sphere, Vec3::new(120., -85., 40.), Vec3::ZERO, Vec3::new(1., 2., 3.), 0.371).unwrap();
+    assert!(check_body(&placed) > 0);
+}
+
+#[test]
+fn exact_refinement_cache_keeps_unnecessary_planar_refinement_absent() {
+    let body = crate::box_solid(Vec3::ZERO, Vec3::new(10., 20., 30.)).unwrap();
+    assert_eq!(check_body(&body), 0);
+}

crates/kernel/src/regularization_protection_tests.rs

@@ -0,0 +1,65 @@
+use super::*;
+use solvecraft_geom::Plane;
+
+fn stamped_stock() -> Body {
+    crate::box_solid(Vec3::new(-20., -15., 0.), Vec3::new(20., 15., 24.)).unwrap().with_box_certificate(7).unwrap()
+}
+
+fn cup(stock: &Body) -> Body {
+    crate::shell(stock, &[Vec3::new(0., 0., 24.)], 1.).unwrap().with_shell_certificate(9).unwrap()
+}
+
+#[test]
+fn stamped_shell_keeps_authored_painted_and_split_boundaries() {
+    let stock = stamped_stock();
+    let ordinary = cup(&stock);
+    assert!(!ordinary.regularization_protected);
+    let painted = stock.clone().with_paint(Some(Paint { opacity: 1., faces: vec![FacePaint { face: 0, color: [1., 0., 0.], opacity: 1. }] }));
+    let side = stock
+        .solid
+        .face_iter()
+        .enumerate()
+        .find(|(i, _)| stock.planar_face(*i).is_some_and(|p| p.normal().dot(Vec3::X) > 0.999 && p.origin.x == 20.))
+        .unwrap()
+        .0;
+    let split = crate::split_faces(&stock, &[side], &crate::SplitTool::Plane(Plane { origin: Vec3::new(0., 0., 8.), ..Plane::XY })).unwrap();
+    assert!(split.split_lines().is_some());
+    for protected in [painted, split] {
+        let result = cup(&protected);
+        assert!(result.regularization_protected);
+        assert!(result.face_count() > ordinary.face_count(), "authored boundaries must survive both Shell regularizers");
+        assert!(result.validity().is_empty());
+        let expected = 40. * 30. * 24. - 38. * 28. * 23.;
+        let mesh = result.tessellate(1e-5).unwrap();
+        assert!((mesh.measure().volume - expected).abs() < 1e-6);
+        assert!(mesh.contains(Vec3::new(19.5, 0., 12.)));
+        assert!(!mesh.contains(Vec3::new(0., 0., 12.)));
+        let count = result.face_count();
+        assert_eq!(result.clone().regularize_certified_planar_faces().unwrap().face_count(), count);
+        assert_eq!(result.clone().regularize_generated_planar_faces().unwrap().face_count(), count);
+        let placed = crate::transform(&result, Vec3::new(30., -40., 7.), Vec3::ZERO, Vec3::Z, 0.3).unwrap();
+        assert!(placed.regularization_protected);
+        for lump in placed.lumps().unwrap() {
+            assert!(lump.regularization_protected);
+        }
+        let cleared = result.clone().with_paint(None).with_split_lines(None);
+        assert!(cleared.regularization_protected, "cleared appearance must not erase inherited boundary protection");
+        assert_eq!(cleared.regularize_certified_planar_faces().unwrap().face_count(), count);
+    }
+}
+
+#[test]
+fn protection_is_identity_and_survives_tool_operand_and_compounds() {
+    let a = stamped_stock();
+    let protected = a.clone().with_paint(Some(Paint { opacity: 1., faces: vec![FacePaint { face: 0, color: [0., 1., 0.], opacity: 1. }] }));
+    let cleared = protected.with_paint(None);
+    assert!(!a.same(&cleared));
+    let tool = crate::box_solid(Vec3::new(-5., -5., 23.), Vec3::new(5., 5., 30.)).unwrap().inherit_regularization_protection(&cleared);
+    let cut = crate::boolean(&a, &tool, crate::BoolOp::Cut).unwrap().unwrap();
+    assert!(cut.regularization_protected);
+    let remote = crate::box_solid(Vec3::new(100., 0., 0.), Vec3::new(110., 10., 10.)).unwrap();
+    let joined = crate::ops::join_pieces(vec![cleared, remote]).unwrap().unwrap();
+    assert!(joined.regularization_protected);
+    assert_eq!(joined.lumps().unwrap().len(), 2);
+    assert!(joined.lumps().unwrap().iter().all(|body| body.regularization_protected));
+}

crates/kernel/src/splitface.rs

@@ -886,6 +886,7 @@ pub(crate) fn split_any(body: &Body, faces: &[usize], tool: &SplitTool) -> Resul
                 paint: None,
                 splits: body.splits.clone(),
                 face_sources: None,
+                regularization_protected: true,
             },
             imp,
         ))

crates/kernel/src/surfaces.rs

@@ -30,6 +30,7 @@ fn surface_body(faces: Vec<mt::Face>) -> Body {
         paint: None,
         splits: None,
         face_sources: None,
+        regularization_protected: false,
     }
 }
 
@@ -47,6 +48,7 @@ fn body_of(faces: Vec<mt::Face>) -> Result<Body> {
             paint: None,
             splits: None,
             face_sources: None,
+            regularization_protected: false,
         })
     }
 }

crates/ui-egui/src/file_load.rs

@@ -102,6 +102,8 @@ fn start(app: &mut SolveApp) {
 
 #[cfg(not(target_arch = "wasm32"))]
 fn compute(mut session: Session, path: &str, insert: bool, phase: &AtomicU8, cancelled: &AtomicBool) -> Job {
+    let profile = std::env::var_os("SOLVECRAFT_PROFILE_OPEN").is_some();
+    let began = std::time::Instant::now();
     if cancelled.load(Ordering::Relaxed) {
         return Err("file operation cancelled".into());
     }
@@ -113,16 +115,31 @@ fn compute(mut session: Session, path: &str, insert: bool, phase: &AtomicU8, can
         "file.insert_step"
     };
     let result = session.execute(command, &json!({"path": path})).map_err(|e| e.to_string())?;
+    let geometry_ms = began.elapsed().as_secs_f64() * 1000.0;
+    let view_began = std::time::Instant::now();
     phase.store(1, Ordering::Relaxed);
+    let world = session.world_state();
+    let placement_ms = view_began.elapsed().as_secs_f64() * 1000.0;
+    let mesh_began = std::time::Instant::now();
     // Fit, picking and the first viewport frame must not trigger cold tessellation on the UI.
-    for b in &session.world_state().bodies {
+    for b in &world.bodies {
         if cancelled.load(Ordering::Relaxed) {
             return Err("file operation cancelled".into());
         }
         let _ = b.mesh();
     }
+    let tessellation_ms = mesh_began.elapsed().as_secs_f64() * 1000.0;
     phase.store(2, Ordering::Relaxed);
+    let view_ms = view_began.elapsed().as_secs_f64() * 1000.0;
+    let thumbnail_began = std::time::Instant::now();
     let image = if insert { None } else { crate::home::remember(&session) };
+    if profile {
+        eprintln!(
+            "SolidCraft open phases: geometry_ms={geometry_ms:.3} placement_ms={placement_ms:.3} tessellation_ms={tessellation_ms:.3} display_warmup_ms={view_ms:.3} thumbnail_ms={:.3} total_ms={:.3}",
+            thumbnail_began.elapsed().as_secs_f64() * 1000.0,
+            began.elapsed().as_secs_f64() * 1000.0
+        );
+    }
     Ok(Made { session, result, image })
 }
 

crates/ui-egui/src/i18n.rs

@@ -33,7 +33,8 @@ impl Catalog {
 
 static ENGLISH: Catalog = Catalog::new("en", "English", include_str!("locales/en.json"));
 static JAPANESE: Catalog = Catalog::new("ja", "日本語", include_str!("locales/ja.json"));
-pub const LOCALES: &[&Catalog] = &[&ENGLISH, &JAPANESE];
+static GERMAN: Catalog = Catalog::new("de", "Deutsch", include_str!("locales/de.json"));
+pub const LOCALES: &[&Catalog] = &[&ENGLISH, &JAPANESE, &GERMAN];
 
 pub fn is_supported(id: &str) -> bool {
     LOCALES.iter().any(|catalog| catalog.id == id)

crates/ui-egui/src/lib.rs

@@ -519,22 +519,6 @@ impl SolveApp {
             let edges = self.session.selection.iter().any(|s| matches!(s, solvecraft_engine::Sel::Edge { .. }));
             return self.start(if edges { "solid.fillet" } else { "solid.extrude" });
         }
-        // Fix/Unfix: the selected sketch points and curves change at once, otherwise pick them.
-        if id == "sketch.constraint.fix" {
-            let ents: Vec<String> = self
-                .session
-                .selection
-                .iter()
-                .filter_map(|s| match s {
-                    solvecraft_engine::Sel::SketchCurve { id } | solvecraft_engine::Sel::SketchPoint { id } => Some(id.clone()),
-                    _ => None,
-                })
-                .collect();
-            if !ents.is_empty() {
-                let _ = self.run(id, json!({ "entities": ents }));
-                return;
-            }
-        }
         // Construction toggle: selected sketch curves switch at once, otherwise pick them.
         // Construction (X): convert the selection, or switch construction mode; no pick tool.
         if id == "sketch.construction" {

crates/ui-egui/src/locales/de.json

@@ -0,0 +1,296 @@
+{
+  "browser.body_name": "Körper {number}",
+  "browser.component_name": "Komponente {number}",
+  "browser.parameters": "Parameter ({count})",
+  "browser.precision": "Genauigkeit: {precision}",
+  "browser.sketch_name": "Skizze {number}",
+  "browser.units": "Einheiten: {units}",
+  "dialog.custom_axis": "↖ Eigene Achse",
+  "dialog.edit_title": "{title} bearbeiten",
+  "dialog.select": "↖ Auswählen",
+  "dialog.selected_count": "↖ {count} ausgewählt",
+  "document.save_changes": "Änderungen in {name} speichern?",
+  "document.unsaved_changes": "{name} enthält ungespeicherte Änderungen. Wenn Sie nicht speichern, gehen sie verloren.",
+  "sketch.degrees_of_freedom": "{count} Freiheitsgrade",
+  "sketch.draw_curves": "{linetype}-Kurven zeichnen",
+  "sketch.make_selection": "Auswahl als {linetype} markieren",
+  "ui.1_degree_of_freedom": "1 Freiheitsgrad",
+  "ui.3d_sketch": "3D-Skizze",
+  "ui.about": "Über",
+  "ui.activate": "Aktivieren",
+  "ui.active_component": "Aktive Komponente",
+  "ui.agent_cursor": "Agent-Cursor",
+  "ui.agent_cursor_speed": "Agent-Cursor-Geschwindigkeit",
+  "ui.all": "Alle",
+  "ui.angle": "Winkel",
+  "ui.angle_decimals": "Winkel-Dezimalstellen",
+  "ui.animate_view_changes": "Ansichtsänderungen animieren",
+  "ui.animation": "Animation",
+  "ui.animation_speed": "Animationsgeschwindigkeit",
+  "ui.apply": "Anwenden",
+  "ui.arc": "Kreisbogen",
+  "ui.assemble": "Zusammenbau",
+  "ui.autosave_every": "Autospeichern alle",
+  "ui.axes": "Achsen",
+  "ui.axis": "Achse",
+  "ui.bodies": "Körper",
+  "ui.box": "Block",
+  "ui.break": "Unterbrechen",
+  "ui.cancel": "Abbrechen",
+  "ui.canvases": "Kanvas",
+  "ui.centerline": "Mittellinie",
+  "ui.chamfer": "Abschrägung",
+  "ui.change_workspace": "Arbeitsbereich wechseln",
+  "ui.chord_length": "Sehnenlänge",
+  "ui.circle": "Kreis",
+  "ui.circular_pattern": "Radiales Muster",
+  "ui.clear_recent": "Zuletzt verwendet leeren",
+  "ui.clear_the_selection": "Auswahl aufheben",
+  "ui.close": "Schließen",
+  "ui.coil": "Schraube",
+  "ui.coincident": "Koinzident",
+  "ui.collapse": "Einklappen",
+  "ui.collinear": "Kollinear",
+  "ui.combine": "Kombinieren",
+  "ui.coming_later": "bald verfügbar",
+  "ui.concentric": "Konzentrisch",
+  "ui.conic_curve": "Kegelschnitt",
+  "ui.constant": "Konstant",
+  "ui.constraints_conflict": "Bedingungen konfliktreich",
+  "ui.construct": "Konstruktion",
+  "ui.construction": "Konstruktionslinie",
+  "ui.copy": "Kopieren",
+  "ui.counterbore": "Tiefenbohrung",
+  "ui.countersink": "Senkung",
+  "ui.create": "Erstellen",
+  "ui.create_sketch": "Skizze erstellen",
+  "ui.current": "aktuell",
+  "ui.curvature": "Krümmung",
+  "ui.cut": "Ausschneiden",
+  "ui.cylinder": "Zylinder",
+  "ui.dark": "Dunkel",
+  "ui.default_modelling_orientation": "Standard-Modellierungsorientierung",
+  "ui.degrees_of_freedom": "Freiheitsgrade",
+  "ui.delete": "Löschen",
+  "ui.depth": "Tiefe",
+  "ui.design": "Design",
+  "ui.diameter": "Durchmesser",
+  "ui.dimension": "Maß",
+  "ui.direction": "Richtung",
+  "ui.distance": "Abstand",
+  "ui.distance_1": "Abstand 1",
+  "ui.distance_2": "Abstand 2",
+  "ui.document_settings": "Dokumenteneinstellungen",
+  "ui.don_t_save": "Nicht speichern",
+  "ui.draft": "Abziehen",
+  "ui.drawing": "Zeichnung",
+  "ui.drill_point": "Bohrpunkt",
+  "ui.edit": "Bearbeiten",
+  "ui.ellipse": "Ellipse",
+  "ui.end_radius": "Endradius",
+  "ui.equal": "Gleich",
+  "ui.expand": "Aufklappen",
+  "ui.export_ellipsis": "Exportieren...",
+  "ui.extend": "Verlängern",
+  "ui.extent_type": "Ausdehnungstyp",
+  "ui.extrude": "Extrudieren",
+  "ui.features": "Funktionen",
+  "ui.file": "Datei",
+  "ui.fillet": "Vollrundung",
+  "ui.finish_sketch": "Skizze beenden",
+  "ui.fix_unfix": "Fixieren/Lösen",
+  "ui.flat": "Flach",
+  "ui.flip": "Umkehren",
+  "ui.front": "Vorne",
+  "ui.fully_constrained": "Vollständig bestimmt",
+  "ui.general": "Allgemein",
+  "ui.generative_design": "Generatives Design",
+  "ui.graphics": "Grafik",
+  "ui.heading_assemble": "ZUSAMMENBAU",
+  "ui.heading_box": "BLOCK",
+  "ui.heading_chamfer": "ABSCHRÄGUNG",
+  "ui.heading_circular_pattern": "RADIALES MUSTER",
+  "ui.heading_coil": "SCHRAUBE",
+  "ui.heading_combine": "KOMBINIEREN",
+  "ui.heading_construct": "KONSTRUKTION",
+  "ui.heading_create": "ERSTELLEN",
+  "ui.heading_create_sketch": "SKIZZE ERSTELLEN",
+  "ui.heading_cylinder": "ZYLINDER",
+  "ui.heading_design": "DESIGN",
+  "ui.heading_draft": "ABZIEHEN",
+  "ui.heading_edit": "BEARBEITEN",
+  "ui.heading_extrude": "EXTRUDIEREN",
+  "ui.heading_fillet": "VOLLRUNDUNG",
+  "ui.heading_finish_sketch": "SKIZZE BEENDEN",
+  "ui.heading_front": "VORNE",
+  "ui.heading_hole": "BOHRUNG",
+  "ui.heading_home": "START",
+  "ui.heading_insert": "EINFÜGEN",
+  "ui.heading_inspect": "PRÜFEN",
+  "ui.heading_loft": "LOFT",
+  "ui.heading_measure": "Messen",
+  "ui.heading_mesh": "MESH",
+  "ui.heading_mirror": "SPIEGELN",
+  "ui.heading_modify": "ÄNDERN",
+  "ui.heading_move": "VERSCHIEBEN",
+  "ui.heading_offset_plane": "ABSTANDSEBENE",
+  "ui.heading_ok": "OK",
+  "ui.heading_parameters": "PARAMETER",
+  "ui.heading_pattern_on_path": "PFADMUSTER",
+  "ui.heading_pipe": "ROHR",
+  "ui.heading_plane_at_angle": "EBENE IM WINKEL",
+  "ui.heading_plastic": "PLASTIK",
+  "ui.heading_rectangular_pattern": "RECHTECKMUSTER",
+  "ui.heading_revolve": "DREHEN",
+  "ui.heading_right": "RECHTS",
+  "ui.heading_scale": "SKALIEREN",
+  "ui.heading_section_analysis": "QUERSCHNITTSANALYSE",
+  "ui.heading_select": "AUSWÄHLEN",
+  "ui.heading_sheet_metal": "BLECH",
+  "ui.heading_shell": "HÜLLE",
+  "ui.heading_sketch": "SKIZZE",
+  "ui.heading_sketch_palette": "SKIZZENPALETTE",
+  "ui.heading_solid": "KÖRPER",
+  "ui.heading_sphere": "SPHÄRE",
+  "ui.heading_split_body": "KÖRPER TRENNEN",
+  "ui.heading_surface": "FLÄCHE",
+  "ui.heading_sweep": "FÜHREN",
+  "ui.heading_thread": "GEWINDE",
+  "ui.heading_top": "OBEN",
+  "ui.heading_torus": "TORUS",
+  "ui.help": "Hilfe",
+  "ui.hide": "Ausblenden",
+  "ui.hole": "Bohrung",
+  "ui.hole_tap_type": "Gewindetyp",
+  "ui.hole_type": "Bohrungstyp",
+  "ui.home": "Start",
+  "ui.horizontal_vertical": "Horizontal/Vertikal",
+  "ui.insert": "Einfügen",
+  "ui.inspect": "Prüfen",
+  "ui.intersect": "Schnitt",
+  "ui.join": "Verbinden",
+  "ui.joints": "Gelenke",
+  "ui.keyboard_shortcuts": "Tastenkürzel",
+  "ui.language": "Sprache",
+  "ui.length_decimals": "Längen-Dezimalstellen",
+  "ui.light": "Hell",
+  "ui.line": "Linie",
+  "ui.linetype": "Linientyp",
+  "ui.loft": "Loft",
+  "ui.look_at": "Ansehen",
+  "ui.manufacture": "Fertigung",
+  "ui.measure": "Messen",
+  "ui.midpoint": "Mittelpunkt",
+  "ui.mirror": "Spiegeln",
+  "ui.modify": "Ändern",
+  "ui.move": "Verschieben",
+  "ui.multiple": "Mehrfach",
+  "ui.named_views": "Benannte Ansichten",
+  "ui.navigation": "Navigation",
+  "ui.new_body": "Neuer Körper",
+  "ui.new_design": "Neues Design",
+  "ui.normal": "Normal",
+  "ui.object_type": "Objekttyp",
+  "ui.objects": "Objekte",
+  "ui.offer_to_stand_up_y_up_files": "Y-hoch-Dateien aufrecht anbieten",
+  "ui.offset": "Abstand",
+  "ui.offset_plane": "Abstandsebene",
+  "ui.one_side": "Einseitig",
+  "ui.open": "Öffnen",
+  "ui.open_ellipsis": "Öffnen...",
+  "ui.open_recent": "Zuletzt verwendet",
+  "ui.operation": "Operation",
+  "ui.options": "Optionen",
+  "ui.orbit_around": "Umkreisen um",
+  "ui.origin": "Ursprung",
+  "ui.pan_zoom_orbit": "Verschieben, zoomen, umkreisen",
+  "ui.parallel": "Parallel",
+  "ui.parameters": "Parameter",
+  "ui.paste": "Einfügen",
+  "ui.path": "Pfad",
+  "ui.pattern_on_path": "Pfadmuster",
+  "ui.perpendicular": "Senkrecht",
+  "ui.pipe": "Rohr",
+  "ui.placement": "Platzierung",
+  "ui.plane": "Ebene",
+  "ui.plane_at_angle": "Ebene im Winkel",
+  "ui.point": "Punkt",
+  "ui.point_under_the_cursor": "Punkt unter dem Cursor",
+  "ui.points": "Punkte",
+  "ui.polygon": "Polygon",
+  "ui.preferences": "Einstellungen",
+  "ui.profile": "Profil",
+  "ui.profile_plane": "Profilebene",
+  "ui.profiles": "Profile",
+  "ui.project": "Projizieren",
+  "ui.quit": "Beenden",
+  "ui.radius": "Radius",
+  "ui.radius_type": "Radius-Typ",
+  "ui.rectangle": "Rechteck",
+  "ui.rectangular_pattern": "Rechteckmuster",
+  "ui.redo": "Wiederholen",
+  "ui.render": "Rendern",
+  "ui.reset_the_settings_on_this_page": "Einstellungen auf dieser Seite zurücksetzen",
+  "ui.restore_defaults": "Standardeinstellungen wiederherstellen",
+  "ui.reverse_zoom_direction": "Zoomrichtung umkehren",
+  "ui.revolve": "Drehen",
+  "ui.right": "Rechts",
+  "ui.save": "Speichern",
+  "ui.save_as": "Speichern unter",
+  "ui.save_as_ellipsis": "Speichern unter...",
+  "ui.scale": "Skalieren",
+  "ui.section_analysis": "Querschnittsanalyse",
+  "ui.select": "Auswählen",
+  "ui.selection": "Auswahl",
+  "ui.shell": "Hülle",
+  "ui.show": "Einblenden",
+  "ui.show_constraints": "Bedingungen anzeigen",
+  "ui.show_dimensions": "Maße anzeigen",
+  "ui.show_points": "Punkte anzeigen",
+  "ui.show_profile": "Profil anzeigen",
+  "ui.show_projected_geometries": "Projizierte Geometrien anzeigen",
+  "ui.simple": "Einfach",
+  "ui.simulation": "Simulation",
+  "ui.single": "Einzel",
+  "ui.sketch": "Skizze",
+  "ui.sketch_dimension": "Skizzenmaß",
+  "ui.sketch_grid": "Skizzenraster",
+  "ui.sketch_scale": "Skizzenskalierung",
+  "ui.sketches": "Skizzen",
+  "ui.slice": "Scheibe",
+  "ui.slot": "Langloch",
+  "ui.smooth": "Glatt",
+  "ui.snap": "Einrasten",
+  "ui.sphere": "Sphäre",
+  "ui.spline": "Spline",
+  "ui.split_body": "Körper trennen",
+  "ui.start": "Start",
+  "ui.start_radius": "Startradius",
+  "ui.sweep": "Führen",
+  "ui.symmetric": "Symmetrisch",
+  "ui.symmetry": "Symmetrie",
+  "ui.system": "System",
+  "ui.tangent": "Tangential",
+  "ui.taper_angle": "Kegelwinkel",
+  "ui.tapped": "Gewindebohrung",
+  "ui.text": "Text",
+  "ui.theme": "Design",
+  "ui.thickness": "Dicke",
+  "ui.thread": "Gewinde",
+  "ui.tip_angle": "Spitzenwinkel",
+  "ui.to_object": "Bis Objekt",
+  "ui.top": "Oben",
+  "ui.torus": "Torus",
+  "ui.trim": "Kürzen",
+  "ui.two_sides": "Beidseitig",
+  "ui.ui_scale": "UI-Skalierung",
+  "ui.undo": "Rückgängig",
+  "ui.units": "Einheiten",
+  "ui.units_of_new_designs": "Einheiten für neue Designs",
+  "ui.untitled": "Ohne Titel",
+  "ui.variable": "Variabel",
+  "ui.view_centre": "Ansichtszentrum",
+  "ui.visual_style": "Ansichtsstil",
+  "ui.workspace": "Arbeitsbereich",
+  "ui.zoom_to_the_cursor": "Zum Cursor zoomen"
+}

crates/ui-egui/src/prefs.rs

@@ -58,6 +58,8 @@ pub struct Prefs {
     pub ui_scale: f32,
     /// The wheel zooms toward the point under the cursor (else toward the view's centre).
     pub zoom_to_cursor: bool,
+    /// Spread discrete wheel input across frames (off: apply each event immediately).
+    pub smooth_wheel_zoom: bool,
     /// View changes (axis view, Look At, Home) animate; `look_at_speed` scales how fast.
     pub look_at_anim: bool,
     pub look_at_speed: f32,
@@ -84,6 +86,7 @@ impl Default for Prefs {
             language: "en".into(),
             ui_scale: 1.0,
             zoom_to_cursor: true,
+            smooth_wheel_zoom: true,
             look_at_anim: true,
             look_at_speed: 1.0,
             up_axis: "z".into(),
@@ -184,6 +187,7 @@ fn defaults(app: &mut SolveApp, page: usize) {
             p.radial_context_menu = d.radial_context_menu;
             p.zoom_reverse = d.zoom_reverse;
             p.zoom_to_cursor = d.zoom_to_cursor;
+            p.smooth_wheel_zoom = d.smooth_wheel_zoom;
             p.orbit_cursor = d.orbit_cursor;
             p.space_mouse_enabled = d.space_mouse_enabled;
             p.space_mouse_speed = d.space_mouse_speed;
@@ -577,6 +581,10 @@ fn page(app: &mut SolveApp, ui: &mut egui::Ui, t: &Tokens) {
             ui.checkbox(&mut app.preferences.zoom_to_cursor, "")
                 .on_hover_text("The wheel zooms toward the point under the cursor (off: toward the view's centre)");
             ui.end_row();
+            ui.label("Smooth wheel zoom");
+            ui.checkbox(&mut app.preferences.smooth_wheel_zoom, "")
+                .on_hover_text("Turn off to apply each wheel event immediately, without a smoothing tail");
+            ui.end_row();
             ui.label("Orbit around");
             ui.horizontal(|ui| {
                 ui.radio_value(&mut app.preferences.orbit_cursor, false, "View centre");
@@ -782,6 +790,26 @@ mod tests {
         assert!(h.app.preferences.radial_context_menu, "Cancel restores the last Apply");
     }
 
+    #[test]
+    fn wheel_smoothing_persists_and_follows_dialog_buttons() {
+        assert!(serde_json::from_value::<Prefs>(json!({})).unwrap().smooth_wheel_zoom);
+        let mut app = SolveApp::new(solvecraft_engine::Session::default(), Default::default());
+        control(&mut app, &json!({"open":"Navigation", "smooth_wheel_zoom":false})).unwrap();
+        control(&mut app, &json!({"button":"cancel"})).unwrap();
+        assert!(app.preferences.smooth_wheel_zoom);
+        control(&mut app, &json!({"open":"Navigation", "smooth_wheel_zoom":false})).unwrap();
+        control(&mut app, &json!({"button":"apply"})).unwrap();
+        control(&mut app, &json!({"smooth_wheel_zoom":true, "button":"cancel"})).unwrap();
+        assert!(!app.preferences.smooth_wheel_zoom);
+        let mut other = SolveApp::new(solvecraft_engine::Session::default(), Default::default());
+        other.load_prefs(&app.prefs());
+        assert!(!other.preferences.smooth_wheel_zoom);
+        control(&mut app, &json!({"open":"Navigation", "button":"defaults"})).unwrap();
+        assert!(app.preferences.smooth_wheel_zoom);
+        control(&mut app, &json!({"button":"cancel"})).unwrap();
+        assert!(!app.preferences.smooth_wheel_zoom);
+    }
+
     #[test]
     fn presets_map_the_mouse_and_prefs_round_trip() {
         let mut app = SolveApp::new(solvecraft_engine::Session::default(), Default::default());

crates/ui-egui/src/toolbar.rs

@@ -542,29 +542,41 @@ pub fn toolbar(app: &mut SolveApp, ui: &mut egui::Ui) {
                         } else if cmds.is_empty() {
                             ui.label(egui::RichText::new("Not available yet").color(t.text_dim));
                         }
+                        let row_w = dropdown_width(app, ui, &cmds);
+                        // Up and Down move the keyboard focus through the enabled rows (from none
+                        // focused: the first or the last), instead of egui's own spatial move.
+                        let (down, up) = ui.input(|i| (i.key_pressed(egui::Key::ArrowDown), i.key_pressed(egui::Key::ArrowUp)));
+                        if down || up {
+                            let enabled: Vec<&str> = cmds.iter().filter(|c| c.info(&app.session).enabled).map(|c| c.id).collect();
+                            let focused = ui.ctx().memory(|m| m.focused());
+                            let at = enabled.iter().position(|id| focused == Some(dropdown_row_id(ui, id)));
+                            let n = enabled.len();
+                            let next = match (at, down) {
+                                (None, true) => Some(0),
+                                (None, false) => n.checked_sub(1),
+                                (Some(i), true) => Some((i + 1) % n.max(1)),
+                                (Some(i), false) => Some((i + n.max(1) - 1) % n.max(1)),
+                            };
+                            if let Some(id) = next.and_then(|i| enabled.get(i)) {
+                                ui.ctx().memory_mut(|m| {
+                                    m.request_focus(dropdown_row_id(ui, id));
+                                    m.move_focus(egui::FocusDirection::None);
+                                });
+                            }
+                        }
                         for c in &cmds {
-                            let info = c.info(&app.session);
-                            ui.horizontal(|ui| {
-                                let (ir, _) = ui.allocate_exact_size(vec2(18.0, 18.0), Sense::hover());
-                                icons::paint(ui.painter(), ir, c.icon, t.icon, t.icon_fill, t.accent);
-                                let b = ui.add_enabled(
-                                    info.enabled,
-                                    egui::Button::new(app.tr_label(c.label)).frame(false).shortcut_text(c.shortcut.unwrap_or("")),
-                                );
-                                crate::scenario::publish_handle(&format!("toolbar:{}", c.id), b.rect.center());
-                                if b.secondary_clicked() {
-                                    menu = Some((b.interact_pointer_pos().unwrap_or(b.rect.left_bottom()), c.id));
-                                }
-                                if b.clicked() {
-                                    let id = c.id;
-                                    app.start(id);
+                            match dropdown_row(app, ui, c, row_w) {
+                                RowAction::None => {}
+                                RowAction::Menu(at) => menu = Some((at, c.id)),
+                                RowAction::Start => {
+                                    app.start(c.id);
                                     ui.ctx().data_mut(|d| d.remove::<egui::Id>(egui::Id::new("sc_panel_open")));
                                 }
-                            });
+                            }
                         }
                     });
                 });
-                if area.response.clicked_elsewhere() && !lresp.clicked() {
+                if (area.response.clicked_elsewhere() && !lresp.clicked()) || ui.input(|i| i.key_pressed(egui::Key::Escape)) {
                     ui.ctx().data_mut(|d| d.remove::<egui::Id>(egui::Id::new("sc_panel_open")));
                 }
             }
@@ -608,6 +620,72 @@ pub fn toolbar(app: &mut SolveApp, ui: &mut egui::Ui) {
     });
 }
 
+/// What a click on a panel drop-down row asks for.
+enum RowAction {
+    None,
+    Start,
+    Menu(egui::Pos2),
+}
+
+const ROW_H: f32 = 24.0;
+
+/// The id of a drop-down row (for keyboard focus).
+fn dropdown_row_id(ui: &egui::Ui, id: &str) -> egui::Id {
+    ui.id().with(("dropdown_row", id))
+}
+
+/// How wide a panel drop-down's rows are: the widest label and shortcut, at least 200.
+fn dropdown_width(app: &SolveApp, ui: &egui::Ui, cmds: &[&'static solvecraft_engine::CommandSpec]) -> f32 {
+    let t = Tokens::get();
+    let font = FontId::proportional(13.0);
+    cmds.iter()
+        .map(|c| {
+            let label = ui.painter().layout_no_wrap(app.tr_label(c.label).to_string(), font.clone(), t.text).size().x;
+            let key = c.shortcut.map(|k| ui.painter().layout_no_wrap(k.to_string(), font.clone(), t.text).size().x + 24.0).unwrap_or(0.0);
+            6.0 + 18.0 + 8.0 + label + key + 30.0
+        })
+        .fold(200.0, f32::max)
+}
+
+/// One command row of a panel drop-down: icon, label and shortcut, with the hover background
+/// under the pointer or keyboard focus (like every menu).
+fn dropdown_row(app: &SolveApp, ui: &mut egui::Ui, c: &'static solvecraft_engine::CommandSpec, width: f32) -> RowAction {
+    let t = Tokens::get();
+    let info = c.info(&app.session);
+    let (rect, _) = ui.allocate_exact_size(vec2(width, ROW_H), Sense::hover());
+    let sense = if info.enabled { Sense::click() } else { Sense::hover() };
+    let resp = ui.interact(rect, dropdown_row_id(ui, c.id), sense);
+    let label = app.tr_label(c.label).to_string();
+    resp.widget_info(|| egui::WidgetInfo::labeled(egui::WidgetType::Button, ui.is_enabled() && info.enabled, &label));
+    crate::scenario::publish_handle(&format!("toolbar:{}", c.id), rect.center());
+    crate::scenario::publish_handle(&format!("dropdown:{}", c.id), rect.center());
+    let hot = info.enabled && (resp.hovered() || resp.has_focus());
+    let p = ui.painter();
+    if hot {
+        p.rect_filled(rect, 3.0, t.hover);
+        crate::scenario::publish_handle(&format!("dropdown_hot:{}", c.id), rect.center());
+    }
+    let (ink, fill, acc, text) =
+        if info.enabled { (t.icon, t.icon_fill, t.accent, t.text) } else { (t.border, t.panel_header, t.border, t.text_dim) };
+    let ir = Rect::from_center_size(pos2(rect.left() + 6.0 + 9.0, rect.center().y), vec2(18.0, 18.0));
+    icons::paint(p, ir, c.icon, ink, fill, acc);
+    p.text(pos2(ir.right() + 8.0, rect.center().y), Align2::LEFT_CENTER, &label, FontId::proportional(13.0), text);
+    if let Some(k) = c.shortcut {
+        p.text(pos2(rect.right() - 8.0, rect.center().y), Align2::RIGHT_CENTER, k, FontId::proportional(13.0), t.text_dim);
+    }
+    let resp = match &info.disabled_reason {
+        Some(why) if !info.enabled => resp.on_hover_text(why),
+        _ => resp,
+    };
+    if resp.secondary_clicked() {
+        return RowAction::Menu(resp.interact_pointer_pos().unwrap_or(rect.left_bottom()));
+    }
+    if resp.clicked() && info.enabled {
+        return RowAction::Start;
+    }
+    RowAction::None
+}
+
 /// A toolbar button being dragged (its command id).
 #[derive(Clone, Copy, Debug)]
 struct ToolbarDrag(&'static str);

crates/ui-egui/src/tools.rs

@@ -326,7 +326,25 @@ fn run_shape(app: &mut SolveApp, t: &Tool) -> Result<Vec<String>, String> {
 /// Only consume a complete, unambiguous selection; command validation owns geometry.
 pub(crate) fn constraint_preselection(command: &str, selection: &[solvecraft_engine::Sel]) -> Option<Value> {
     use solvecraft_engine::Sel::{SketchCurve, SketchPoint};
+    let selected_ids = |curves_only: bool, minimum: usize| -> Option<Vec<&str>> {
+        if !(minimum..=200).contains(&selection.len()) {
+            return None;
+        }
+        let ids: Vec<&str> = selection
+            .iter()
+            .map(|s| match s {
+                SketchCurve { id } => Some(id.as_str()),
+                SketchPoint { id } if !curves_only => Some(id.as_str()),
+                _ => None,
+            })
+            .collect::<Option<_>>()?;
+        let unique: std::collections::BTreeSet<_> = ids.iter().copied().collect();
+        (unique.len() == ids.len()).then_some(ids)
+    };
     match (command, selection) {
+        ("sketch.constraint.fix", _) => selected_ids(false, 1).map(|ids| json!({"entities":ids})),
+        ("sketch.constraint.polygon", _) => selected_ids(true, 3).map(|ids| json!({"lines":ids})),
+        ("sketch.constraint.curvature", [SketchCurve { id: a }, SketchCurve { id: b }]) if a != b => Some(json!({"a":a,"b":b})),
         ("sketch.constraint.horizontal_vertical", [SketchCurve { id }]) => Some(json!({"line":id})),
         ("sketch.constraint.horizontal_vertical", [SketchPoint { id: a }, SketchPoint { id: b }]) if a != b => Some(json!({"points":[a,b]})),
         ("sketch.constraint.coincident", [a, b]) => {

crates/ui-egui/src/viewport.rs

@@ -62,6 +62,8 @@ pub struct ViewportState {
     pub orbit_pivot: Option<Vec3>,
     /// Continuous orbit: the view turns about the vertical until the next click or key.
     pub spin: bool,
+    /// After immediate zoom, ignore egui's outstanding smoothing until the gesture ends.
+    wheel_zoom_raw_until_idle: bool,
     /// A primary press on the axis gizmo: the pointer position used by its last orbit step.
     pub axis_drag: Option<Pos2>,
     /// Unsnapped camera while Shift-orbit previews a standard or diagonal view.
@@ -1471,6 +1473,34 @@ pub fn delete_selection(app: &mut SolveApp) {
     crate::delete::delete_selection(app);
 }
 
+/// Match egui's wheel units and modifier routing, without its temporal smoothing.
+fn immediate_wheel_delta(input: &egui::InputState, options: egui::InputOptions, page_height: f32) -> f32 {
+    input
+        .events
+        .iter()
+        .filter_map(|event| {
+            let egui::Event::MouseWheel { unit, delta, modifiers, phase: egui::TouchPhase::Move } = event else { return None };
+            if modifiers.matches_any(options.zoom_modifier) {
+                return None;
+            }
+            let delta = match unit {
+                egui::MouseWheelUnit::Point => *delta,
+                egui::MouseWheelUnit::Line => *delta * options.line_scroll_speed,
+                egui::MouseWheelUnit::Page => *delta * page_height,
+            };
+            let horizontal = modifiers.matches_any(options.horizontal_scroll_modifier);
+            let vertical = modifiers.matches_any(options.vertical_scroll_modifier);
+            Some(if horizontal && !vertical {
+                0.0
+            } else if vertical && !horizontal {
+                delta.x + delta.y
+            } else {
+                delta.y
+            })
+        })
+        .sum()
+}
+
 pub fn show(app: &mut SolveApp, ui: &mut egui::Ui) {
     let t = Tokens::get();
     let rect = ui.max_rect();
@@ -1499,6 +1529,18 @@ pub fn show(app: &mut SolveApp, ui: &mut egui::Ui) {
     crate::drag_snap::set_suppressed(mods.ctrl || mods.alt || mods.command);
 
     // ---- navigation ----
+    if !app.preferences.smooth_wheel_zoom {
+        app.viewport.wheel_zoom_raw_until_idle = true;
+    } else if !ui.input(|i| i.is_scrolling()) {
+        app.viewport.wheel_zoom_raw_until_idle = false;
+    }
+    let scroll = if app.viewport.wheel_zoom_raw_until_idle {
+        let options = ui.ctx().options(|o| o.input_options);
+        let page_height = ui.ctx().viewport_rect().height();
+        ui.input(|i| immediate_wheel_delta(i, options, page_height))
+    } else {
+        scroll
+    };
     let h = rect.height().max(1.0) as f64;
     if inside && scroll != 0.0 {
         app.viewport.orbit_snap = None;
@@ -3113,72 +3155,144 @@ mod tests {
         }
     }
 
+    #[test]
+    fn immediate_wheel_zoom_applies_normalized_input_once() {
+        let mut h = crate::scenario::Harness::new();
+        h.app.preferences.smooth_wheel_zoom = false;
+        h.app.preferences.zoom_to_cursor = false;
+        h.call("ui.move", json!({"x":800,"y":500}));
+        let before = h.app.cam;
+        let line = h.ctx.options(|o| o.input_options.line_scroll_speed);
+        for (unit, amount, points) in
+            [(egui::MouseWheelUnit::Point, 120.0, 120.0), (egui::MouseWheelUnit::Line, 1.0, line), (egui::MouseWheelUnit::Page, 0.1, 100.0)]
+        {
+            let height = h.app.cam.half_height();
+            h.app.synthetic.push(egui::Event::MouseWheel {
+                unit,
+                delta: vec2(0.0, amount),
+                modifiers: egui::Modifiers::NONE,
+                phase: egui::TouchPhase::Move,
+            });
+            h.frame();
+            let expected = height * (-f64::from(points) * 0.0015).exp();
+            assert!((h.app.cam.half_height() - expected).abs() < 1e-6);
+            let after = h.app.cam;
+            h.frames(30);
+            assert_eq!(h.app.cam, after, "idle frames must not replay wheel input");
+        }
+        assert_eq!(h.app.cam.target, before.target);
+        h.app.preferences.zoom_reverse = true;
+        let height = h.app.cam.half_height();
+        h.call("ui.scroll", json!({"x":800,"y":500,"delta":120}));
+        assert!((h.app.cam.half_height() - height * 0.18_f64.exp()).abs() < 1e-6);
+    }
+
+    #[test]
+    fn wheel_zoom_setting_changes_do_not_replay_smoothing() {
+        let mut h = crate::scenario::Harness::new();
+        h.app.preferences.zoom_to_cursor = false;
+        h.call("ui.move", json!({"x":800,"y":500}));
+        h.app.synthetic.push(egui::Event::MouseWheel {
+            unit: egui::MouseWheelUnit::Point,
+            delta: vec2(0.0, 120.0),
+            modifiers: egui::Modifiers::NONE,
+            phase: egui::TouchPhase::Move,
+        });
+        h.frame();
+        assert!(h.ctx.input(|i| i.is_scrolling()));
+        h.app.preferences.smooth_wheel_zoom = false;
+        let stopped = h.app.cam;
+        h.frame();
+        assert_eq!(h.app.cam, stopped);
+        h.app.preferences.smooth_wheel_zoom = true;
+        h.frames(90);
+        assert_eq!(h.app.cam, stopped, "re-enabling must not replay the old smoothing tail");
+        assert!(!h.app.viewport.wheel_zoom_raw_until_idle);
+        h.app.preferences.smooth_wheel_zoom = false;
+        for _ in 0..3 {
+            h.app.synthetic.push(egui::Event::MouseWheel {
+                unit: egui::MouseWheelUnit::Point,
+                delta: vec2(0.0, 120.0),
+                modifiers: egui::Modifiers::NONE,
+                phase: egui::TouchPhase::Move,
+            });
+            h.frame();
+        }
+        assert!((h.app.cam.half_height() - stopped.half_height() * (-0.54_f64).exp()).abs() < 1e-6);
+        let after = h.app.cam;
+        h.frames(90);
+        assert_eq!(h.app.cam, after);
+    }
+
     #[test]
     fn shortcuts_window_wheel_does_not_zoom_the_viewport() {
-        let ctx = egui::Context::default();
-        let mut app = SolveApp::new(solvecraft_engine::Session::default(), crate::Services::default());
-        app.viewport.no_pixels = true;
-        crate::help::run(&mut app, &ctx, "shortcuts");
-        let mut time = 0.0;
-        let mut frame = |app: &mut SolveApp, pointer: Option<Pos2>, wheel: f32| {
-            time += 1.0 / 60.0;
-            let mut events = Vec::new();
-            if let Some(p) = pointer {
-                events.push(egui::Event::PointerMoved(p));
+        for smooth in [true, false] {
+            let ctx = egui::Context::default();
+            let mut app = SolveApp::new(solvecraft_engine::Session::default(), crate::Services::default());
+            app.preferences.smooth_wheel_zoom = smooth;
+            app.viewport.no_pixels = true;
+            crate::help::run(&mut app, &ctx, "shortcuts");
+            let mut time = 0.0;
+            let mut frame = |app: &mut SolveApp, pointer: Option<Pos2>, wheel: f32| {
+                time += 1.0 / 60.0;
+                let mut events = Vec::new();
+                if let Some(p) = pointer {
+                    events.push(egui::Event::PointerMoved(p));
+                }
+                if wheel != 0.0 {
+                    events.push(egui::Event::MouseWheel {
+                        unit: egui::MouseWheelUnit::Point,
+                        delta: vec2(0.0, wheel),
+                        modifiers: egui::Modifiers::NONE,
+                        phase: egui::TouchPhase::Move,
+                    });
+                }
+                let mut output = ctx.run_ui(
+                    egui::RawInput {
+                        screen_rect: Some(Rect::from_min_size(Pos2::ZERO, vec2(1100.0, 800.0))),
+                        time: Some(time),
+                        events,
+                        ..Default::default()
+                    },
+                    |ui| {
+                        egui::CentralPanel::default().show(ui, |ui| show(app, ui));
+                        crate::prefs::show(app, ui.ctx());
+                    },
+                );
+                output.textures_delta.clear();
+            };
+            // Let egui establish the floating window's size and hit-test widgets.
+            for _ in 0..4 {
+                frame(&mut app, None, 0.0);
             }
-            if wheel != 0.0 {
-                events.push(egui::Event::MouseWheel {
-                    unit: egui::MouseWheelUnit::Point,
-                    delta: vec2(0.0, wheel),
-                    modifiers: egui::Modifiers::NONE,
-                    phase: egui::TouchPhase::Move,
-                });
-            }
-            let mut output = ctx.run_ui(
-                egui::RawInput {
-                    screen_rect: Some(Rect::from_min_size(Pos2::ZERO, vec2(1100.0, 800.0))),
-                    time: Some(time),
-                    events,
-                    ..Default::default()
-                },
-                |ui| {
-                    egui::CentralPanel::default().show(ui, |ui| show(app, ui));
-                    crate::prefs::show(app, ui.ctx());
-                },
-            );
-            output.textures_delta.clear();
-        };
-        // Let egui establish the floating window's size and hit-test widgets.
-        for _ in 0..4 {
-            frame(&mut app, None, 0.0);
-        }
-        let window = ctx.memory(|m| m.area_rect(egui::Id::new("sc_prefs"))).unwrap();
-        let list = window.center() + vec2(140.0, 0.0);
-        let height = app.cam.half_height();
-        let target = app.cam.target;
-        frame(&mut app, Some(list), 0.0);
-        for n in 0..12 {
-            frame(&mut app, Some(list), if n == 0 { -120.0 } else { 0.0 });
-            assert_eq!(app.cam.half_height(), height, "wheel input over shortcuts must stay in the popup");
-            assert_eq!(app.cam.target, target);
-        }
-        // The window's non-scrolling sidebar must also shield the model.
-        frame(&mut app, Some(window.left_center() + vec2(30.0, 0.0)), -120.0);
-        assert_eq!(app.cam.half_height(), height);
-        // An exposed part of the viewport still accepts wheel navigation with the popup open.
-        let exposed = pos2(40.0, 700.0);
-        assert!(!window.contains(exposed));
-        frame(&mut app, Some(exposed), 0.0);
-        frame(&mut app, Some(exposed), -120.0);
-        assert_ne!(app.cam.half_height(), height);
-        // Closing the popup returns its former area to the viewport.
-        app.prefs_window.open = false;
-        for _ in 0..12 {
+            let window = ctx.memory(|m| m.area_rect(egui::Id::new("sc_prefs"))).unwrap();
+            let list = window.center() + vec2(140.0, 0.0);
+            let height = app.cam.half_height();
+            let target = app.cam.target;
             frame(&mut app, Some(list), 0.0);
+            for n in 0..12 {
+                frame(&mut app, Some(list), if n == 0 { -120.0 } else { 0.0 });
+                assert_eq!(app.cam.half_height(), height, "wheel input over shortcuts must stay in the popup");
+                assert_eq!(app.cam.target, target);
+            }
+            // The window's non-scrolling sidebar must also shield the model.
+            frame(&mut app, Some(window.left_center() + vec2(30.0, 0.0)), -120.0);
+            assert_eq!(app.cam.half_height(), height);
+            // An exposed part of the viewport still accepts wheel navigation with the popup open.
+            let exposed = pos2(40.0, 700.0);
+            assert!(!window.contains(exposed));
+            frame(&mut app, Some(exposed), 0.0);
+            frame(&mut app, Some(exposed), -120.0);
+            assert_ne!(app.cam.half_height(), height);
+            // Closing the popup returns its former area to the viewport.
+            app.prefs_window.open = false;
+            for _ in 0..12 {
+                frame(&mut app, Some(list), 0.0);
+            }
+            let height = app.cam.half_height();
+            frame(&mut app, Some(list), -120.0);
+            assert_ne!(app.cam.half_height(), height);
         }
-        let height = app.cam.half_height();
-        frame(&mut app, Some(list), -120.0);
-        assert_ne!(app.cam.half_height(), height);
     }
 
     #[test]

crates/ui-egui/tests/constraint_preselection.rs

@@ -146,3 +146,106 @@ fn rejected_preselection_preserves_document_and_error() {
     assert!(!h.app.status.as_ref().is_some_and(|(_, _, error)| *error));
     assert!(h.app.session.selection.is_empty());
 }
+
+#[test]
+fn curvature_polygon_and_fix_consume_clicked_operands_atomically() {
+    for command in ["fix", "curvature", "polygon"] {
+        let mut h = Harness::new();
+        h.app.run("sketch.create", json!({"plane":"XY"})).unwrap();
+        let picks = match command {
+            "curvature" => {
+                h.app.run("sketch.line", json!({"points":[[10,10],[30,10]],"infer":false})).unwrap();
+                h.app.run("sketch.spline.control_point", json!({"points":["l1.end",[40,12],[50,16],[60,25]]})).unwrap();
+                vec![[20., 10.], [45., 14.875]]
+            }
+            "polygon" => {
+                h.app.run("sketch.line", json!({"points":[[10,10],[40,10],[40,30],[10,30]],"closed":true,"infer":false})).unwrap();
+                vec![[25., 10.], [40., 20.], [25., 30.], [10., 20.]]
+            }
+            _ => {
+                h.app.run("sketch.line", json!({"points":[[10,10],[40,10]],"infer":false})).unwrap();
+                h.app.run("sketch.point", json!({"point":[20,25],"id":"p"})).unwrap();
+                vec![[25., 10.], [20., 25.]]
+            }
+        };
+        h.call("ui.view", json!({"view":"top"}));
+        h.app.cam.distance = 80.0;
+        h.app.cam.target = solvecraft_engine::geom::Vec3::new(30.0, 15.0, 0.0);
+        h.settle();
+        for (i, p) in picks.iter().enumerate() {
+            h.step(&json!({"click":{"sketch":p},"shift":i>0})).unwrap();
+        }
+        assert_eq!(h.app.session.selection.len(), picks.len(), "{command}: {:?}", h.app.session.selection);
+        let before = h.app.session.doc.to_json();
+        let undo = h.app.session.undo.len();
+        h.step(&json!({"start":format!("sketch.constraint.{command}")})).unwrap();
+        assert!(!h.app.status.as_ref().is_some_and(|(_, _, error)| *error), "{command}: {:?}", h.app.status);
+        assert!(h.app.tool.is_none());
+        assert!(h.app.session.selection.is_empty());
+        assert_eq!(h.app.session.undo.len(), undo + 1);
+        let st = h.app.session.world_state();
+        let sk = &st.sketch(h.app.session.active_sketch.unwrap()).unwrap().sketch;
+        assert!(sk.constraints.iter().any(|c| match command {
+            "fix" => matches!(c.kind, ConstraintKind::Fix { .. }),
+            "curvature" => matches!(c.kind, ConstraintKind::Smooth { .. }),
+            _ => matches!(c.kind, ConstraintKind::Equal { .. }),
+        }));
+        match command {
+            "fix" => {
+                assert!(sk.curve_locked(sk.curve_index("l1").unwrap()));
+                assert!(sk.point_locked(sk.resolve_point("p").unwrap()));
+            }
+            "curvature" => {
+                let spline = sk.curves.iter().find(|c| c.id != "l1").unwrap();
+                let pts: Vec<_> = spline.kind.point_ids().iter().map(|i| sk.point(*i).unwrap()).collect();
+                let line = sk.polyline(sk.curve_index("l1").unwrap());
+                let direction = (line[1] - line[0]).normalized().unwrap();
+                assert!((pts[1] - pts[0]).cross(direction).abs() < 1e-5);
+                assert!((pts[2] - pts[1]).cross(pts[1] - pts[0]).abs() < 1e-3);
+            }
+            _ => {
+                let lengths: Vec<_> = ["l1", "l2", "l3", "l4"]
+                    .iter()
+                    .map(|id| {
+                        let pts = sk.polyline(sk.curve_index(id).unwrap());
+                        pts[0].dist(pts[1])
+                    })
+                    .collect();
+                assert!(lengths[0] > 1.0);
+                assert!(lengths.iter().all(|l| (l - lengths[0]).abs() < 1e-6));
+            }
+        }
+        assert!(st.sketch(h.app.session.active_sketch.unwrap()).unwrap().report.ok());
+        let after = h.app.session.doc.to_json();
+        h.app.run("edit.undo", json!({})).unwrap();
+        assert_eq!(h.app.session.doc.to_json(), before);
+        h.app.run("edit.redo", json!({})).unwrap();
+        assert_eq!(h.app.session.doc.to_json(), after);
+    }
+}
+
+#[test]
+fn remaining_constraints_preserve_mixed_selections_and_rejected_geometry() {
+    for command in ["fix", "curvature", "polygon"] {
+        let mut h = lines();
+        let before = h.app.session.doc.to_json();
+        let undo = h.app.session.undo.len();
+        let mixed = vec![Sel::SketchCurve { id: "l1".into() }, Sel::Body { name: "missing".into() }];
+        h.app.session.selection = mixed.clone();
+        h.step(&json!({"start":format!("sketch.constraint.{command}")})).unwrap();
+        assert!(h.app.tool.is_some());
+        assert_eq!(h.app.session.selection, mixed);
+        assert_eq!(h.app.session.doc.to_json(), before);
+        assert_eq!(h.app.session.undo.len(), undo);
+    }
+    let mut h = lines();
+    let selection = vec![Sel::SketchCurve { id: "l1".into() }, Sel::SketchCurve { id: "missing".into() }];
+    h.app.session.selection = selection.clone();
+    let before = h.app.session.doc.to_json();
+    let undo = h.app.session.undo.len();
+    h.step(&json!({"start":"sketch.constraint.curvature"})).unwrap();
+    assert!(h.app.status.as_ref().is_some_and(|(_, _, error)| *error));
+    assert_eq!(h.app.session.selection, selection);
+    assert_eq!(h.app.session.doc.to_json(), before);
+    assert_eq!(h.app.session.undo.len(), undo);
+}

crates/ui-egui/tests/scenarios/s46_toolbar_dropdown_hover.json

@@ -0,0 +1,75 @@
+[
+ {
+  "note": "#288: a panel drop-down highlights the row under the pointer with the hover background, and the row with keyboard focus. Drop-down rows publish `dropdown:<command id>`, the highlighted one also `dropdown_hot:<command id>`."
+ },
+ {
+  "click": {
+   "handle": "panel:SOLID:CREATE"
+  }
+ },
+ {
+  "expect": {
+   "shown_handles": ["dropdown:solid.box", "dropdown:solid.sphere"],
+   "hidden_handles": ["dropdown_hot:solid.box", "dropdown_hot:solid.sphere"]
+  }
+ },
+ {
+  "move": {
+   "handle": "dropdown:solid.box"
+  }
+ },
+ {
+  "expect": {
+   "shown_handles": ["dropdown_hot:solid.box"],
+   "hidden_handles": ["dropdown_hot:solid.sphere", "dropdown_hot:solid.cylinder"]
+  }
+ },
+ {
+  "move": {
+   "handle": "dropdown:solid.sphere"
+  }
+ },
+ {
+  "expect": {
+   "shown_handles": ["dropdown_hot:solid.sphere"],
+   "hidden_handles": ["dropdown_hot:solid.box"]
+  }
+ },
+ {
+  "move": [700, 600]
+ },
+ {
+  "expect": {
+   "shown_handles": ["dropdown:solid.box"],
+   "hidden_handles": ["dropdown_hot:solid.sphere", "dropdown_hot:solid.box"]
+  }
+ },
+ {
+  "note": "The keyboard: Down focuses the first row, Down again the next; the highlight follows."
+ },
+ {
+  "key": "ArrowDown"
+ },
+ {
+  "expect": {
+   "shown_handles": ["dropdown_hot:sketch.create"]
+  }
+ },
+ {
+  "key": "ArrowDown"
+ },
+ {
+  "expect": {
+   "shown_handles": ["dropdown_hot:solid.extrude"],
+   "hidden_handles": ["dropdown_hot:sketch.create"]
+  }
+ },
+ {
+  "key": "Enter"
+ },
+ {
+  "expect": {
+   "hidden_handles": ["dropdown:solid.box"]
+  }
+ }
+]

docs/book/src/guide/ui-tour.md

@@ -39,5 +39,10 @@ Preferences (File › Preferences) hold the theme, the units of new designs, the
 visual style and autosave. Help › Keyboard Shortcuts lists every key, and File › Keyboard
 Shortcuts changes them.
 
+Navigation › **Smooth wheel zoom** is on by default. Turn it off to apply each wheel or
+trackpad event immediately, with no smoothing tail. It is independent of **Animate view
+changes**, which controls axis views, Look At, Home and Fit. Re-enabling smoothing during
+a wheel gesture takes effect after that gesture ends, avoiding leftover zoom being replayed.
+
 Shift-orbit snapping includes 45-degree edge views and isometric corner views, with a
 lightly damped spring transition and a small boundary margin to prevent flicker.

docs/control-protocol.md

@@ -70,7 +70,7 @@ rolls the numbering back with the design), so they can go straight into later co
 | `ui.home` | `open?`: bool; `sample?`: index | the start page: show or hide it, open a built-in sample (once built); returns `open` and the recent designs |
 | `ui.shortcut` | `command`, `key?`, `replace?` | a command's key, or rebinds it (`""` clears; a key another command uses is refused unless `replace`) |
 | `ui.help` | `item?`: `about`, `shortcuts` (read only), `report` (copies diagnostics) | the version, commit, build date and diagnostic text |
-| `ui.prefs` | any of `default_units`, `nav` (`fusion`, `solidworks`, `inventor`, `alias`, `tinkercad`), `zoom_reverse`, `zoom_to_cursor`, `orbit_cursor`, `look_at_anim`, `look_at_speed`, `msaa`, `length_decimals`, `angle_decimals`, `theme` (`dark`, `light`, `system`), `language` (`en`, `ja`; see [localization](localization.md)), `ui_scale`, `up_axis` (`z`, `y`), `offer_stand_up`; `open` (a page: General, Navigation, Keyboard Shortcuts, Design, Graphics, Sketch, Selection) opens the Preferences dialog there; `button`: `ok`, `cancel`, `apply`, `defaults`; `stand_up: true` stands up a just-opened Y-up file | sets preferences (kept between runs), returns them all plus `dialog` (the open page or null), `dark` and `stand_up_offer` |
+| `ui.prefs` | any of `default_units`, `nav` (`fusion`, `solidworks`, `inventor`, `alias`, `tinkercad`), `zoom_reverse`, `zoom_to_cursor`, `smooth_wheel_zoom` (default true), `orbit_cursor`, `look_at_anim`, `look_at_speed`, `msaa`, `length_decimals`, `angle_decimals`, `theme` (`dark`, `light`, `system`), `language` (`en`, `ja`; see [localization](localization.md)), `ui_scale`, `up_axis` (`z`, `y`), `offer_stand_up`; `open` (a page: General, Navigation, Keyboard Shortcuts, Design, Graphics, Sketch, Selection) opens the Preferences dialog there; `button`: `ok`, `cancel`, `apply`, `defaults`; `stand_up: true` stands up a just-opened Y-up file | sets preferences (kept between runs), returns them all plus `dialog` (the open page or null), `dark` and `stand_up_offer` |
 | `ui.capture` | `action?`: `capture`, `revert`, `cancel` | answers the Capture Position question (asked when a command starts or the design is saved while components were moved without capturing); without `action`, what waits |
 | `ui.window` | `action`: minimize, maximize, restore, toggle, close | what the title bar's caption buttons do (on Windows and Linux the application bar is the title bar); close asks about unsaved designs first |
 | `ui.agent_cursor` | `show` (bool), `speed`: a number from 1 to 5 (times the normal speed) or `"instant"` (no animation: the command runs at once and the pointer jumps to where it acted), `follow_camera` (bool); all optional | the settings. While the cursor is shown, `engine.execute` first glides to the command's toolbar button and to each pick, then runs and replies; later requests wait their turn. `"animate": false` on a call skips it |

docs/perf.md

@@ -1,5 +1,60 @@
 # Design loading
 
+## Cold geometry rebuilds after 0.3.1
+
+Three alternating cold-process comparisons on the same Windows machine and optimized
+`ci` profile, with no concurrent build, compare the unchanged 0.3.1 source with the
+straight-line projection and exact surface-refinement reuse changes:
+
+| Saved design | Before, median evaluation | After | Reduction |
+|---|---:|---:|---:|
+| Public sensor enclosure, 21 features, 52 KB | 11.96 s | 8.85 s | 26.0% |
+| Local Pi case assembly, 25 features, 2,990 bodies | 14.75 s | 11.57 s | 21.6% |
+
+These are geometry rebuild times, not complete desktop opening times. The public fixture
+can be generated with `solvecraft-cli run examples/acceptance/sensor_enclosure.json
+--save sensor.solvecraft --quiet`, then measured with `solvecraft-cli bench-open
+sensor.solvecraft`. Each benchmark starts a new process; this does not measure a warm
+timeline-cache hit. The local assembly is private and is not part of the repository.
+
+Straight segments now use guarded algebraic closest-point projection instead of sampling
+65 points and running Newton iterations. Other curve types retain their existing behavior.
+Curved-face refinement reuses derivative and midpoint evaluations with exact finite input
+keys and bounded, local caches. It keeps the original tolerance, seam and singularity
+checks, refinement passes, and triangle limits.
+
+Identity assembly placements retain the definition body's shared display-mesh cache.
+Changed placements continue to build separate meshes in their own coordinates. Face-name
+preparation remains eager during placement: deferring it merely shifted expensive work to
+thumbnails and the first face query, so that approach was excluded.
+
+Both saved fixtures retain exactly the same body names, face/edge/vertex/shell counts,
+bounds, volumes, and surface areas. Focused tests compare cached and uncached refinement
+coordinates and normals bit for bit on periodic, singular and transformed surfaces.
+
+For desktop phase profiling, set `SOLVECRAFT_PROFILE_OPEN=1` before launching the app.
+Interactive Open reports geometry, placement, tessellation, thumbnail and total worker
+times to stderr without logging the source path. Thumbnails were about 0.1 seconds of
+the slow assembly's open and were not the main bottleneck. Further cold Boolean and
+import costs remain; these changes do not make all documents open instantly.
+
+### Prepared assembly geometry and selection
+
+Prepared world geometry is now keyed by the document, evaluated model and exact placement
+context instead of the session revision. Selecting a face or edge, changing visibility,
+or moving the view no longer discards already prepared assembly bodies and meshes.
+Geometry edits, pending occurrence moves, authoring context changes, undo/redo and timeline
+rollback still invalidate the cache. Scratch sessions share prepared geometry while their
+inputs match, and adopting a computed session retains its warm cache.
+
+On the private 2,990-body Pi assembly, a matched Linux desktop control probe reduced an
+edge-selection round trip from 9.24 s to 0.57 s. Initial opening stayed essentially unchanged
+(33.54 s to 33.32 s); this fixes a separate selection stall, not cold geometry evaluation.
+Three fresh Windows desktop runs with the corrected cache measured a median 15.87 s to
+ready: 13.04 s geometry, 2.20 s placement, 0.53 s meshing and 0.07 s thumbnails. These used
+the optimized `ci` profile and actual Vulkan rendering, with isolated settings and caches.
+Linux and Windows timings are separate measurements and must not be compared as a speedup.
+
 `solvecraft-cli bench-open design.solvecraft` reports JSON lines for file reading,
 JSON decoding and migrations (including input-name repair), timeline evaluation, individual
 features, and world placement/display meshing. `--parse-only` stops before geometry evaluation.

docs/releasing.md

@@ -54,7 +54,7 @@ deployment. The stable Flatpak repository is not automatically updated with nigh
 2. Update `[workspace.package] version` in root `Cargo.toml`. Then run
    `cargo metadata --format-version 1 --no-deps > /dev/null` to refresh workspace package
    versions in `Cargo.lock`. Inspect the diff and keep unrelated dependency changes out.
-   SolidCraft does not currently implement the siblings' `cargo xtask version set` command.
+   SolidCraft does not currently implement `cargo xtask version set`.
 3. Run `cargo xtask ci` and the packaging checks in `.github/workflows/packaging-lint.yml`.
    Commit the version files through the normal review flow and land them on `main`.
    Do not use `[skip ci]`. Record the exact commit SHA to release. If it changes, revalidate it.

vendor/README.md

@@ -7,6 +7,9 @@ are marked `SolveCraft:` in the source.
 ## truck-shapeops 0.4.0 (Apache-2.0, © RICOS Co. Ltd., https://github.com/ricosjp/truck)
 
 Changes:
+- `transversal/intersection_curve/mod.rs`: reject empty/single-point polylines and
+  collapsed or non-finite segments before endpoint indexing and normalization. A hidden
+  constructor re-export lets the kernel workspace tests exercise the actual vendored code.
 - `transversal/integrate/mod.rs`: mesh both shells with `robust_triangulation` (faces made by
   earlier booleans have boundaries that lie on their surface only within tolerance).
 - `transversal/divide_face/mod.rs`: when projecting a loop onto a face's surface, fall back to

vendor/truck-shapeops/src/lib.rs

@@ -34,4 +34,7 @@ mod healing;
 pub use healing::{RobustSplitClosedEdgesAndFaces, SplitClosedEdgesAndFaces};
 mod transversal;
 pub use transversal::{and, or, ShapeOpsCurve, ShapeOpsSurface};
+// SolveCraft: exercised by kernel regressions in the workspace CI.
+#[doc(hidden)]
+pub use transversal::IntersectionCurveWithParameters;
 mod alternative;

vendor/truck-shapeops/src/transversal/intersection_curve/mod.rs

@@ -19,12 +19,21 @@ impl<S> From<IntersectionCurveWithParameters<S>> for IntersectionCurve<PolylineC
 impl<S> IntersectionCurveWithParameters<S>
 where S: ParametricSurface3D + SearchNearestParameter<D2, Point = Point3>
 {
+    /// SolveCraft: construct a projected curve, returning `None` for degenerate input.
     pub fn try_new(
         surface0: S,
         surface1: S,
         poly: PolylineCurve<Point3>,
         tol: f64,
     ) -> Option<Self> {
+        // SolveCraft: a point contact is not a curve. Reject it before indexing the
+        // endpoints, and reject collapsed/non-finite segments before normalizing.
+        if poly.len() < 2 || poly.windows(2).any(|p| {
+            let length2 = (p[1] - p[0]).magnitude2();
+            !length2.is_finite() || length2 <= 0.0
+        }) {
+            return None;
+        }
         let mut polyline = PolylineCurve(Vec::new());
         let mut params0 = PolylineCurve(Vec::new());
         let mut params1 = PolylineCurve(Vec::new());

vendor/truck-shapeops/src/transversal/mod.rs

@@ -2,6 +2,9 @@ mod divide_face;
 mod faces_classification;
 mod integrate;
 mod intersection_curve;
+// SolveCraft: expose the constructor for workspace regression coverage of the vendored fix.
+#[doc(hidden)]
+pub use intersection_curve::IntersectionCurveWithParameters;
 mod loops_store;
 mod polyline_construction;
 pub use integrate::{and, or, ShapeOpsCurve, ShapeOpsSurface};