Merge origin/main (with #86): sketch.dimension reports the solved value in the dimension's unit; the spout test expects the solved 30 and 60 degrees

.github/workflows/ci.yml

@@ -98,17 +98,29 @@ jobs:
     if: needs.changes.outputs.native == 'true'
     runs-on: ubuntu-24.04
     timeout-minutes: 90
+    env:
+      CARGO_INCREMENTAL: "0"
+      RUSTC_WRAPPER: sccache
+      SCCACHE_GHA_ENABLED: "true"
+      SCCACHE_IGNORE_SERVER_IO_ERROR: "1"
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - uses: dtolnay/rust-toolchain@stable
       - uses: Swatinem/rust-cache@6323deb102c322ba6fcbdcafc7e3dddab59af2b6 # v2.9.2
         with:
           key: native-tests
+      - name: Set up compiler cache
+        uses: mozilla-actions/sccache-action@fc920bf0ec8de6ee65d409111f7ec508035751ba # v0.0.11
+        with:
+          version: v0.16.0
       - name: Compile tests
         run: cargo test --workspace --profile ci --locked --no-run
       - name: Run tests
         # Every test binary at once (cargo test runs them one after another).
         run: cargo xtask test --locked
+      - name: Compiler cache statistics
+        if: always()
+        run: sccache --show-stats
 
   # Preserve the existing check name for branch protection, including docs-only PRs.
   ci:

.github/workflows/flatpak-pages.yml

@@ -23,7 +23,6 @@ jobs:
     runs-on: ubuntu-24.04
     permissions:
       contents: read
-      pages: write
     env:
       GH_TOKEN: ${{ github.token }}
       RELEASE_TAG: ${{ github.event.release.tag_name || inputs.release_tag }}

ATTRIBUTION.md

@@ -49,3 +49,4 @@ 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/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) |

Cargo.lock

@@ -1753,8 +1753,6 @@ checksum = "f9f8bd3e56ce4dfc153cf470fffbfa98c7620958b312ca5c3a4b8d5181fd13c6"
 [[package]]
 name = "matext4cgmath"
 version = "0.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e6541e181de37f70f0aceb25441823a3d0efa9cc1d23f475a0d3926678949178"
 dependencies = [
  "cgmath",
  "katexit",

Cargo.toml

@@ -98,3 +98,4 @@ debug = 0
 truck-shapeops = { path = "vendor/truck-shapeops" }
 truck-stepio = { path = "vendor/truck-stepio" }
 truck-meshalgo = { path = "vendor/truck-meshalgo" }
+matext4cgmath = { path = "vendor/matext4cgmath" }

ROADMAP.md

@@ -1,6 +1,6 @@
 # SolveCraft roadmap
 
-Status as of **2026-10-09**. SolveCraft targets Fusion-style parametric modelling (sketch →
+Status as of **2026-10-10**. SolveCraft targets Fusion-style parametric modelling (sketch →
 features → parametric timeline) as an open, pure-Rust, agent-drivable application.
 
 ## At a glance
@@ -10,12 +10,19 @@ features → parametric timeline) as an open, pure-Rust, agent-drivable applicat
 | Where are we? | **M0, M1, M13 done; M2, M5–M7, M9, M10, M14 in progress.** Sketch with solver and the full SKETCH create/modify set; extrude, revolve (two sides, symmetric, to object), fillet/chamfer (variable radius, chord length, a radius per edge, corner patches), holes, threads (cosmetic and modelled), patterns, mirror, shell (inside/outside/both), draft, loft, sweep, coil, split body and split face, delete face, construction planes, axes and points; persistent naming of faces and edges; parameters and configurations; components, joints, motion studies, exploded views; sheet metal and a plastic enclosure subset; STEP/IGES/3MF/STL/OBJ/DXF; autosave and crash recovery; desktop and browser (wasm) app, CLI, MCP server, oracle harness. |
 | Command parity (in scope) | **328 / 541 (61%)** in-scope commands; SOLID + SKETCH **185 / 291 (64%)** — [docs/parity.md](docs/parity.md) |
 | Fusion oracle | **76 / 76 parts match** — [docs/oracle.md](docs/oracle.md) |
-| Tests | 596 (41 of them UI scenarios): solver, profiles, kernel booleans/blends/measures, expressions, timeline, persistent naming, file formats and migrations, assemblies, sheet metal, engine end-to-end, hostile-input fuzz over every command |
+| Tests | Solver, profiles, kernel booleans/blends/measures, expressions, timeline, persistent naming, file formats and migrations, assemblies, sheet metal, engine end-to-end, hostile-input fuzz over every command and headless UI scenarios. `cargo xtask ci` reports the current passing counts. |
 | Gates | `cargo xtask ci`: fmt, clippy -D warnings, tests, asset attribution, layering, wasm32 build — green |
 | Time to a useful alpha (M0–M6) | ≈ **82 agent hours** remain (sum of the M1–M6 estimates below) |
 
 ## Scope (owner decision, 2026-10-07)
 
+The issue batch adds preservation of blind pockets in through cuts, associative projected
+offsets and plastic face placements, XZ (+Y normal) with a v6 migration preserving older
+designs, interactive angle placement, file-picker sketch imports, Home/recent controls,
+toolbar overflow, and the remaining component-frame and assembly WIP work. The enclosure
+acceptance scenarios now include board resizes; STEP reopening is automated. Inspection in
+Fusion remains an external acceptance step. See [WIP reconciliation](docs/wip-reconciliation.md).
+
 In scope, in priority order:
 1. SOLID and SKETCH (now).
 2. Parameters / functional constraints (done: see `parameters.*`, `expr.evaluate`; unit-aware,

apps/solvecraft-cli/src/recipe.rs

@@ -10,7 +10,7 @@ fn plane_param(pl: &Value) -> Value {
     let origin_zero = pl.get("origin").and_then(Value::as_array).is_none_or(|o| o.iter().all(|x| x.as_f64().unwrap_or(0.0).abs() < 1e-12));
     let std = match r.to_ascii_uppercase().as_str() {
         "XY" => Some(([1.0, 0.0, 0.0], [0.0, 1.0, 0.0])),
-        "XZ" => Some(([1.0, 0.0, 0.0], [0.0, 0.0, 1.0])),
+        "XZ" => Some(([1.0, 0.0, 0.0], [0.0, 0.0, -1.0])),
         "YZ" => Some(([0.0, 1.0, 0.0], [0.0, 0.0, 1.0])),
         _ => None,
     };

apps/solvecraft/src/main.rs

@@ -61,6 +61,7 @@ fn services() -> Services {
                 .add_filter("STEP", &["step", "stp", "STEP", "STP"])
                 .add_filter("IGES", &["igs", "iges", "IGS", "IGES"])
                 .add_filter("Mesh (3MF, STL)", &["3mf", "3MF", "stl", "STL"])
+                .add_filter("Sketch drawings (DXF, SVG)", &["dxf", "DXF", "svg", "SVG"])
                 .add_filter("All files", &["*"])
                 .pick_file()
                 .map(|p| p.to_string_lossy().to_string())
@@ -69,6 +70,23 @@ fn services() -> Services {
             rfd::FileDialog::new().set_file_name(name).add_filter("File", exts).save_file().map(|p| p.to_string_lossy().to_string())
         })),
         graphics_path: graphics_path().map(|p| p.to_string_lossy().to_string()),
+        show_in_folder: Some(Box::new(|path| {
+            let folder = std::path::Path::new(path).parent().unwrap_or_else(|| std::path::Path::new("."));
+            let mut command = std::process::Command::new(if cfg!(target_os = "windows") {
+                "explorer"
+            } else if cfg!(target_os = "macos") {
+                "open"
+            } else {
+                "xdg-open"
+            });
+            command.arg(folder);
+            #[cfg(target_os = "windows")]
+            {
+                use std::os::windows::process::CommandExt;
+                command.creation_flags(0x08000000);
+            }
+            let _ = command.spawn();
+        })),
     }
 }
 

crates/doc/src/canvas.rs

@@ -34,6 +34,14 @@ pub struct Canvas {
     pub flip: bool,
     #[serde(default = "yes")]
     pub visible: bool,
+    /// The component it belongs to (its plane is in that component's frame, so it moves with
+    /// the component's occurrence); 0 = the root.
+    #[serde(default, skip_serializing_if = "is_root")]
+    pub component: u64,
+}
+
+fn is_root(c: &u64) -> bool {
+    *c == 0
 }
 
 fn half() -> f64 {
@@ -57,7 +65,7 @@ impl Canvas {
         let f = if self.flip { -1.0 } else { 1.0 };
         [rot(-hw * f, -hh), rot(hw * f, -hh), rot(hw * f, hh), rot(-hw * f, hh)]
     }
-    /// Corners in world coordinates.
+    /// Corners on `plane` (in whatever frame the plane is given).
     pub fn world_corners(&self, plane: &Plane) -> [Vec3; 4] {
         self.corners().map(|p| plane.to_world(p))
     }
@@ -66,6 +74,19 @@ impl Canvas {
     }
 }
 
+impl crate::Document {
+    /// A canvas's plane in the world: resolved in its component's frame, then placed where the
+    /// component's occurrence puts it.
+    pub fn canvas_plane(&self, vals: &std::collections::BTreeMap<String, crate::expr::Value>, c: &Canvas) -> crate::Result<Plane> {
+        let p = self.resolve_plane(vals, &c.plane, 0)?;
+        let m = self.component_transform(c.component);
+        if crate::is_identity(&m) {
+            return Ok(p);
+        }
+        Ok(Plane::new(crate::apply_point(&m, p.origin), crate::apply_vector(&m, p.x), crate::apply_vector(&m, p.y)).unwrap_or(p))
+    }
+}
+
 /// Image kind and pixel size from the file header (PNG or JPEG).
 pub fn image_info(b: &[u8]) -> Option<(&'static str, [u32; 2])> {
     if b.len() > 24 && b.starts_with(b"\x89PNG\r\n\x1a\n") {

crates/doc/src/document.rs

@@ -125,7 +125,8 @@ pub struct Extent {
     /// Optional second side distance (two-sided extrude), along the negative normal.
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub distance2: Option<String>,
-    /// Start offset from the sketch plane (expression).
+    /// Start offset from the sketch plane (expression), along the sketch normal whatever the
+    /// direction.
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub start_offset: Option<String>,
     /// Through all bodies in the direction(s) instead of `distance`.
@@ -939,6 +940,66 @@ fn z_axis() -> Vec3 {
 }
 
 impl FeatureKind {
+    /// Sketches the feature is built from (profiles, paths, points): deleting one of them
+    /// deletes the feature. Every kind is listed, so a new one has to say what it uses.
+    pub fn input_sketches(&self) -> Vec<u64> {
+        use FeatureKind as K;
+        match self {
+            K::Extrude { sketch, .. }
+            | K::Revolve { sketch, .. }
+            | K::Emboss { sketch, .. }
+            | K::Rib { sketch, .. }
+            | K::SheetBase { sketch, .. }
+            | K::SheetContour { sketch, .. } => vec![*sketch],
+            K::Sweep { sketch, path_sketch, .. } => vec![*sketch, *path_sketch],
+            K::Pipe { path_sketch, .. } | K::Pattern { pattern: PatternKind::Path { path_sketch, .. }, .. } => vec![*path_sketch],
+            K::Loft { sections, .. } => sections.iter().map(|s| s.sketch).collect(),
+            K::SheetFold { sketch, .. } | K::SplitFace { sketch, .. } | K::Patch { sketch, .. } => sketch.iter().copied().collect(),
+            K::Hole { points, .. } => points.iter().map(|p| p.sketch).collect(),
+            K::Sketch { .. }
+            | K::Pattern { .. }
+            | K::Fillet { .. }
+            | K::Chamfer { .. }
+            | K::Box { .. }
+            | K::Cylinder { .. }
+            | K::Sphere { .. }
+            | K::Torus { .. }
+            | K::Combine { .. }
+            | K::Mirror { .. }
+            | K::Thread { .. }
+            | K::Shell { .. }
+            | K::Draft { .. }
+            | K::ConstructionPlane { .. }
+            | K::Split { .. }
+            | K::ConstructionAxis { .. }
+            | K::ConstructionPoint { .. }
+            | K::Scale { .. }
+            | K::OffsetFace { .. }
+            | K::DeleteFace { .. }
+            | K::BoundingSolid { .. }
+            | K::ReplaceFace { .. }
+            | K::Align { .. }
+            | K::Coil { .. }
+            | K::SheetFlange { .. }
+            | K::SheetHem { .. }
+            | K::SheetUnfold { .. }
+            | K::SheetConvert { .. }
+            | K::Boss { .. }
+            | K::Lip { .. }
+            | K::SnapFit { .. }
+            | K::Rest { .. }
+            | K::BoundaryFill { .. }
+            | K::Remove { .. }
+            | K::Stitch { .. }
+            | K::Thicken { .. }
+            | K::SurfaceExtend { .. }
+            | K::SurfaceTrim { .. }
+            | K::Move { .. }
+            | K::Import { .. }
+            | K::MeshImport { .. } => Vec::new(),
+        }
+    }
+
     /// A sheet metal feature (its result depends on the sheet metal rules).
     pub fn is_plastic(&self) -> bool {
         matches!(self, FeatureKind::Boss { .. } | FeatureKind::Lip { .. } | FeatureKind::SnapFit { .. } | FeatureKind::Rest { .. })
@@ -1115,6 +1176,7 @@ impl FeatureKind {
             FeatureKind::Extrude { extent, .. } => extent.to.iter_mut().chain(extent.from.iter_mut()).collect(),
             FeatureKind::Revolve { to: Some(p), .. } => vec![p],
             FeatureKind::Thread { face, .. } => vec![face],
+            FeatureKind::Boss { position, .. } | FeatureKind::SnapFit { position, .. } | FeatureKind::Rest { position, .. } => vec![position],
             _ => Vec::new(),
         }
     }
@@ -1619,18 +1681,7 @@ impl Document {
     pub fn delete_feature(&mut self, id: u64) -> Result<Vec<u64>> {
         let idx = self.feature_index(id).ok_or_else(|| DocError::Unknown(format!("feature {id}")))?;
         let mut gone = vec![id];
-        for f in &self.features {
-            match &f.kind {
-                FeatureKind::Extrude { sketch, .. } | FeatureKind::Revolve { sketch, .. } if *sketch == id => gone.push(f.id),
-                FeatureKind::Sweep { sketch, path_sketch, .. } if *sketch == id || *path_sketch == id => gone.push(f.id),
-                FeatureKind::Loft { sections, .. } if sections.iter().any(|s| s.sketch == id) => gone.push(f.id),
-                FeatureKind::Pattern { pattern: PatternKind::Path { path_sketch, .. }, .. } if *path_sketch == id => gone.push(f.id),
-                FeatureKind::Emboss { sketch, .. } | FeatureKind::Rib { sketch, .. } if *sketch == id => gone.push(f.id),
-                FeatureKind::SheetBase { sketch, .. } | FeatureKind::SheetContour { sketch, .. } if *sketch == id => gone.push(f.id),
-                FeatureKind::SheetFold { sketch: Some(s), .. } | FeatureKind::SplitFace { sketch: Some(s), .. } if *s == id => gone.push(f.id),
-                _ => {}
-            }
-        }
+        gone.extend(self.features.iter().filter(|f| f.kind.input_sketches().contains(&id)).map(|f| f.id));
         self.features.retain(|f| !gone.contains(&f.id));
         // Configuration columns of deleted features go with them.
         let keep: Vec<bool> = self.configs.columns.iter().map(|c| !matches!(c, crate::config::Column::Suppress(id) if gone.contains(id))).collect();

crates/doc/src/eval.rs

@@ -377,6 +377,10 @@ pub struct Model {
     empty: Arc<ModelState>,
     /// Features recomputed by the last `evaluate`.
     pub last_recomputed: usize,
+    /// Features whose result the last `evaluate` took from the cache instead of recomputing: the
+    /// same feature on the same inputs was evaluated before (an edit set back, undo, redo, a
+    /// configuration row). Their geometry did change since the previous evaluation.
+    pub last_restored: usize,
     /// Results by inputs, shared with this model's copies.
     pub cache: Arc<std::sync::Mutex<EvalCache>>,
     /// Evaluate everything from scratch (no reuse; tests compare the two).
@@ -467,6 +471,22 @@ fn cache_key(f: &Feature, chain_fp: u64, local: u64, ctx: u64, state: &ModelStat
     h.finish()
 }
 
+/// Where components are placed, for a sketch that sees other components' geometry (on a face,
+/// or with projections): it is resolved in its own component's view of them.
+fn placement_digest(doc: &Document, f: &Feature) -> u64 {
+    let FeatureKind::Sketch { plane, sketch } = &f.kind else { return 0 };
+    if doc.occurrences.is_empty() || (!matches!(plane, PlaneRef::Face { .. }) && sketch.links.is_empty()) {
+        return 0;
+    }
+    let mut h = std::collections::hash_map::DefaultHasher::new();
+    for o in &doc.occurrences {
+        o.id.hash(&mut h);
+        o.transform.iter().flatten().for_each(|x| x.to_bits().hash(&mut h));
+    }
+    serde_json::to_string(&doc.body_offsets).unwrap_or_default().hash(&mut h);
+    h.finish()
+}
+
 fn now() -> web_time::Instant {
     web_time::Instant::now()
 }
@@ -505,11 +525,12 @@ impl Model {
         let mut out: Vec<FeatureResult> = Vec::with_capacity(doc.features.len());
         let mut reuse = !self.no_cache;
         let mut recomputed = 0;
+        let mut restored = 0;
         let marker = doc.marker.unwrap_or(usize::MAX);
         let ctx = context_digest(doc, &vals);
         for (i, f) in doc.features.iter().enumerate() {
             let rolled_back = i >= marker;
-            let mut fp = fingerprint(prev_fp, f, &vals, rolled_back);
+            let mut fp = fingerprint(prev_fp, f, &vals, rolled_back) ^ placement_digest(doc, f);
             // Sheet metal features also depend on the rules (and the parameters they use).
             if f.kind.is_sheet() {
                 let mut h = std::collections::hash_map::DefaultHasher::new();
@@ -565,10 +586,11 @@ impl Model {
                 continue;
             }
             // The same feature on the same inputs: its earlier result.
-            let key = cache_key(f, fp, fingerprint(0, f, &vals, false), ctx, &state);
+            let key = cache_key(f, fp, fingerprint(0, f, &vals, false) ^ placement_digest(doc, f), ctx, &state);
             if !self.no_cache
                 && let Some(c) = self.cache.lock().ok().and_then(|mut m| m.get(key))
             {
+                restored += 1;
                 if c.error.is_none() {
                     state = c.state.clone();
                 }
@@ -652,6 +674,7 @@ impl Model {
         }
         self.results = out;
         self.last_recomputed = recomputed;
+        self.last_restored = restored;
     }
 }
 
@@ -1398,6 +1421,20 @@ fn feature_tools(vals: &BTreeMap<String, Value>, f: &Feature, st: &ModelState) -
             }
             let mut tools = Vec::new();
             for r in &regions {
+                if *operation == Operation::Join {
+                    let exact = kernel::extrude(&ss.plane, std::slice::from_ref(r), lo + off, hi + off)?;
+                    if exact.iter().all(|tool| {
+                        st.bodies
+                            .iter()
+                            .filter(|b| targets.is_empty() || targets.contains(&b.name))
+                            .any(|b| kernel::can_join_touching_faces(&b.body, tool))
+                    }) {
+                        // Preserve a whole touching face: extending into a chamfer replaces
+                        // the sewable seam with a coincident curved intersection.
+                        tools.extend(exact);
+                        continue;
+                    }
+                }
                 let (l2, h2) = extend_for_coplanar(st, &ss.plane, r, lo + off, hi + off, *operation, targets);
                 let probe = |p: Vec2| (1..4).map(|k| ss.plane.to_world(p) + n * (lo + off + (hi - lo) * k as f64 / 4.0)).collect::<Vec<_>>();
                 let r = grow_profile_for_coplanar(st, r, *operation, targets, &probe);
@@ -2281,17 +2318,25 @@ fn eval_feature(doc: &Document, vals: &BTreeMap<String, Value>, f: &Feature, st:
         | FeatureKind::Align { .. }
         | FeatureKind::Remove { .. } => more::eval(doc, vals, f, st),
         FeatureKind::Sketch { plane, sketch } => {
+            let fst = state_in_frame(doc, st, f.component);
             let (plane, face_warning) = match plane {
-                PlaneRef::Face { plane: picked, at, name } => face_plane(st, picked, *at, name.as_deref()),
-                other => (doc.resolve_plane_in(vals, other, 0, Some(st))?, None),
+                PlaneRef::Face { plane: picked, at, name } => face_plane(&fst, picked, *at, name.as_deref()),
+                other => (doc.resolve_plane_in(vals, other, 0, Some(&fst))?, None),
             };
             let mut sk = sketch.clone();
-            let mut warns = crate::project::refresh_links(doc, vals, st, &plane, &mut sk);
+            let mut warns = crate::project::refresh_links(doc, vals, &fst, &plane, &mut sk);
+            drop(fst);
+            sk.refresh_offsets()?;
             if let Some(w) = face_warning {
                 warns.insert(0, w);
             }
             doc.apply_dimension_values(vals, &mut sk)?;
-            let report = solve(&mut sk);
+            let mut report = solve(&mut sk);
+            if !sk.offsets.is_empty() {
+                // Source dimensions may have moved curves during the solve.
+                sk.refresh_offsets()?;
+                report = solve(&mut sk);
+            }
             if !report.ok() {
                 warns.insert(0, format!("the sketch constraints conflict ({})", report.failing.join(", ")));
             }
@@ -2811,6 +2856,52 @@ fn unique_body_name(st: &ModelState, base: &str) -> String {
     (2..).map(|i| format!("{base} ({i})")).find(|n| st.body(n).is_none()).unwrap_or_else(|| base.to_string())
 }
 
+/// The model as a component sees it: bodies and sketches of components placed differently from
+/// it are moved into its frame (through both placements), so a sketch on another component's
+/// face finds the face where it is shown and projects its edges there. The model itself when
+/// every placement agrees (the usual case).
+pub fn state_in_frame<'a>(doc: &Document, st: &'a ModelState, comp: u64) -> std::borrow::Cow<'a, ModelState> {
+    use std::borrow::Cow;
+    if doc.occurrences.is_empty() && doc.body_offsets.is_empty() {
+        return Cow::Borrowed(st);
+    }
+    let Some(inv) = crate::mat_inverse(&doc.component_transform(comp)) else { return Cow::Borrowed(st) };
+    let comp_of_feature = |id: u64| doc.feature(id).map(|f| f.component).unwrap_or(0);
+    let rel = |c: u64, body: Option<&str>| {
+        let m = crate::mat_mul(&inv, &doc.component_transform(c));
+        match body.and_then(|b| doc.body_offsets.get(b)) {
+            Some(o) => crate::mat_mul(&m, o),
+            None => m,
+        }
+    };
+    let body_m: Vec<Mat> = st.bodies.iter().map(|b| rel(doc.body_component(&b.name, b.feature), Some(&b.name))).collect();
+    let sketch_m: Vec<Mat> = st.sketches.iter().map(|s| rel(comp_of_feature(s.feature), None)).collect();
+    if body_m.iter().chain(&sketch_m).all(crate::is_identity) {
+        return Cow::Borrowed(st);
+    }
+    let mut out = st.clone();
+    for (b, m) in out.bodies.iter_mut().zip(&body_m) {
+        if !crate::is_identity(m)
+            && let Ok(t) = kernel::transform_matrix(&b.body, *m)
+        {
+            // Moving a body keeps its faces (and their order): it keeps their names.
+            let names = crate::naming::face_names(b);
+            let mut nb = ModelBody::new(b.name.clone(), t, b.feature);
+            nb.component = b.component;
+            nb.names = crate::naming::NameCell::known(names);
+            *b = nb;
+        }
+    }
+    for (s, m) in out.sketches.iter_mut().zip(&sketch_m) {
+        if !crate::is_identity(m)
+            && let Some(np) = Plane::new(crate::apply_point(m, s.plane.origin), crate::apply_vector(m, s.plane.x), crate::apply_vector(m, s.plane.y))
+        {
+            s.plane = np;
+        }
+    }
+    Cow::Owned(out)
+}
+
 /// The model placed in the world: each component's bodies, sketches and threads through every
 /// occurrence of it (bodies of the first placement keep their names; further instances get the
 /// occurrence path in brackets). Without components this is the model itself.

crates/doc/src/eval_more.rs

@@ -613,7 +613,12 @@ fn face_loops(mesh: &solvecraft_geom::Mesh, plane: &Plane, at: Vec3, n: Vec3, le
 /// The body a placed plastic feature joins: by name, else the one under the point.
 fn body_under(st: &ModelState, body: &Option<String>, p: Vec3) -> Result<String> {
     let i = body_at(st, body, &[p])?;
-    st.bodies.get(i).map(|b| b.name.clone()).ok_or_else(|| DocError::Invalid("there is no body".into()))
+    let b = st.bodies.get(i).ok_or_else(|| DocError::Invalid("there is no body".into()))?;
+    let tolerance = (b.body.size() * 1e-5).max(1e-4);
+    if crate::project::nearest_face(&b.mesh(), p).is_none_or(|(_, _, distance)| distance > tolerance) {
+        return Err(DocError::Invalid("the plastic feature's placement is no longer on its body face".into()));
+    }
+    Ok(b.name.clone())
 }
 
 /// Axes with z along `z` (and x along `x` when given).

crates/doc/src/format.rs

@@ -18,13 +18,15 @@
 //!   ["*"]` (every body), which is what they did, so those designs keep their shape.
 //! - 4: joint origins mate by default (B's z against A's, as Fusion does); `flip` now means
 //!   "don't mate". Older joints keep their placement: their `flip` is inverted.
+//! - 6: XZ origin planes use sketch y = -Z and normal +Y. Older XZ references become
+//!   explicit planes retaining their previous axes, including offset-plane expressions.
 
 use serde_json::Value;
 
 use crate::{DocError, Document, Result};
 
 /// The format this build writes.
-pub const FORMAT: u32 = 5;
+pub const FORMAT: u32 = 6;
 
 pub fn format_string(n: u32) -> String {
     format!("solvecraft/{n}")
@@ -37,7 +39,30 @@ pub fn version_of(s: &str) -> Option<u32> {
 
 /// JSON-level upgrades: entry `i` turns format `i + 1` into `i + 2`.
 type JsonStep = fn(&mut Value) -> Result<()>;
-const JSON_STEPS: [JsonStep; 4] = [|_| Ok(()), v2_to_v3, v3_to_v4, v4_to_v5];
+const JSON_STEPS: [JsonStep; 5] = [|_| Ok(()), v2_to_v3, v3_to_v4, v4_to_v5, v5_to_v6];
+
+/// Old XZ references retain their exact frame, including nested offset and angled planes.
+/// New origin references use +Y; freezing the old frame avoids changing sketch coordinates,
+/// dimensions, profiles, extrude directions or parameter expressions in saved designs.
+fn v5_to_v6(v: &mut Value) -> Result<()> {
+    fn preserve(v: &mut Value) {
+        match v {
+            Value::Object(o) => {
+                let old_xz = o.get("type").and_then(Value::as_str) == Some("origin")
+                    && o.get("name").and_then(Value::as_str).is_some_and(|n| n.eq_ignore_ascii_case("XZ") || n.eq_ignore_ascii_case("FRONT"));
+                if old_xz {
+                    *v = serde_json::json!({"type": "custom", "plane": {"origin": [0, 0, 0], "x_dir": [1, 0, 0], "y_dir": [0, 0, 1]}});
+                } else {
+                    o.values_mut().for_each(preserve);
+                }
+            }
+            Value::Array(a) => a.iter_mut().for_each(preserve),
+            _ => {}
+        }
+    }
+    preserve(v);
+    Ok(())
+}
 
 /// Features in designs with components keep reaching every body.
 fn v4_to_v5(v: &mut Value) -> Result<()> {
@@ -198,6 +223,32 @@ mod tests {
         assert_eq!(back, d);
     }
 
+    #[test]
+    fn old_xz_and_nested_offsets_keep_their_frame() {
+        let mut doc = Document::new("old XZ");
+        let id = doc
+            .add_feature(
+                crate::FeatureKind::ConstructionPlane {
+                    plane: crate::PlaneRef::Offset { base: Box::new(crate::PlaneRef::Origin { name: "XZ".into() }), distance: "7 mm".into() },
+                },
+                None,
+            )
+            .unwrap();
+        let mut json: Value = serde_json::from_str(&doc.to_json()).unwrap();
+        json["format"] = Value::from("solvecraft/5");
+        let migrated = read(&json.to_string()).unwrap();
+        let crate::FeatureKind::ConstructionPlane { plane } = &migrated.feature(id).unwrap().kind else { panic!("plane") };
+        let (values, errors) = migrated.param_values();
+        assert!(errors.is_empty());
+        let p = migrated.resolve_plane(&values, plane, 0).unwrap();
+        assert_eq!(p.y, solvecraft_geom::Vec3::Z);
+        assert_eq!(p.normal(), -solvecraft_geom::Vec3::Y);
+        assert_eq!(p.origin, solvecraft_geom::Vec3::new(0.0, -7.0, 0.0));
+        assert_eq!(read(&migrated.to_json()).unwrap(), migrated);
+        let fresh = doc.resolve_plane(&values, &crate::PlaneRef::Origin { name: "XZ".into() }, 0).unwrap();
+        assert_eq!(fresh.normal(), solvecraft_geom::Vec3::Y);
+    }
+
     #[test]
     fn older_upgraded_newer_refused_others_rejected() {
         let mut v: Value = serde_json::from_str(&Document::new("A").to_json()).unwrap();

crates/doc/src/lib.rs

@@ -29,7 +29,7 @@ pub use assembly::{IDENTITY, Mat, Occurrence, apply_point, apply_vector, is_iden
 pub use document::*;
 pub use eval::{
     EdgeRef, FeatureResult, Model, ModelBody, ModelState, SolvedSketch, ThreadInfo, edge_names_for, edge_refs, parse_metric_thread, pattern_matrices,
-    world_state,
+    state_in_frame, world_state,
 };
 pub use params::{ParamRow, ParamUser, cycles};
 pub use solvecraft_kernel as kernel;

crates/doc/src/naming.rs

@@ -34,6 +34,12 @@ impl NameCell {
     pub fn new(origin: Option<Arc<NamingOrigin>>) -> Self {
         NameCell { origin, names: Arc::new(OnceLock::new()) }
     }
+    /// Names already known (a moved copy of a body keeps its faces' names).
+    pub fn known(names: Arc<Vec<String>>) -> Self {
+        let cell = OnceLock::new();
+        let _ = cell.set(names);
+        NameCell { origin: None, names: Arc::new(cell) }
+    }
 }
 
 /// Deeper chains than this are named by position only (bounded work and stack).

crates/doc/src/project.rs

@@ -273,7 +273,20 @@ pub fn refresh_links(doc: &Document, vals: &BTreeMap<String, Value>, st: &ModelS
     let mut warn = Vec::new();
     let links = sk.links.clone();
     for l in &links {
-        match resolve(doc, vals, st, plane, l.kind, &l.source) {
+        let mut source = l.source.clone();
+        if let (Some(name), LinkSource::Face { at, .. }) = (&l.face_name, &mut source) {
+            if let Some((p, split)) = crate::naming::point_on_face(st, name, *at) {
+                *at = p;
+                if split {
+                    warn.push(format!("projected face `{name}` was split; using the nearest piece"));
+                }
+            } else {
+                sk.set_link_lost(&l.id, true);
+                warn.push(format!("projected face `{name}` no longer exists"));
+                continue;
+            }
+        }
+        match resolve(doc, vals, st, plane, l.kind, &source) {
             Ok(r) => {
                 sk.set_link_source(&l.id, r.source);
                 let _ = sk.set_link_wires(&l.id, &r.wires);
@@ -472,7 +485,7 @@ fn tilted_circle(plane: &Plane, pts: &[Vec3]) -> Option<Vec<LinkGeom>> {
     let (c, n, r, closed) = circle3(pts)?;
     let sn = plane.normal();
     let cosang = n.dot(sn).abs();
-    if cosang > 1.0 - 1e-12 || cosang < 1e-9 {
+    if !(1e-9..=1.0 - 1e-12).contains(&cosang) {
         return None;
     }
     if closed {

crates/doc/src/sheet.rs

@@ -899,7 +899,7 @@ impl SheetBody {
             return Err(DocError::Invalid("the hem is shorter than its bend".into()));
         }
         // A hem folds back over the face it starts from (toward the bottom unless flipped).
-        let up = !top == flip;
+        let up = top != flip;
         let up = !up;
         self.flanges.push(SheetFlange {
             parent: panel,

crates/doc/src/tests.rs

@@ -81,6 +81,26 @@ fn parametric_plate_reevaluates() {
     assert!(rel(measure(&m.state().bodies[0].body).unwrap().volume, 50.0 * 30.0 * 10.0) < 1e-9);
 }
 
+/// Setting a parameter back takes the earlier results from the cache: nothing is recomputed, but
+/// the evaluation reports the features it restored (their geometry did change back).
+#[test]
+fn set_back_reports_restored_features() {
+    let (mut doc, _) = plate_doc();
+    let mut m = Model::new();
+    m.evaluate(&doc);
+    assert_eq!((m.last_recomputed, m.last_restored), (2, 0));
+    doc.set_param("width", "50 mm", None, None).unwrap();
+    m.evaluate(&doc);
+    assert_eq!((m.last_recomputed, m.last_restored), (2, 0));
+    doc.set_param("width", "40 mm", None, None).unwrap();
+    m.evaluate(&doc);
+    assert_eq!((m.last_recomputed, m.last_restored), (0, 2));
+    assert!(rel(measure(&m.state().bodies[0].body).unwrap().volume, 24000.0) < 1e-9);
+    // No change: nothing recomputed and nothing restored.
+    m.evaluate(&doc);
+    assert_eq!((m.last_recomputed, m.last_restored), (0, 0));
+}
+
 #[test]
 fn box_fillet_cut_timeline() {
     let (mut doc, _) = plate_doc();
@@ -275,3 +295,53 @@ fn parameter_cycles_are_found() {
     assert!(errs["a"].contains("circular reference: a → b → c → a"), "{}", errs["a"]);
     assert!(vals.contains_key("d") && errs.contains_key("a") && errs.contains_key("e"));
 }
+
+/// Features that use a sketch's points or regions go with it (not only profile and path users).
+#[test]
+fn input_sketches_cover_points_and_patches() {
+    let hole: FeatureKind = serde_json::from_value(serde_json::json!({
+        "type": "hole", "position": [0, 0, 0], "direction": [0, 0, -1], "diameter": "3",
+        "points": {"sketch": 7, "ids": ["p1"]},
+    }))
+    .unwrap();
+    assert_eq!(hole.input_sketches(), vec![7]);
+    let patch: FeatureKind = serde_json::from_value(serde_json::json!({"type": "patch", "sketch": 9})).unwrap();
+    assert_eq!(patch.input_sketches(), vec![9]);
+    let pipe: FeatureKind = serde_json::from_value(serde_json::json!({"type": "pipe", "path_sketch": 72, "path": ["l1"], "diameter": "4"})).unwrap();
+    assert_eq!(pipe.input_sketches(), vec![72]);
+}
+
+/// Guard for `FeatureKind::input_sketches`: a variant with a field that refers to a sketch
+/// (a field named `*sketch*` holding an id, sketch points or loft sections) must not sit in the
+/// arm that returns no sketches. New variants are caught by the compiler (the match has no
+/// wildcard); this catches a sketch field added to an existing variant.
+#[test]
+fn input_sketches_lists_every_variant_with_a_sketch_field() {
+    let src = include_str!("document.rs");
+    let body = src.split("pub enum FeatureKind {").nth(1).and_then(|s| s.split("\n}\n").next()).unwrap();
+    let mut with_sketch = Vec::new();
+    let mut variant = "";
+    for line in body.lines() {
+        let t = line.trim();
+        if line.starts_with("    ") && !line.starts_with("     ") && t.chars().next().is_some_and(|c| c.is_ascii_uppercase()) {
+            variant = t.split(|c: char| !c.is_alphanumeric()).next().unwrap_or("");
+            continue;
+        }
+        let Some((name, ty)) = t.strip_prefix("pub ").unwrap_or(t).split_once(':') else { continue };
+        let refers = (name.contains("sketch") && (ty.contains("u64") || ty.contains("SketchPoints")))
+            || ty.contains("SketchPoints")
+            || ty.contains("LoftSection");
+        if refers && !line.trim_start().starts_with("//") && !with_sketch.contains(&variant) {
+            with_sketch.push(variant);
+        }
+    }
+    assert!(with_sketch.len() >= 10, "the FeatureKind parse found too few sketch users: {with_sketch:?}");
+    let f = src.split("pub fn input_sketches(&self)").nth(1).unwrap();
+    let empty_arm = f.split("=> Vec::new()").next().and_then(|s| s.rsplit("=> ").next()).unwrap();
+    for v in with_sketch {
+        assert!(
+            !empty_arm.contains(&format!("K::{v} {{")),
+            "FeatureKind::{v} has a sketch field but input_sketches says it uses no sketch: deleting the sketch would leave it broken"
+        );
+    }
+}

crates/engine/src/boolean_regression_tests.rs

@@ -0,0 +1,66 @@
+//! Booleans that failed, panicked or hung, replayed from the scripts in
+//! `examples/regressions/` (each script's description says what went wrong).
+
+use serde_json::{Value, json};
+
+use crate::Session;
+
+fn replay(script: &str) -> Session {
+    let mut s = Session::default();
+    let script: Value = serde_json::from_str(script).unwrap();
+    s.run_script(&script).unwrap();
+    s
+}
+
+fn volume(s: &Session, body: &str) -> f64 {
+    s.model.state().body(body).map(|b| solvecraft_kernel::measure(&b.body).unwrap().volume).unwrap_or(0.0)
+}
+
+/// Slab less a 557.68 × 100 × 120 pocket and the loft below its floor (556.68 × 99 down 4 mm to
+/// 80 × 80; prismatoid: h/6 · (A_top + A_bottom + 4 A_mid)).
+fn slab_pocket_loft() -> (f64, f64) {
+    let slab = 900.0 * 480.0 * 160.0;
+    let loft = 4.0 / 6.0 * (556.68 * 99.0 + 80.0 * 80.0 + 4.0 * (556.68 + 80.0) / 2.0 * (99.0 + 80.0) / 2.0);
+    (slab - 557.68 * 100.0 * 120.0, loft)
+}
+
+#[test]
+fn loft_cut_beside_a_round_hole() {
+    let s = replay(include_str!("../../../examples/regressions/loft_cut_beside_round_hole.json"));
+    let (pocketed, loft) = slab_pocket_loft();
+    let hole = std::f64::consts::PI * 17.5 * 17.5 * 25.0;
+    let want = pocketed - loft - hole;
+    let got = volume(&s, "Body1");
+    assert!((got - want).abs() < 1e-6 * want, "{got} vs {want}");
+}
+
+#[test]
+fn shallow_loft_cut_from_the_top_face() {
+    let s = replay(include_str!("../../../examples/regressions/shallow_loft_cut_from_top_face.json"));
+    let (_, loft) = slab_pocket_loft();
+    let want = 900.0 * 480.0 * 160.0 - loft;
+    let got = volume(&s, "Body1");
+    assert!((got - want).abs() < 1e-9 * want, "{got} vs {want}");
+}
+
+#[test]
+fn oblique_cut_through_a_small_arc_matches_a_split() {
+    let scripts = [
+        include_str!("../../../examples/regressions/oblique_cut_of_cylinder.json"),
+        include_str!("../../../examples/regressions/oblique_cut_of_cylinder_hang.json"),
+    ];
+    // The same bar split by the prism's tilted top: the piece above it is the cut's result.
+    let mut split = Session::default();
+    let script: Value = serde_json::from_str(scripts[0]).unwrap();
+    let steps = script.get("commands").and_then(Value::as_array).unwrap();
+    split.run_script(&Value::Array(steps[..5].to_vec())).unwrap();
+    let whole = volume(&split, "Tool");
+    split.execute("solid.split_body", &json!({"body": "Tool", "plane": {"origin": [0, -472, 853.91], "normal": [0, 15.44, 40]}})).unwrap();
+    let above = volume(&split, "Tool");
+    assert!(above < whole - 10.0, "{above} of {whole}");
+    for script in scripts {
+        let s = replay(script);
+        let got = volume(&s, "Tool");
+        assert!((got - above).abs() < 1e-6 * above, "{got} vs {above}");
+    }
+}

crates/engine/src/cmd/browser.rs

@@ -495,7 +495,9 @@ mod tests {
         assert!((zmax(&mut s) - 5.0).abs() < 1e-6);
         run(&mut s, "sketch.redefine", json!({"sketch": sk, "plane": "XZ"}));
         let z = zmax(&mut s);
-        assert!(z > 9.0, "the profile stands up on XZ: {z}");
+        assert!(z.abs() < 1e-6, "positive sketch Y on XZ extends toward -Z: {z}");
+        let ymin = run(&mut s, "inspect.measure", json!({}))["bodies"][0]["bbox"]["min"][2].as_f64().unwrap();
+        assert!((ymin + 20.0).abs() < 1e-6);
         assert!(s.execute("sketch.redefine", &json!({"sketch": sk, "plane": "nope"})).is_err());
         assert!(s.execute("sketch.redefine", &json!({"sketch": 999, "plane": "XY"})).is_err());
     }

crates/engine/src/cmd/edit.rs

@@ -10,6 +10,12 @@ use crate::{EngineError, Result, Sel, Session, Snapshot};
 pub static COMMANDS: &[CommandSpec] = &[
     CommandSpec::new("edit.undo", "Undo", undo).icon("undo").key("Ctrl+Z").noundo(),
     CommandSpec::new("edit.redo", "Redo", redo).icon("redo").key("Ctrl+Y").noundo(),
+    CommandSpec::new("edit.checkpoint", "Checkpoint", checkpoint)
+        .noundo()
+        .params("→ {checkpoint: id}: remember the design, active sketch and undo history (restore with edit.restore_checkpoint)"),
+    CommandSpec::new("edit.restore_checkpoint", "Restore Checkpoint", restore_checkpoint)
+        .noundo()
+        .params("checkpoint: id; forget?: bool (true = drop it without going back). Goes back to it, undo history included"),
     CommandSpec::new("timeline.compute_all", "Compute All", compute_all).at("SOLID", "MODIFY").icon("compute").noundo(),
     CommandSpec::new("timeline.delete", "Delete", delete)
         .at("SOLID", "MODIFY")
@@ -28,8 +34,10 @@ pub static COMMANDS: &[CommandSpec] = &[
         .noundo()
         .params("feature: id|name → features deleted with it, and features that would fail without it"),
     CommandSpec::new("timeline.suppress", "Suppress Feature", suppress).params("feature: id|name, suppressed?: bool (default toggles)"),
-    CommandSpec::new("timeline.edit", "Edit Feature", edit_feature)
-        .params("feature: id|name, set: {fields to change, e.g. {\"extent\": {\"distance\": \"30\"}}}"),
+    CommandSpec::new("timeline.edit", "Edit Feature", edit_feature).params(
+        "feature: id|name, set: {fields to change, e.g. {\"extent\": {\"distance\": \"30\"}}} → recomputed: features rebuilt, \
+             restored: features whose earlier result for the same inputs was reused",
+    ),
     CommandSpec::new("select.set", "Select", select_set)
         .noundo()
         .params("items: [{type: body|edge|face|feature|sketch_curve|sketch_point|profile, …}], add?: bool"),
@@ -58,6 +66,21 @@ fn redo(s: &mut Session, _p: &Value) -> Result<Value> {
     Ok(json!({"redone": label}))
 }
 
+fn checkpoint(s: &mut Session, _p: &Value) -> Result<Value> {
+    Ok(json!({"checkpoint": s.checkpoint()}))
+}
+
+fn restore_checkpoint(s: &mut Session, p: &Value) -> Result<Value> {
+    let cmd = "edit.restore_checkpoint";
+    let id = p.get("checkpoint").and_then(Value::as_u64).ok_or_else(|| bad(cmd, "`checkpoint` must be an id from edit.checkpoint"))?;
+    if bool_(p, "forget") == Some(true) {
+        s.drop_checkpoint(id);
+        return Ok(json!({"checkpoint": id, "restored": false}));
+    }
+    s.restore_checkpoint(id)?;
+    Ok(json!({"checkpoint": id, "restored": true}))
+}
+
 fn compute_all(s: &mut Session, _p: &Value) -> Result<Value> {
     s.model = solvecraft_doc::Model::new();
     s.refresh();
@@ -204,7 +227,7 @@ fn edit_feature(s: &mut Session, p: &Value) -> Result<Value> {
     if let Some(e) = s.model.result(id).and_then(|r| r.error.clone()) {
         return Err(EngineError::Other(e));
     }
-    Ok(json!({"feature": id, "recomputed": s.model.last_recomputed}))
+    Ok(json!({"feature": id, "recomputed": s.model.last_recomputed, "restored": s.model.last_restored}))
 }
 
 fn select_set(s: &mut Session, p: &Value) -> Result<Value> {
@@ -307,7 +330,7 @@ fn redefine(s: &mut Session, p: &Value) -> Result<Value> {
     if let Some(e) = s.model.result(id).and_then(|r| r.error.clone()) {
         return Err(EngineError::Other(e));
     }
-    Ok(json!({"feature": id, "recomputed": s.model.last_recomputed}))
+    Ok(json!({"feature": id, "recomputed": s.model.last_recomputed, "restored": s.model.last_restored}))
 }
 
 fn dependents(s: &mut Session, p: &Value) -> Result<Value> {

crates/engine/src/cmd/features.rs

@@ -13,7 +13,7 @@ pub static COMMANDS: &[CommandSpec] = &[
         .at("SOLID", "CREATE")
         .icon("extrude")
         .key("E")
-        .params("distance: expr (or through_all: true); taper?: angle expr; sketch?: id|name (default: active or last sketch); profiles?: all | [index] | [[curve ids]] | [{point:[x,y]}]; face?: [x,y,z] (extrude a planar body face instead of a sketch profile); direction?: positive|negative|symmetric; distance2?; start_offset?; to?: [x,y,z] (To Object: a face, vertex or point; to_offset?: expr past it); from?: [x,y,z] (From Object: start at that face or point); operation?: new|join|cut|intersect|auto (cut into a body, join out of one, else new); targets?: [body]; name?; body_name?"),
+        .params("distance: expr (or through_all: true); taper?: angle expr; sketch?: id|name (default: active or last sketch); profiles?: all | [index] | [[curve ids]] | [{point:[x,y]}]; face?: [x,y,z] (extrude a planar body face instead of a sketch profile); direction?: positive|negative|symmetric; distance2?; start_offset?: expr (along the sketch normal, also with direction: negative); to?: [x,y,z] (To Object: a face, vertex or point; to_offset?: expr past it); from?: [x,y,z] (From Object: start at that face or point); operation?: new|join|cut|intersect|auto (cut into a body, join out of one, else new); targets?: [body]; name?; body_name?"),
     CommandSpec::new("solid.revolve", "Revolve", revolve)
         .at("SOLID", "CREATE")
         .icon("revolve")
@@ -581,7 +581,7 @@ fn press_pull(s: &mut Session, p: &Value) -> Result<Value> {
             let new = format!("({old}) + ({distance})");
             let r = super::find_command("timeline.edit").ok_or_else(|| bad(cmd, "timeline.edit"))?;
             let out = (r.run)(s, &json!({"feature": f.id, "set": {key: new}}))?;
-            return Ok(json!({"feature": f.id, "edited": f.name, key: new, "recomputed": out.get("recomputed")}));
+            return Ok(json!({"feature": f.id, "edited": f.name, key: new, "recomputed": out.get("recomputed"), "restored": out.get("restored")}));
         }
         // Another curved face moves along its normal.
         let r = super::find_command("solid.offset_face").ok_or_else(|| bad(cmd, "solid.offset_face"))?;

crates/engine/src/cmd/measure_sel.rs

@@ -55,13 +55,13 @@ fn densify(pts: &[Vec3]) -> Vec<Vec3> {
 
 /// The mesh edge a selection means: by index if it still passes through the point, otherwise
 /// the nearest.
-fn edge_points(m: &Mesh, index: usize, point: Vec3) -> Option<Vec<Vec3>> {
+fn edge_index(m: &Mesh, index: usize, point: Vec3) -> Option<usize> {
     let near = |e: &Vec<Vec3>| e.windows(2).map(|w| point.dist_to_segment(w[0], w[1])).fold(f64::INFINITY, f64::min);
     let tol = m.bounds().diagonal().max(1.0) * 1e-6;
-    if let Some(e) = m.edges.get(index).filter(|e| near(e) < tol) {
-        return Some(e.clone());
+    if m.edges.get(index).is_some_and(|e| near(e) < tol) {
+        return Some(index);
     }
-    m.edges.iter().min_by(|a, b| near(a).total_cmp(&near(b))).cloned()
+    m.edges.iter().enumerate().min_by(|(_, a), (_, b)| near(a).total_cmp(&near(b))).map(|(i, _)| i)
 }
 
 fn face_tris(m: &Mesh, f: usize) -> Vec<[Vec3; 3]> {
@@ -75,15 +75,23 @@ fn describe(s: &Session, sel: &Sel) -> Option<(Geo, Option<Vec3>, Value)> {
         Sel::Vertex { point, .. } => (Geo::Points(vec![*point]), None, json!({"type": "vertex", "position": point})),
         Sel::Edge { body, index, point } => {
             let m = st.body(body)?.mesh();
-            let pts = edge_points(&m, *index, *point)?;
+            let index = edge_index(&m, *index, *point)?;
+            let pts = m.edges.get(index)?;
+            let rim = m.circular_rim(index);
+            if rim.len() > 1 {
+                let pieces: Vec<&Vec<Vec3>> = rim.iter().filter_map(|&i| m.edges.get(i)).collect();
+                let len: f64 = pieces.iter().map(|p| polyline_len(p)).sum();
+                let points = pieces.iter().flat_map(|p| densify(p)).collect();
+                return Some((Geo::Points(points), None, json!({"type": "edge", "length_mm": len})));
+            }
             let (a, b) = (*pts.first()?, *pts.last()?);
             let straight = (b - a).normalized().filter(|d| pts.iter().all(|p| (*p - a).cross(*d).len() < 1e-6 * (1.0 + a.dist(b))));
-            let len = polyline_len(&pts);
-            (Geo::Points(densify(&pts)), straight, json!({"type": "edge", "length_mm": len}))
+            let len = polyline_len(pts);
+            (Geo::Points(densify(pts)), straight, json!({"type": "edge", "length_mm": len}))
         }
         Sel::Face { body, index, .. } => {
             let m = st.body(body)?.mesh();
-            let tris = face_tris(&m, *index);
+            let tris = m.surface_patch(*index).into_iter().flat_map(|f| face_tris(&m, f)).collect::<Vec<_>>();
             let area: f64 = tris.iter().map(|[a, b, c]| (*b - *a).cross(*c - *a).len() * 0.5).sum();
             let normals: Vec<Vec3> = tris.iter().filter_map(|[a, b, c]| (*b - *a).cross(*c - *a).normalized()).collect();
             let planar = normals.first().copied().filter(|n0| normals.iter().all(|n| n.dot(*n0) > 1.0 - 1e-6));
@@ -150,10 +158,41 @@ fn closest(a: &Geo, b: &Geo) -> Option<(Vec3, Vec3)> {
 pub(crate) fn measure_items(s: &Session, items: &Value) -> Result<Value> {
     let cmd = "inspect.measure";
     let list = items.as_array().ok_or_else(|| bad(cmd, "`items` must be a list of selections"))?;
-    if list.is_empty() || list.len() > 2 {
+    if list.is_empty() || list.len() > 1000 {
         return Err(bad(cmd, "measure one or two items"));
     }
-    let sels: Vec<Sel> = list.iter().map(|v| serde_json::from_value::<Sel>(v.clone()).map_err(|e| bad(cmd, e.to_string()))).collect::<Result<_>>()?;
+    let st = s.world_state();
+    let mut sels = Vec::new();
+    for value in list {
+        let mut sel = serde_json::from_value::<Sel>(value.clone()).map_err(|e| bad(cmd, e.to_string()))?;
+        // Two kernel halves of one visible item are one measurement target.
+        match &mut sel {
+            Sel::Edge { body, index, point } => {
+                if let Some(b) = st.body(body) {
+                    let m = b.mesh();
+                    let resolved = edge_index(&m, *index, *point).unwrap_or(*index);
+                    *index = m.circular_rim(resolved).first().copied().unwrap_or(resolved);
+                }
+            }
+            Sel::Face { body, index, .. } => {
+                if let Some(b) = st.body(body) {
+                    *index = b.mesh().surface_patch(*index).first().copied().unwrap_or(*index);
+                }
+            }
+            _ => {}
+        }
+        let duplicate = sels.iter().any(|x| match (x, &sel) {
+            (Sel::Edge { body: a, index: i, .. }, Sel::Edge { body: b, index: j, .. })
+            | (Sel::Face { body: a, index: i, .. }, Sel::Face { body: b, index: j, .. }) => a == b && i == j,
+            _ => false,
+        });
+        if !duplicate {
+            sels.push(sel);
+        }
+        if sels.len() > 2 {
+            return Err(bad(cmd, "measure one or two items"));
+        }
+    }
     let mut described = Vec::new();
     for x in &sels {
         described.push(describe(s, x).ok_or_else(|| bad(cmd, "an item can't be measured (pick vertices, edges, faces or bodies)"))?);

crates/engine/src/cmd/parameters.rs

@@ -12,7 +12,8 @@ use crate::{EngineError, Result, Session};
 pub static COMMANDS: &[CommandSpec] = &[
     CommandSpec::new("parameters.change", "Change Parameters", change_param).at("SOLID", "MODIFY").icon("params").params(
         "name, expression (number or text), unit?: mm|cm|m|in|ft|deg|rad|\"\" (new parameters default to their value's unit), comment?, \
-             favorite?: bool, new_name?: rename (references follow); or delete: name",
+             favorite?: bool, new_name?: rename (references follow); or delete: name → recomputed: features rebuilt, \
+         restored: features whose earlier result for the same inputs was reused (e.g. a value set back)",
     ),
     CommandSpec::new("parameters.list", "List Parameters", list).noundo().params(
         "favorites?: bool (only favourites), filter?: all|user|sketch|feature|favorites → parameters (name, expression, unit, value in its unit, \
@@ -107,6 +108,7 @@ fn change_param(s: &mut Session, p: &Value) -> Result<Value> {
     out["value"] = json!(vals.get(&name).map(|v| v.v));
     out["display_value"] = json!(s.doc.param_display_value(&vals, &name));
     out["recomputed"] = json!(s.model.last_recomputed);
+    out["restored"] = json!(s.model.last_restored);
     out["errors"] = json!(failing(s));
     Ok(out)
 }

crates/engine/src/cmd/parameters_tests.rs

@@ -67,6 +67,25 @@ fn width_follows_an_expression() {
     assert!(e.contains("expected a length, got an angle"), "{e}");
 }
 
+/// Setting a parameter back rebuilds nothing (the earlier results are reused) and says so: the
+/// features it restored are reported next to `recomputed`, so `recomputed: 0` is not mistaken
+/// for "nothing changed". timeline.edit reports the same.
+#[test]
+fn setting_a_parameter_back_reports_restored_features() {
+    let mut s = Session::default();
+    block(&mut s);
+    let r = run(&mut s, "parameters.change", json!({"name": "len", "expression": "100 mm"}));
+    assert_eq!((r["recomputed"].as_u64(), r["restored"].as_u64()), (Some(2), Some(0)), "{r}");
+    let r = run(&mut s, "parameters.change", json!({"name": "len", "expression": "60 mm"}));
+    assert_eq!((r["recomputed"].as_u64(), r["restored"].as_u64()), (Some(0), Some(2)), "{r}");
+    assert!(rel(volume(&mut s), 40.0 * 30.0 * 10.0) < 1e-9);
+    let r = run(&mut s, "timeline.edit", json!({"feature": "Extrude1", "set": {"extent": {"distance": "20"}}}));
+    assert_eq!((r["recomputed"].as_u64(), r["restored"].as_u64()), (Some(1), Some(0)), "{r}");
+    let r = run(&mut s, "timeline.edit", json!({"feature": "Extrude1", "set": {"extent": {"distance": "10"}}}));
+    assert_eq!((r["recomputed"].as_u64(), r["restored"].as_u64()), (Some(0), Some(1)), "{r}");
+    assert!(rel(volume(&mut s), 40.0 * 30.0 * 10.0) < 1e-9);
+}
+
 #[test]
 fn feature_inputs_are_named_and_editable() {
     let mut s = Session::default();

crates/engine/src/cmd/parts.rs

@@ -231,7 +231,7 @@ fn cyl(s: &mut Session, d: f64, z0: f64, z1: f64, op: &str) -> Result<()> {
 /// A solid of revolution about z from a closed (r, z) outline, as one body or joined.
 fn revolve(s: &mut Session, pts: &[(f64, f64)], op: &str) -> Result<()> {
     run(s, "sketch.create", json!({"plane": "XZ"}))?;
-    let points: Vec<[f64; 2]> = pts.iter().map(|(r, z)| [*r, *z]).collect();
+    let points: Vec<[f64; 2]> = pts.iter().map(|(r, z)| [*r, -*z]).collect();
     run(s, "sketch.line", json!({"points": points, "closed": true}))?;
     run(s, "sketch.finish", json!({}))?;
     run(s, "solid.revolve", json!({"axis": "y", "operation": op}))?;

crates/engine/src/cmd/section.rs

@@ -10,7 +10,7 @@ use crate::{Result, Session};
 
 pub static COMMANDS: &[CommandSpec] =
     &[CommandSpec::new("inspect.section", "Section Analysis", section).at("SOLID", "INSPECT").icon("section").noundo().params(
-        "plane: XY|XZ|YZ | {origin, normal}; offset?: expr along the plane's normal (XY: +Z, XZ: -Y, YZ: +X); \
+        "plane: XY|XZ|YZ | {origin, normal}; offset?: expr along the plane's normal (XY: +Z, XZ: +Y, YZ: +X); \
          at?: expr, the cut's world coordinate on the named plane's axis (XY: Z, XZ: Y, YZ: X), instead of offset; \
          flip?: bool; or clear: true. Returns the cut's origin and normal, and for a named plane its axis and at",
     )];

crates/engine/src/cmd/sketch.rs

@@ -1,7 +1,7 @@
 //! Sketch commands: create/edit/finish sketches, draw curves, constraints and dimensions.
 
 use serde_json::{Value, json};
-use solvecraft_doc::{FeatureKind, PlaneRef};
+use solvecraft_doc::{FeatureKind, PlaneRef, expr::Kind};
 use solvecraft_geom::{Plane, Vec2, Vec3};
 use solvecraft_sketch::{ConstraintKind, CurveKind, Hold, Sketch, SolveReport, solve, solve_holding};
 
@@ -94,7 +94,7 @@ pub static COMMANDS: &[CommandSpec] = &[
         .params(concat!("p0, p1: overall ends, width", connect_doc!())),
     CommandSpec::new("sketch.point", "Point", draw_point).at("SKETCH", "CREATE").icon("point").enabled(in_sketch).params(concat!("point: [x,y], id?", connect_doc!())),
     CommandSpec::new("sketch.dimension", "Sketch Dimension", dimension).at("SKETCH", "CREATE").icon("dimension").key("D").enabled(in_sketch).params(
-        "entities: [refs], type?: auto|distance|horizontal|vertical|length|radius|diameter|angle, value?: number or expression (default: current)",
+        "entities: [refs], type?: auto|distance|horizontal|vertical|length|radius|diameter|angle, value?: number or expression (default: current); text_at?: [x, y]. Two lines: the angle between them (acute, or 180° − it when the value is nearer that) unless text_at picks a sector. Returns measured in unit (mm or deg)",
     ),
     CommandSpec::new("sketch.constraint.horizontal_vertical", "Horizontal/Vertical", c_horizontal_vertical)
         .at("SKETCH", "CONSTRAINTS")
@@ -359,8 +359,10 @@ pub(super) fn plane_ref(s: &Session, p: &Value, cmd: &str) -> Result<PlaneRef> {
         }
         Some(v @ Value::Object(o)) => {
             if let Some(fp) = o.get("face").and_then(vec3) {
-                // A planar face of a body at this point.
-                let st = s.model.state();
+                // A planar face of a body at this point, as the active component sees the model
+                // (another component's face where it is placed).
+                let model = s.model.state();
+                let st = solvecraft_doc::state_in_frame(&s.doc, &model, s.active_component);
                 let mut found = None;
                 let mut face_name = None;
                 for b in &st.bodies {
@@ -406,7 +408,10 @@ fn face_contains(m: &solvecraft_geom::Mesh, fi: usize, p: Vec3, tol: f64) -> boo
         let s1 = (b - a).cross(p - a).dot(n);
         let s2 = (c - b).cross(p - b).dot(n);
         let s3 = (a - c).cross(p - c).dot(n);
-        (s1 >= 0.0 && s2 >= 0.0 && s3 >= 0.0) || (s1 <= 0.0 && s2 <= 0.0 && s3 <= 0.0)
+        (s1 >= 0.0 && s2 >= 0.0 && s3 >= 0.0)
+            || (s1 <= 0.0 && s2 <= 0.0 && s3 <= 0.0)
+            // Exact curved boundaries can sit just outside their tessellated chords.
+            || p.dist_to_segment(a, b).min(p.dist_to_segment(b, c)).min(p.dist_to_segment(c, a)) <= tol * 0.1
     })
 }
 
@@ -1332,7 +1337,9 @@ fn dimension(s: &mut Session, p: &Value) -> Result<Value> {
         };
         let is_line = |c: usize| matches!(sk.curves.get(c).map(|c| &c.kind), Some(CurveKind::Line { .. }));
         let is_circle = |c: usize| matches!(sk.curves.get(c).map(|c| &c.kind), Some(CurveKind::Circle { .. }));
-        let (k, cur): (ConstraintKind, f64) = match (e0, e1) {
+        // The other reading of an angle between two lines (see below).
+        let mut alt: Option<(ConstraintKind, f64)> = None;
+        let (mut k, mut cur): (ConstraintKind, f64) = match (e0, e1) {
             ((None, Some(c)), None) if is_line(c) => {
                 let (a, b) = line_pts(sk, c).unwrap_or_default();
                 match ty.as_str() {
@@ -1409,7 +1416,14 @@ fn dimension(s: &mut Session, p: &Value) -> Result<Value> {
                                 ang = -ang;
                                 std::mem::swap(&mut ka, &mut kb);
                             }
-                            (ConstraintKind::Angle { a: ka, b: kb, value: ang, flip: false }, ang)
+                            // Two lines make two angles, θ and 180° − θ, whichever way they were
+                            // drawn: the acute one unless the value asks for the other.
+                            let direct = (ConstraintKind::Angle { a: ka, b: kb, value: ang, flip: false }, ang);
+                            let supplement =
+                                (ConstraintKind::Angle { a: kb, b: ka, value: std::f64::consts::PI - ang, flip: true }, std::f64::consts::PI - ang);
+                            let (acute, obtuse) = if ang <= std::f64::consts::FRAC_PI_2 { (direct, supplement) } else { (supplement, direct) };
+                            alt = Some(obtuse);
+                            acute
                         }
                     }
                 }
@@ -1426,7 +1440,7 @@ fn dimension(s: &mut Session, p: &Value) -> Result<Value> {
                 c.driven = true;
             }
             before = None;
-            return Ok((String::new(), name, cur));
+            return Ok((String::new(), name, measured(is_angle, cur)));
         }
         let (unit, default_expr) =
             if is_angle { ("deg", format!("{} deg", round6(cur.to_degrees()))) } else { ("mm", format!("{} mm", round6(cur))) };
@@ -1437,28 +1451,39 @@ fn dimension(s: &mut Session, p: &Value) -> Result<Value> {
         if let Some(err) = errs.get(&pname) {
             return Err(bad(cmd, format!("value: {err}")));
         }
-        let _ = vals;
+        // An angle between two lines dimensions whichever of its two readings is nearer the value.
+        if let (Some((ka, ca)), Some(want)) = (alt, vals.get(&pname).and_then(|v| v.to_kind(Kind::Angle).ok()))
+            && (want - ca).abs() < (want - cur).abs()
+        {
+            (k, cur) = (ka, ca);
+        }
         let name = k.name();
         let id = sk.add_constraint(k, Some(pname.clone()))?;
         place_text(sk, &id, text_at);
-        Ok((pname, name, cur))
+        Ok((pname, name, measured(is_angle, cur)))
     })?;
     // Report what the dimension measures once the sketch is solved, not the geometry before.
     let current = solved_measure(s, p, cmd).unwrap_or(current);
     if driven {
-        return Ok(json!({"param": Value::Null, "driven": true, "type": kind_name, "measured": current, "sketch": info}));
+        return Ok(json!({"param": Value::Null, "driven": true, "type": kind_name, "measured": current.0, "unit": current.1, "sketch": info}));
     }
     if reject_redundant(before, &info, cmd).is_err() {
         return Err(bad(cmd, "that dimension would over-constrain the sketch; add it as a driven (reference) dimension with driven: true"));
     }
     let v = s.doc.param(&param).map(|p| p.expr.clone()).unwrap_or_default();
-    Ok(json!({"param": param, "type": kind_name, "expression": v, "measured": current, "sketch": info}))
+    Ok(json!({"param": param, "type": kind_name, "expression": v, "measured": current.0, "unit": current.1, "sketch": info}))
+}
+
+/// A dimension's measured value as reported, in the unit its expression is written in.
+fn measured(is_angle: bool, v: f64) -> (f64, &'static str) {
+    if is_angle { (round6(v.to_degrees()), "deg") } else { (round6(v), "mm") }
 }
 
 /// What the dimension just added (the sketch's last constraint) measures on the solved sketch.
-fn solved_measure(s: &Session, p: &Value, cmd: &str) -> Option<f64> {
+fn solved_measure(s: &Session, p: &Value, cmd: &str) -> Option<(f64, &'static str)> {
     let sk = s.doc.sketch(target_sketch(s, p, cmd).ok()?).ok()?;
-    solvecraft_sketch::measure_dimension(sk, &sk.constraints.last()?.kind)
+    let k = &sk.constraints.last()?.kind;
+    Some(measured(k.is_angle(), solvecraft_sketch::measure_dimension(sk, k)?))
 }
 
 /// Keep a dimension's text where it was placed (`at`, sketch coordinates), relative to the

crates/engine/src/cmd/sketch_canvas.rs

@@ -57,6 +57,8 @@ fn make(s: &mut Session, p: &Value, cmd: &str, decal: bool) -> Result<Value> {
         return Err(bad(cmd, "`width` must be positive"));
     }
     let opacity = num(p, "opacity").unwrap_or(if decal { 1.0 } else { 0.5 }).clamp(0.0, 1.0);
+    // It belongs to the active component (its plane is in that frame) and moves with it.
+    let component = s.active_component;
     let doc = s.doc_mut();
     let id = doc.canvases.iter().map(|c| c.id).max().unwrap_or(0) + 1;
     let base = if decal { "Decal" } else { "Canvas" };
@@ -74,6 +76,7 @@ fn make(s: &mut Session, p: &Value, cmd: &str, decal: bool) -> Result<Value> {
         opacity,
         flip: bool_(p, "flip").unwrap_or(false),
         visible: true,
+        component,
     });
     Ok(json!({"canvas": id, "name": name, "pixels": pixels}))
 }

crates/engine/src/cmd/sketch_constraints_tests.rs

@@ -221,3 +221,65 @@ fn drawing_onto_a_curve_keeps_the_point_on_it() {
     let cc = sk.center(sk.curve_index(&c).unwrap()).unwrap();
     assert!((st.dist(cc) - 8.0).abs() < 1e-7, "{st:?} {cc:?}");
 }
+
+/// A faucet spout path: a vertical riser, a horizontal top and an outlet sloping down, joined
+/// by fillets. The riser points up and the outlet down-left, so their directions are 150° apart
+/// while the lines meet at 30°.
+fn spout() -> Session {
+    let mut s = new_sketch();
+    run(&mut s, "sketch.line", json!({"points": [[795, 955], [795, 1068], [689, 1068], [661, 1020]], "ids": ["l1", "l2", "l3"]}));
+    run(&mut s, "sketch.fillet", json!({"point": "l1.end", "radius": 50}));
+    run(&mut s, "sketch.fillet", json!({"point": "l2.end", "radius": 35}));
+    run(&mut s, "sketch.constraint.horizontal_vertical", json!({"line": "l1", "mode": "vertical"}));
+    run(&mut s, "sketch.constraint.horizontal_vertical", json!({"line": "l2", "mode": "horizontal"}));
+    run(&mut s, "sketch.dimension", json!({"entities": ["origin", "l1.start"], "type": "horizontal", "value": 795}));
+    run(&mut s, "sketch.dimension", json!({"entities": ["origin", "l1.start"], "type": "vertical", "value": 955}));
+    run(&mut s, "sketch.dimension", json!({"entities": ["origin", "l2.start"], "type": "vertical", "value": 1068}));
+    run(&mut s, "sketch.dimension", json!({"entities": ["l3.end", "l1.start"], "type": "horizontal", "value": 134}));
+    let d = run(&mut s, "sketch.dimension", json!({"entities": ["origin", "l3.end"], "type": "vertical", "value": 1020}));
+    assert_eq!(d["sketch"]["dof"], 1, "{d}");
+    s
+}
+
+/// The angle (degrees, 0..=90) between two lines of the active sketch.
+fn line_angle(s: &Session, a: &str, b: &str) -> f64 {
+    let sk = sketch(s);
+    let dir = |l: &str| {
+        let c = sk.curve_index(l).unwrap();
+        let (p, q) = crate::cmd::sketch::line_pts(&sk, c).unwrap();
+        q - p
+    };
+    let (u, v) = (dir(a), dir(b));
+    let t = u.cross(v).abs().atan2(u.dot(v)).to_degrees();
+    t.min(180.0 - t)
+}
+
+#[test]
+fn an_angle_between_lines_takes_the_reading_nearest_its_value_and_reports_degrees() {
+    // The riser and the outlet are not adjacent and meet at 30°; their directions are 150°
+    // apart. Asking for 30° used to swing the outlet round and was refused as over-constraining.
+    for ents in [["l1", "l3"], ["l3", "l1"]] {
+        let mut s = spout();
+        let d = run(&mut s, "sketch.dimension", json!({"entities": ents, "type": "angle", "value": "30 deg"}));
+        assert_eq!(d["sketch"]["dof"], 0, "{d}");
+        assert_eq!(d["unit"], "deg", "{d}");
+        assert!((d["measured"].as_f64().unwrap() - 30.0).abs() < 1e-6, "{d}");
+        assert!((line_angle(&s, "l1", "l3") - 30.0).abs() < 1e-6);
+    }
+    // The other reading still works, and the adjacent top line measures 60° the same way.
+    let mut s = spout();
+    let d = run(&mut s, "sketch.dimension", json!({"entities": ["l1", "l3"], "value": "150 deg"}));
+    assert_eq!(d["sketch"]["dof"], 0, "{d}");
+    assert!((line_angle(&s, "l1", "l3") - 30.0).abs() < 1e-6);
+    let mut s = spout();
+    let d = run(&mut s, "sketch.dimension", json!({"entities": ["l2", "l3"], "value": "60 deg"}));
+    assert!((d["measured"].as_f64().unwrap() - 60.0).abs() < 1e-6, "{d}");
+    // Without a value the acute angle is kept as it is.
+    let mut s = spout();
+    let d = run(&mut s, "sketch.dimension", json!({"entities": ["l1", "l3"]}));
+    let e = d["expression"].as_str().unwrap();
+    assert!(e.ends_with(" deg") && (e.trim_end_matches(" deg").parse::<f64>().unwrap() - 30.3).abs() < 0.1, "{d}");
+    // Lengths report millimetres.
+    let d = run(&mut s, "sketch.dimension", json!({"entities": ["l2"], "driven": true}));
+    assert_eq!(d["unit"], "mm", "{d}");
+}

crates/engine/src/cmd/sketch_modify.rs

@@ -520,7 +520,7 @@ fn fillet_corner(sk: &mut Sketch, p: &Value, r: f64, cmd: &str) -> Result<(usize
     let u = (pa - pc).normalized().ok_or_else(|| bad(cmd, "degenerate line"))?;
     let v = (pb - pc).normalized().ok_or_else(|| bad(cmd, "degenerate line"))?;
     let half = 0.5 * u.cross(v).atan2(u.dot(v)).abs();
-    if half < 1e-6 || half > std::f64::consts::FRAC_PI_2 - 1e-9 {
+    if !(1e-6..=std::f64::consts::FRAC_PI_2 - 1e-9).contains(&half) {
         return Err(bad(cmd, "the lines are parallel"));
     }
     let d = r / half.tan();
@@ -813,6 +813,12 @@ fn offset(s: &mut Session, p: &Value) -> Result<Value> {
             }
             let ci = sk.add_circle(cc, nr, Some(c), None)?;
             made.push(ci);
+            sk.offsets.push(solvecraft_sketch::OffsetChain {
+                sources: vec![(ids[0].clone(), true)],
+                outputs: ids_of(sk, &made),
+                distance: r - nr,
+                closed: true,
+            });
             return Ok((ids_of(sk, &made), cons));
         }
         let pool: Vec<usize> = if use_chain {
@@ -916,7 +922,13 @@ fn offset(s: &mut Session, p: &Value) -> Result<Value> {
                 }
             }
         }
-        Ok((ids_of(sk, &made), cons))
+        let outputs = ids_of(sk, &made);
+        if pieces.iter().all(|p| !matches!(p, Piece::Free(_))) {
+            let sources = order.iter().filter_map(|(i, forward)| sk.curves.get(*i).map(|c| (c.id.clone(), *forward))).collect();
+            sk.offsets.push(solvecraft_sketch::OffsetChain { sources, outputs: outputs.clone(), distance: d, closed });
+            sk.refresh_offsets()?;
+        }
+        Ok((outputs, cons))
     })?;
     Ok(json!({"curves": out.0, "constraints": out.1, "sketch": info}))
 }

crates/engine/src/cmd/sketch_project.rs

@@ -140,8 +140,20 @@ pub(super) fn add_link(s: &Session, doc: &Document, id: u64, sk: &mut Sketch, ki
     let plane = sketch_plane(doc, id)?;
     let (vals, _) = doc.param_values();
     let st = s.model.state_before(id);
+    // The model as the sketch's component sees it.
+    let comp = doc.feature(id).map(|f| f.component).unwrap_or(0);
+    let st = solvecraft_doc::state_in_frame(doc, &st, comp);
     let r = resolve(doc, &vals, &st, &plane, kind, &src)?;
-    Ok(sk.add_link_with_wires(kind, r.source, &r.geom, &r.wires)?)
+    let name = if let LinkSource::Face { at, .. } = &r.source {
+        solvecraft_doc::naming::face_names_at(&st, &[*at]).into_iter().next().filter(|n| !n.is_empty())
+    } else {
+        None
+    };
+    let link = sk.add_link_with_wires(kind, r.source, &r.geom, &r.wires)?;
+    if let Some(l) = sk.links.iter_mut().find(|l| l.id == link) {
+        l.face_name = name;
+    }
+    Ok(link)
 }
 
 fn link_json(sk: &Sketch, link: &str) -> Value {

crates/engine/src/frames.rs

@@ -30,6 +30,12 @@ enum K {
     Plane,
     /// A body name, or a list of them.
     Body,
+    /// A point (or a list of picks) for the sketch being made or edited: into that sketch's
+    /// component frame, whichever component the geometry under it belongs to (a sketch in the
+    /// root on a moved component's face finds the face where it is shown).
+    Here,
+    /// A plane object for a new sketch or canvas: into the active component's frame.
+    HerePlane,
 }
 
 use K::*;
@@ -56,11 +62,12 @@ fn table(id: &str) -> &'static [(&'static str, K)] {
         "plastic.lip" | "sheet.convert" => &[("face", Pick), ("body", Body)],
         "sheet.flange" | "sheet.hem" => &[("edges", Picks), ("body", Body)],
         "sheet.fold" => &[("points", Picks), ("fixed", Pick), ("body", Body)],
-        "sketch.create" | "sketch.redefine" => &[("plane", Plane)],
-        "canvas.decal" => &[("face", Pick)],
-        "sketch.intersect" => &[("refs", Picks)],
-        "sketch.project_to_surface" | "sketch.isoparametric_curve" => &[("face", Pick), ("body", Body)],
-        "sketch.intersection_curve" => &[("a", Picks), ("b", Picks)],
+        "sketch.create" | "sketch.redefine" => &[("plane", HerePlane)],
+        "canvas.decal" => &[("face", Here)],
+        "canvas.insert" => &[("plane", HerePlane), ("at", Here)],
+        "sketch.project" | "sketch.intersect" | "sketch.include_3d" => &[("refs", Here), ("ref", Here)],
+        "sketch.project_to_surface" | "sketch.isoparametric_curve" => &[("face", Here)],
+        "sketch.intersection_curve" => &[("a", Here), ("b", Here)],
         "inspect.curvature_comb" | "inspect.minimum_radius" | "inspect.isocurve" => &[("edges", Picks), ("faces", Picks)],
         "parts.insert" | "parts.fastener" => &[("at", Pick), ("point", Make), ("direction", Dir)],
         "appearance.assign" => &[("faces", Picks), ("bodies", Body), ("body", Body)],
@@ -75,6 +82,8 @@ fn table(id: &str) -> &'static [(&'static str, K)] {
 struct Frames {
     bodies: Vec<(String, String, Mat)>,
     active: Mat,
+    /// The frame of the sketch being edited (its component), else the active component's.
+    sketch: Mat,
 }
 
 fn frames(s: &Session) -> Frames {
@@ -104,7 +113,8 @@ fn frames(s: &Session) -> Frames {
             (world, own, m)
         })
         .collect();
-    Frames { bodies, active: doc.component_transform(s.active_component) }
+    let sketch_comp = s.active_sketch.and_then(|id| doc.feature(id)).map(|f| f.component).unwrap_or(s.active_component);
+    Frames { bodies, active: doc.component_transform(s.active_component), sketch: doc.component_transform(sketch_comp) }
 }
 
 /// Does any placement move anything (so the world differs from the components' frames)?
@@ -171,12 +181,14 @@ struct Mapper<'a> {
     /// The frame of the command's first pick (its directions turn with it).
     first: Option<Mat>,
     changed: bool,
+    /// Picks go into the sketch's frame (`Here`), not the frame of the body under them.
+    here: bool,
 }
 
 impl Mapper<'_> {
     fn pick(&mut self, v: &Value, body: Option<&str>) -> Option<Value> {
         let p = vec3(v)?;
-        let m = frame_at(self.s, &self.f, p, body).unwrap_or(self.f.active);
+        let m = if self.here { self.f.sketch } else { frame_at(self.s, &self.f, p, body).unwrap_or(self.f.active) };
         self.first.get_or_insert(m);
         self.local_point(&m, p)
     }
@@ -325,14 +337,14 @@ pub fn to_local(s: &Session, id: &str, params: &Value) -> Option<Value> {
         return None;
     }
     let obj = params.as_object()?;
-    let mut m = Mapper { s, f: frames(s), first: None, changed: false };
+    let mut m = Mapper { s, f: frames(s), first: None, changed: false, here: false };
     let body = obj.get("body").and_then(Value::as_str).map(str::to_string);
     let mut out: Map<String, Value> = obj.clone();
     // Picks first: their frame turns the directions.
     for pass in [true, false] {
         for (k, kind) in keys {
             let Some(v) = obj.get(*k) else { continue };
-            let is_pick = matches!(kind, Pick | Picks | Plane);
+            let is_pick = matches!(kind, Pick | Picks | Plane | Here | HerePlane);
             if is_pick != pass {
                 continue;
             }
@@ -343,6 +355,19 @@ pub fn to_local(s: &Session, id: &str, params: &Value) -> Option<Value> {
                 Dir => m.dir(v),
                 Plane => m.plane(v),
                 Body => m.body(v),
+                Here | HerePlane => {
+                    // A new sketch or canvas goes into the active component.
+                    let keep = m.f.sketch;
+                    if *kind == HerePlane {
+                        m.f.sketch = m.f.active;
+                    }
+                    m.here = true;
+                    // Body names stay: the sketch's view of the model keeps them.
+                    let r = if *kind == HerePlane { m.plane(v) } else { m.picks(v, None) };
+                    m.here = false;
+                    m.f.sketch = keep;
+                    r
+                }
             };
             if let Some(n) = new {
                 out.insert((*k).to_string(), n);

crates/engine/src/frames_tests.rs

@@ -144,3 +144,106 @@ fn sketch_on_a_face_follows_a_moved_body() {
     let c = sketch_point_world(&mut s, "OnTop", "p1");
     assert!((c.z - 25.0).abs() < 1e-6, "{c:?}");
 }
+
+/// A 1 x 1 PNG for canvases.
+const PNG: &str = "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+M9QDwADhgGAWjR9awAAAABJRU5ErkJggg==";
+
+/// Canvases belong to the active component and move with its occurrence; one put on a moved
+/// component's face from the root sits on the face (and stays the root's).
+#[test]
+fn canvases_move_with_their_component() {
+    let mut s = moved_part();
+    let part = s.active_component;
+    assert_ne!(part, 0);
+    run(&mut s, "canvas.insert", json!({"data": PNG, "plane": "XY", "name": "Plan"}));
+    // From the root, on the moved block's top face (world).
+    run(&mut s, "component.activate", json!({"component": "root"}));
+    run(&mut s, "canvas.insert", json!({"data": PNG, "plane": {"face": [65, 10, 10]}, "name": "Lid", "width": 10}));
+    run(&mut s, "canvas.insert", json!({"data": PNG, "plane": "XZ", "name": "Root"}));
+    let (vals, _) = s.doc.param_values();
+    let world = |s: &Session, name: &str| {
+        let c = s.doc.canvases.iter().find(|c| c.name == name).unwrap();
+        (c.component, s.doc.canvas_plane(&vals, c).unwrap())
+    };
+    let (c, p) = world(&s, "Plan");
+    assert_eq!(c, part);
+    assert!(near(p.origin, Vec3::new(50.0, 0.0, 0.0)), "{:?}", p.origin);
+    let (c, p) = world(&s, "Lid");
+    assert_eq!(c, 0, "the active component's");
+    let lid = s.doc.canvases.iter().find(|c| c.name == "Lid").unwrap();
+    let centre = p.to_world(lid.center);
+    assert!(near(centre, Vec3::new(65.0, 10.0, 10.0)), "{centre:?}");
+    assert_eq!(world(&s, "Root").0, 0);
+    // Moving the occurrence carries its canvases, not the root's.
+    run(&mut s, "occurrence.move", json!({"occurrence": "Part:1", "translate": [0, 40, 0]}));
+    let (vals, _) = s.doc.param_values();
+    let plan = s.doc.canvases.iter().find(|c| c.name == "Plan").unwrap();
+    assert!(near(s.doc.canvas_plane(&vals, plan).unwrap().origin, Vec3::new(50.0, 40.0, 0.0)));
+    let lid = s.doc.canvases.iter().find(|c| c.name == "Lid").unwrap();
+    let centre = s.doc.canvas_plane(&vals, lid).unwrap().to_world(lid.center);
+    assert!(near(centre, Vec3::new(65.0, 10.0, 10.0)), "{centre:?}");
+    let root = s.doc.canvases.iter().find(|c| c.name == "Root").unwrap();
+    assert!(near(s.doc.canvas_plane(&vals, root).unwrap().origin, Vec3::ZERO));
+    // The component survives a save and reopen.
+    let back = solvecraft_doc::Document::from_json(&s.doc.to_json()).unwrap();
+    assert_eq!(back.canvases, s.doc.canvases);
+}
+
+/// World points of a sketch's curves' points (sorted).
+fn sketch_world_points(s: &mut Session, sketch: &str) -> Vec<Vec3> {
+    let si = run(s, "sketch.inspect", json!({ "sketch": sketch }));
+    si["points"]
+        .as_array()
+        .unwrap()
+        .iter()
+        .map(|p| {
+            let w = &p["world"];
+            Vec3::new(w[0].as_f64().unwrap(), w[1].as_f64().unwrap(), w[2].as_f64().unwrap())
+        })
+        .collect()
+}
+
+/// A block "C" (40 x 30 x 20) in its own component, the root active again.
+fn block_in_component() -> Session {
+    let mut s = Session::default();
+    run(&mut s, "component.create", json!({"name": "C"}));
+    run(&mut s, "solid.box", json!({"length": 40, "width": 30, "height": 20}));
+    run(&mut s, "component.activate", json!({"component": "root"}));
+    s
+}
+
+/// The user's "big square": a sketch made in the root on a moved component's face lies on the
+/// face where it is shown, its projected loop on the face's edges (moved and turned), and it
+/// follows when the occurrence moves on.
+#[test]
+fn root_sketch_on_a_moved_components_face() {
+    let mut s = block_in_component();
+    run(&mut s, "occurrence.move", json!({"occurrence": "C:1", "translate": [100, 0, 0]}));
+    let r = run(&mut s, "sketch.create", json!({"plane": {"face": [120, 15, 20]}, "name": "Top"}));
+    assert!(!r["projected"].is_null(), "the face's edges are projected: {r}");
+    run(&mut s, "sketch.finish", json!({}));
+    let pts = sketch_world_points(&mut s, "Top");
+    assert!(pts.len() >= 4, "{pts:?}");
+    // Every point but the sketch's origin (the model origin on the face plane).
+    for p in pts.iter().filter(|p| !near(**p, Vec3::new(0.0, 0.0, 20.0))) {
+        assert!((p.z - 20.0).abs() < 1e-6 && p.x > 100.0 - 1e-6 && p.x < 140.0 + 1e-6 && p.y > -1e-6 && p.y < 30.0 + 1e-6, "{p:?}");
+    }
+    for corner in [Vec3::new(100.0, 0.0, 20.0), Vec3::new(140.0, 30.0, 20.0)] {
+        assert!(pts.iter().any(|p| near(*p, corner)), "{corner:?} in {pts:?}");
+    }
+    assert_eq!(s.doc.find_feature("Top").unwrap().component, 0, "the sketch is the root's");
+
+    // Turned 90 degrees about Z (around the world origin): the top face is now x -30..0, y 0..40.
+    let mut s = block_in_component();
+    run(&mut s, "occurrence.move", json!({"occurrence": "C:1", "axis": [0, 0, 1], "angle": "90 deg", "origin": [0, 0, 0]}));
+    run(&mut s, "sketch.create", json!({"plane": {"face": [-15, 20, 20]}, "name": "Top"}));
+    run(&mut s, "sketch.finish", json!({}));
+    let pts = sketch_world_points(&mut s, "Top");
+    for corner in [Vec3::new(0.0, 0.0, 20.0), Vec3::new(-30.0, 40.0, 20.0)] {
+        assert!(pts.iter().any(|p| near(*p, corner)), "{corner:?} in {pts:?}");
+    }
+    // Projected geometry stays on the face when the occurrence moves on (the link re-resolves).
+    run(&mut s, "occurrence.move", json!({"occurrence": "C:1", "translate": [0, 0, 5]}));
+    let pts = sketch_world_points(&mut s, "Top");
+    assert!(pts.iter().any(|p| near(*p, Vec3::new(-30.0, 40.0, 25.0))), "{pts:?}");
+}

crates/engine/src/lib.rs

@@ -170,6 +170,20 @@ pub struct Session {
     pub analysis: Option<SurfaceAnalysis>,
     /// What is hidden or shown in the view (`browser.visibility`).
     pub visibility: Visibility,
+    /// States to go back to (`edit.checkpoint`, `edit.restore_checkpoint`): how batches of
+    /// commands are undone however long the undo history is.
+    pub(crate) checkpoints: Vec<Checkpoint>,
+    next_checkpoint: u64,
+}
+
+/// The design, active sketch and undo history at an `edit.checkpoint`.
+#[derive(Clone, Debug)]
+pub(crate) struct Checkpoint {
+    pub id: u64,
+    pub doc: Arc<Document>,
+    pub active_sketch: Option<u64>,
+    pub undo: Vec<Snapshot>,
+    pub redo: Vec<Snapshot>,
 }
 
 /// Items hidden or shown one by one (view state, not part of the design and not an undo step).
@@ -204,6 +218,8 @@ pub enum SurfaceAnalysis {
 }
 
 const MAX_UNDO: usize = 200;
+/// Checkpoints kept (the oldest go first).
+const MAX_CHECKPOINTS: usize = 16;
 const MAX_LOG: usize = 2000;
 
 impl Default for Session {
@@ -235,6 +251,8 @@ impl Session {
             clipboard: Vec::new(),
             section: None,
             analysis: None,
+            checkpoints: Vec::new(),
+            next_checkpoint: 1,
             visibility: Visibility::default(),
         }
     }
@@ -356,6 +374,44 @@ impl Session {
         }
     }
 
+    /// Remember the design, active sketch and undo history; returns the checkpoint's id.
+    pub fn checkpoint(&mut self) -> u64 {
+        let id = self.next_checkpoint;
+        self.next_checkpoint += 1;
+        self.checkpoints.push(Checkpoint {
+            id,
+            doc: self.doc.clone(),
+            active_sketch: self.active_sketch,
+            undo: self.undo.clone(),
+            redo: self.redo.clone(),
+        });
+        if self.checkpoints.len() > MAX_CHECKPOINTS {
+            self.checkpoints.remove(0);
+        }
+        id
+    }
+
+    /// Go back to checkpoint `id` as if nothing since had happened (the undo history too). It
+    /// and later checkpoints are used up.
+    pub fn restore_checkpoint(&mut self, id: u64) -> Result<()> {
+        let i = self.checkpoints.iter().position(|c| c.id == id).ok_or_else(|| EngineError::Other(format!("no checkpoint {id}")))?;
+        let Some(c) = self.checkpoints.drain(i..).next() else { return Err(EngineError::Other(format!("no checkpoint {id}"))) };
+        self.doc = c.doc;
+        self.active_sketch = c.active_sketch;
+        self.undo = c.undo;
+        self.redo = c.redo;
+        self.selection.clear();
+        self.refresh();
+        Ok(())
+    }
+
+    /// Forget checkpoint `id` (and later ones) without going back.
+    pub fn drop_checkpoint(&mut self, id: u64) {
+        if let Some(i) = self.checkpoints.iter().position(|c| c.id == id) {
+            self.checkpoints.truncate(i);
+        }
+    }
+
     /// A scratch copy of the session (same design and model, no history or log) to try
     /// commands on without touching this one.
     pub fn scratch(&self) -> Session {
@@ -377,6 +433,8 @@ impl Session {
             clipboard: self.clipboard.clone(),
             section: None,
             analysis: None,
+            checkpoints: Vec::new(),
+            next_checkpoint: 1,
             visibility: Visibility::default(),
         }
     }
@@ -445,6 +503,8 @@ impl Session {
     }
 }
 
+#[cfg(test)]
+mod boolean_regression_tests;
 #[cfg(test)]
 mod construct_tests;
 #[cfg(test)]

crates/engine/src/tests.rs

@@ -20,6 +20,21 @@ fn rel(a: f64, b: f64) -> f64 {
     (a - b).abs() / b.abs().max(1e-12)
 }
 
+#[test]
+fn join_extrude_from_a_chamfered_top_face() {
+    let mut s = Session::default();
+    run(&mut s, "sketch.create", json!({"plane": "XY"}));
+    run(&mut s, "sketch.circle.center", json!({"center": [0, 0], "radius": 10}));
+    run(&mut s, "solid.extrude", json!({"distance": 20}));
+    run(&mut s, "solid.chamfer", json!({"edges": [[10, 0, 20]], "distance": 2}));
+    let base = volume(&mut s);
+    run(&mut s, "sketch.create", json!({"plane": {"face": [0, 0, 20]}}));
+    run(&mut s, "sketch.finish", json!({}));
+    run(&mut s, "solid.extrude", json!({"distance": 5, "operation": "join"}));
+    assert_eq!(s.model.state().bodies.len(), 1);
+    assert!(rel(volume(&mut s), base + PI * 64.0 * 5.0) < 5e-4);
+}
+
 mod component_frames;
 mod robustness;
 
@@ -650,10 +665,10 @@ fn section_analysis() {
     assert!(s.execute("inspect.section", &json!({"plane": {"normal": [0, 0, 0]}})).is_err());
     run(&mut s, "inspect.section", json!({"clear": true}));
     assert!(s.section.is_none());
-    // XZ's normal is -Y: an offset moves the cut to -Y, `at` places it at a world Y, and the
+    // XZ's normal is +Y: an offset moves the cut to +Y, `at` places it at a world Y, and the
     // result says where the cut landed either way.
     let r = run(&mut s, "inspect.section", json!({"plane": "XZ", "offset": 10}));
-    assert_eq!((r["section"]["axis"].as_str(), r["section"]["at"].as_f64()), (Some("Y"), Some(-10.0)), "{r}");
+    assert_eq!((r["section"]["axis"].as_str(), r["section"]["at"].as_f64()), (Some("Y"), Some(10.0)), "{r}");
     for (plane, at, flip) in [("XZ", -282.5, false), ("XZ", 7.0, true), ("XY", 3.0, false), ("YZ", -4.0, true)] {
         let r = run(&mut s, "inspect.section", json!({"plane": plane, "at": at, "flip": flip}));
         assert_eq!(r["section"]["at"].as_f64(), Some(at), "{plane} {r}");
@@ -824,6 +839,51 @@ fn pipe_scale_offset_bounding_and_materials() {
     assert!(s.execute("material.assign", &json!({"bodies": ["Cube"], "material": "unobtainium"})).is_err());
 }
 
+/// Regression: deleting a pipe's path sketch left the pipe in the timeline ("unknown sketch").
+#[test]
+fn deleting_a_path_sketch_deletes_its_pipe() {
+    let mut s = Session::default();
+    run(&mut s, "sketch.create", json!({"plane": "XY", "name": "Path"}));
+    run(&mut s, "sketch.line", json!({"points": [[0, 0], [30, 0]], "ids": ["l1"]}));
+    run(&mut s, "sketch.finish", json!({}));
+    let pipe = run(&mut s, "solid.pipe", json!({"path_sketch": "Path", "path": ["l1"], "diameter": 4}));
+    let deps = run(&mut s, "timeline.dependents", json!({"feature": "Path"}));
+    assert_eq!(deps["deleted_with_it"].as_array().map(Vec::len), Some(1), "{deps} (pipe {pipe})");
+    let r = run(&mut s, "timeline.delete", json!({"features": ["Path"]}));
+    assert_eq!(r["deleted"].as_array().map(Vec::len), Some(2), "{r}");
+    assert!(s.doc.features.is_empty(), "{:?}", s.doc.features.iter().map(|f| &f.name).collect::<Vec<_>>());
+    assert!(s.model.results.iter().all(|r| r.error.is_none()));
+}
+
+/// Regression: batches were rolled back by undoing as many steps as the undo history grew,
+/// which is none once the history is full, leaving their sketches behind.
+#[test]
+fn checkpoint_restores_with_a_full_undo_history() {
+    let mut s = Session::default();
+    for i in 0..MAX_UNDO + 5 {
+        run(&mut s, "parameters.add", json!({"name": format!("p{i}"), "expression": "1 mm"}));
+    }
+    assert_eq!(s.undo.len(), MAX_UNDO);
+    let labels: Vec<String> = s.undo.iter().map(|u| u.label.clone()).collect();
+    let doc = s.doc.clone();
+    let id = run(&mut s, "edit.checkpoint", json!({}))["checkpoint"].as_u64().unwrap();
+    run(&mut s, "sketch.create", json!({"plane": "XY", "name": "TapHole"}));
+    run(&mut s, "sketch.circle.center", json!({"center": [0, 0], "radius": 2}));
+    assert!(s.active_sketch.is_some());
+    run(&mut s, "edit.restore_checkpoint", json!({"checkpoint": id}));
+    assert!(Arc::ptr_eq(&s.doc, &doc) && s.active_sketch.is_none());
+    assert!(s.doc.find_feature("TapHole").is_none());
+    assert_eq!(s.undo.iter().map(|u| u.label.clone()).collect::<Vec<_>>(), labels);
+    // Used up: a second restore is an error, not a jump somewhere else.
+    assert!(s.execute("edit.restore_checkpoint", &json!({"checkpoint": id})).is_err());
+    // Forgetting one leaves the design alone.
+    let id = run(&mut s, "edit.checkpoint", json!({}))["checkpoint"].as_u64().unwrap();
+    run(&mut s, "sketch.create", json!({"plane": "XY", "name": "Kept"}));
+    run(&mut s, "edit.restore_checkpoint", json!({"checkpoint": id, "forget": true}));
+    assert!(s.doc.find_feature("Kept").is_some());
+    assert!(s.execute("edit.restore_checkpoint", &json!({"checkpoint": id})).is_err());
+}
+
 #[test]
 fn components_occurrences_and_world_placement() {
     let mut s = Session::default();

crates/geom/src/mesh.rs

@@ -82,6 +82,71 @@ impl Mesh {
     pub fn face_edges(&self, f: u32) -> Vec<usize> {
         self.edge_faces.iter().enumerate().filter(|(_, fs)| fs.contains(&f)).map(|(i, _)| i).collect()
     }
+    /// Pieces of one surface joined across hidden seams, including `face` itself.
+    pub fn surface_patch(&self, face: usize) -> Vec<usize> {
+        let mut patch = vec![face];
+        let mut todo = vec![face];
+        while let Some(f) = todo.pop() {
+            for (ei, fs) in self.edge_faces.iter().enumerate() {
+                if !self.seams.get(ei).copied().unwrap_or(false) || !fs.iter().any(|x| *x as usize == f) {
+                    continue;
+                }
+                for &next in fs {
+                    let next = next as usize;
+                    if !patch.contains(&next) {
+                        patch.push(next);
+                        todo.push(next);
+                    }
+                }
+            }
+        }
+        patch.sort_unstable();
+        patch
+    }
+
+    /// A complete circular rim may be split into several kernel edges. Keep its pieces
+    /// together for picking, without joining other tangent curves or changing edge indices.
+    pub fn circular_rim(&self, edge: usize) -> Vec<usize> {
+        let single = vec![edge];
+        let Some(p) = self.edges.get(edge).filter(|p| p.len() >= 3) else { return single };
+        let (Some(&a), Some(&b), Some(&c)) = (p.first(), p.get(p.len() / 2), p.last()) else { return single };
+        let (u, v) = (b - a, c - a);
+        let n = u.cross(v);
+        if !(n.len2() > u.len2() * v.len2() * 1e-12) {
+            return single;
+        }
+        let center = a + (v.cross(n) * u.len2() + n.cross(u) * v.len2()) / (2.0 * n.len2());
+        let radius = center.dist(a);
+        let normal = n.normalized().unwrap_or(Vec3::ZERO);
+        let tol = (radius * 1e-6).max(1e-9);
+        let mut rim = self.tangent_chain(edge, 2f64.to_radians());
+        if rim.len() < 2 || !radius.is_finite() {
+            return single;
+        }
+        // All samples must lie on this circle, and every end must join exactly one other
+        // piece. Open arcs, ellipses, and branching tangent chains stay separate.
+        for &i in &rim {
+            let Some(points) = self.edges.get(i) else { return single };
+            if points.iter().any(|q| !q.is_finite() || (q.dist(center) - radius).abs() > tol || (*q - center).dot(normal).abs() > tol) {
+                return single;
+            }
+            for end in [points.first(), points.last()].into_iter().flatten() {
+                let joins = rim
+                    .iter()
+                    .filter(|&&j| j != i)
+                    .filter_map(|&j| self.edges.get(j))
+                    .flat_map(|q| [q.first(), q.last()])
+                    .flatten()
+                    .filter(|q| q.dist(*end) < tol)
+                    .count();
+                if joins != 1 {
+                    return single;
+                }
+            }
+        }
+        rim.sort_unstable();
+        rim
+    }
     /// The edges reached from `e` through vertices where the next edge continues smoothly
     /// (angle between the end tangents below `max_angle`), including `e` itself.
     pub fn tangent_chain(&self, e: usize, max_angle: f64) -> Vec<usize> {

crates/geom/src/plane.rs

@@ -17,8 +17,8 @@ pub struct Plane {
 impl Plane {
     /// Top: sketch x = +X, y = +Y, normal +Z.
     pub const XY: Plane = Plane { origin: Vec3::ZERO, x: Vec3::X, y: Vec3::Y };
-    /// Front: sketch x = +X, y = +Z, normal −Y.
-    pub const XZ: Plane = Plane { origin: Vec3::ZERO, x: Vec3::X, y: Vec3::Z };
+    /// Front: sketch x = +X, y = −Z, normal +Y.
+    pub const XZ: Plane = Plane { origin: Vec3::ZERO, x: Vec3::X, y: Vec3::new(0.0, 0.0, -1.0) };
     /// Right: sketch x = +Y, y = +Z, normal +X.
     pub const YZ: Plane = Plane { origin: Vec3::ZERO, x: Vec3::Y, y: Vec3::Z };
 

crates/geom/src/tests.rs

@@ -28,10 +28,10 @@ fn raycast_hits_front_face() {
 #[test]
 fn planes() {
     assert_eq!(Plane::XY.normal(), Vec3::Z);
-    assert_eq!(Plane::XZ.normal(), Vec3::new(0.0, -1.0, 0.0));
+    assert_eq!(Plane::XZ.normal(), Vec3::Y);
     assert_eq!(Plane::YZ.normal(), Vec3::X);
     let p = Plane::XZ.to_world(Vec2::new(3.0, 4.0));
-    assert_eq!(p, Vec3::new(3.0, 0.0, 4.0));
+    assert_eq!(p, Vec3::new(3.0, 0.0, -4.0));
     assert_eq!(Plane::XZ.to_local(p), Vec2::new(3.0, 4.0));
     let hit = Plane::XY.offset(5.0).intersect_ray(Vec3::new(1.0, 2.0, 10.0), Vec3::new(0.0, 0.0, -2.0)).unwrap();
     assert!(hit.dist(Vec3::new(1.0, 2.0, 5.0)) < 1e-12);
@@ -84,6 +84,46 @@ fn tangent_chains_follow_smooth_edges() {
     assert_eq!(m.face_edges(1), vec![1, 2]);
 }
 
+#[test]
+fn circular_rims_group_only_closed_cocircular_edges() {
+    let arc = |start: f64, sweep: f64, yscale: f64| -> Vec<Vec3> {
+        (0..=32)
+            .map(|i| {
+                let a = start + sweep * i as f64 / 32.0;
+                Vec3::new(10.0 * a.cos(), yscale * 10.0 * a.sin(), 5.0)
+            })
+            .collect()
+    };
+    let pi = std::f64::consts::PI;
+    let mut m = Mesh {
+        positions: vec![Vec3::new(-10.0, -10.0, 5.0), Vec3::new(10.0, 10.0, 5.0)],
+        edges: vec![arc(0.0, pi, 1.0), arc(2.0 * pi, -pi, 1.0)],
+        ..Default::default()
+    };
+    assert_eq!(m.circular_rim(0), vec![0, 1]);
+    assert_eq!(m.circular_rim(1), vec![0, 1]);
+    // A hidden seam cannot form a selectable rim.
+    m.seams = vec![false, true];
+    assert_eq!(m.circular_rim(0), vec![0]);
+    m.seams.clear();
+    m.edges[1] = arc(pi, pi / 2.0, 1.0);
+    assert_eq!(m.circular_rim(0), vec![0]);
+    // A closed, smooth ellipse is not a circle.
+    m.edges = vec![arc(0.0, pi, 0.7), arc(pi, pi, 0.7)];
+    assert_eq!(m.circular_rim(0), vec![0]);
+    assert_eq!(m.circular_rim(99), vec![99]);
+}
+
+#[test]
+fn surface_patches_cross_only_hidden_seams() {
+    let mut m = Mesh { edge_faces: vec![vec![0, 1], vec![1, 2], vec![2, 3]], seams: vec![true, true, false], ..Default::default() };
+    assert_eq!(m.surface_patch(0), vec![0, 1, 2]);
+    assert_eq!(m.surface_patch(2), vec![0, 1, 2]);
+    assert_eq!(m.surface_patch(3), vec![3]);
+    m.seams.clear();
+    assert_eq!(m.surface_patch(0), vec![0]);
+}
+
 #[test]
 fn cubic_and_conic_segments_measure_exactly() {
     use crate::{Loop2, Seg2, Vec2};

crates/kernel/src/build.rs

@@ -795,13 +795,68 @@ pub enum PathSeg {
     },
 }
 
+impl PathSeg {
+    /// Unit directions of the path where the segment starts and ends.
+    fn tangents(&self) -> Option<(Vec3, Vec3)> {
+        match *self {
+            PathSeg::Line { a, b } => {
+                let t = (b - a).normalized()?;
+                Some((t, t))
+            }
+            PathSeg::Arc { a, center, axis, angle } => {
+                let k = axis.normalized()?;
+                let end = rotate_about(a, center, k, angle);
+                Some((k.cross(a - center).normalized()?, k.cross(end - center).normalized()?))
+            }
+        }
+    }
+
+    /// Points along the segment (an arc within `tol` of its chords), without its start.
+    fn points_after_start(&self, tol: f64) -> Vec<Vec3> {
+        match *self {
+            PathSeg::Line { b, .. } => vec![b],
+            PathSeg::Arc { a, center, axis, angle } => {
+                let Some(k) = axis.normalized() else { return vec![a] };
+                let r = (a - center).len();
+                let step = if r > tol { 2.0 * (1.0 - tol / r).acos() } else { angle.abs() };
+                let n = ((angle.abs() / step.max(1e-6)).ceil() as usize).clamp(1, 512);
+                (1..=n).map(|i| rotate_about(a, center, k, angle * i as f64 / n as f64)).collect()
+            }
+        }
+    }
+}
+
+/// `p` turned by `angle` about the unit axis `k` through `center` (right hand).
+fn rotate_about(p: Vec3, center: Vec3, k: Vec3, angle: f64) -> Vec3 {
+    let v = p - center;
+    let (s, c) = angle.sin_cos();
+    center + v * c + k.cross(v) * s + k * (k.dot(v) * (1.0 - c))
+}
+
 /// Sweep a planar region (outer loop) along a chain of path segments, keeping the profile
-/// perpendicular to the path (lines translate it, arcs rotate it).
+/// perpendicular to the path (lines translate it, arcs rotate it). A path with sharp corners
+/// is swept as a polyline, mitred at the corners.
 pub fn sweep(plane: &Plane, region: &Region2, path: &[PathSeg]) -> Result<Body> {
     region_ok(region)?;
     if path.is_empty() || path.len() > 1000 {
         return Err(KernelError::Invalid("the path needs 1…1000 segments".into()));
     }
+    // Segment by segment the profile only follows a path whose direction runs on across each
+    // joint: at a corner the next line would slide the profile within its own plane.
+    let ends: Vec<(Vec3, Vec3)> =
+        path.iter().map(PathSeg::tangents).collect::<Option<_>>().ok_or_else(|| KernelError::Invalid("a path segment has no direction".into()))?;
+    let corner = ends.windows(2).any(|w| w[0].1.dot(w[1].0) < (1e-3f64).cos());
+    if corner {
+        let first = match path.first() {
+            Some(PathSeg::Line { a, .. } | PathSeg::Arc { a, .. }) => *a,
+            None => return Err(KernelError::Invalid("the path needs 1…1000 segments".into())),
+        };
+        let mut pts = vec![first];
+        for seg in path {
+            pts.extend(seg.points_after_start(1e-2));
+        }
+        return crate::sweep_path::sweep_path(plane, region, &pts);
+    }
     // The outer loop and each hole, swept along the path; the ends are capped with holes.
     let mut starts = vec![wire(plane, &region.outer.ccw())?];
     for h in &region.holes {

crates/kernel/src/heal.rs

@@ -404,6 +404,12 @@ pub fn heal(solid: Solid, size: f64) -> Solid {
 
 /// [`heal`], keeping faces apart along lines they were split along on purpose.
 pub(crate) fn heal_keep(solid: Solid, size: f64, keep: &[Vec<Vec3>]) -> Solid {
+    // Edges a boolean made are intersection curves, which panic where they no longer
+    // evaluate; the solid then stays as it is.
+    crate::guard("heal", || Ok(heal_shells(&solid, size, keep))).ok().flatten().unwrap_or(solid)
+}
+
+fn heal_shells(solid: &Solid, size: f64, keep: &[Vec<Vec3>]) -> Option<Solid> {
     let tol = (size * 1e-7).max(1e-9);
     let mut shells = Vec::new();
     let mut changed = false;
@@ -428,9 +434,9 @@ pub(crate) fn heal_keep(solid: Solid, size: f64, keep: &[Vec<Vec3>]) -> Solid {
         shells.push(cur);
     }
     if !changed {
-        return solid;
+        return None;
     }
-    Solid::try_new(shells).unwrap_or(solid)
+    Solid::try_new(shells).ok()
 }
 
 #[cfg(test)]

crates/kernel/src/iges_in/tests.rs

@@ -150,7 +150,8 @@ fn a_drill_point_round_trips_through_iges() {
     let plate = box_solid(Vec3::new(-20.0, -15.0, 0.0), Vec3::new(20.0, 15.0, 10.0)).unwrap();
     let profile =
         Region2 { outer: Loop2::polygon(&[Vec2::new(0.0, 2.0), Vec2::new(4.0, 5.0), Vec2::new(4.0, 11.0), Vec2::new(0.0, 11.0)]), holes: vec![] };
-    let hole = crate::revolve(&Plane::XZ, &[profile], Vec2::ZERO, Vec2::new(0.0, 1.0), std::f64::consts::TAU).unwrap().pop().unwrap();
+    let plane = Plane { y: Vec3::Z, ..Plane::XZ }; // Positive profile heights are world +Z.
+    let hole = crate::revolve(&plane, &[profile], Vec2::ZERO, Vec2::new(0.0, 1.0), std::f64::consts::TAU).unwrap().pop().unwrap();
     let drilled = boolean(&plate, &hole, BoolOp::Cut).unwrap().unwrap();
     let v = 12000.0 - std::f64::consts::PI * 16.0 * (5.0 + 1.0);
     assert!(rel(measure(&drilled).unwrap().volume, v) < 1e-3);

crates/kernel/src/lib.rs

@@ -61,7 +61,7 @@ pub use lip::raise_band;
 pub use measure::{BodyMeasure, measure};
 pub use meshbody::{MAX_TRIANGLES, mesh_body};
 pub use offset::with_same_surface;
-pub use ops::{BoolOp, boolean, split_by_plane, transform, transform_matrix};
+pub use ops::{BoolOp, boolean, can_join_touching_faces, split_by_plane, transform, transform_matrix};
 pub use polybool::{faceted_boolean, planar_boolean};
 pub use polyhedron::{HalfSpace, convex_polyhedron, draft, offset_faces, shell};
 pub use sew::{EdgeSpec, FaceSpec, SurfSpec, sew};

crates/kernel/src/ops.rs

@@ -15,6 +15,12 @@ pub enum BoolOp {
     Intersect,
 }
 
+/// Whether a union can sew two matching planar faces without intersecting them.
+/// Callers can retain the exact touching tool instead of extending it into material.
+pub fn can_join_touching_faces(a: &Body, b: &Body) -> bool {
+    a.solid.boundaries().len() == 1 && b.solid.boundaries().len() == 1 && crate::coplanar::glue(a, b).is_some_and(|r| r.is_ok())
+}
+
 /// Shifts applied to both operands on retries. The boolean classifies some faces by casting a
 /// ray whose direction is derived from point coordinates; moving both solids (and the result
 /// back) leaves the geometry unchanged but changes those rays.
@@ -46,7 +52,10 @@ fn mismatch(a: &solvecraft_geom::Mesh, b: &solvecraft_geom::Mesh, result: &solve
     let hi = ba.max.min(bb.max);
     let all = ba.union(&bb);
     let mut boxes = vec![(all, 300usize)];
-    if lo.x < hi.x && lo.y < hi.y && lo.z < hi.z {
+    // A touching seam can overlap by round-off only. Samples there sit on the
+    // operands' boundaries, where ray parity cannot classify membership reliably.
+    let gap = all.diagonal().max(1.0) * 1e-9;
+    if hi.x - lo.x > gap && hi.y - lo.y > gap && hi.z - lo.z > gap {
         boxes.push((solvecraft_geom::Aabb3 { min: lo, max: hi }, 900));
     }
     let (ia_idx, ib_idx, ir_idx) = (a.inside_index(), b.inside_index(), result.inside_index());
@@ -180,11 +189,28 @@ pub fn boolean(a: &Body, b: &Body, op: BoolOp) -> Result<Option<Body>> {
     r
 }
 
+/// Smallest side of the box where the bodies' vertex boxes overlap (infinite when they don't).
+fn meeting_size(a: &Body, b: &Body) -> f64 {
+    let bbox = |x: &Body| {
+        let mut bb = solvecraft_geom::Aabb3::EMPTY;
+        for v in x.solid.vertex_iter() {
+            bb.add(from_p3(v.point()));
+        }
+        bb
+    };
+    let (ba, bb) = (bbox(a), bbox(b));
+    let s = solvecraft_geom::Aabb3 { min: ba.min.max(bb.min), max: ba.max.min(bb.max) }.size();
+    if s.x > 0.0 && s.y > 0.0 && s.z > 0.0 { s.x.min(s.y).min(s.z) } else { f64::INFINITY }
+}
+
 fn boolean_whole(a: &Body, b: &Body, op: BoolOp) -> Result<Option<Body>> {
     a.require_brep("a boolean")?;
     b.require_brep("a boolean")?;
     let size = a.size().max(b.size());
-    let tol_m = size * 5e-4;
+    // The checks mesh both bodies; where they meet in a region much thinner than they are (a
+    // thin part trimmed by a long one), a step from their size would facet the small faces
+    // there coarsely enough to fail the membership test on a correct result.
+    let tol_m = (size * 5e-4).min(meeting_size(a, b) * 2e-3).max(size * 1e-5);
     let meshes = (a.tessellate(tol_m).ok(), b.tessellate(tol_m).ok());
     let (va, vb) = match &meshes {
         (Some(ma), Some(mb)) => (ma.measure().volume, mb.measure().volume),
@@ -287,7 +313,7 @@ fn boolean_whole(a: &Body, b: &Body, op: BoolOp) -> Result<Option<Body>> {
                     empty_votes += 1;
                     last = "empty result".into();
                 }
-                Ok(s) => match Body::new(crate::heal::heal_keep(s, size, &keep)) {
+                Ok(s) => match guard("boolean result", || Body::new(crate::heal::heal_keep(s, size, &keep))) {
                     Ok(body) => {
                         let (ok, v) = check(&body);
                         if ok {
@@ -489,6 +515,15 @@ pub fn transform(body: &Body, translate: Vec3, origin: Vec3, axis: Vec3, angle:
 /// Split a body with a plane: the parts on the positive and the negative side of the plane
 /// (only the non-empty ones).
 pub fn split_by_plane(body: &Body, plane: &solvecraft_geom::Plane) -> Result<Vec<Body>> {
+    let mut out = Vec::new();
+    for positive in [true, false] {
+        out.extend(half_space(body, plane, positive)?);
+    }
+    Ok(out)
+}
+
+/// The part of a body on one side of a plane (`None` when nothing is there).
+pub(crate) fn half_space(body: &Body, plane: &solvecraft_geom::Plane, positive: bool) -> Result<Option<Body>> {
     body.require_brep("split")?;
     let size = body.size();
     let mut bb = solvecraft_geom::Aabb3::EMPTY;
@@ -506,12 +541,7 @@ pub fn split_by_plane(body: &Body, plane: &solvecraft_geom::Plane) -> Result<Vec
         ]),
         holes: vec![],
     };
-    let mut out = Vec::new();
-    for (lo, hi) in [(0.0, reach), (-reach, 0.0)] {
-        let half = crate::build::extrude(plane, std::slice::from_ref(&sq), lo, hi)?.pop().ok_or_else(|| KernelError::Failed("half space".into()))?;
-        if let Some(part) = boolean(body, &half, BoolOp::Intersect)? {
-            out.push(part);
-        }
-    }
-    Ok(out)
+    let (lo, hi) = if positive { (0.0, reach) } else { (-reach, 0.0) };
+    let half = crate::build::extrude(plane, std::slice::from_ref(&sq), lo, hi)?.pop().ok_or_else(|| KernelError::Failed("half space".into()))?;
+    boolean(body, &half, BoolOp::Intersect)
 }

crates/kernel/src/polybool.rs

@@ -306,12 +306,118 @@ pub fn planar_boolean(a: &Body, b: &Body, op: BoolOp) -> Result<Option<Body>> {
     a.require_brep("a boolean")?;
     b.require_brep("a boolean")?;
     let (Some(pa), Some(pb)) = (planar_polys(a), planar_polys(b)) else {
+        if let Some(r) = sliced_planar_boolean(a, b, op) {
+            return r;
+        }
         return Err(KernelError::Failed("not supported yet: coincident faces on curved bodies".into()));
     };
     let size = a.size().max(b.size());
     polys_boolean(pa, pb, size, op, size * 1e-9)
 }
 
+/// [`planar_boolean`] of a body with curved faces and an all-planar one, when a slab between
+/// two parallel planes holds `b` and none of `a`'s curved faces (a pocket cut beside a round
+/// hole): `a` is split across the slab, the middle piece takes the exact boolean, and the
+/// pieces outside are joined back on. `None` when no such slab exists.
+fn sliced_planar_boolean(a: &Body, b: &Body, op: BoolOp) -> Option<Result<Option<Body>>> {
+    let pb = planar_polys(b)?;
+    let size = a.size().max(b.size());
+    let tol = (a.size() * 1e-3).max(1e-3);
+    let infos = a.faces(tol).ok()?;
+    let mesh = a.tessellate(tol).ok()?;
+    let mut curved: HashMap<u32, solvecraft_geom::Aabb3> = HashMap::new();
+    for (t, fi) in mesh.triangles.iter().zip(&mesh.tri_face) {
+        if infos.get(*fi as usize)?.plane_normal.is_some() {
+            continue;
+        }
+        let bx = curved.entry(*fi).or_insert(solvecraft_geom::Aabb3::EMPTY);
+        for p in mesh.tri(t)? {
+            bx.add(p);
+        }
+    }
+    let mut tool = solvecraft_geom::Aabb3::EMPTY;
+    for p in pb.iter().flat_map(|p| &p.v) {
+        tool.add(*p);
+    }
+    let at = |v: Vec3, k: usize| [v.x, v.y, v.z].get(k).copied().unwrap_or(0.0);
+    let axes = [Vec3::X, Vec3::Y, Vec3::Z];
+    // Planar faces of `a` square to an axis: a cut must not land in one of their planes.
+    let flat: Vec<(Vec3, Vec3)> = infos.iter().filter_map(|f| Some((f.plane_normal?, f.centroid))).collect();
+    let gap = size * 1e-4;
+    let place = |k: usize, near: f64, far: f64| -> Option<f64> {
+        let axis = *axes.get(k)?;
+        [0.5, 0.37, 0.63, 0.25, 0.75]
+            .iter()
+            .map(|t| near + (far - near) * t)
+            .find(|x| !flat.iter().any(|(n, c)| n.dot(axis).abs() > 1.0 - 1e-9 && (at(*c, k) - x).abs() < gap))
+    };
+    // An axis along which every curved face lies clear of the tool: the cuts either side.
+    let (k, lo, hi) = (0..3).find_map(|k| {
+        let (t0, t1) = (at(tool.min, k), at(tool.max, k));
+        let (mut below, mut above) = (None::<f64>, None::<f64>);
+        for bx in curved.values() {
+            let (c0, c1) = (at(bx.min, k), at(bx.max, k));
+            if c1 < t0 - gap {
+                below = Some(below.map_or(c1, |x| x.max(c1)));
+            } else if c0 > t1 + gap {
+                above = Some(above.map_or(c0, |x| x.min(c0)));
+            } else {
+                return None;
+            }
+        }
+        let lo = match below {
+            Some(c) => Some(place(k, t0, c)?),
+            None => None,
+        };
+        let hi = match above {
+            Some(c) => Some(place(k, t1, c)?),
+            None => None,
+        };
+        Some((k, lo, hi))
+    })?;
+    let (u, w) = match k {
+        0 => (Vec3::Y, Vec3::Z),
+        1 => (Vec3::Z, Vec3::X),
+        _ => (Vec3::X, Vec3::Y),
+    };
+    let axis = *axes.get(k)?;
+    let run = || -> Result<Option<Body>> {
+        let fail = |m: &str| KernelError::Failed(format!("planar boolean beside curved faces: {m}"));
+        let mut middle = a.clone();
+        let mut outside = Vec::new();
+        for (cut, keep_positive) in [(lo, true), (hi, false)] {
+            let Some(x) = cut else { continue };
+            let plane = solvecraft_geom::Plane::new(axis * x, u, w).ok_or_else(|| fail("plane"))?;
+            outside.extend(crate::ops::half_space(&middle, &plane, !keep_positive)?);
+            middle = crate::ops::half_space(&middle, &plane, keep_positive)?.ok_or_else(|| fail("nothing beside the tool"))?;
+        }
+        let pm = planar_polys(&middle).ok_or_else(|| fail("the middle piece is not planar"))?;
+        let r = polys_boolean(pm, pb, size, op, size * 1e-9)?;
+        if op == BoolOp::Intersect {
+            return Ok(r);
+        }
+        // The rebuild leaves the cut faces' edges split where other polygons were cut; healed,
+        // they match the pieces outside edge for edge.
+        let mut pieces: Vec<Body> = match r {
+            Some(m) => vec![Body::new(crate::heal::heal_keep(m.deep_copy(), size, a.split_keep()))?],
+            None => Vec::new(),
+        };
+        // Each piece outside meets the middle along its cut face (glued one shell to another).
+        if pieces.iter().chain(&outside).any(|x| x.solid.boundaries().len() != 1) {
+            return Err(fail("a piece in several parts"));
+        }
+        for o in outside {
+            let joined = pieces.iter().enumerate().find_map(|(i, m)| Some((i, crate::coplanar::glue(m, &o)?.ok()?)));
+            let (i, j) = joined.ok_or_else(|| fail("a piece does not join back"))?;
+            if let Some(slot) = pieces.get_mut(i) {
+                *slot = j;
+            }
+        }
+        crate::ops::join_pieces(pieces)
+    };
+    Some(run())
+}
+
 fn polys_boolean(pa: Vec<Poly>, pb: Vec<Poly>, size: f64, op: BoolOp, eps: f64) -> Result<Option<Body>> {
     let polys = csg(pa, pb, op, eps)?;
     if polys.is_empty() {

crates/kernel/src/prism.rs

@@ -77,6 +77,7 @@ fn prism_of(b: &Body, d: Vec3, plane: &Plane, tol: f64) -> Option<Prism> {
     let mut hi = f64::NEG_INFINITY;
     let mut tops: Vec<&mt::Face> = Vec::new();
     let mut top_h = Vec::new();
+    let mut bottom_h = Vec::new();
     for f in b.solid.face_iter() {
         let surf = f.oriented_surface();
         if let mt::Surface::Plane(p) = &surf {
@@ -90,6 +91,7 @@ fn prism_of(b: &Body, d: Vec3, plane: &Plane, tol: f64) -> Option<Prism> {
                 continue;
             }
             if n.dot(d) < -1.0 + 1e-9 {
+                bottom_h.push(h);
                 lo = lo.min(h);
                 continue;
             }
@@ -110,7 +112,7 @@ fn prism_of(b: &Body, d: Vec3, plane: &Plane, tol: f64) -> Option<Prism> {
         }
     }
     // One height for every top (and bottom) cap.
-    if top_h.iter().any(|h| (h - hi).abs() > tol) || !(lo.is_finite() && hi > lo + tol) {
+    if top_h.iter().any(|h| (h - hi).abs() > tol) || bottom_h.iter().any(|h| (h - lo).abs() > tol) || !(lo.is_finite() && hi > lo + tol) {
         return None;
     }
     let mut regions = Vec::new();
@@ -382,6 +384,129 @@ fn boolean2d(a: &[Region2], b: &[Region2], op: BoolOp, tol: f64) -> Option<Vec<R
 }
 
 /// The boolean done on prism sections, or `None` when it doesn't apply.
+/// The pieces of a segment between the given points (those lying on it, inside it).
+fn split_seg(seg: &Seg2, pts: &[Vec2], tol: f64) -> Option<Vec<Seg2>> {
+    if !matches!(seg, Seg2::Line { .. } | Seg2::Arc { .. }) {
+        return None;
+    }
+    let mut ts: Vec<f64> = pts
+        .iter()
+        .filter_map(|p| {
+            let t = seg.closest_param(*p);
+            (t > 1e-9 && t < 1.0 - 1e-9 && seg.point_at(t).dist(*p) < tol).then_some(t)
+        })
+        .collect();
+    ts.sort_by(f64::total_cmp);
+    ts.dedup_by(|x, y| (*x - *y).abs() < 1e-9);
+    let mut out = Vec::new();
+    let mut t0 = 0.0;
+    for t1 in ts.into_iter().chain(std::iter::once(1.0)) {
+        out.push(match *seg {
+            Seg2::Line { .. } => Seg2::Line { a: seg.point_at(t0), b: seg.point_at(t1) },
+            Seg2::Arc { center, radius, start, sweep } => Seg2::Arc { center, radius, start: start + sweep * t0, sweep: sweep * (t1 - t0) },
+            _ => return None,
+        });
+        t0 = t1;
+    }
+    Some(out)
+}
+
+/// The union of two prisms along `d` stacked end to end (or overlapping) with different
+/// sections, sewn from its faces: each slab between the prisms' end levels has walls over its
+/// section's outline; each level has a face up over the section below less the one above, and
+/// a face down over the one above less the one below. Every outline is split where any other
+/// meets it, so the faces share their edges. `None` when a slab is empty or a curve isn't a
+/// line or an arc.
+fn sew_stack(plane: &Plane, d: Vec3, pa: &Prism, pb: &Prism, tol: f64) -> Option<Result<Body>> {
+    use crate::sew::{EdgeSpec, FaceSpec, SurfSpec};
+    let mut levels = vec![pa.lo, pa.hi, pb.lo, pb.hi];
+    levels.sort_by(f64::total_cmp);
+    levels.dedup_by(|x, y| (*x - *y).abs() < tol);
+    let covers = |p: &Prism, z0: f64, z1: f64| p.lo <= z0 + tol && p.hi >= z1 - tol;
+    let mut slabs: Vec<Vec<Region2>> = Vec::new();
+    for w in levels.windows(2) {
+        let (z0, z1) = (*w.first()?, *w.get(1)?);
+        let s = match (covers(pa, z0, z1), covers(pb, z0, z1)) {
+            (true, true) => boolean2d(&pa.regions, &pb.regions, BoolOp::Union, tol)?,
+            (true, false) => pa.regions.clone(),
+            (false, true) => pb.regions.clone(),
+            (false, false) => return None,
+        };
+        slabs.push(oriented(&s));
+    }
+    // Faces at each level: up where the slab below sticks out, down where the one above does.
+    let diff = |x: &[Region2], y: &[Region2]| -> Option<Vec<Region2>> {
+        match (x.is_empty(), y.is_empty()) {
+            (true, _) => Some(Vec::new()),
+            (false, true) => Some(x.to_vec()),
+            (false, false) => boolean2d(x, y, BoolOp::Cut, tol).map(|r| oriented(&r)),
+        }
+    };
+    let mut caps: Vec<(f64, bool, Vec<Region2>)> = Vec::new();
+    for (k, z) in levels.iter().enumerate() {
+        let below: &[Region2] = if k == 0 { &[] } else { slabs.get(k - 1)? };
+        let above: &[Region2] = slabs.get(k).map(Vec::as_slice).unwrap_or(&[]);
+        caps.push((*z, true, diff(below, above)?));
+        caps.push((*z, false, diff(above, below)?));
+    }
+    // Every segment end, everywhere: outlines split there.
+    let loops_of =
+        |rs: &[Region2]| -> Vec<Loop2> { rs.iter().flat_map(|r| std::iter::once(r.outer.clone()).chain(r.holes.iter().cloned())).collect() };
+    let mut pts: Vec<Vec2> = Vec::new();
+    for lp in slabs.iter().flat_map(|s| loops_of(s)).chain(caps.iter().flat_map(|c| loops_of(&c.2))) {
+        for sg in &lp.segs {
+            pts.push(sg.start());
+            pts.push(sg.end());
+        }
+    }
+    let at = |u: Vec2, z: f64| plane.to_world(u) + d * z;
+    let edge = |sg: &Seg2, z: f64| -> EdgeSpec {
+        match sg {
+            Seg2::Arc { .. } => EdgeSpec::Arc { a: at(sg.start(), z), b: at(sg.end(), z), mid: at(sg.point_at(0.5), z) },
+            _ => EdgeSpec::Line { a: at(sg.start(), z), b: at(sg.end(), z) },
+        }
+    };
+    let mut faces: Vec<FaceSpec> = Vec::new();
+    for (i, s) in slabs.iter().enumerate() {
+        let (z0, z1) = (*levels.get(i)?, *levels.get(i + 1)?);
+        for lp in loops_of(s) {
+            for sg0 in &lp.segs {
+                for sg in split_seg(sg0, &pts, tol)? {
+                    let (a, b) = (sg.start(), sg.end());
+                    let lp3 = vec![
+                        edge(&sg, z0),
+                        EdgeSpec::Line { a: at(b, z0), b: at(b, z1) },
+                        edge(&sg.reversed(), z1),
+                        EdgeSpec::Line { a: at(a, z1), b: at(a, z0) },
+                    ];
+                    let tangent = plane.dir_to_world(sg.derivative(0.5));
+                    let outward = tangent.cross(d).normalized()?;
+                    let surface = match sg {
+                        Seg2::Arc { .. } => SurfSpec::Extruded { a: at(a, z0), b: at(b, z0), mid: at(sg.point_at(0.5), z0), dir: d * (z1 - z0) },
+                        _ => SurfSpec::Plane,
+                    };
+                    faces.push(FaceSpec { loops: vec![lp3], surface, probe: Some((at(sg.point_at(0.5), (z0 + z1) / 2.0), outward)) });
+                }
+            }
+        }
+    }
+    for (z, up, rs) in &caps {
+        for r in rs {
+            let mut loops = Vec::new();
+            for lp in std::iter::once(&r.outer).chain(&r.holes) {
+                let mut segs: Vec<Seg2> = Vec::new();
+                for sg in &lp.segs {
+                    segs.extend(split_seg(sg, &pts, tol)?);
+                }
+                let segs: Vec<Seg2> = if *up { segs } else { segs.iter().rev().map(Seg2::reversed).collect() };
+                loops.push(segs.iter().map(|sg| edge(sg, *z)).collect::<Vec<_>>());
+            }
+            faces.push(FaceSpec { loops, surface: SurfSpec::Plane, probe: None });
+        }
+    }
+    Some(crate::sew::sew(&faces))
+}
+
 pub(crate) fn prism_boolean(a: &Body, b: &Body, op: BoolOp) -> Option<Result<Option<Body>>> {
     let size = a.size().max(b.size());
     let tol = (size * 1e-7).max(1e-9) * 10.0;
@@ -423,10 +548,10 @@ pub(crate) fn prism_boolean(a: &Body, b: &Body, op: BoolOp) -> Option<Result<Opt
         return Some(Ok(None));
     }
     let (lo, hi) = if stacked {
-        // Only when the sections are the same (the union adds nothing to either).
+        // Different sections (a boss hanging over a plate's edge): sewn slab by slab.
         let (u, x, y) = (area(&regions), area(&pa.regions), area(&pb.regions));
         if (u - x).abs() > tol * (1.0 + u) || (u - y).abs() > tol * (1.0 + u) {
-            return None;
+            return sew_stack(&plane, d, &pa, &pb, tol).map(|r| r.map(Some));
         }
         (pa.lo.min(pb.lo), pa.hi.max(pb.hi))
     } else {

crates/kernel/src/splitface.rs

@@ -1208,7 +1208,7 @@ mod tests {
         let m0 = measure(&c).unwrap();
         let side = c.faces(0.01).unwrap().iter().position(|f| f.plane_normal.is_none()).unwrap();
         // A horizontal line seen from the front (XZ sketch) at z = 5, swept along y.
-        let xz = Plane::XZ;
+        let xz = Plane { y: Vec3::Z, ..Plane::XZ };
         let tool = SplitTool::Curves { plane: xz, curves: vec![vec![Seg2::Line { a: Vec2::new(-20.0, 5.0), b: Vec2::new(20.0, 5.0) }]] };
         let s = split_faces(&c, &[side], &tool).unwrap();
         let m = measure(&s).unwrap();

crates/kernel/src/tests.rs

@@ -40,8 +40,8 @@ fn extrude_on_other_planes_and_offsets() {
     let b = extrude(&Plane::XZ, &[rect(10.0, 5.0)], -2.0, 3.0).unwrap().pop().unwrap();
     let m = measure(&b).unwrap();
     assert!(rel(m.volume, 250.0) < 1e-9);
-    // XZ normal is -Y: the body spans y in [-3, 2].
-    assert!((m.bbox.min.y + 3.0).abs() < 1e-6 && (m.bbox.max.y - 2.0).abs() < 1e-6, "{:?}", m.bbox);
+    // XZ normal is +Y: the body spans y in [-2, 3].
+    assert!((m.bbox.min.y + 2.0).abs() < 1e-6 && (m.bbox.max.y - 3.0).abs() < 1e-6, "{:?}", m.bbox);
 }
 
 #[test]
@@ -52,6 +52,39 @@ fn region_with_hole() {
     assert!(rel(m.volume, (1200.0 - PI * 25.0) * 10.0) < 5e-4, "{}", m.volume);
 }
 
+#[test]
+fn through_cut_preserves_a_larger_blind_pocket() {
+    let plate = box_solid(Vec3::new(-30.0, -28.0, 0.0), Vec3::new(60.0, 22.0, 8.0)).unwrap();
+    let pocket = cylinder(Vec3::ZERO, Vec3::Z, 11.0, 6.0).unwrap();
+    let through = cylinder(Vec3::new(0.0, 0.0, -1.0), Vec3::Z, 9.5, 10.0).unwrap();
+    let expected = 90.0 * 50.0 * 8.0 - PI * 11.0_f64.powi(2) * 6.0 - PI * 9.5_f64.powi(2) * 2.0;
+    for reverse in [false, true] {
+        let (first, second) = if reverse { (&through, &pocket) } else { (&pocket, &through) };
+        let cut = boolean(&plate, first, BoolOp::Cut).unwrap().unwrap();
+        let result = boolean(&cut, second, BoolOp::Cut).unwrap().unwrap();
+        let m = measure(&result).unwrap();
+        assert!(rel(m.volume, expected) < 5e-4, "reverse={reverse}: {} vs {expected}", m.volume);
+        assert_eq!(m.merged.faces, 9);
+        assert!(!result.tessellate(0.01).unwrap().contains(Vec3::new(10.0, 0.0, 3.0)));
+    }
+}
+
+#[test]
+fn join_a_cylinder_on_its_chamfered_top() {
+    for seam in [0.0, crate::build::SEAM_ANGLE] {
+        let region = Region2 { outer: Loop2::circle_from(Vec2::ZERO, 10.0, seam), holes: vec![] };
+        let base = extrude(&Plane::XY, &[region], 0.0, 20.0).unwrap().pop().unwrap();
+        let base = chamfer(&base, &[Vec3::new(10.0, 0.0, 20.0)], 2.0).unwrap();
+        let region = Region2 { outer: Loop2::circle_from(Vec2::new(0.0, -3.774758283725534e-15), 8.0, seam), holes: vec![] };
+        let plane = Plane { origin: Vec3::new(0.0, 0.0, 20.000000000000007), ..Plane::XY };
+        let tool = extrude(&plane, &[region], 0.0, 5.0).unwrap().pop().unwrap();
+        let expected = measure(&base).unwrap().volume + PI * 64.0 * 5.0;
+        let joined = boolean(&base, &tool, BoolOp::Union).unwrap().unwrap();
+        assert!(rel(measure(&joined).unwrap().volume, expected) < 5e-4);
+        assert_eq!(joined.lumps().unwrap().len(), 1);
+    }
+}
+
 #[test]
 fn box_fillet_cut_volume() {
     let b = box_solid(Vec3::ZERO, Vec3::new(40.0, 30.0, 20.0)).unwrap();
@@ -225,6 +258,38 @@ fn loft_and_sweep() {
     assert!(rel(measure(&t).unwrap().volume, expect) < 1e-3, "{} vs {expect}", measure(&t).unwrap().volume);
 }
 
+#[test]
+fn sweep_round_a_sharp_corner_is_mitred() {
+    // A 2 × 2 square centred on an L of two 10 mm lines: lines alone would slide the profile
+    // along the second leg within its own plane (an empty, inside-out body). Mitred, the
+    // volume is the area times the path length.
+    let sq =
+        Region2 { outer: Loop2::polygon(&[Vec2::new(-1.0, -1.0), Vec2::new(1.0, -1.0), Vec2::new(1.0, 1.0), Vec2::new(-1.0, 1.0)]), holes: vec![] };
+    let path = [
+        PathSeg::Line { a: Vec3::ZERO, b: Vec3::new(0.0, 0.0, 10.0) },
+        PathSeg::Line { a: Vec3::new(0.0, 0.0, 10.0), b: Vec3::new(10.0, 0.0, 10.0) },
+    ];
+    let b = sweep(&Plane::XY, &sq, &path).unwrap();
+    let m = measure(&b).unwrap();
+    assert!(rel(m.volume, 80.0) < 1e-9, "{}", m.volume);
+}
+
+#[test]
+fn moving_a_body_with_an_intersection_curve_edge_ends() {
+    // A cylinder cut by a tilted box keeps an elliptical intersection curve as an edge. Moving
+    // such a body scales the curve's tolerance by the matrix norm, whose root refinement cycled
+    // forever for about one translation in eight (this one included): the app hung.
+    let cyl = cylinder(Vec3::ZERO, Vec3::Z, 5.0, 40.0).unwrap();
+    let block = box_solid(Vec3::new(-20.0, -20.0, 20.0), Vec3::new(20.0, 20.0, 60.0)).unwrap();
+    let block = crate::ops::transform(&block, Vec3::ZERO, Vec3::new(0.0, 0.0, 20.0), Vec3::X, 0.4).unwrap();
+    let cut = boolean(&cyl, &block, BoolOp::Cut).unwrap().unwrap();
+    assert!(cut.solid.edge_iter().any(|e| matches!(e.curve(), truck_modeling::Curve::IntersectionCurve(_))));
+    let t = Vec3::new(0.6911, -0.3337, -0.6127) * 2.334;
+    let moved = crate::ops::transform(&cut, t, Vec3::ZERO, Vec3::Z, 0.0).unwrap();
+    let (v0, v1) = (measure(&cut).unwrap().volume, measure(&moved).unwrap().volume);
+    assert!(rel(v0, v1) < 1e-6, "{v0} vs {v1}");
+}
+
 #[test]
 fn planar_booleans_with_coincident_faces() {
     // L-bracket: a wall flush with three sides of its base.
@@ -1344,7 +1409,8 @@ fn boolean_identity_survey() {
 fn partial_revolve_on_the_axis() {
     let sq =
         Region2 { outer: Loop2::polygon(&[Vec2::new(0.0, 0.0), Vec2::new(20.0, 0.0), Vec2::new(20.0, 7.5), Vec2::new(0.0, 7.5)]), holes: vec![] };
-    let pie = revolve(&Plane::XZ, &[sq], Vec2::ZERO, Vec2::Y, std::f64::consts::FRAC_PI_2).unwrap().pop().unwrap();
+    let plane = Plane { y: Vec3::Z, ..Plane::XZ }; // This fixture's rectangle is above z = 0.
+    let pie = revolve(&plane, &[sq], Vec2::ZERO, Vec2::Y, std::f64::consts::FRAC_PI_2).unwrap().pop().unwrap();
     assert!(pie.validity().is_empty(), "{:?}", pie.validity());
     let v = measure(&pie).unwrap().volume;
     assert!((v - PI * 400.0 / 4.0 * 7.5).abs() < 1e-3 * v, "{v}");

crates/mcp/src/tests.rs

@@ -213,6 +213,35 @@ fn batch_stops_at_first_error_and_rolls_back() {
     assert_eq!(tool(&mut s, "measure", json!({}))["body_count"], 2);
 }
 
+/// Regression: with a full undo history a failed batch reported `undone: 0` and left its
+/// sketches behind (an empty "Sketch1", two sketches named "TapHole").
+#[test]
+fn batch_rolls_back_with_a_full_undo_history() {
+    let mut s = server();
+    let fill: Vec<Value> =
+        (0..230).map(|i| json!({"command": "parameters.add", "params": {"name": format!("p{i}"), "expression": "1 mm"}})).collect();
+    tool(&mut s, "batch", json!({"commands": fill}));
+    let undo = tool(&mut s, "inspect_design", json!({"measure": false}))["undo"].clone();
+    for _ in 0..2 {
+        let r = raw_tool(
+            &mut s,
+            "batch",
+            json!({"commands": [
+                {"command": "sketch.create", "params": {"plane": "XY", "name": "TapHole"}},
+                {"command": "sketch.circle.center", "params": {"center": [0, 0], "radius": 2}},
+                {"command": "sketch.dimension", "params": {"entities": ["nope"], "value": 3}},
+            ]}),
+        );
+        let body: Value = serde_json::from_str(r["result"]["content"][0]["text"].as_str().unwrap()).unwrap();
+        assert_eq!(body["failed"]["index"], 2, "{body}");
+        assert_eq!(body["undone"], 2, "{body}");
+    }
+    let d = tool(&mut s, "inspect_design", json!({"measure": false, "sketches": false}));
+    assert_eq!(d["sketches"].as_array().map(Vec::len), Some(0), "{d}");
+    assert!(d["active_sketch"].is_null(), "{d}");
+    assert_eq!(d["undo"], undo);
+}
+
 #[test]
 fn helper_sketches_can_be_hidden() {
     let mut s = server();

crates/mcp/src/tools.rs

@@ -129,7 +129,8 @@ pub fn tool_definitions() -> Vec<Value> {
             "set_parameter",
             "Set a parameter",
             "Create or change a user parameter and re-evaluate the timeline. `value` is a number (mm) or an expression \
-             (\"40 mm\", \"width * 2\", \"30 deg\"). Returns the new value, the features recomputed and any features that now fail.",
+             (\"40 mm\", \"width * 2\", \"30 deg\"). Returns the new value, the features recomputed (`recomputed`), the features whose earlier \
+             result for the same inputs was reused instead (`restored`, e.g. after setting a value back) and any features that now fail.",
             obj(
                 json!({
                     "name": string("Parameter name"),
@@ -360,7 +361,56 @@ fn undo_depth(b: &mut dyn Backend) -> Option<u64> {
     b.call("document.inspect", json!({})).ok().and_then(|d| d["undo"].as_u64())
 }
 
-/// `batch`: run steps in order, stop at the first failure and (by default) undo what ran.
+/// How a failed batch goes back to where it started.
+enum Undo {
+    /// An engine checkpoint: the design, active sketch and undo history exactly as they were.
+    Checkpoint(u64),
+    /// An app without checkpoints: undo as many steps as the batch added (wrong once the undo
+    /// history is full, as its depth no longer grows).
+    Depth(u64),
+    None,
+}
+
+impl Undo {
+    fn begin(b: &mut dyn Backend) -> Undo {
+        match exec(b, "edit.checkpoint", json!({})).ok().and_then(|v| v["checkpoint"].as_u64()) {
+            Some(id) => Undo::Checkpoint(id),
+            None => undo_depth(b).map_or(Undo::None, Undo::Depth),
+        }
+    }
+
+    /// Go back; the number of steps undone.
+    fn rollback(self, b: &mut dyn Backend, steps: usize) -> u64 {
+        match self {
+            Undo::Checkpoint(id) => match exec(b, "edit.restore_checkpoint", json!({"checkpoint": id})) {
+                Ok(_) => steps as u64,
+                Err(_) => 0,
+            },
+            Undo::Depth(before) => {
+                let after = undo_depth(b).unwrap_or(before);
+                let mut undone = 0u64;
+                for _ in before..after {
+                    if exec(b, "edit.undo", json!({})).is_err() {
+                        break;
+                    }
+                    undone += 1;
+                }
+                undone
+            }
+            Undo::None => 0,
+        }
+    }
+
+    /// The batch went through: forget the checkpoint.
+    fn finish(self, b: &mut dyn Backend) {
+        if let Undo::Checkpoint(id) = self {
+            let _ = exec(b, "edit.restore_checkpoint", json!({"checkpoint": id, "forget": true}));
+        }
+    }
+}
+
+/// `batch`: run steps in order, stop at the first failure and (by default) go back to the
+/// design as it was before the batch.
 fn batch(b: &mut dyn Backend, a: &Map<String, Value>) -> Value {
     let Some(steps) = a.get("commands").and_then(Value::as_array) else {
         return text_result(&json!("`commands` must be an array of {command, params}"), true);
@@ -369,7 +419,7 @@ fn batch(b: &mut dyn Backend, a: &Map<String, Value>) -> Value {
         return text_result(&json!(format!("batch too long ({} steps, at most {MAX_BATCH})", steps.len())), true);
     }
     let rollback = a.get("rollback").and_then(Value::as_bool).unwrap_or(true);
-    let before = if rollback { undo_depth(b) } else { None };
+    let start = if rollback { Undo::begin(b) } else { Undo::None };
     let mut results = Vec::with_capacity(steps.len());
     for (i, step) in steps.iter().enumerate() {
         let command = step.get("command").or_else(|| step.get("id")).and_then(Value::as_str);
@@ -380,15 +430,7 @@ fn batch(b: &mut dyn Backend, a: &Map<String, Value>) -> Value {
         match r {
             Ok(v) => results.push(v),
             Err(e) => {
-                let mut undone = 0u64;
-                if let (Some(before), Some(after)) = (before, rollback.then(|| undo_depth(b)).flatten()) {
-                    for _ in before..after {
-                        if exec(b, "edit.undo", json!({})).is_err() {
-                            break;
-                        }
-                        undone += 1;
-                    }
-                }
+                let undone = start.rollback(b, i);
                 return text_result(
                     &json!({
                         "ok": false,
@@ -403,6 +445,7 @@ fn batch(b: &mut dyn Backend, a: &Map<String, Value>) -> Value {
             }
         }
     }
+    start.finish(b);
     text_result(&json!({"ok": true, "completed": results.len(), "results": results}), false)
 }
 

crates/sketch/src/lib.rs

@@ -13,6 +13,7 @@ mod dims;
 mod linalg;
 mod link;
 mod model;
+mod offset;
 mod profiles;
 mod shape;
 mod solver;
@@ -25,6 +26,7 @@ pub use curves::{
 pub use dims::{DimFrame, DimLayout, chain_centres, default_text, dim_frame, dim_layout, encode_text};
 pub use link::{Link, LinkGeom, LinkKind, LinkSource, MAX_LINK_ENTITIES};
 pub use model::{Constraint, ConstraintKind, Curve, CurveKind, SPoint, Sketch, SketchError, SketchView};
+pub use offset::OffsetChain;
 pub use profiles::{Profile, find_drawn_profiles, find_profiles, merge_regions};
 pub use shape::{Shape, intersections};
 pub use solver::{Hold, SolveReport, SolveStatus, measure_dimension, solve, solve_holding};

crates/sketch/src/link.rs

@@ -104,6 +104,9 @@ pub struct Link {
     #[serde(default)]
     pub kind: LinkKind,
     pub source: LinkSource,
+    /// Persistent model face identity, resolved by the document before geometry refresh.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub face_name: Option<String>,
     /// The reference could not be found on the last recompute; the geometry is the last good one.
     #[serde(default, skip_serializing_if = "std::ops::Not::not")]
     pub lost: bool,
@@ -169,7 +172,7 @@ struct Layout {
     curves: Vec<LCurve>,
 }
 
-#[derive(Clone, Copy, PartialEq)]
+#[derive(Clone, Copy, Debug, PartialEq)]
 enum LCurve {
     Line(usize, usize),
     Circle(usize, f64),
@@ -368,7 +371,7 @@ impl Sketch {
             return Err(SketchError::TooLarge);
         }
         let id = self.fresh("j");
-        self.links.push(Link { id: id.clone(), kind, source, lost: false });
+        self.links.push(Link { id: id.clone(), kind, source, face_name: None, lost: false });
         self.build_link(&id, &lay)?;
         Ok(id)
     }
@@ -579,6 +582,77 @@ impl Sketch {
                 return Ok(false);
             }
         }
+        // A resized face can enumerate the same boundary in another order. Match the
+        // shared-point graph in normalized sketch space before discarding its identity.
+        if let Some(cur) = &cur
+            && points.len() == lay.pts.len()
+            && cur.len() == lay.curves.len()
+            && points.len() <= 512
+        {
+            let old: Vec<Vec2> = points.iter().filter_map(|i| self.point(*i)).collect();
+            let normalized = |ps: &[Vec2]| -> Vec<Vec2> {
+                let lo = ps.iter().fold(Vec2::new(f64::INFINITY, f64::INFINITY), |a, p| Vec2::new(a.x.min(p.x), a.y.min(p.y)));
+                let hi = ps.iter().fold(Vec2::new(f64::NEG_INFINITY, f64::NEG_INFINITY), |a, p| Vec2::new(a.x.max(p.x), a.y.max(p.y)));
+                ps.iter().map(|p| Vec2::new((p.x - lo.x) / (hi.x - lo.x).max(1e-9), (p.y - lo.y) / (hi.y - lo.y).max(1e-9))).collect()
+            };
+            let (a, b) = (normalized(&old), normalized(&lay.pts));
+            let mut mapping = Vec::new();
+            for p in &a {
+                let mut candidates: Vec<(usize, f64)> = b.iter().enumerate().map(|(i, q)| (i, p.dist(*q))).collect();
+                candidates.sort_by(|x, y| x.1.total_cmp(&y.1));
+                if let Some((i, d)) = candidates.first()
+                    && *d < 0.1
+                    && candidates.get(1).is_none_or(|(_, second)| *d < *second * 0.5)
+                    && !mapping.contains(i)
+                {
+                    mapping.push(*i);
+                } else {
+                    break;
+                }
+            }
+            let mut used = Vec::new();
+            let mut curve_map = Vec::new();
+            if mapping.len() == points.len() {
+                for c in cur {
+                    let mapped: Option<Vec<usize>> = curve_points(c).iter().map(|i| mapping.get(*i).copied()).collect();
+                    let found = lay
+                        .curves
+                        .iter()
+                        .enumerate()
+                        .find(|(i, fresh)| {
+                            if used.contains(i) || !same_shape(c, fresh) {
+                                return false;
+                            }
+                            let fresh_pts = curve_points(fresh);
+                            mapped.as_ref().is_some_and(|p| {
+                                *p == fresh_pts || matches!(c, LCurve::Line(..)) && p.iter().rev().copied().collect::<Vec<_>>() == fresh_pts
+                            })
+                        })
+                        .map(|(i, _)| i);
+                    if let Some(i) = found {
+                        used.push(i);
+                        curve_map.push(i);
+                    } else {
+                        break;
+                    }
+                }
+            }
+            if curve_map.len() == cur.len() && mapping.len() == points.len() {
+                for (pi, li) in points.iter().zip(mapping) {
+                    if let (Some(p), Some(q)) = (self.points.get_mut(*pi), lay.pts.get(li)) {
+                        p.pos = *q;
+                    }
+                }
+                for (ci, li) in curves.iter().zip(curve_map) {
+                    if let (Some(Curve { kind: CurveKind::Circle { r, .. }, .. }), Some(LCurve::Circle(_, value))) =
+                        (self.curves.get_mut(*ci), lay.curves.get(li))
+                    {
+                        *r = *value;
+                    }
+                }
+                return Ok(false);
+            }
+        }
         // Rebuild: drop the old entities (constraints on them go too) and make new ones.
         self.drop_link_entities(id);
         self.build_link(id, &lay)?;

crates/sketch/src/model.rs

@@ -467,6 +467,8 @@ pub struct Sketch {
     /// Links to geometry outside the sketch (projections, intersections, includes).
     #[serde(default, skip_serializing_if = "Vec::is_empty")]
     pub links: Vec<crate::link::Link>,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub offsets: Vec<crate::offset::OffsetChain>,
     /// 3D curves (world coordinates) carried by the sketch.
     #[serde(default, skip_serializing_if = "Vec::is_empty")]
     pub wires: Vec<crate::wire::Wire>,
@@ -495,6 +497,7 @@ impl Sketch {
             curves: Vec::new(),
             constraints: Vec::new(),
             links: Vec::new(),
+            offsets: Vec::new(),
             wires: Vec::new(),
             counters: Default::default(),
             view: SketchView::default(),
@@ -695,10 +698,8 @@ impl Sketch {
             | Symmetric { l, .. }
             | PointLineDistance { l, .. }
             | LinearDiameter { l, .. } => need_line(l)?,
-            ArcLength { c, .. } => {
-                if !matches!(self.curves.get(c).map(|c| &c.kind), Some(CurveKind::Arc { .. })) {
-                    return Err(SketchError::WrongKind(name(c), "arc length needs an arc".into()));
-                }
+            ArcLength { c, .. } if !matches!(self.curves.get(c).map(|c| &c.kind), Some(CurveKind::Arc { .. })) => {
+                return Err(SketchError::WrongKind(name(c), "arc length needs an arc".into()));
             }
             Smooth { a, b } => {
                 let ends = |i: usize| self.curves.get(i).and_then(|c| c.kind.ends());
@@ -727,10 +728,8 @@ impl Sketch {
                     return Err(SketchError::WrongKind(name(a), "tangent needs a circle or arc".into()));
                 }
             }
-            Equal { a, b } => {
-                if is_line(a) != is_line(b) {
-                    return Err(SketchError::WrongKind(name(b), "equal needs two lines or two circles/arcs".into()));
-                }
+            Equal { a, b } if is_line(a) != is_line(b) => {
+                return Err(SketchError::WrongKind(name(b), "equal needs two lines or two circles/arcs".into()));
             }
             Coincident { p, q } if p == q => return Err(SketchError::Invalid("a point is always coincident with itself".into())),
             _ => {}

crates/sketch/src/offset.rs

@@ -0,0 +1,116 @@
+//! Associative offsets keep their output entity ids while their source curves move.
+use crate::{CurveKind, Shape, Sketch, SketchError, intersections};
+use serde::{Deserialize, Serialize};
+use solvecraft_geom::Vec2;
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub struct OffsetChain {
+    pub sources: Vec<(String, bool)>,
+    pub outputs: Vec<String>,
+    pub distance: f64,
+    pub closed: bool,
+}
+
+impl Sketch {
+    pub fn refresh_offsets(&mut self) -> Result<(), SketchError> {
+        for offset in self.offsets.clone() {
+            if offset.sources.len() != offset.outputs.len() || offset.sources.len() > 10_000 || !offset.distance.is_finite() {
+                return Err(SketchError::Invalid("damaged offset chain".into()));
+            }
+            let bad = || SketchError::Invalid("an offset source vanished or changed shape".into());
+            let mut pieces = Vec::new();
+            for (id, forward) in &offset.sources {
+                let i = self.curve_index(id).ok_or_else(bad)?;
+                let kind = &self.curves.get(i).ok_or_else(bad)?.kind;
+                let piece = match *kind {
+                    CurveKind::Line { a, b } => {
+                        let (a, b) = (self.point(a).ok_or_else(bad)?, self.point(b).ok_or_else(bad)?);
+                        let (a, b) = if *forward { (a, b) } else { (b, a) };
+                        let n = (b - a).normalized().ok_or_else(bad)?.perp() * offset.distance;
+                        (Shape::Line { a: a + n, b: b + n }, a + n, b + n)
+                    }
+                    CurveKind::Arc { c, a, b } => {
+                        let (c, a, b) = (self.point(c).ok_or_else(bad)?, self.point(a).ok_or_else(bad)?, self.point(b).ok_or_else(bad)?);
+                        let r = c.dist(a) - if *forward { offset.distance } else { -offset.distance };
+                        if r <= 1e-9 {
+                            return Err(SketchError::Invalid("the offset collapses an arc".into()));
+                        }
+                        let a = c + (a - c).normalized().ok_or_else(bad)? * r;
+                        let b = c + (b - c).normalized().ok_or_else(bad)? * r;
+                        let (a, b) = if *forward { (a, b) } else { (b, a) };
+                        (Shape::Round { c, r, start: 0.0, sweep: std::f64::consts::TAU }, a, b)
+                    }
+                    CurveKind::Circle { c, r } => {
+                        let c = self.point(c).ok_or_else(bad)?;
+                        let r = r - offset.distance;
+                        if r <= 1e-9 {
+                            return Err(SketchError::Invalid("the offset collapses a circle".into()));
+                        }
+                        let out = offset.outputs.first().and_then(|id| self.curve_index(id)).ok_or_else(bad)?;
+                        if let Some(crate::Curve { kind: CurveKind::Circle { r: target, .. }, .. }) = self.curves.get_mut(out) {
+                            *target = r;
+                        } else {
+                            return Err(bad());
+                        }
+                        let _ = c;
+                        continue;
+                    }
+                    _ => return Err(bad()),
+                };
+                pieces.push(piece);
+            }
+            if pieces.is_empty() {
+                continue;
+            }
+            let joint = |i: usize, j: usize| -> Result<Vec2, SketchError> {
+                let (x, y) = (pieces.get(i).ok_or_else(bad)?, pieces.get(j).ok_or_else(bad)?);
+                if x.2.dist(y.1) < 1e-6 {
+                    return Ok(x.2);
+                }
+                let guess = (x.2 + y.1) * 0.5;
+                intersections(&x.0, &y.0)
+                    .into_iter()
+                    .min_by(|a, b| a.dist(guess).total_cmp(&b.dist(guess)))
+                    .ok_or_else(|| SketchError::Invalid("the offset curves no longer meet".into()))
+            };
+            let n = pieces.len();
+            let mut joints = vec![if offset.closed { joint(n - 1, 0)? } else { pieces.first().ok_or_else(bad)?.1 }];
+            for i in 0..n.saturating_sub(1) {
+                joints.push(joint(i, i + 1)?);
+            }
+            if !offset.closed {
+                joints.push(pieces.last().ok_or_else(bad)?.2);
+            }
+            for (i, id) in offset.outputs.iter().enumerate() {
+                let a = *joints.get(i).ok_or_else(bad)?;
+                let b = *joints.get(if offset.closed { (i + 1) % n } else { i + 1 }).ok_or_else(bad)?;
+                let shape = &pieces.get(i).ok_or_else(bad)?.0;
+                if let Shape::Line { a: p, b: q } = shape
+                    && (b - a).dot(*q - *p) <= 1e-9
+                {
+                    return Err(SketchError::Invalid("the offset curves would cross".into()));
+                }
+                let ci = self.curve_index(id).ok_or_else(bad)?;
+                let kind = self.curves.get(ci).ok_or_else(bad)?.kind.clone();
+                let (pa, pb) = match kind {
+                    CurveKind::Line { a, b } => (a, b),
+                    CurveKind::Arc { a, b, .. } => {
+                        if offset.sources.get(i).is_some_and(|x| x.1) {
+                            (a, b)
+                        } else {
+                            (b, a)
+                        }
+                    }
+                    _ => return Err(bad()),
+                };
+                for (pi, pos) in [(pa, a), (pb, b)] {
+                    if let Some(p) = self.points.get_mut(pi) {
+                        p.pos = pos;
+                        p.fixed = true;
+                    }
+                }
+            }
+        }
+        Ok(())
+    }
+}

crates/sketch/src/text.rs

@@ -74,7 +74,7 @@ pub fn text_geometry(text: &str, at: Vec2, height: f64, angle: f64) -> Result<Ve
     if text.chars().count() > MAX_TEXT_CHARS {
         return Err(SketchError::TooLarge);
     }
-    if !(height.is_finite() && height > 1e-6 && height < 1e6) || !angle.is_finite() || !at.is_finite() {
+    if !(height.is_finite() && height > 1e-6 && height < 1e6 && angle.is_finite() && at.is_finite()) {
         return Err(SketchError::Invalid("text height must be positive".into()));
     }
     let face = ttf_parser::Face::parse(FONT, 0).map_err(|e| SketchError::Invalid(format!("font: {e}")))?;

crates/sketch/src/wire.rs

@@ -98,7 +98,7 @@ impl Sketch {
         }
         let id = if geom.is_empty() {
             let id = self.fresh("j");
-            self.links.push(Link { id: id.clone(), kind, source, lost: false });
+            self.links.push(Link { id: id.clone(), kind, source, face_name: None, lost: false });
             id
         } else {
             self.add_link(kind, source, geom)?

crates/ui-egui/src/browser.rs

@@ -232,41 +232,41 @@ const INDENT: f32 = 14.0;
 
 /// One row's look.
 #[derive(Default)]
-struct Row<'a> {
-    depth: usize,
+pub(crate) struct Row<'a> {
+    pub(crate) depth: usize,
     /// Some(open) for rows that fold.
-    fold: Option<bool>,
+    pub(crate) fold: Option<bool>,
     /// Some(visible) for rows with an eye.
-    eye: Option<bool>,
-    icon: &'a str,
-    label: &'a str,
-    selected: bool,
-    dim: bool,
-    color: Option<Color32>,
+    pub(crate) eye: Option<bool>,
+    pub(crate) icon: &'a str,
+    pub(crate) label: &'a str,
+    pub(crate) selected: bool,
+    pub(crate) dim: bool,
+    pub(crate) color: Option<Color32>,
     /// Component rows: is it the active one?
-    radio: Option<bool>,
+    pub(crate) radio: Option<bool>,
     /// Trailing badges: "lock", "pin".
-    badges: &'a [&'a str],
+    pub(crate) badges: &'a [&'a str],
 }
 
 /// What happened on a row.
 #[derive(Default)]
-struct RowResp {
-    rect: Option<Rect>,
-    clicked: bool,
-    double: bool,
-    secondary: Option<Pos2>,
-    fold: bool,
-    eye: bool,
-    radio: bool,
-    hovered: bool,
+pub(crate) struct RowResp {
+    pub(crate) rect: Option<Rect>,
+    pub(crate) clicked: bool,
+    pub(crate) double: bool,
+    pub(crate) secondary: Option<Pos2>,
+    pub(crate) fold: bool,
+    pub(crate) eye: bool,
+    pub(crate) radio: bool,
+    pub(crate) hovered: bool,
     /// The row's response (drag and drop).
-    resp: Option<egui::Response>,
+    pub(crate) resp: Option<egui::Response>,
     /// The press began on the fold arrow, eye or radio (not a drag of the row).
-    on_control: bool,
+    pub(crate) on_control: bool,
 }
 
-fn draw_row(ui: &mut egui::Ui, id: egui::Id, row: &Row) -> RowResp {
+pub(crate) fn draw_row(ui: &mut egui::Ui, id: egui::Id, row: &Row) -> RowResp {
     let t = Tokens::get();
     // Rows scrolled out of view only take their space: no widgets, no painting.
     let r = Rect::from_min_size(ui.cursor().min, vec2(ui.available_width(), ROW_H));
@@ -449,11 +449,11 @@ fn sel_of_key(k: &str) -> Option<Sel> {
     None
 }
 
-fn is_open(app: &SolveApp, key: &str, default: bool) -> bool {
+pub(crate) fn is_open(app: &SolveApp, key: &str, default: bool) -> bool {
     if default { !app.tree.collapsed.contains(key) } else { app.tree.expanded.contains(key) }
 }
 
-fn toggle(app: &mut SolveApp, key: &str, default: bool) {
+pub(crate) fn toggle(app: &mut SolveApp, key: &str, default: bool) {
     if default {
         if !app.tree.collapsed.remove(key) {
             app.tree.collapsed.insert(key.to_string());

crates/ui-egui/src/context_menu.rs

@@ -493,7 +493,10 @@ fn joint_items(app: &SolveApp, id: u64) -> Vec<Item> {
     let rigid = j.kind == solvecraft_engine::doc::joints::JointKind::Rigid;
     vec![
         act("ui.editJoint", "Edit Joint", "joint").with(json!({ "joint": id })),
+        act("ui.editJoint", "Edit Joint Limits", "").with(json!({ "joint": id })).on(!rigid),
         act("ui.driveJoint", "Drive Joint", "").with(json!({ "joint": id })).on(!rigid),
+        act("ui.animateJoint", "Animate Joint", "").with(json!({ "joint": id })).on(!rigid && !j.suppressed),
+        act("ui.findJoint", "Find in Window", "").with(json!({ "joint": id })),
         cmd(app, "joint.edit", if j.suppressed { "Unsuppress" } else { "Suppress" }).with(json!({ "joint": id, "suppressed": !j.suppressed })),
         Item::sep(),
         cmd(app, "joint.delete", "Delete").key("Del").with(json!({ "joint": id })),
@@ -792,12 +795,17 @@ pub fn run_item(app: &mut SolveApp, item: &Item, at: Pos2) {
         "ui.canvasVisible" => drop(app.run("canvas.edit", p)),
         "ui.toolbarPin" | "ui.toolbarRemove" | "ui.toolbarReset" | "ui.shortcutPin" => crate::toolbar_custom::run(app, &item.id, &p),
         "ui.workspace" => {}
-        "ui.editJoint" | "ui.driveJoint" => {
+        "ui.findJoint" => {
             if let Some(id) = id_of(&p, "joint") {
-                let d = if item.id == "ui.editJoint" {
-                    crate::dialogs_assembly::edit_joint(app, id)
-                } else {
-                    crate::dialogs_assembly::drive_joint(app, id)
+                crate::dialogs_assembly::find_joint(app, id);
+            }
+        }
+        "ui.editJoint" | "ui.driveJoint" | "ui.animateJoint" => {
+            if let Some(id) = id_of(&p, "joint") {
+                let d = match item.id.as_str() {
+                    "ui.editJoint" => crate::dialogs_assembly::edit_joint(app, id),
+                    "ui.animateJoint" => crate::dialogs_assembly::animate_joint(app, id),
+                    _ => crate::dialogs_assembly::drive_joint(app, id),
                 };
                 if let Some(d) = d {
                     app.tool = None;

crates/ui-egui/src/dialogs.rs

@@ -480,10 +480,12 @@ impl Dialog {
                                 .collect::<Vec<_>>()
                         })
                         .unwrap_or_else(|| vec![sel.clone()]),
+                    (Kind::Measure { .. }, _) => vec![crate::viewport::measurement_selection(s, sel)],
+                    _ if inp.multi => crate::viewport::grouped_selection(s, sel),
                     _ => vec![sel.clone()],
                 };
                 for x in picked {
-                    if !inp.items.contains(&x) {
+                    if !inp.items.iter().any(|y| selection::same_item(y, &x)) {
                         inp.items.push(x);
                     }
                 }
@@ -631,8 +633,11 @@ impl Dialog {
 
     /// A pick in the viewport (already accepted by the active input).
     pub fn pick(&mut self, s: &Session, sel: Sel) {
+        let measure = matches!(self.kind, Kind::Measure { .. });
+        let sel = if measure { crate::viewport::measurement_selection(s, &sel) } else { sel };
         let chain = matches!(self.kind, Kind::Fillet { chain: true, .. });
-        let mut picked = vec![sel.clone()];
+        let mut picked =
+            if !measure && self.active_input().is_some_and(|i| i.multi) { crate::viewport::grouped_selection(s, &sel) } else { vec![sel.clone()] };
         // Tangent chain: an edge brings the edges that continue it smoothly.
         if chain
             && let Sel::Edge { body, index, .. } = &sel
@@ -667,13 +672,15 @@ impl Dialog {
     }
 
     /// Box selection result: replace (or add to) the active input.
-    pub fn take_box(&mut self, sels: Vec<Sel>, add: bool) {
+    pub fn take_box(&mut self, s: &Session, sels: Vec<Sel>, add: bool) {
+        let measure = matches!(self.kind, Kind::Measure { .. });
         let Some(inp) = self.inputs.get_mut(self.active) else { return };
         if !add {
             inp.items.clear();
         }
         for x in sels {
-            if fits(inp.accept, &x) && !inp.items.contains(&x) {
+            let x = if measure { crate::viewport::measurement_selection(s, &x) } else { x };
+            if fits(inp.accept, &x) && !inp.items.iter().any(|y| selection::same_item(y, &x)) {
                 inp.items.push(x);
             }
         }
@@ -1848,7 +1855,7 @@ pub fn show(app: &mut SolveApp, ctx: &egui::Context) {
             Err(e) => d.error = Some(e),
         }
     }
-    if !(keep && !cancel) {
+    if !keep || cancel {
         crate::dialogs_motion::closed(app, &mut d, applied);
     }
     if keep && !cancel {
@@ -2691,11 +2698,50 @@ pub(crate) fn profile_indices(ss: &solvecraft_engine::doc::SolvedSketch, sel: &P
     }
 }
 
+thread_local! {
+    /// A dialog is being filled from a feature: its points are in component frames.
+    static REFILL: std::cell::Cell<bool> = const { std::cell::Cell::new(false) };
+}
+
+/// While filling a dialog from a feature (dropped at the end).
+struct Refill;
+
+impl Refill {
+    fn start() -> Refill {
+        REFILL.with(|r| r.set(true));
+        Refill
+    }
+}
+
+impl Drop for Refill {
+    fn drop(&mut self) {
+        REFILL.with(|r| r.set(false));
+    }
+}
+
+/// A point stored in a feature, as it shows on world body `body`: features keep their picks in
+/// the frame of the body they were on, so each body's placement takes the point to the world
+/// (a moved component, a pasted instance). Other points are the world already.
+fn stored_on(frames: &Option<Vec<(String, solvecraft_engine::doc::Mat)>>, body: &str, p: Vec3) -> Vec3 {
+    frames.as_ref().and_then(|f| f.iter().find(|(n, _)| n == body)).map(|(_, m)| solvecraft_engine::doc::apply_point(m, p)).unwrap_or(p)
+}
+
+/// Body placements while filling a dialog from a feature (when anything is placed).
+fn stored_frames(s: &Session) -> Option<Vec<(String, solvecraft_engine::doc::Mat)>> {
+    if !REFILL.with(std::cell::Cell::get) || !solvecraft_engine::frames::placed(s) {
+        return None;
+    }
+    let st = s.model.state();
+    Some(s.doc.body_frames(&st).into_iter().map(|(w, _, _, m)| (w, m)).collect())
+}
+
 /// The edge of a visible body through (or nearest) a point.
-pub(crate) fn edge_sel(s: &Session, p: Vec3) -> Option<Sel> {
+pub(crate) fn edge_sel(s: &Session, p0: Vec3) -> Option<Sel> {
     let st = s.world_state();
+    let frames = stored_frames(s);
     let mut best: Option<(f64, Sel)> = None;
     for b in &st.bodies {
+        let p = stored_on(&frames, &b.name, p0);
         let m = b.mesh();
         for (i, e) in m.edges.iter().enumerate() {
             let d = e.windows(2).map(|w| p.dist_to_segment(w[0], w[1])).fold(f64::INFINITY, f64::min);
@@ -2708,10 +2754,12 @@ pub(crate) fn edge_sel(s: &Session, p: Vec3) -> Option<Sel> {
 }
 
 /// The body face containing a point (nearest triangle).
-pub(crate) fn face_sel(s: &Session, p: Vec3) -> Option<Sel> {
+pub(crate) fn face_sel(s: &Session, p0: Vec3) -> Option<Sel> {
     let st = s.world_state();
+    let frames = stored_frames(s);
     let mut best: Option<(f64, Sel)> = None;
     for b in &st.bodies {
+        let p = stored_on(&frames, &b.name, p0);
         let m = b.mesh();
         for (t, f) in m.triangles.iter().zip(&m.tri_face) {
             let Some([a, bb, c]) = m.tri(t) else { continue };
@@ -2721,7 +2769,7 @@ pub(crate) fn face_sel(s: &Session, p: Vec3) -> Option<Sel> {
             }
         }
     }
-    best.filter(|(d, _)| *d < 1e-3 + 1e-6 * p.len()).map(|x| x.1)
+    best.filter(|(d, _)| *d < 1e-3 + 1e-6 * p0.len()).map(|x| x.1)
 }
 
 pub(crate) fn plane_sel(s: &Session, pl: &PlaneRef) -> Option<Sel> {
@@ -2756,6 +2804,7 @@ fn pt3(v: Vec3) -> Value {
 /// A dialog that edits an existing feature, filled from it. The timeline is rolled back to just
 /// before the feature, so its references show on the geometry they refer to.
 pub fn for_feature(app: &SolveApp, id: u64, marker: Option<usize>) -> Option<Dialog> {
+    let _refill = Refill::start();
     let s = &app.session;
     let f = s.doc.feature(id)?.clone();
     let st = s.world_state();

crates/ui-egui/src/dialogs_assembly.rs

@@ -209,6 +209,38 @@ pub fn edit_joint(app: &SolveApp, id: u64) -> Option<Dialog> {
 }
 
 /// The Drive Joints dialog on a joint (by id).
+/// Edit Joint with its motion playing (the browser's Animate Joint).
+pub fn animate_joint(app: &SolveApp, id: u64) -> Option<Dialog> {
+    let mut d = edit_joint(app, id)?;
+    if let Kind::Assembly(Asm::Joint(f)) = &mut d.kind {
+        f.animate = true;
+    }
+    Some(d)
+}
+
+/// Frame the two components a joint connects (the browser's Find in Window).
+pub fn find_joint(app: &mut SolveApp, id: u64) {
+    let s = &app.session;
+    let Some(j) = s.doc.assembly.joints.iter().find(|j| j.id == id) else { return };
+    let occs = [j.a.occurrence, j.b.occurrence];
+    let model = s.model.state();
+    let world = s.world_state();
+    let mut bb = Aabb3::default();
+    for (name, _, path, _) in s.doc.body_frames(&model) {
+        // The root (occurrence 0) holds the bodies outside every occurrence.
+        let on = occs.iter().any(|o| if *o == 0 { path.is_empty() } else { path.contains(o) });
+        if on && let Some(b) = world.body(&name) {
+            bb = bb.union(&b.mesh().bounds());
+        }
+    }
+    if bb.is_empty() {
+        return;
+    }
+    let mut cam = app.cam;
+    cam.fit(&bb);
+    app.animate_to(cam);
+}
+
 pub fn drive_joint(app: &SolveApp, id: u64) -> Option<Dialog> {
     let joint = app.session.doc.assembly.joints.iter().position(|j| j.id == id)?;
     Some(Dialog::new(Kind::Assembly(Asm::Drive { joint, values: current_values(&app.session, joint), focus: true }), vec![]))
@@ -494,12 +526,25 @@ pub fn rows(app: &mut SolveApp, ui: &mut egui::Ui, k: &mut Asm, inputs: &mut [Se
                 let cur = s.doc.eval(v, unit_kind).ok().filter(|x| x.is_finite()).unwrap_or(0.0);
                 let (mut shown, scale) = if angle { (cur.to_degrees(), 1f64.to_degrees()) } else { (cur, 1.0) };
                 row_label(ui, "");
-                ui.spacing_mut().slider_width = 124.0;
+                ui.spacing_mut().slider_width = 160.0;
                 let r = ui.add(egui::Slider::new(&mut shown, lo * scale..=hi * scale).show_value(false));
                 if r.changed() {
                     *v = if angle { format!("{shown:.1} deg") } else { format!("{shown:.2} mm") };
                 }
                 ui.end_row();
+                // The slider's range: the joint's limits, or the default span when it has none.
+                let limited = j.limits.get(i).copied().flatten().is_some();
+                let fmt = |x: f64| {
+                    let (x, unit) = if angle { (x.to_degrees(), "°") } else { (x, " mm") };
+                    if x.fract().abs() < 1e-6 { format!("{x:.0}{unit}") } else { format!("{x:.1}{unit}") }
+                };
+                row_label(ui, "");
+                ui.label(
+                    RichText::new(format!("{} … {}{}", fmt(lo), fmt(hi), if limited { "  (limits)" } else { "  (no limits)" }))
+                        .size(11.0)
+                        .color(if limited { t.text } else { t.text_dim }),
+                );
+                ui.end_row();
             }
         }
         Asm::MotionLink { a, b, ia, ib, ratio, offset } => {
@@ -826,6 +871,8 @@ pub fn overlay(app: &SolveApp, painter: &egui::Painter, proj: &Proj, d: &mut Dia
         }
         return;
     }
+    // A joint names its two picks; a joint origin has one.
+    let two = matches!(k, Asm::Joint(_));
     let hover = match k {
         Asm::Joint(f) => Some(&mut f.hover),
         Asm::JointOrigin { hover, .. } => Some(hover),
@@ -840,8 +887,9 @@ pub fn overlay(app: &SolveApp, painter: &egui::Painter, proj: &Proj, d: &mut Dia
         .filter(|(_, i)| i.accept == SNAPS)
         .filter_map(|(n, i)| i.items.first().and_then(|x| snap_of(&app.session, x)).map(|s| (s, if n == 0 { t.accent } else { t.warning })))
         .collect();
-    for (s, c) in &picked {
-        glyph(painter, proj, s, *c, app.cam.half_height());
+    for (n, (s, c)) in picked.iter().enumerate() {
+        let tag = format!("Component {}", n + 1);
+        glyph(painter, proj, s, *c, app.cam.half_height(), two.then_some(tag.as_str()));
     }
     // The snap under the cursor (found again only when the hovered item changes).
     let accepting = d.inputs.get(d.active).is_some_and(|i| i.accept == SNAPS);
@@ -853,7 +901,7 @@ pub fn overlay(app: &SolveApp, painter: &egui::Painter, proj: &Proj, d: &mut Dia
                 *hover = Some((sel.clone(), snap_of(&app.session, &sel)));
             }
             if let Some((_, Some(s))) = hover.as_ref() {
-                glyph(painter, proj, s, t.hover_profile_edge, app.cam.half_height());
+                glyph(painter, proj, s, t.hover_profile_edge, app.cam.half_height(), Some(snap_name(s.kind)));
             }
         }
         None => *hover = None,
@@ -861,36 +909,70 @@ pub fn overlay(app: &SolveApp, painter: &egui::Painter, proj: &Proj, d: &mut Dia
 }
 
 /// A snap: its kind's marker at the point and the z axis as an arrow.
-fn glyph(painter: &egui::Painter, proj: &Proj, s: &SnapPt, col: Color32, half_height: f64) {
+fn glyph(painter: &egui::Painter, proj: &Proj, s: &SnapPt, col: Color32, half_height: f64, tag: Option<&str>) {
     let Some(c) = proj.to_screen(s.at) else { return };
     let len = half_height * 2.0 * 0.06;
+    // A dark halo under every stroke keeps the glyph readable on light and dark faces alike.
+    let halo = Stroke::new(4.5, Color32::from_black_alpha(150));
+    let white = Stroke::new(1.5, Color32::WHITE);
     if let Some(tip) = proj.to_screen(s.at + s.z * len) {
-        painter.line_segment([c, tip], Stroke::new(2.0, col));
         let d = (tip - c).normalized();
         let n = vec2(-d.y, d.x);
-        painter.add(egui::Shape::convex_polygon(vec![tip, tip - d * 8.0 + n * 4.0, tip - d * 8.0 - n * 4.0], col, Stroke::NONE));
+        let head = vec![tip + d * 2.0, tip - d * 9.0 + n * 5.0, tip - d * 9.0 - n * 5.0];
+        painter.line_segment([c, tip], halo);
+        painter.add(egui::Shape::convex_polygon(head.clone(), Color32::TRANSPARENT, halo));
+        painter.line_segment([c, tip], Stroke::new(2.0, col));
+        painter.add(egui::Shape::convex_polygon(head, col, Stroke::NONE));
     }
-    let white = Stroke::new(1.5, Color32::WHITE);
+    let shape = |fill: Color32, stroke: Stroke, grow: f32| -> egui::Shape {
+        match s.kind {
+            SnapKind::FaceCenter => egui::Shape::rect_filled(egui::Rect::from_center_size(c, vec2(12.0 + grow, 12.0 + grow)), 1.5, fill),
+            SnapKind::CircleCenter => egui::Shape::circle_filled(c, 7.0 + grow / 2.0, fill),
+            SnapKind::EdgeMid => {
+                let r = 8.0 + grow / 2.0;
+                egui::Shape::convex_polygon(vec![c + vec2(0.0, -r), c + vec2(r * 0.93, r * 0.7), c + vec2(-r * 0.93, r * 0.7)], fill, stroke)
+            }
+            SnapKind::Vertex => {
+                let r = 7.5 + grow / 2.0;
+                egui::Shape::convex_polygon(vec![c + vec2(0.0, -r), c + vec2(r, 0.0), c + vec2(0.0, r), c + vec2(-r, 0.0)], fill, stroke)
+            }
+        }
+    };
+    painter.add(shape(Color32::from_black_alpha(150), Stroke::NONE, 4.0));
+    painter.add(shape(col, Stroke::NONE, 0.0));
     match s.kind {
         SnapKind::FaceCenter => {
-            painter.rect(egui::Rect::from_center_size(c, vec2(10.0, 10.0)), 1.0, col, white, egui::StrokeKind::Middle);
+            painter.rect_stroke(egui::Rect::from_center_size(c, vec2(12.0, 12.0)), 1.5, white, egui::StrokeKind::Middle);
         }
         SnapKind::CircleCenter => {
-            painter.circle(c, 6.0, col, white);
-            painter.line_segment([c - vec2(4.0, 0.0), c + vec2(4.0, 0.0)], Stroke::new(1.2, Color32::WHITE));
-            painter.line_segment([c - vec2(0.0, 4.0), c + vec2(0.0, 4.0)], Stroke::new(1.2, Color32::WHITE));
+            painter.circle_stroke(c, 7.0, white);
+            painter.line_segment([c - vec2(4.5, 0.0), c + vec2(4.5, 0.0)], Stroke::new(1.2, Color32::WHITE));
+            painter.line_segment([c - vec2(0.0, 4.5), c + vec2(0.0, 4.5)], Stroke::new(1.2, Color32::WHITE));
         }
-        SnapKind::EdgeMid => {
-            painter.add(egui::Shape::convex_polygon(vec![c + vec2(0.0, -7.0), c + vec2(6.5, 5.0), c + vec2(-6.5, 5.0)], col, white));
-        }
-        SnapKind::Vertex => {
-            painter.add(egui::Shape::convex_polygon(
-                vec![c + vec2(0.0, -6.5), c + vec2(6.5, 0.0), c + vec2(0.0, 6.5), c + vec2(-6.5, 0.0)],
-                col,
-                white,
-            ));
+        SnapKind::EdgeMid | SnapKind::Vertex => {
+            painter.add(shape(Color32::TRANSPARENT, white, 0.0));
         }
     }
+    // What it snaps to (hovered), or which component it is (picked): a small label.
+    if let Some(tag) = tag {
+        let t = Tokens::get();
+        let font = egui::FontId::proportional(11.5);
+        let g = painter.layout_no_wrap(tag.to_string(), font, t.text);
+        let at = c + vec2(12.0, 10.0);
+        let r = egui::Rect::from_min_size(at, g.size()).expand2(vec2(5.0, 2.0));
+        painter.rect(r, 3.0, t.panel.gamma_multiply(0.92), Stroke::new(1.0, col), egui::StrokeKind::Inside);
+        painter.galley(at, g, t.text);
+    }
+}
+
+/// What a snap is called (the hover label).
+fn snap_name(k: SnapKind) -> &'static str {
+    match k {
+        SnapKind::FaceCenter => "Face center",
+        SnapKind::CircleCenter => "Circle center",
+        SnapKind::EdgeMid => "Edge midpoint",
+        SnapKind::Vertex => "Vertex",
+    }
 }
 
 // ---- timeline and browser ----
@@ -963,61 +1045,36 @@ pub fn timeline_joints(app: &mut SolveApp, ui: &mut egui::Ui, p: &egui::Painter,
 /// The Joints folder at the end of the Browser: a row per joint (double-click edits, the menu
 /// edits, drives, suppresses or deletes).
 pub fn browser_joints(app: &mut SolveApp, ui: &mut egui::Ui, depth: usize) {
-    let t = Tokens::get();
+    use crate::browser::{Row, draw_row, is_open, toggle};
     let joints: Vec<(u64, String, JointKind, bool)> =
         app.session.doc.assembly.joints.iter().map(|j| (j.id, j.name.clone(), j.kind, j.suppressed)).collect();
     if joints.is_empty() {
         return;
     }
-    let fold_id = egui::Id::new("sc_browser_joints_open");
-    let mut open = ui.data(|d| d.get_temp::<bool>(fold_id)).unwrap_or(true);
-    let row = |ui: &mut egui::Ui, depth: f32, icon: &str, label: &str, dim: bool, fold: Option<bool>| -> egui::Response {
-        let (r, resp) = ui.allocate_exact_size(vec2(ui.available_width(), 22.0), egui::Sense::click());
-        if resp.hovered() {
-            ui.painter().rect_filled(r, 3.0, t.hover);
-        }
-        let x = r.left() + 2.0 + depth * 14.0;
-        let cy = r.center().y;
-        if let Some(o) = fold {
-            let c = egui::pos2(x + 6.0, cy);
-            let pts = if o {
-                vec![c + vec2(-4.0, -2.0), c + vec2(4.0, -2.0), c + vec2(0.0, 3.0)]
-            } else {
-                vec![c + vec2(-2.0, -4.0), c + vec2(3.0, 0.0), c + vec2(-2.0, 4.0)]
-            };
-            ui.painter().add(egui::Shape::convex_polygon(pts, t.text_dim, Stroke::NONE));
-        }
-        let ir = egui::Rect::from_center_size(egui::pos2(x + 26.0, cy), vec2(16.0, 16.0));
-        crate::icons::paint(ui.painter(), ir, icon, if dim { t.border } else { t.icon }, t.icon_fill, t.accent);
-        ui.painter().text(
-            egui::pos2(x + 38.0, cy),
-            egui::Align2::LEFT_CENTER,
-            label,
-            egui::FontId::proportional(13.0),
-            if dim { t.text_dim } else { t.text },
-        );
-        resp
-    };
-    let depth = depth as f32;
-    if row(ui, depth, "folder", "Joints", false, Some(open)).clicked() {
-        open = !open;
-        ui.data_mut(|d| d.insert_temp(fold_id, open));
+    // Drawn like every other browser node (its fold and rows publish `fold:Joints`, `row:<name>`).
+    let key = "c0/joints";
+    let open = is_open(app, key, true);
+    let r = draw_row(ui, ui.id().with(key), &Row { depth, fold: Some(open), icon: "folder", label: "Joints", ..Default::default() });
+    if r.fold || r.clicked {
+        toggle(app, key, true);
     }
     if !open {
         return;
     }
     let mut dialog: Option<Dialog> = None;
     for (id, name, kind, suppressed) in joints {
-        let resp = row(ui, depth + 1.0, "joint", &name, suppressed, None).on_hover_text(format!("{kind:?} joint"));
-        if resp.double_clicked() {
+        let r =
+            draw_row(ui, ui.id().with(("joint", id)), &Row { depth: depth + 1, icon: "joint", label: &name, dim: suppressed, ..Default::default() });
+        if let Some(resp) = &r.resp {
+            resp.clone().on_hover_text(format!("{kind:?} joint"));
+        }
+        if r.double {
             dialog = edit_joint(app, id);
         }
         // The same menus as the rest of the browser.
-        if resp.secondary_clicked() {
-            let at = resp.interact_pointer_pos().unwrap_or(resp.rect.left_bottom());
+        if let Some(at) = r.secondary {
             crate::context_menu::open_for(app, at, crate::context_menu::Target::Joint { id });
         }
-        let _ = (kind, suppressed);
     }
     if let Some(d) = dialog {
         app.tool = None;
@@ -1028,3 +1085,51 @@ pub fn browser_joints(app: &mut SolveApp, ui: &mut egui::Ui, depth: usize) {
 #[cfg(test)]
 #[path = "dialogs_assembly_tests.rs"]
 mod tests;
+
+thread_local! {
+    /// Named joint origins in the world, for the design state they were found in.
+    static ORIGINS: std::cell::RefCell<Option<(String, Vec<(String, solvecraft_engine::doc::Mat)>)>> = const { std::cell::RefCell::new(None) };
+}
+
+/// Named joint origins in the world: on their occurrence's component, so they move with it
+/// (joint drives, free moves not captured yet, Capture Position).
+pub fn origins_world(s: &Session) -> Vec<(String, solvecraft_engine::doc::Mat)> {
+    if s.doc.assembly.origins.is_empty() {
+        return Vec::new();
+    }
+    let key = format!("{}:{:?}", s.revision, s.pending_moves);
+    if let Some(v) = ORIGINS.with(|o| o.borrow().as_ref().filter(|(k, _)| *k == key).map(|(_, v)| v.clone())) {
+        return v;
+    }
+    let doc: std::borrow::Cow<solvecraft_engine::doc::Document> = if s.pending_moves.is_empty() {
+        std::borrow::Cow::Borrowed(&*s.doc)
+    } else {
+        let mut d = (*s.doc).clone();
+        for o in &mut d.occurrences {
+            if let Some(m) = s.pending_moves.get(&o.id) {
+                o.transform = *m;
+            }
+        }
+        std::borrow::Cow::Owned(d)
+    };
+    let st = s.model.state();
+    let v: Vec<_> = doc.assembly.origins.iter().filter_map(|o| doc.origin_world(&st, &o.origin).ok().map(|m| (o.name.clone(), m))).collect();
+    ORIGINS.with(|o| *o.borrow_mut() = Some((key, v.clone())));
+    v
+}
+
+/// Named joint origins in the viewport: a small triad where each sits.
+pub fn origins(app: &SolveApp, painter: &egui::Painter, proj: &Proj) {
+    let t = Tokens::get();
+    let len = app.cam.half_height() * 2.0 * 0.04;
+    for (_, m) in origins_world(&app.session) {
+        let at = solvecraft_engine::doc::apply_point(&m, Vec3::ZERO);
+        let Some(c) = proj.to_screen(at) else { continue };
+        for (axis, col) in [(Vec3::X, t.axis_x), (Vec3::Y, t.axis_y), (Vec3::Z, t.axis_z)] {
+            if let Some(tip) = proj.to_screen(at + solvecraft_engine::doc::apply_vector(&m, axis) * len) {
+                painter.line_segment([c, tip], Stroke::new(2.0, col));
+            }
+        }
+        painter.circle(c, 4.5, t.panel, Stroke::new(1.5, t.text));
+    }
+}

crates/ui-egui/src/dialogs_assembly_tests.rs

@@ -263,3 +263,41 @@ fn drive_value_takes_the_keyboard() {
     assert!((j.values[0] - 90f64.to_radians()).abs() < 1e-9, "{:?}", j.values);
     assert!(app.dialog.is_none());
 }
+
+/// Named joint origins are drawn where their component is: a drive of the occurrence, or a free
+/// move not captured yet, carries them along.
+#[test]
+fn joint_origins_follow_their_component() {
+    let mut app = two_boxes();
+    app.session.execute("joint.origin", &json!({"name": "Top of B", "face": [40, 10, 10]})).unwrap();
+    let at = |app: &SolveApp| {
+        let v = origins_world(&app.session);
+        let (_, m) = v.iter().find(|(n, _)| n == "Top of B").unwrap();
+        solvecraft_engine::doc::apply_point(m, Vec3::ZERO)
+    };
+    assert!(at(&app).dist(Vec3::new(40.0, 10.0, 10.0)) < 1e-6, "{:?}", at(&app));
+    let b = occ(&app, "B");
+    app.session.execute("occurrence.move", &json!({"occurrence": b, "translate": [0, 0, 15]})).unwrap();
+    assert!(at(&app).dist(Vec3::new(40.0, 10.0, 25.0)) < 1e-6, "{:?}", at(&app));
+    // A drag not captured yet.
+    let mut m = app.session.doc.occurrence_of(app.session.doc.find_component("B").unwrap()).unwrap().transform;
+    m[3][0] += 5.0;
+    app.session.pending_moves.insert(b, m);
+    assert!(at(&app).dist(Vec3::new(45.0, 10.0, 25.0)) < 1e-6, "{:?}", at(&app));
+}
+
+/// Edit Feature on a moved component: the dialog shows the feature's picks where the
+/// component is (its stored points are in the component's frame).
+#[test]
+fn edit_feature_on_a_moved_component_refills_in_the_world() {
+    let mut app = two_boxes();
+    let b = occ(&app, "B");
+    app.session.execute("occurrence.move", &json!({"occurrence": b, "translate": [0, 0, 15]})).unwrap();
+    let r = app.session.execute("solid.fillet", &json!({"edges": [[40, 0, 25]], "radius": 2})).unwrap();
+    let id = r["feature"].as_u64().unwrap();
+    let d = crate::dialogs::for_feature(&app, id, None).unwrap();
+    let items: Vec<Sel> = d.inputs.iter().flat_map(|i| i.items.clone()).collect();
+    let Some(Sel::Edge { body, point, .. }) = items.first() else { panic!("{items:?}") };
+    assert_eq!(body, "Body2");
+    assert!(point.dist(Vec3::new(40.0, 0.0, 25.0)) < 1e-6, "{point:?}");
+}

crates/ui-egui/src/dialogs_motion.rs

@@ -41,6 +41,10 @@ pub enum Mo {
         tracks: Vec<Track>,
         step: f64,
         playing: bool,
+        /// Playback starts over at the end (else it stops there).
+        looping: bool,
+        /// Playback speed (index into `SPEEDS`).
+        speed: usize,
         /// The step the shown pose is for (and its revision).
         shown: Option<(u64, u64)>,
         saved: Option<BTreeMap<u64, Mat>>,
@@ -101,6 +105,8 @@ pub fn start(app: &SolveApp, id: &str) -> Option<(Kind, Vec<SelInput>)> {
                 tracks: Vec::new(),
                 step: 0.0,
                 playing: false,
+                looping: true,
+                speed: 2,
                 shown: None,
                 saved: None,
                 error: None,
@@ -116,6 +122,73 @@ pub fn start(app: &SolveApp, id: &str) -> Option<(Kind, Vec<SelInput>)> {
 
 // ---- pure mappings (tested) ----
 
+/// Playback speeds offered (times `STEPS_PER_S`).
+pub const SPEEDS: [f64; 5] = [0.25, 0.5, 1.0, 2.0, 4.0];
+/// Steps played per second at 1×.
+const STEPS_PER_S: f64 = 24.0;
+
+/// The next playback step: `by` steps on; at the end it starts over (looping) or stops there.
+/// Returns the step and whether it still plays.
+pub fn advance(step: f64, by: f64, total: u32, looping: bool) -> (f64, bool) {
+    let last = f64::from(total);
+    let next = step + by.max(0.0);
+    if next <= last {
+        (next, true)
+    } else if looping && last > 0.0 {
+        (next % (last + 1.0), true)
+    } else {
+        (last, false)
+    }
+}
+
+#[derive(Clone, Copy)]
+enum Transport {
+    Start,
+    Back,
+    Play,
+    Stop,
+    Forward,
+    End,
+}
+
+/// A media button drawn in code: bars and triangles.
+fn transport(ui: &mut egui::Ui, what: Transport, tip: &str) -> egui::Response {
+    let t = Tokens::get();
+    let (r, resp) = ui.allocate_exact_size(vec2(26.0, 22.0), Sense::click());
+    let fill = if resp.hovered() { t.hover } else { t.field };
+    ui.painter().rect(r, 3.0, fill, Stroke::new(1.0, t.border), egui::StrokeKind::Inside);
+    let c = r.center();
+    let ink = if matches!(what, Transport::Play | Transport::Stop) { t.accent } else { t.icon };
+    let p = ui.painter();
+    let tri = |dir: f32, x: f32| {
+        egui::Shape::convex_polygon(vec![pos2(x - 4.0 * dir, c.y - 5.0), pos2(x + 4.0 * dir, c.y), pos2(x - 4.0 * dir, c.y + 5.0)], ink, Stroke::NONE)
+    };
+    let bar = |x: f32| egui::Shape::rect_filled(egui::Rect::from_center_size(pos2(x, c.y), vec2(2.0, 10.0)), 0.0, ink);
+    match what {
+        Transport::Play => drop(p.add(tri(1.0, c.x + 1.0))),
+        Transport::Stop => drop(p.rect_filled(egui::Rect::from_center_size(c, vec2(9.0, 9.0)), 1.0, ink)),
+        Transport::Back => {
+            p.add(bar(c.x + 4.0));
+            p.add(tri(-1.0, c.x - 1.0));
+        }
+        Transport::Forward => {
+            p.add(bar(c.x - 4.0));
+            p.add(tri(1.0, c.x + 1.0));
+        }
+        Transport::Start => {
+            p.add(bar(c.x - 6.0));
+            p.add(tri(-1.0, c.x - 0.5));
+            p.add(tri(-1.0, c.x + 5.0));
+        }
+        Transport::End => {
+            p.add(tri(1.0, c.x - 5.0));
+            p.add(tri(1.0, c.x + 0.5));
+            p.add(bar(c.x + 6.0));
+        }
+    }
+    resp.on_hover_text(tip)
+}
+
 /// The study command's parameters.
 pub fn study_params(s: &Session, name: &str, study: Option<&str>, steps: &str, tracks: &[Track]) -> Result<Value, String> {
     let steps: u32 = steps.trim().parse().map_err(|_| "steps must be a whole number".to_string())?;
@@ -321,7 +394,7 @@ pub fn rows(app: &mut SolveApp, ui: &mut egui::Ui, k: &mut Mo, inputs: &mut [Sel
                 ui.end_row();
             }
         }
-        Mo::MotionStudy { name, study, steps, tracks, step, playing, shown, saved, error } => {
+        Mo::MotionStudy { name, study, steps, tracks, step, playing, looping, speed, shown, saved, error } => {
             row_label(ui, "Name");
             ui.text_edit_singleline(name);
             ui.end_row();
@@ -336,19 +409,54 @@ pub fn rows(app: &mut SolveApp, ui: &mut egui::Ui, k: &mut Mo, inputs: &mut [Sel
                 ui.end_row();
                 return enter;
             }
-            // Playback.
-            row_label(ui, "Step");
+            // Playback: to start, step back, play/stop, step on, to end; loop and speed.
+            row_label(ui, "Playback");
             ui.horizontal(|ui| {
-                if ui.button(if *playing { "■" } else { "▶" }).on_hover_text(if *playing { "Stop" } else { "Play" }).clicked() {
+                let last = f64::from(total);
+                if transport(ui, Transport::Start, "To the start").clicked() {
+                    *step = 0.0;
+                    *playing = false;
+                }
+                if transport(ui, Transport::Back, "Step back").clicked() {
+                    *step = (step.round() - 1.0).max(0.0);
+                    *playing = false;
+                }
+                let (what, tip) = if *playing { (Transport::Stop, "Stop") } else { (Transport::Play, "Play") };
+                if transport(ui, what, tip).clicked() {
+                    // Play from the start again when at the end.
+                    if !*playing && step.round() >= last {
+                        *step = 0.0;
+                    }
                     *playing = !*playing;
                 }
-                ui.spacing_mut().slider_width = 220.0;
-                ui.add(egui::Slider::new(step, 0.0..=f64::from(total)).integer());
+                if transport(ui, Transport::Forward, "Step on").clicked() {
+                    *step = (step.round() + 1.0).min(last);
+                    *playing = false;
+                }
+                if transport(ui, Transport::End, "To the end").clicked() {
+                    *step = last;
+                    *playing = false;
+                }
+                ui.add_space(6.0);
+                ui.checkbox(looping, "Loop");
+                let names: Vec<String> = SPEEDS.iter().map(|x| format!("{x}×")).collect();
+                let refs: Vec<&str> = names.iter().map(String::as_str).collect();
+                combo(ui, "ms_speed", &refs, speed);
+            });
+            ui.end_row();
+            row_label(ui, "Step");
+            ui.horizontal(|ui| {
+                ui.spacing_mut().slider_width = 260.0;
+                if ui.add(egui::Slider::new(step, 0.0..=f64::from(total)).integer().show_value(false)).dragged() {
+                    *playing = false;
+                }
+                ui.label(RichText::new(format!("{} / {total}", step.round() as u32)).color(t.text_dim));
             });
             ui.end_row();
             if *playing {
-                let dt = ui.input(|i| i.stable_dt).min(0.1);
-                *step = (*step + f64::from(dt) * 24.0) % (f64::from(total) + 1.0);
+                let dt = f64::from(ui.input(|i| i.stable_dt).min(0.1));
+                let fps = STEPS_PER_S * SPEEDS.get(*speed).copied().unwrap_or(1.0);
+                (*step, *playing) = advance(*step, dt * fps, total, *looping);
                 ui.ctx().request_repaint();
             }
             // Tracks: a row per keyed joint value, its keys on a strip under the steps.
@@ -667,6 +775,15 @@ pub fn commands(app: &SolveApp, k: &Mo, inputs: &[SelInput]) -> Result<Vec<(Stri
 mod tests {
     use super::*;
 
+    /// Playback runs on, starts over at the end when looping, else stops on the last step.
+    #[test]
+    fn playback_advances_loops_and_stops() {
+        assert_eq!(advance(3.0, 2.0, 10, true), (5.0, true));
+        assert_eq!(advance(9.5, 2.0, 10, true), (0.5, true));
+        assert_eq!(advance(9.5, 2.0, 10, false), (10.0, false));
+        assert_eq!(advance(4.0, -3.0, 10, false), (4.0, true));
+    }
+
     /// What a dialog shows goes away when it closes; an exploded view applied with OK stays.
     #[test]
     fn shown_poses_are_put_back() {
@@ -688,6 +805,8 @@ mod tests {
                     tracks: vec![],
                     step: 0.0,
                     playing: false,
+                    looping: true,
+                    speed: 2,
                     shown: None,
                     saved,
                     error: None,

crates/ui-egui/src/dim_view.rs

@@ -187,7 +187,7 @@ pub fn show(app: &mut SolveApp, ui: &egui::Ui, painter: &egui::Painter, proj: &P
     }
     let tk = Tokens::get();
     let is_sel = |id: &str| app.session.selection.iter().any(|s| matches!(s, Sel::SketchConstraint { id: x } if x == id));
-    let hover = ui.input(|i| i.pointer.hover_pos()).filter(|p| proj.rect.contains(*p)).and_then(hit);
+    let hover = ui.input(|i| i.pointer.hover_pos()).filter(|_| ui.rect_contains_pointer(proj.rect)).and_then(hit);
     let to = |p: Vec2| proj.to_screen(ss.plane.to_world(p));
     let font = FontId::proportional(12.0);
     let centres = chain_centres(sk);

crates/ui-egui/src/documents.rs

@@ -98,6 +98,7 @@ fn swap_in(app: &mut SolveApp, slot: DocSlot) -> DocSlot {
 
 /// Make tab `i` the active design.
 pub fn switch(app: &mut SolveApp, i: usize) {
+    app.home.open = false;
     if i == app.docs.active || i >= app.docs.slots.len() {
         return;
     }
@@ -293,6 +294,25 @@ pub fn control(app: &mut SolveApp, p: &Value) -> Value {
 /// + for a new design.
 pub fn tabs(app: &mut SolveApp, ui: &mut egui::Ui, r: Rect, x0: f32, x1: f32) {
     let t = Tokens::get();
+    let home = Rect::from_min_size(pos2(x0, r.top() + 5.0), vec2(66.0, r.height() - 5.0));
+    let response = ui.interact(home, ui.id().with("home_tab"), Sense::click());
+    ui.painter().rect_filled(
+        home,
+        5.0,
+        if app.home.open {
+            t.toolbar
+        } else if response.hovered() {
+            t.hover
+        } else {
+            Color32::from_white_alpha(10)
+        },
+    );
+    ui.painter().text(home.center(), Align2::CENTER_CENTER, "Home", FontId::proportional(13.0), if app.home.open { t.text } else { t.app_bar_text });
+    crate::scenario::publish_handle("tab:home", home.center());
+    if response.clicked() {
+        app.home.show(app.session.revision);
+    }
+    let x0 = x0 + 70.0;
     let info = tabs_info(app);
     let n = info.len();
     let (first, shown, w) = layout(n, app.docs.active, x1 - x0);
@@ -301,8 +321,9 @@ pub fn tabs(app: &mut SolveApp, ui: &mut egui::Ui, r: Rect, x0: f32, x1: f32) {
     let mut shut: Option<usize> = None;
     for (i, (name, dirty)) in info.iter().enumerate().skip(first).take(shown) {
         let tr = Rect::from_min_size(pos2(x, r.top() + 5.0), vec2(w - 2.0, r.height() - 5.0));
-        let active = i == app.docs.active || app.docs.slots.is_empty();
+        let active = !app.home.open && (i == app.docs.active || app.docs.slots.is_empty());
         let resp = ui.interact(tr, ui.id().with(("doc_tab", i)), Sense::click_and_drag());
+        crate::scenario::publish_handle(&format!("tab:design:{i}"), tr.center());
         // The tabs are part of the title bar: dragging one moves the window, a double click
         // maximizes it.
         if app.custom_titlebar || app.integrated_titlebar {
@@ -389,7 +410,6 @@ pub fn tabs(app: &mut SolveApp, ui: &mut egui::Ui, r: Rect, x0: f32, x1: f32) {
     ui.painter().line_segment([c - vec2(0.0, 6.0), c + vec2(0.0, 6.0)], s);
     if presp.on_hover_text("New Design (Ctrl+N)").clicked() {
         new_design(app);
-        app.home.show(app.session.revision);
     }
     if let Some(i) = shut {
         close(app, i, false);

crates/ui-egui/src/gizmo.rs

@@ -255,7 +255,7 @@ pub fn show(ui: &mut egui::Ui, painter: &egui::Painter, proj: &Proj, id: egui::I
     }
     let state: Option<State> = ui.data(|d| d.get_temp(id));
     let pointer = ui.input(|i| i.pointer.hover_pos());
-    let hovered = if state.is_none() { pointer.filter(|p| proj.rect.contains(*p)).and_then(|p| hit(&sh, p)) } else { None };
+    let hovered = if state.is_none() { pointer.filter(|_| ui.rect_contains_pointer(proj.rect)).and_then(|p| hit(&sh, p)) } else { None };
     let active = state.map(|s| s.handle).or(hovered);
     let hot = |h: Handle| active == Some(h);
     let col = |h: Handle, i: usize| if hot(h) { tk.accent } else { axis_color(i) };

crates/ui-egui/src/home.rs

@@ -1,6 +1,6 @@
 //! The start page: New Design, Open, the recent designs and the built-in samples, each with a
 //! picture of the design rendered from it. Shown on launch without a file and from the house
-//! button; it closes when a design is opened or started, or the design changes.
+//! button or the first document tab; selecting a design returns to its view.
 
 use std::collections::HashMap;
 
@@ -24,8 +24,7 @@ pub struct HomeState {
     pub open: bool,
     /// Recent design paths, newest first (kept in the preferences).
     pub recent: Vec<String>,
-    /// The session revision when the page opened (a change closes it).
-    rev: u64,
+    pub opened_at: std::collections::BTreeMap<String, u64>,
     thumbs: HashMap<String, Option<egui::TextureHandle>>,
     samples: HashMap<usize, Session>,
     /// Keys asked for and not made yet.
@@ -37,9 +36,8 @@ pub struct HomeState {
 }
 
 impl HomeState {
-    pub fn show(&mut self, rev: u64) {
+    pub fn show(&mut self, _rev: u64) {
         self.open = true;
-        self.rev = rev;
     }
 
     /// Put a design at the top of the recent list.
@@ -47,6 +45,8 @@ impl HomeState {
         self.recent.retain(|p| p != path);
         self.recent.insert(0, path.to_string());
         self.recent.truncate(MAX_RECENT);
+        self.opened_at.insert(path.to_string(), web_time::SystemTime::now().duration_since(web_time::UNIX_EPOCH).map(|d| d.as_secs()).unwrap_or(0));
+        self.opened_at.retain(|p, _| self.recent.contains(p));
         self.thumbs.remove(path);
     }
 }
@@ -179,9 +179,8 @@ pub fn open_sample(app: &mut SolveApp, i: usize) {
     }
 }
 
-fn open_recent(app: &mut SolveApp, path: &str) {
+pub fn open_recent(app: &mut SolveApp, path: &str) {
     if !solvecraft_engine::io::vfs::exists(path) {
-        app.home.recent.retain(|p| p != path);
         app.set_status(format!("{path} is no longer there"), true);
         return;
     }
@@ -191,10 +190,6 @@ fn open_recent(app: &mut SolveApp, path: &str) {
 
 /// The page itself (in place of the toolbar, browser and viewport).
 pub fn show(app: &mut SolveApp, ui: &mut egui::Ui) {
-    if app.session.revision != app.home.rev {
-        app.home.open = false;
-        return;
-    }
     poll(app, ui.ctx());
     let t = Tokens::get();
     let samples = solvecraft_engine::sample::samples();
@@ -261,6 +256,19 @@ pub fn show(app: &mut SolveApp, ui: &mut egui::Ui) {
                 }
             });
             ui.add_space(24.0);
+            ui.horizontal_wrapped(|ui| {
+                ui.hyperlink_to("Documentation", crate::help::DOCS_URL);
+                ui.hyperlink_to("Report an Issue", "https://github.com/bherbruck/solvecraft/issues/new");
+                ui.hyperlink_to("What's new", "https://github.com/bherbruck/solvecraft/releases/latest");
+                if ui.link("Keyboard Shortcuts").clicked() {
+                    app.keymap.open = true;
+                    app.keymap.read_only = true;
+                }
+                if ui.link("Preferences").clicked() {
+                    crate::prefs::open_at(app, 0);
+                }
+            });
+            ui.add_space(16.0);
             section(ui, "Recent");
             if recent.is_empty() {
                 ui.label(RichText::new("Designs you open or save appear here.").color(t.text_dim));
@@ -269,20 +277,46 @@ pub fn show(app: &mut SolveApp, ui: &mut egui::Ui) {
                     let Some(p) = recent.get(i) else { return };
                     let path = std::path::Path::new(p);
                     let name = path.file_stem().map(|x| x.to_string_lossy().to_string()).unwrap_or_else(|| p.clone());
-                    let folder = path.parent().map(|x| x.to_string_lossy().to_string()).unwrap_or_default();
                     let missing = !solvecraft_engine::io::vfs::exists(p);
-                    let sub = if missing {
+                    let mut sub = if missing {
                         "missing".to_string()
                     } else if p.starts_with("/opfs/") {
                         // The web build keeps designs in the browser's own storage.
                         "in this browser".to_string()
                     } else {
-                        folder
+                        p.clone()
                     };
-                    if card(ui, Pic::Ready(app.home.thumbs.get(p.as_str()).and_then(Option::as_ref)), &name, &sub, missing)
-                        .on_hover_text(p.as_str())
-                        .clicked()
-                    {
+                    if let Some(time) = app.home.opened_at.get(p) {
+                        let now = web_time::SystemTime::now().duration_since(web_time::UNIX_EPOCH).map(|d| d.as_secs()).unwrap_or(*time);
+                        let seconds = now.saturating_sub(*time);
+                        let ago = if seconds < 60 {
+                            "just now".to_string()
+                        } else if seconds < 3600 {
+                            format!("{} min ago", seconds / 60)
+                        } else if seconds < 86400 {
+                            format!("{} h ago", seconds / 3600)
+                        } else {
+                            format!("{} days ago", seconds / 86400)
+                        };
+                        sub.push_str(&format!("\nOpened {ago}"));
+                    }
+                    let response = card(ui, Pic::Ready(app.home.thumbs.get(p.as_str()).and_then(Option::as_ref)), &name, &sub, missing)
+                        .on_hover_text(p.as_str());
+                    crate::scenario::publish_handle(&format!("home:recent:{i}"), response.rect.center());
+                    response.context_menu(|ui| {
+                        if ui.button("Remove from list").clicked() {
+                            app.home.recent.retain(|x| x != p);
+                            app.home.opened_at.remove(p);
+                            ui.close();
+                        }
+                        if !cfg!(target_arch = "wasm32") && ui.button("Show in folder").clicked() {
+                            if let Some(show) = &app.services.show_in_folder {
+                                show(p);
+                            }
+                            ui.close();
+                        }
+                    });
+                    if response.clicked() {
                         let p = p.clone();
                         action = Some(Box::new(move |app: &mut SolveApp| open_recent(app, &p)));
                     }
@@ -340,7 +374,7 @@ enum Pic<'a> {
 /// A design card: its picture (a spinner while it renders), name and a line under it.
 fn card(ui: &mut egui::Ui, pic: Pic, name: &str, sub: &str, dim: bool) -> egui::Response {
     let t = Tokens::get();
-    let size = vec2(THUMB[0] as f32 + 16.0, THUMB[1] as f32 + 62.0);
+    let size = vec2(THUMB[0] as f32 + 16.0, THUMB[1] as f32 + 80.0);
     let (r, resp) = ui.allocate_exact_size(size, Sense::click());
     let hover = resp.hovered();
     ui.painter().rect(

crates/ui-egui/src/lib.rs

@@ -155,6 +155,7 @@ impl Default for UiState {
 pub struct Services {
     pub pick_open: Option<Box<dyn Fn() -> Option<String>>>,
     pub pick_save: Option<Box<dyn Fn(&str, &[&str]) -> Option<String>>>,
+    pub show_in_folder: Option<Box<dyn Fn(&str)>>,
     /// Where the host reads the anti-aliasing preference at start (a small JSON file).
     pub graphics_path: Option<String>,
 }
@@ -304,6 +305,7 @@ impl SolveApp {
             "browser_collapsed": self.tree.collapsed,
             "browser_expanded": self.tree.expanded,
             "recent": self.home.recent,
+            "recent_opened_at": self.home.opened_at,
             "shortcut_box": self.sbox.prefs(),
             "shortcuts": self.keymap.prefs(),
             "toolbar": self.toolbar_custom.prefs(),
@@ -319,6 +321,7 @@ impl SolveApp {
     pub fn load_prefs(&mut self, prefs: &str) {
         let Ok(v) = serde_json::from_str::<Value>(prefs) else { return };
         let flag = |k: &str| v.get(k).and_then(Value::as_bool);
+        self.home.opened_at = v.get("recent_opened_at").and_then(|x| serde_json::from_value(x.clone()).ok()).unwrap_or_default();
         if let Some(d) = flag("dark") {
             self.ui.dark = d;
         }
@@ -430,6 +433,12 @@ impl SolveApp {
         }
         self.tool = None;
         self.home.open = false;
+        if matches!(id, "sketch.insert_dxf" | "sketch.insert_svg") {
+            if let Some(path) = self.services.pick_open.as_ref().and_then(|f| f()) {
+                let _ = self.run(id, json!({"path": path}));
+            }
+            return;
+        }
         if matches!(id, "file.insert_step" | "file.insert_mesh") {
             if let Some(p) = self.services.pick_open.as_ref().and_then(|f| f()) {
                 self.insert_path(&p);
@@ -480,7 +489,20 @@ impl SolveApp {
         {
             self.last_command = Some((spec.id.to_string(), spec.label.to_string()));
         }
-        if let Some(t) = tools::Tool::for_command(id) {
+        if let Some(mut t) = tools::Tool::for_command(id) {
+            if id == "sketch.dimension" {
+                t.picks = self
+                    .session
+                    .selection
+                    .iter()
+                    .filter_map(|s| match s {
+                        solvecraft_engine::Sel::SketchCurve { id } | solvecraft_engine::Sel::SketchPoint { id } => Some(id.clone()),
+                        _ => None,
+                    })
+                    .take(2)
+                    .collect();
+                let _ = self.session.execute("select.clear", &json!({}));
+            }
             self.tool = Some(t);
             self.set_status(tools::hint(id), false);
             return;

crates/ui-egui/src/menu_tests.rs

@@ -232,8 +232,10 @@ fn delete_key_handles_every_kind_and_asks_about_dependents() {
     app.run("edit.undo", json!({})).unwrap();
     assert_eq!(app.session.doc.features.len(), n);
     // A face its neighbours can't close (a side of the plate): refused, nothing changes.
-    let b0 = app.session.model.state().bodies[0].name.clone();
-    app.run("select.set", json!({"items": [{"type": "face", "body": b0, "index": 0, "point": [0, 0, 0]}]})).unwrap();
+    let body = &app.session.model.state().bodies[0];
+    let face = body.body.faces(0.01).unwrap().into_iter().find(|f| f.plane_normal.is_some_and(|n| n.x < -0.99)).unwrap();
+    let b0 = body.name.clone();
+    app.run("select.set", json!({"items": [{"type": "face", "body": b0, "index": face.index, "point": face.centroid}]})).unwrap();
     crate::delete::delete_selection(&mut app);
     assert!(app.status.as_ref().is_some_and(|s| s.0.contains("Delete Face")), "{:?}", app.status);
     assert_eq!(app.session.doc.features.len(), n);

crates/ui-egui/src/ref_images.rs

@@ -68,7 +68,7 @@ pub fn gpu_images(app: &SolveApp) -> Vec<GpuImage> {
         .iter()
         .filter(|c| c.visible && c.opacity > 0.0)
         .filter_map(|c| {
-            let plane = doc.resolve_plane(&vals, &c.plane, 0).ok()?;
+            let plane = doc.canvas_plane(&vals, c).ok()?;
             let (_, version, size, rgba) = pixels(c)?;
             let corners = c.world_corners(&plane).map(|p| [p.x as f32, p.y as f32, p.z as f32]);
             Some(GpuImage { id: c.id, version, size, rgba, corners, opacity: c.opacity.clamp(0.0, 1.0) as f32 })
@@ -105,7 +105,7 @@ pub fn show(app: &SolveApp, ui: &egui::Ui, painter: &egui::Painter, proj: &Proj)
     }
     let (vals, _) = doc.param_values();
     for c in doc.canvases.iter().filter(|c| c.visible) {
-        let Ok(plane) = doc.resolve_plane(&vals, &c.plane, 0) else { continue };
+        let Ok(plane) = doc.canvas_plane(&vals, c) else { continue };
         let Some(tex) = texture(ui.ctx(), c) else { continue };
         let [bl, br, _, tl] = c.corners();
         let (u, v) = (br - bl, tl - bl);

crates/ui-egui/src/scenario.rs

@@ -245,6 +245,15 @@ impl Harness {
     }
 
     pub fn call(&mut self, method: &str, params: Value) -> Value {
+        if method == "ui.resize"
+            && let (Some(w), Some(h)) = (params["width"].as_f64(), params["height"].as_f64())
+            && w.is_finite()
+            && h.is_finite()
+            && w > 0.0
+            && h > 0.0
+        {
+            self.size = egui::vec2(w as f32, h as f32);
+        }
         let (req, _rx) = ControlRequest::new(method, params);
         let out = match handle(&mut self.app, &self.ctx, &req) {
             Outcome::Done(v) => v,

crates/ui-egui/src/selection.rs

@@ -8,6 +8,15 @@ use solvecraft_engine::geom::Vec3;
 
 use crate::viewport::Hit;
 
+/// Model picks retain an on-surface point, but their identity is the body and topology index.
+pub(crate) fn same_item(a: &Sel, b: &Sel) -> bool {
+    match (a, b) {
+        (Sel::Edge { body: a, index: i, .. }, Sel::Edge { body: b, index: j, .. })
+        | (Sel::Face { body: a, index: i, .. }, Sel::Face { body: b, index: j, .. }) => a == b && i == j,
+        _ => a == b,
+    }
+}
+
 /// What a selection input accepts (bit set).
 pub type Accept = u16;
 pub const PROFILES: Accept = 1;
@@ -73,11 +82,11 @@ impl SelInput {
             return;
         }
         // A pick of something already in (or a chain fully in) takes it out.
-        if picked.iter().all(|p| self.items.contains(p)) {
-            self.items.retain(|x| !picked.contains(x));
+        if picked.iter().all(|p| self.items.iter().any(|x| same_item(x, p))) {
+            self.items.retain(|x| !picked.iter().any(|p| same_item(x, p)));
         } else {
             for p in picked {
-                if !self.items.contains(&p) {
+                if !self.items.iter().any(|x| same_item(x, &p)) {
                     self.items.push(p);
                 }
             }

crates/ui-egui/src/sketch_tools.rs

@@ -1090,7 +1090,7 @@ fn snap_hint(app: &SolveApp, painter: &egui::Painter, proj: &Proj) {
 /// Per frame, after the viewport is drawn: constraint glyphs and the text-entry box.
 pub fn show(app: &mut SolveApp, ui: &egui::Ui, painter: &egui::Painter, proj: &Proj) {
     SHIFT.with(|c| c.set(ui.input(|i| i.modifiers.shift)));
-    glyphs(app, painter, proj, ui.input(|i| i.pointer.hover_pos()));
+    glyphs(app, painter, proj, ui.input(|i| i.pointer.hover_pos()).filter(|_| ui.rect_contains_pointer(proj.rect)));
     snap_hint(app, painter, proj);
     combs(app, painter, proj);
     if DEFERRED.with(|d| d.replace(false)) {

crates/ui-egui/src/toolbar.rs

@@ -54,6 +54,7 @@ pub fn app_bar(app: &mut SolveApp, ui: &mut egui::Ui) {
             let br = Rect::from_center_size(pos2(x, r.center().y), vec2(26.0, 26.0));
             x += 30.0;
             let resp = ui.interact(br, ui.id().with(("ab", icon)), Sense::click());
+            crate::scenario::publish_handle(&format!("appbar:{icon}"), br.center());
             if resp.hovered() {
                 ui.painter().rect_filled(br, 4.0, Color32::from_white_alpha(30));
             }
@@ -148,8 +149,11 @@ fn file_menu(app: &mut SolveApp, ctx: &egui::Context) {
         .show(ctx, |ui| {
             egui::Frame::popup(ui.style()).show(ui, |ui| {
                 ui.set_min_width(190.0);
+                ui.visuals_mut().widgets.inactive.weak_bg_fill = Color32::TRANSPARENT;
+                ui.visuals_mut().widgets.inactive.bg_stroke = Stroke::NONE;
+                ui.visuals_mut().widgets.hovered.weak_bg_fill = Tokens::get().hover;
                 let item = |ui: &mut egui::Ui, label: &str, key: &str| {
-                    ui.add(egui::Button::new(label).shortcut_text(key).frame(false).min_size(vec2(180.0, 22.0))).clicked()
+                    ui.add(egui::Button::new(label).shortcut_text(key).min_size(vec2(180.0, 22.0))).clicked()
                 };
                 if item(ui, "New Design", "Ctrl+N") {
                     crate::documents::new_design(app);
@@ -161,6 +165,24 @@ fn file_menu(app: &mut SolveApp, ctx: &egui::Context) {
                     }
                     close = true;
                 }
+                ui.menu_button("Open Recent", |ui| {
+                    for path in app.home.recent.clone() {
+                        let missing = !solvecraft_engine::io::vfs::exists(&path);
+                        let label = format!("{path}{}", if missing { " (missing)" } else { "" });
+                        if ui.button(label).clicked() {
+                            crate::home::open_recent(app, &path);
+                            close = true;
+                            ui.close();
+                        }
+                    }
+                    ui.separator();
+                    if ui.button("Clear Recent").clicked() {
+                        app.home.recent.clear();
+                        app.home.opened_at.clear();
+                        close = true;
+                        ui.close();
+                    }
+                });
                 if item(ui, "Insert STEP…", "") {
                     app.start("file.insert_step");
                     close = true;
@@ -308,11 +330,16 @@ pub fn toolbar(app: &mut SolveApp, ui: &mut egui::Ui) {
         let top = r.top() + 26.0;
         let mut drop: Option<(&'static str, &'static str, Option<&'static str>)> = None;
         let mut menu: Option<(egui::Pos2, &'static str)> = None;
+        let mut overflow = Vec::new();
         for (panel, cmds, promote) in crate::toolbar_custom::panel_lists(&tab) {
             let panel: &&str = &panel;
             let shown = crate::toolbar_custom::buttons(app, &tab, panel, &cmds, promote);
             let n = shown.len().max(1);
             let width = (n as f32 * 40.0).max(64.0) + 8.0;
+            if !overflow.is_empty() || px + width > r.right() - 40.0 {
+                overflow.push((*panel, cmds));
+                continue;
+            }
             let enabled_panel = !cmds.is_empty() || *panel == "SELECT";
             // Dropped on the panel's free space: the button goes to its end.
             let free = Rect::from_min_size(
@@ -433,6 +460,31 @@ pub fn toolbar(app: &mut SolveApp, ui: &mut egui::Ui) {
             painter.line_segment([pos2(px, top + 4.0), pos2(px, top + 58.0)], Stroke::new(1.0, t.border));
             px += 2.0;
         }
+        if !overflow.is_empty() {
+            let at = Rect::from_min_size(pos2(px.min(r.right() - 40.0), top + 4.0), vec2(38.0, 52.0));
+            ui.scope_builder(egui::UiBuilder::new().max_rect(at), |ui| {
+                let response = ui.menu_button("»", |ui| {
+                    for (panel, cmds) in &overflow {
+                        ui.menu_button(*panel, |ui| {
+                            if *panel == "SELECT" {
+                                selection_filter(app, ui);
+                            }
+                            for c in cmds {
+                                let info = c.info(&app.session);
+                                let response = ui.add_enabled(info.enabled, egui::Button::new(c.label).shortcut_text(c.shortcut.unwrap_or("")));
+                                crate::scenario::publish_handle(&format!("toolbar:{}", c.id), response.rect.center());
+                                if response.clicked() {
+                                    app.start(c.id);
+                                    ui.close();
+                                }
+                            }
+                        });
+                    }
+                });
+                crate::scenario::publish_handle("toolbar:overflow", response.response.rect.center());
+                response.response.on_hover_text("More toolbar panels");
+            });
+        }
         painter.line_segment([pos2(r.left(), r.bottom() - 0.5), pos2(r.right(), r.bottom() - 0.5)], Stroke::new(1.0, t.border));
         if let Some((id, panel, before)) = drop {
             crate::toolbar_custom::reorder(app, &tab, id, panel, before);

crates/ui-egui/src/tools.rs

@@ -80,7 +80,7 @@ pub fn hint(id: &str) -> String {
         "sketch.circle.center" => "Circle: click the centre, then a point on the circle".into(),
         "sketch.arc.three_point" => "Arc: click start, end, then a point on the arc".into(),
         "sketch.arc.center_point" => "Arc: click centre, start, then end (counter-clockwise)".into(),
-        "sketch.dimension" => "Dimension: pick a line, circle or arc (or two points/lines)".into(),
+        "sketch.dimension" => "Dimension: pick one or two entities, then click to place the value".into(),
         "sketch.slot.center_to_center" | "sketch.slot.overall" => "Slot: click both ends, then the width".into(),
         _ if id.starts_with("sketch.constraint.") => "Constraint: pick the sketch entities".into(),
         _ => crate::sketch_tools::hint(id).unwrap_or_else(|| "Click in the sketch".into()),
@@ -142,31 +142,21 @@ pub fn on_click(app: &mut SolveApp, proj: &Proj, pos: Pos2) {
         Kind::Dimension => {
             let hits = pick(app, proj, pos);
             let hit = hits.iter().find_map(|h| match h {
-                Hit::SketchPoint { id, .. } => Some((id.clone(), true)),
-                Hit::SketchCurve { id, .. } => Some((id.clone(), false)),
+                Hit::SketchPoint { id, .. } | Hit::SketchCurve { id, .. } => Some(id.clone()),
                 _ => None,
             });
-            if let Some((id, is_point)) = hit {
-                tool.picks.push(id.clone());
-                let st = app.session.world_state();
-                let is_line = app
-                    .session
-                    .active_sketch
-                    .and_then(|s| st.sketch(s))
-                    .and_then(|ss| ss.sketch.curve_index(&id).and_then(|c| ss.sketch.curves.get(c).cloned()))
-                    .map(|c| matches!(c.kind, solvecraft_engine::sketch::CurveKind::Line { .. }));
-                let ready = (tool.picks.len() == 1 && !is_point && is_line != Some(true)) || tool.picks.len() >= 2;
-                let single_line = tool.picks.len() == 1 && is_line == Some(true);
-                if ready || single_line {
-                    // A single line gets its length right away; a second pick (line or point) replaces it.
-                    if let Ok(v) = app.run("sketch.dimension", json!({"entities": tool.picks}))
-                        && let Some(p) = v["param"].as_str()
-                    {
-                        // The value is edited in place, selected so typing replaces it.
-                        crate::dim_view::edit_param(app, p);
-                    }
-                    tool.picks.clear();
+            if let Some(id) = hit {
+                if !tool.picks.contains(&id) && tool.picks.len() < 2 {
+                    tool.picks.push(id);
                 }
+            } else if !tool.picks.is_empty()
+                && let Some((at, _)) = sketch_point_at(app, proj, pos)
+                && let Ok(v) = app.run("sketch.dimension", json!({"entities": tool.picks, "text_at": [at.x, at.y]}))
+            {
+                if let Some(p) = v["param"].as_str() {
+                    crate::dim_view::edit_param(app, p);
+                }
+                tool.picks.clear();
             }
         }
     }

crates/ui-egui/src/viewport.rs

@@ -1091,7 +1091,14 @@ fn build_highlight(app: &SolveApp) -> GpuScene {
     let t = Tokens::get();
     let mut sc = GpuScene::default();
     let st = app.session.world_state();
-    let sel = app.highlighted();
+    let mut sel = Vec::new();
+    for item in app.highlighted() {
+        for piece in grouped_selection(&app.session, &item) {
+            if !sel.iter().any(|x| crate::selection::same_item(x, &piece)) {
+                sel.push(piece);
+            }
+        }
+    }
     let hover = app.viewport.hover.as_ref();
     let size = origin_size(app.cam.half_height());
     // Origin planes and construction planes.
@@ -1242,9 +1249,12 @@ fn build_highlight(app: &SolveApp) -> GpuScene {
             if let Some(b) = st.body(body) {
                 let k = t.hover_face_lift;
                 let c = body_rgb(app, body);
-                face_tris(&mut sc, &b.mesh(), *index, [c.0.saturating_add(k), c.1.saturating_add(k), c.2.saturating_add(k), 255], true);
                 let m = b.mesh();
-                for e in m.face_edges(u32::try_from(*index).unwrap_or(u32::MAX)) {
+                let patch = m.surface_patch(*index);
+                for &f in &patch {
+                    face_tris(&mut sc, &m, f, [c.0.saturating_add(k), c.1.saturating_add(k), c.2.saturating_add(k), 255], true);
+                }
+                for (e, _) in m.edge_faces.iter().enumerate().filter(|(_, fs)| fs.iter().any(|f| patch.contains(&(*f as usize)))) {
                     if let Some(p) = m.edges.get(e)
                         && !m.seams.get(e).copied().unwrap_or(false)
                     {
@@ -1254,12 +1264,13 @@ fn build_highlight(app: &SolveApp) -> GpuScene {
             }
         }
         Some(Hit::Edge { body, index, mid }) => {
-            if let Some(b) = st.body(body)
-                && let Some(e) = edge_of(&b.mesh(), *index, *mid)
-            {
-                let selected = sel.iter().any(|x| matches!(x, Sel::Edge { point, .. } if point.dist(*mid) < 1e-9));
-                if !selected {
-                    edge_lines(&mut sc, e, t.hover_edge, t.hover_edge_halo, 2.0);
+            if let Some(b) = st.body(body) {
+                let m = b.mesh();
+                for i in m.circular_rim(*index) {
+                    let selected = sel.iter().any(|x| matches!(x, Sel::Edge { body: b, index: j, .. } if b == body && *j == i));
+                    if !selected && let Some(e) = if i == *index { edge_of(&m, i, *mid) } else { m.edges.get(i) } {
+                        edge_lines(&mut sc, e, t.hover_edge, t.hover_edge_halo, 2.0);
+                    }
                 }
             }
         }
@@ -1286,7 +1297,7 @@ fn body_rgb(app: &SolveApp, name: &str) -> (u8, u8, u8) {
     (c.r(), c.g(), c.b())
 }
 
-fn polyline_mid(pts: &[Vec3]) -> Vec3 {
+pub(crate) fn polyline_mid(pts: &[Vec3]) -> Vec3 {
     let len: f64 = pts.windows(2).map(|w| w[0].dist(w[1])).sum();
     let mut acc = 0.0;
     for w in pts.windows(2) {
@@ -1360,7 +1371,8 @@ pub fn show(app: &mut SolveApp, ui: &mut egui::Ui) {
     let secondary_down = secondary_down && app.viewport.context_menu.is_none();
     // The view cube handles its own clicks; the model underneath must not see them.
     let cube = Rect::from_center_size(pos2(rect.right() - 80.0, rect.top() + 80.0), vec2(150.0, 150.0));
-    let inside = hover.is_some_and(|p| rect.contains(p) && !cube.contains(p));
+    // Floating windows and menus own input over the model, including wheel navigation.
+    let inside = resp.contains_pointer() && hover.is_some_and(|p| !cube.contains(p));
     app.viewport.mouse = hover.filter(|_| inside);
     // Ctrl or Alt held: drawing and dragging don't snap.
     crate::drag_snap::set_suppressed(mods.ctrl || mods.alt || mods.command);
@@ -1682,6 +1694,7 @@ pub fn show(app: &mut SolveApp, ui: &mut egui::Ui) {
         app.viewport.boxsel = None;
     }
     crate::ref_images::show(app, ui, &painter, &proj);
+    crate::dialogs_assembly::origins(app, &painter, &proj);
     overlays(app, &painter, &proj);
     crate::dim_view::show(app, ui, &painter, &proj);
     crate::sketch3d::show(app, &painter, &proj);
@@ -1729,12 +1742,13 @@ pub fn show(app: &mut SolveApp, ui: &mut egui::Ui) {
 fn select(app: &mut SolveApp, sel: Option<Sel>, add: bool) {
     match sel {
         Some(x) => {
-            let item = serde_json::to_value(&x).unwrap_or_default();
-            if add && app.session.selection.contains(&x) {
-                let rest: Vec<Sel> = app.session.selection.iter().filter(|y| **y != x).cloned().collect();
+            let items = grouped_selection(&app.session, &x);
+            if add && items.iter().all(|x| app.session.selection.iter().any(|y| crate::selection::same_item(x, y))) {
+                let rest: Vec<Sel> =
+                    app.session.selection.iter().filter(|y| !items.iter().any(|x| crate::selection::same_item(x, y))).cloned().collect();
                 let _ = app.run("select.set", json!({ "items": rest }));
             } else {
-                let _ = app.run("select.set", json!({"items": [item], "add": add}));
+                let _ = app.run("select.set", json!({"items": items, "add": add}));
             }
         }
         None if !add => {
@@ -1744,6 +1758,75 @@ fn select(app: &mut SolveApp, sel: Option<Sel>, add: bool) {
     }
 }
 
+/// Expand a visible rim or surface into the kernel pieces a command needs. The original
+/// face pick keeps its point (used by tools such as Hole and construction geometry).
+pub(crate) fn grouped_selection(s: &solvecraft_engine::Session, sel: &Sel) -> Vec<Sel> {
+    let st = s.world_state();
+    match sel {
+        Sel::Edge { body, index, .. } => {
+            if let Some(b) = st.body(body) {
+                let m = b.mesh();
+                return m
+                    .circular_rim(*index)
+                    .into_iter()
+                    .filter_map(|i| m.edges.get(i).map(|e| Sel::Edge { body: body.clone(), index: i, point: polyline_mid(e) }))
+                    .collect();
+            }
+        }
+        Sel::Face { body, index, .. } => {
+            if let Some(b) = st.body(body) {
+                let m = b.mesh();
+                let mut patch = m.surface_patch(*index);
+                patch.sort_by_key(|i| usize::from(i != index));
+                return patch
+                    .into_iter()
+                    .filter_map(|i| {
+                        if i == *index {
+                            return Some(sel.clone());
+                        }
+                        m.triangles.iter().zip(&m.tri_face).find_map(|(t, f)| {
+                            if *f as usize != i {
+                                return None;
+                            }
+                            let [a, b, c] = m.tri(t)?;
+                            Some(Sel::Face { body: body.clone(), index: i, point: (a + b + c) / 3.0 })
+                        })
+                    })
+                    .collect();
+            }
+        }
+        _ => {}
+    }
+    vec![sel.clone()]
+}
+
+/// Measure keeps one entry per visible item, rather than using its two slots for kernel halves.
+pub(crate) fn measurement_selection(s: &solvecraft_engine::Session, sel: &Sel) -> Sel {
+    let pieces = grouped_selection(s, sel);
+    let mut representative = sel.clone();
+    match &mut representative {
+        Sel::Edge { index, .. } => {
+            if let Some(Sel::Edge { index: i, .. }) = pieces.first() {
+                *index = *i;
+            }
+        }
+        Sel::Face { index, .. } => {
+            if let Some(i) = pieces
+                .iter()
+                .filter_map(|p| match p {
+                    Sel::Face { index, .. } => Some(*index),
+                    _ => None,
+                })
+                .min()
+            {
+                *index = i;
+            }
+        }
+        _ => {}
+    }
+    representative
+}
+
 /// What a box selects: sketch entities while sketching, otherwise what the open dialog's
 /// active input takes (edges, faces or bodies), otherwise bodies.
 fn box_select(app: &mut SolveApp, proj: &Proj, bx: BoxSel, add: bool) {
@@ -1793,7 +1876,9 @@ fn box_select(app: &mut SolveApp, proj: &Proj, bx: BoxSel, add: bool) {
             let m = b.mesh();
             if accept & EDGES != 0 {
                 for (ei, e) in m.edges.iter().enumerate() {
-                    if !m.seams.get(ei).copied().unwrap_or(false) && bx.takes(&to2(e)) {
+                    let rim = m.circular_rim(ei);
+                    let takes = if bx.crossing { bx.takes(&to2(e)) } else { rim.iter().all(|&i| m.edges.get(i).is_some_and(|p| bx.takes(&to2(p)))) };
+                    if !m.seams.get(ei).copied().unwrap_or(false) && takes {
                         out.push(Sel::Edge { body: b.name.clone(), index: ei, point: polyline_mid(e) });
                     }
                 }
@@ -1810,8 +1895,15 @@ fn box_select(app: &mut SolveApp, proj: &Proj, bx: BoxSel, add: bool) {
                         .find(|(_, tf)| **tf as usize == f)
                         .and_then(|(t, _)| m.tri(t))
                         .map(|[a, bb, c]| (a + bb + c) / 3.0);
+                    let takes = bx.takes(&to2(&pts))
+                        && (bx.crossing
+                            || m.surface_patch(f).iter().all(|&face| {
+                                m.face_edges(u32::try_from(face).unwrap_or(u32::MAX))
+                                    .iter()
+                                    .all(|&e| m.edges.get(e).is_some_and(|p| bx.takes(&to2(p))))
+                            }));
                     if let Some(point) = point
-                        && bx.takes(&to2(&pts))
+                        && takes
                     {
                         out.push(Sel::Face { body: b.name.clone(), index: f, point });
                     }
@@ -1836,8 +1928,17 @@ fn box_select(app: &mut SolveApp, proj: &Proj, bx: BoxSel, add: bool) {
             }
         }
     }
+    let mut grouped = Vec::new();
+    for item in out {
+        for piece in grouped_selection(&app.session, &item) {
+            if !grouped.iter().any(|x| crate::selection::same_item(x, &piece)) {
+                grouped.push(piece);
+            }
+        }
+    }
+    let out = grouped;
     if let Some(mut d) = app.dialog.take() {
-        d.take_box(out, add);
+        d.take_box(&app.session, out, add);
         app.dialog = Some(d);
         return;
     }
@@ -1986,7 +2087,7 @@ fn view_cube(app: &mut SolveApp, ui: &mut egui::Ui, rect: Rect) {
     let (r, u, b) = cube_basis(&app.cam);
     let (wr, wu, _) = app.cam.basis();
     let painter = ui.painter_at(rect);
-    let hover = ui.input(|i| i.pointer.hover_pos());
+    let hover = ui.input(|i| i.pointer.hover_pos()).filter(|_| ui.rect_contains_pointer(rect));
     let targets = cube_targets();
     let shapes = cube_projected(&targets, (r, u, b), c);
     let hovered = hover.and_then(|h| cube_hit(&shapes, h));
@@ -2303,6 +2404,255 @@ fn view_menu(app: &mut SolveApp, ui: &mut egui::Ui, button: Rect) -> bool {
 mod tests {
     use super::*;
 
+    fn cylinder_app() -> SolveApp {
+        let mut s = solvecraft_engine::Session::default();
+        s.execute("solid.cylinder", &json!({"radius": 10, "height": 20})).unwrap();
+        let mut app = SolveApp::new(s, crate::Services::default());
+        app.ui.show_origin = false;
+        app
+    }
+
+    #[test]
+    fn circular_items_measure_as_whole_rims_and_surfaces() {
+        let mut app = cylinder_app();
+        let st = app.session.world_state();
+        let b = &st.bodies[0];
+        let m = b.mesh();
+        let edges: Vec<Sel> = m
+            .edges
+            .iter()
+            .enumerate()
+            .filter(|(_, p)| p.len() > 3 && p.iter().all(|q| (q.z - 20.0).abs() < 1e-6))
+            .map(|(index, p)| Sel::Edge { body: b.name.clone(), index, point: polyline_mid(p) })
+            .collect();
+        let result = app.session.measure_items(&edges);
+        assert_eq!(result["items"].as_array().unwrap().len(), 1);
+        assert!((result["items"][0]["length_mm"].as_f64().unwrap() - 20.0 * std::f64::consts::PI).abs() < 0.2, "{result}");
+        app.session.selection = edges;
+        let d = crate::dialogs::Dialog::for_command(&app, "inspect.measure").unwrap();
+        assert_eq!(d.items().len(), 1);
+
+        let faces = m.edge_faces.iter().zip(&m.seams).find(|(_, seam)| **seam).unwrap().0;
+        let wall = Sel::Face { body: b.name.clone(), index: faces[0] as usize, point: Vec3::new(10.0, 0.0, 10.0) };
+        let wall_pieces = grouped_selection(&app.session, &wall);
+        let result = app.session.measure_items(&wall_pieces);
+        assert_eq!(result["items"].as_array().unwrap().len(), 1);
+        assert!((result["items"][0]["area_mm2"].as_f64().unwrap() - 400.0 * std::f64::consts::PI).abs() < 10.0, "{result}");
+        let mut d = crate::dialogs::Dialog::for_command(&app, "inspect.measure").unwrap();
+        d.pick(&app.session, wall.clone());
+        assert_eq!(d.items().len(), 2, "a rim and a wall are two measurement targets");
+        d.pick(&app.session, Sel::Face { body: b.name.clone(), index: faces[1] as usize, point: Vec3::new(-10.0, 0.0, 10.0) });
+        assert_eq!(d.items().len(), 1, "the other half toggles the same wall");
+    }
+
+    #[test]
+    fn circular_rim_hover_click_and_dialog_pick_include_both_halves() {
+        let mut app = cylinder_app();
+        let st = app.session.world_state();
+        let b = &st.bodies[0];
+        let m = b.mesh();
+        let top = m.edges.iter().position(|e| e.len() > 3 && e.iter().all(|p| (p.z - 20.0).abs() < 1e-6)).unwrap();
+        let rim = m.circular_rim(top);
+        assert_eq!(rim.len(), 2);
+        let line_count: usize = rim.iter().map(|&i| m.edges[i].len() - 1).sum();
+        for &i in &rim {
+            let mid = polyline_mid(&m.edges[i]);
+            app.viewport.hover = Some(Hit::Edge { body: b.name.clone(), index: i, mid });
+            assert_eq!(build_highlight(&app).lines.len(), 2 * line_count * crate::gpu::LINE_SIZE);
+            let item = hit_sel(app.viewport.hover.as_ref().unwrap()).unwrap();
+            select(&mut app, Some(item.clone()), false);
+            assert_eq!(app.session.selection.len(), 2);
+            // Selecting both pieces must not draw each highlight twice.
+            assert_eq!(build_highlight(&app).lines.len(), 2 * line_count * crate::gpu::LINE_SIZE);
+            // Ctrl/Shift clicking either half deselects the entire rim.
+            select(&mut app, Some(item.clone()), true);
+            assert!(app.session.selection.is_empty());
+            let mut d = crate::dialogs::Dialog::for_command(&app, "solid.chamfer").unwrap();
+            if let crate::dialogs::Kind::Fillet { chain, .. } = &mut d.kind {
+                *chain = false;
+            }
+            d.pick(&app.session, item.clone());
+            assert_eq!(d.items().len(), 2);
+            d.pick(&app.session, item);
+            assert!(d.items().is_empty());
+        }
+        // Screen-space picking works from either side of the rim as the model turns.
+        for &i in &rim {
+            let mid = polyline_mid(&m.edges[i]);
+            app.cam = app.cam.looking_from(Vec3::new(mid.x, mid.y, 20.0));
+            app.cam.target = Vec3::new(0.0, 0.0, 10.0);
+            for perspective in [false, true] {
+                app.ui.perspective = perspective;
+                let proj = projection(&app, Rect::from_min_size(pos2(0.0, 0.0), vec2(800.0, 600.0)));
+                let hits = pick(&app, &proj, proj.to_screen(mid).unwrap());
+                let (_, sel) = candidate(&app, &hits).unwrap();
+                assert!(matches!(sel, Sel::Edge { .. }), "{hits:?}");
+                assert_eq!(grouped_selection(&app.session, &sel).len(), 2);
+            }
+        }
+    }
+
+    #[test]
+    fn curved_face_hover_selection_and_dialogs_cross_the_seam() {
+        let mut app = cylinder_app();
+        let st = app.session.world_state();
+        let b = &st.bodies[0];
+        let m = b.mesh();
+        let faces = m.edge_faces.iter().zip(&m.seams).find(|(_, seam)| **seam).unwrap().0;
+        assert_eq!(faces.len(), 2);
+        let triangle_count = m.tri_face.iter().filter(|f| faces.contains(f)).count();
+        for &f in faces {
+            let index = f as usize;
+            let t = m.triangles.iter().zip(&m.tri_face).find(|(_, tf)| **tf == f).unwrap().0;
+            let [a, c, d] = m.tri(t).unwrap();
+            let point = (a + c + d) / 3.0;
+            app.viewport.hover = Some(Hit::Face { body: b.name.clone(), index, point });
+            assert_eq!(build_highlight(&app).tris.len(), triangle_count * 3 * crate::gpu::TRI_SIZE);
+            let item = hit_sel(app.viewport.hover.as_ref().unwrap()).unwrap();
+            select(&mut app, Some(item.clone()), false);
+            assert_eq!(app.session.selection.len(), 2);
+            assert_eq!(build_highlight(&app).tris.len(), triangle_count * 3 * crate::gpu::TRI_SIZE);
+            assert_eq!(app.session.selection.first(), Some(&item), "keep the original tool placement point first");
+            let mut dialog = crate::dialogs::Dialog::for_command(&app, "solid.chamfer").unwrap();
+            assert_eq!(dialog.items().len(), 2);
+            dialog.pick(&app.session, item.clone());
+            assert!(dialog.items().is_empty());
+            dialog.pick(&app.session, item);
+            assert_eq!(dialog.items().len(), 2);
+            // A point elsewhere on the opposite half still toggles the whole surface off.
+            let other = faces.iter().find(|&&x| x != f).unwrap();
+            select(&mut app, Some(Sel::Face { body: b.name.clone(), index: *other as usize, point: m.positions[0] }), true);
+            assert!(app.session.selection.is_empty());
+        }
+        // Planar caps and box corners stay separate.
+        let cap = (0..b.body.face_count()).find(|&i| m.surface_patch(i).len() == 1).unwrap();
+        assert_eq!(m.surface_patch(cap), vec![cap]);
+        app.session.execute("solid.box", &json!({"length": 10, "width": 10, "height": 10})).unwrap();
+        let st = app.session.world_state();
+        let box_body = st.bodies.last().unwrap();
+        for i in 0..box_body.body.face_count() {
+            assert_eq!(box_body.mesh().surface_patch(i), vec![i]);
+        }
+    }
+
+    #[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));
+            }
+            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 _ = 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());
+                },
+            );
+        };
+        // 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 {
+            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);
+    }
+
+    #[test]
+    fn floating_dialog_blocks_viewport_hover_and_clicks() {
+        let mut h = crate::scenario::Harness::new();
+        h.call("engine.execute", json!({"command": "solid.box", "params": {"length": 40, "width": 30, "height": 20}}));
+        h.call("ui.view", json!({"view": "fit"}));
+        h.app.ui.pick_bodies = true;
+        let p = h.app.viewport.rect.unwrap().center();
+        h.call("ui.move", json!({"x": p.x, "y": p.y}));
+        assert!(h.app.viewport.hover.is_some(), "the test point must hover over the model");
+        h.call("ui.click", json!({"x": p.x, "y": p.y}));
+        assert!(!h.app.session.selection.is_empty(), "the uncovered model must be selectable");
+        h.app.session.selection.clear();
+
+        h.call("ui.prefs", json!({"open": "Navigation"}));
+        let window = h.ctx.memory(|m| m.area_rect(egui::Id::new("sc_prefs"))).unwrap();
+        assert!(window.contains(p), "the dialog must cover the model at the test point");
+        h.call("ui.move", json!({"x": p.x, "y": p.y}));
+        assert!(h.app.viewport.hover.is_none(), "the dialog must block model highlights");
+        assert!(h.app.viewport.mouse.is_none());
+        h.call("ui.click", json!({"x": p.x, "y": p.y}));
+        assert!(h.app.session.selection.is_empty(), "clicks in the dialog must not select the model");
+
+        h.call("ui.prefs", json!({"button": "cancel"}));
+        h.call("ui.move", json!({"x": p.x, "y": p.y}));
+        assert!(h.app.viewport.hover.is_some(), "closing the dialog must restore model highlights");
+        h.call("ui.click", json!({"x": p.x, "y": p.y}));
+        assert!(!h.app.session.selection.is_empty());
+    }
+
+    #[test]
+    fn floating_dialog_blocks_view_cube_highlights_and_clicks() {
+        let mut h = crate::scenario::Harness::new();
+        h.call("ui.resize", json!({"width": 800, "height": 700}));
+        let p = crate::scenario::handle_at("cube:top").unwrap();
+        h.call("ui.move", json!({"x": p.x, "y": p.y}));
+        assert_eq!(crate::scenario::count_of("cube_highlights"), Some(1.0));
+        h.call("ui.prefs", json!({"open": "Navigation"}));
+        let window = h.ctx.memory(|m| m.area_rect(egui::Id::new("sc_prefs"))).unwrap();
+        assert!(window.contains(p), "the floating dialog must cover the cube target");
+        let camera = serde_json::to_value(h.app.cam).unwrap();
+        h.call("ui.move", json!({"x": p.x, "y": p.y}));
+        assert_eq!(crate::scenario::count_of("cube_highlights"), Some(0.0));
+        h.call("ui.click", json!({"x": p.x, "y": p.y}));
+        assert_eq!(serde_json::to_value(h.app.cam).unwrap(), camera, "dialog clicks must not turn the view cube");
+        h.call("ui.prefs", json!({"button": "cancel"}));
+        h.call("ui.move", json!({"x": p.x, "y": p.y}));
+        assert_eq!(crate::scenario::count_of("cube_highlights"), Some(1.0));
+        h.call("ui.click", json!({"x": p.x, "y": p.y}));
+        assert_ne!(serde_json::to_value(h.app.cam).unwrap(), camera);
+    }
+
     #[test]
     fn section_outlines_follow_the_cut() {
         let mut s = solvecraft_engine::Session::default();

crates/ui-egui/tests/scenarios.rs

@@ -31,3 +31,98 @@ fn adhoc() {
         panic!("{path}: {e}");
     }
 }
+
+#[test]
+fn angle_dimension_both_interactive_workflows() {
+    use serde_json::json;
+    for preselect in [false, true] {
+        let mut h = Harness::new();
+        h.run(&json!([
+            {"call":"engine.execute","params":{"command":"sketch.create","params":{"plane":"XY"}}},
+            {"call":"engine.execute","params":{"command":"sketch.line","params":{"points":[[0,0],[40,0]]}}},
+            {"call":"engine.execute","params":{"command":"sketch.line","params":{"points":[[0,0],[30,30]]}}},
+            {"call":"ui.view","params":{"view":"top"}}
+        ]))
+        .unwrap();
+        let picks = json!([
+            {"click":{"sketch":[20,0]}},
+            {"click":{"sketch":[15,15]},"shift":true}
+        ]);
+        if preselect {
+            h.run(&picks).unwrap();
+            h.run(&json!([{ "key":"D" }])).unwrap();
+        } else {
+            h.run(&json!([{ "key":"D" }])).unwrap();
+            h.run(&picks).unwrap();
+        }
+        h.run(&json!([
+            {"click":{"sketch":[20,8]}},
+            {"text":"45"}, {"key":"Enter"},
+            {"expect":{"errors":0,"param":{"d1":std::f64::consts::FRAC_PI_4}}}
+        ]))
+        .unwrap();
+        let sk = &h.app.session.model.state().sketches[0].sketch;
+        assert!(sk.constraints.iter().any(|c| matches!(c.kind, solvecraft_engine::sketch::ConstraintKind::Angle { .. })));
+    }
+}
+
+#[test]
+fn home_tab_and_file_recent_open_designs() {
+    use serde_json::json;
+    let mut h = Harness::new();
+    let path = h.dir.join("recent.solvecraft").to_string_lossy().into_owned();
+    h.run(&json!([
+        {"call":"engine.execute","params":{"command":"solid.box","params":{"length":10,"width":10,"height":10}}},
+        {"call":"engine.execute","params":{"command":"file.save_as","params":{"path":path}}},
+        {"click":{"handle":"tab:home"}},
+        {"expect":{"home":true,"documents":1}},
+        {"click":{"handle":"tab:design:0"}},
+        {"expect":{"home":false,"bodies":1}},
+        {"click":{"handle":"tab:home"}},
+        {"click":{"handle":"home:recent:0"}},
+        {"expect":{"home":false,"bodies":1,"documents":2}},
+        {"click":{"handle":"appbar:folder"}},
+        {"widget":"Open Recent"}
+    ]))
+    .unwrap();
+    h.run(&json!([
+        {"widget":path},
+        {"expect":{"home":false,"bodies":1,"documents":3}}
+    ]))
+    .unwrap();
+}
+
+#[test]
+fn sketch_toolbar_imports_use_file_picker() {
+    use serde_json::json;
+    let mut h = Harness::new();
+    let path = h.dir.join("drawing.svg");
+    std::fs::write(
+        &path,
+        r#"<svg xmlns="http://www.w3.org/2000/svg" width="40mm" height="20mm" viewBox="0 0 40 20"><path d="M 0 0 L 40 0 L 40 20 L 0 20 Z"/></svg>"#,
+    )
+    .unwrap();
+    h.run(&json!([
+        {"call":"engine.execute","params":{"command":"sketch.create","params":{"plane":"XY"}}},
+        {"choose_file":path},
+        {"start":"sketch.insert_svg"},
+        {"expect":{"errors":0,"sketch_curves":{"own":4}}}
+    ]))
+    .unwrap();
+}
+
+#[test]
+fn narrow_toolbar_reaches_collapsed_commands() {
+    use serde_json::json;
+    let mut h = Harness::new();
+    h.run(&json!([
+        {"call":"ui.resize","params":{"width":640,"height":800}},
+        {"expect":{"shown_handles":["toolbar:overflow"]}},
+        {"click":{"handle":"toolbar:overflow"}},
+        {"widget":"CONSTRUCT"},
+        {"expect":{"shown_handles":["toolbar:construct.plane.offset"]}},
+        {"click":{"handle":"toolbar:construct.plane.offset"}},
+        {"expect":{"dialog":"OffsetPlane"}}
+    ]))
+    .unwrap();
+}

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

@@ -1,7 +1,4 @@
 [
- {
-  "pending": "#40: offsets of projected geometry get new ids on recompute, the lid's lip fails"
- },
  {
   "note": "Acceptance (#27): the board grows 60 \u2192 70 mm; the lid's lip (offsets of the case's projected rim) follows."
  },

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

@@ -87,6 +87,70 @@
    }
   }
  },
+ {
+  "call": "engine.execute",
+  "params": {
+   "command": "parameters.change",
+   "params": {
+    "name": "wall",
+    "expression": "2.4 mm"
+   }
+  }
+ },
+ {
+  "expect": {
+   "errors": 0,
+   "bodies": 2
+  }
+ },
+ {
+  "call": "engine.execute",
+  "params": {
+   "command": "parameters.change",
+   "params": {
+    "name": "height",
+    "expression": "30 mm"
+   }
+  }
+ },
+ {
+  "expect": {
+   "errors": 0,
+   "bodies": 2
+  }
+ },
+ {
+  "call": "engine.execute",
+  "params": {
+   "command": "parameters.change",
+   "params": {
+    "name": "height",
+    "expression": "25 mm"
+   }
+  }
+ },
+ {
+  "expect": {
+   "errors": 0,
+   "bodies": 2
+  }
+ },
+ {
+  "call": "engine.execute",
+  "params": {
+   "command": "parameters.change",
+   "params": {
+    "name": "wall",
+    "expression": "2 mm"
+   }
+  }
+ },
+ {
+  "expect": {
+   "errors": 0,
+   "bodies": 2
+  }
+ },
  {
   "call": "engine.execute",
   "params": {

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

@@ -1,7 +1,4 @@
 [
- {
-  "pending": "#41: a snap fit stays at its old point when its wall moves (a floating body)"
- },
  {
   "note": "Acceptance (#27): the board grows 40 \u2192 50 mm deep; the snap fit stays on the moved front wall."
  },

crates/ui-egui/tests/scenarios/s01_box_fillet_hole_shell.json

@@ -50,6 +50,7 @@
    ]
   }
  },
+ {"click": {"sketch": [20, -8]}},
  {
   "text": "50"
  },

crates/ui-egui/tests/scenarios/s06_edit_early_feature.json

@@ -40,6 +40,7 @@
    ]
   }
  },
+ {"click": {"sketch": [20, -8]}},
  {
   "text": "40"
  },

crates/ui-egui/tests/scenarios/s07_components_joint_drive.json

@@ -76,6 +76,14 @@
  {
   "key": "Enter"
  },
+ {
+  "call": "ui.set",
+  "params": {
+   "hiddenBodies": [
+    "Body1"
+   ]
+  }
+ },
  {
   "start": "sketch.create"
  },
@@ -84,6 +92,12 @@
    "plane": "XZ"
   }
  },
+ {
+  "call": "ui.set",
+  "params": {
+   "hiddenBodies": []
+  }
+ },
  {
   "start": "sketch.rectangle.two_point"
  },
@@ -99,7 +113,7 @@
   "click": {
    "sketch": [
     50,
-    10
+    -10
    ]
   }
  },
@@ -116,16 +130,13 @@
   }
  },
  {
-  "start": "solid.extrude"
+  "call": "ui.view",
+  "params": {
+   "view": "fit"
+  }
  },
  {
-  "click": {
-   "world": [
-    40,
-    0,
-    5
-   ]
-  }
+  "start": "solid.extrude"
  },
  {
   "text": "20"
@@ -199,7 +210,7 @@
     "max": [
      null,
      null,
-     20
+     30
     ]
    }
   }
@@ -231,4 +242,4 @@
  {
   "shot": "s07_driven"
  }
-]
+]

crates/ui-egui/tests/scenarios/s10_parameters_drive_model.json

@@ -40,6 +40,7 @@
    ]
   }
  },
+ {"click": {"sketch": [20, -8]}},
  {
   "text": "40"
  },

crates/ui-egui/tests/scenarios/s11_sketch_constraints.json

@@ -95,6 +95,14 @@
    ]
   }
  },
+ {
+  "click": {
+   "sketch": [
+    20,
+    -8
+   ]
+  }
+ },
  {
   "text": "40"
  },
@@ -109,6 +117,14 @@
    ]
   }
  },
+ {
+  "click": {
+   "sketch": [
+    48,
+    12
+   ]
+  }
+ },
  {
   "text": "25"
  },
@@ -123,6 +139,14 @@
    ]
   }
  },
+ {
+  "click": {
+   "sketch": [
+    30,
+    20
+   ]
+  }
+ },
  {
   "text": "10"
  },
@@ -219,4 +243,4 @@
  {
   "shot": "s11_done"
  }
-]
+]

crates/ui-egui/tests/scenarios/s20_section_with_joint_drive.json

@@ -76,6 +76,14 @@
  {
   "key": "Enter"
  },
+ {
+  "call": "ui.set",
+  "params": {
+   "hiddenBodies": [
+    "Body1"
+   ]
+  }
+ },
  {
   "start": "sketch.create"
  },
@@ -84,6 +92,12 @@
    "plane": "XZ"
   }
  },
+ {
+  "call": "ui.set",
+  "params": {
+   "hiddenBodies": []
+  }
+ },
  {
   "start": "sketch.rectangle.two_point"
  },
@@ -99,7 +113,7 @@
   "click": {
    "sketch": [
     50,
-    10
+    -10
    ]
   }
  },
@@ -116,16 +130,13 @@
   }
  },
  {
-  "start": "solid.extrude"
+  "call": "ui.view",
+  "params": {
+   "view": "fit"
+  }
  },
  {
-  "click": {
-   "world": [
-    40,
-    0,
-    5
-   ]
-  }
+  "start": "solid.extrude"
  },
  {
   "text": "20"
@@ -236,4 +247,4 @@
  {
   "shot": "s20_section_driven"
  }
-]
+]

crates/ui-egui/tests/scenarios/s23_configurations.json

@@ -43,6 +43,7 @@
    ]
   }
  },
+ {"click": {"sketch": [20, -8]}},
  {
   "text": "40"
  },

crates/ui-egui/tests/scenarios/s26_drive_joint_typed.json

@@ -76,6 +76,14 @@
  {
   "key": "Enter"
  },
+ {
+  "call": "ui.set",
+  "params": {
+   "hiddenBodies": [
+    "Body1"
+   ]
+  }
+ },
  {
   "start": "sketch.create"
  },
@@ -84,6 +92,12 @@
    "plane": "XZ"
   }
  },
+ {
+  "call": "ui.set",
+  "params": {
+   "hiddenBodies": []
+  }
+ },
  {
   "start": "sketch.rectangle.two_point"
  },
@@ -99,7 +113,7 @@
   "click": {
    "sketch": [
     50,
-    10
+    -10
    ]
   }
  },
@@ -116,16 +130,13 @@
   }
  },
  {
-  "start": "solid.extrude"
+  "call": "ui.view",
+  "params": {
+   "view": "fit"
+  }
  },
  {
-  "click": {
-   "world": [
-    40,
-    0,
-    5
-   ]
-  }
+  "start": "solid.extrude"
  },
  {
   "text": "20"
@@ -240,4 +251,4 @@
  {
   "shot": "s26_drive_typed"
  }
-]
+]

crates/ui-egui/tests/scenarios/s32_cut_in_active_component.json

@@ -102,7 +102,7 @@
   "click": {
    "sketch": [
     52,
-    10
+    -10
    ]
   }
  },
@@ -187,7 +187,7 @@
   "click": {
    "sketch": [
     48,
-    25
+    15
    ]
   }
  },
@@ -239,4 +239,4 @@
  {
   "shot": "s27_cut"
  }
-]
+]

crates/ui-egui/tests/scenarios/s37_browser_chevrons.json

@@ -1,7 +1,4 @@
 [
- {
-  "pending": "every chevron works; the browser has no Joints folder (solvecraft-shell)"
- },
  {
   "note": "Browser chevrons expand and collapse every kind of node (folders, components, groups, the origin, named views, document settings). Model: two components with a body each, a joint, a sketch, an offset plane, a named view."
  },
@@ -82,6 +79,14 @@
  {
   "key": "Enter"
  },
+ {
+  "call": "ui.set",
+  "params": {
+   "hiddenBodies": [
+    "Body1"
+   ]
+  }
+ },
  {
   "start": "sketch.create"
  },
@@ -90,6 +95,12 @@
    "plane": "XZ"
   }
  },
+ {
+  "call": "ui.set",
+  "params": {
+   "hiddenBodies": []
+  }
+ },
  {
   "start": "sketch.rectangle.two_point"
  },
@@ -105,7 +116,7 @@
   "click": {
    "sketch": [
     50,
-    10
+    -10
    ]
   }
  },
@@ -122,16 +133,13 @@
   }
  },
  {
-  "start": "solid.extrude"
+  "call": "ui.view",
+  "params": {
+   "view": "fit"
+  }
  },
  {
-  "click": {
-   "world": [
-    40,
-    0,
-    5
-   ]
-  }
+  "start": "solid.extrude"
  },
  {
   "text": "20"

crates/ui-egui/tests/scenarios/s43_root_sketch_on_moved_component_face.json

@@ -0,0 +1,103 @@
+[
+ {
+  "note": "User bug 1/4 (\"big square\"): with the root active, Create Sketch on a moved component's face puts the sketch on the face where it is shown, its projected loop on the face's edges (not at the component's own coordinates)."
+ },
+ {
+  "call": "engine.execute",
+  "params": {
+   "command": "component.create",
+   "params": {
+    "name": "C"
+   }
+  }
+ },
+ {
+  "call": "engine.execute",
+  "params": {
+   "command": "solid.box",
+   "params": {
+    "length": 40,
+    "width": 30,
+    "height": 20
+   }
+  }
+ },
+ {
+  "call": "engine.execute",
+  "params": {
+   "command": "component.activate",
+   "params": {
+    "component": "root"
+   }
+  }
+ },
+ {
+  "call": "engine.execute",
+  "params": {
+   "command": "occurrence.move",
+   "params": {
+    "occurrence": "C:1",
+    "translate": [
+     100,
+     0,
+     0
+    ]
+   }
+  }
+ },
+ {
+  "call": "ui.view",
+  "params": {
+   "view": "fit"
+  }
+ },
+ {
+  "start": "sketch.create"
+ },
+ {
+  "click": {
+   "world": [
+    120,
+    15,
+    20
+   ]
+  }
+ },
+ {
+  "expect": {
+   "sketching": true
+  }
+ },
+ {
+  "expect": {
+   "sketch_curves": {
+    "linked": 4,
+    "own": 0
+   }
+  }
+ },
+ {
+  "expect": {
+   "sketch_world": {
+    "sketch": "Sketch1",
+    "point": "p1",
+    "at": [
+     140,
+     0,
+     20
+    ]
+   }
+  }
+ },
+ {
+  "shot": "s43_root_sketch_on_moved_face"
+ },
+ {
+  "start": "sketch.finish"
+ },
+ {
+  "expect": {
+   "errors": 0
+  }
+ }
+]

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

@@ -1,7 +1,4 @@
 [
- {
-  "pending": "a root-active sketch on a face of a moved component lands in body-local coordinates (solvecraft-dialogs)"
- },
  {
   "note": "A box in a new component, the component moved +100 in x, the root active: a sketch on the box's top face projects the face's edges where the face is (x 100-140), not at the body's own coordinates (x 0-40)."
  },

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

@@ -1,7 +1,7 @@
 [
- {"note": "With Y up (#3) the view cube turns with the world: its TOP is world +Y and clicking it looks down −Y in the standard plan orientation; FRONT looks along −Z."},
+ {"note": "With Y up (#3) the view cube turns with the world: its TOP is world +Y and clicking it looks down −Y in the standard plan orientation; FRONT looks along −Z."},
  {"call": "engine.execute", "params": {"command": "solid.box", "params": {"length": 40, "width": 30, "height": 20}}},
- {"call": "ui.set", "params": {"upAxis": "y"}},
+ {"call": "ui.prefs", "params": {"up_axis": "y"}},
  {"call": "ui.view", "params": {"view": "home"}},
  {"move": {"cube": [0, 0, 1]}},
  {"expect": {"shown_handles": ["cube_hover:top"]}},

docs/mcp.md

@@ -54,7 +54,7 @@ Claude Desktop (`claude_desktop_config.json`), bridged to a running app:
 | `inspect_design` | `measure?` (default true), `sketches?` (default true) | Parameters, timeline (type, suppressed, rolled back, error, warning, timing), bodies (volume, area, centre of mass, bbox, face/edge/vertex counts, visible), sketches (curves, points, constraints, profiles, DOF, solve status, visible), selection, undo depth. Hide helper sketches, bodies or construction planes with `execute` `browser.visibility` (`{items, visible}` or `{folder, visible}`). |
 | `measure` | `body?` | Volume (mm³), area (mm²), centre of mass, bbox and topology counts per body, with totals. |
 | `body_topology` | `body` | Edges (index, midpoint, length, ends) and faces (index, area, centroid, normal). An edge midpoint is the `[x,y,z]` that picks that edge for fillet and chamfer. |
-| `set_parameter` | `name`, `value` (number or expression), `unit?`, `comment?` | Create or change a user parameter and recompute; reports features that now fail. |
+| `set_parameter` | `name`, `value` (number or expression), `unit?`, `comment?` | Create or change a user parameter and recompute; reports `recomputed` (features rebuilt), `restored` (features whose earlier result for the same inputs was reused, e.g. a value set back) and features that now fail. |
 | `screenshot` | `view?` (iso, top, front, back, bottom, left, right, home, fit), `path?`, `width?`, `height?`, `source?` (window, model) | A PNG image content block. Headless: CPU render fitted to the model. Bridged: the app window (default) or a model render with the app's camera. |
 | `export` | `path`, `format?` (step, 3mf, stl, stla, obj), `bodies?` | STEP, 3MF or mesh export. |
 | `undo`, `redo` | — | Undo / redo one change. |
@@ -69,8 +69,11 @@ Errors: an unknown tool or arguments that don't match the tool's schema are JSON
 `-32602` errors; an engine failure (bad command parameters, a feature that fails) is a tool
 result with `isError: true` and the engine's message, which the model can read and correct.
 
-`batch` rollback undoes as many steps as the batch added to the undo history; batches that
-themselves call `edit.undo`, `file.new` or `doc.open` are not rolled back exactly.
+`batch` rollback goes back to an engine checkpoint (`edit.checkpoint`) taken before the first
+step: the design, the active sketch and the undo history are restored exactly as they were,
+however long the history is. Batches that call `file.new` or `doc.open` get the design back,
+not its file path. (An older app without checkpoints falls back to undoing as many steps as
+the batch added to the undo history.)
 
 ## Demo: an enclosure built over MCP
 

docs/wip-reconciliation.md

@@ -0,0 +1,22 @@
+# WIP branch reconciliation (#6)
+
+The branches predate the dotted command IDs. Their remaining changes were ported through
+`crates/engine/src/legacy_ids.rs` and reconciled with the current implementation.
+
+| Branches | Result |
+|---|---|
+| `solvecraft-sk`, `solvecraft-d2` | Ported `62d22e2` and `e0b3138`: sketches/projections see placed components; cache keys include placements; moved feature dialogs resolve world picks; Joints uses Browser rows. |
+| `solvecraft-b4` | Ported `2c18dac`: canvases carry component ownership and named joint origins follow component placements. |
+| `solvecraft-asm` | Ported `bc05805`: joint snap feedback, Drive limits, joint menus, and Motion Study editing/playback controls. |
+| `solvecraft-shell`, `solvecraft-shell-b` | Browser chevrons, shared occurrence Move triad, toolbar customization, workspace switcher and status labels are already present on main. Their scenarios remain active; the Joints chevron scenario is now active too. |
+| `solvecraft-kdev3`, `solvecraft-kdev`, `solvecraft-kdev2` | Previously landed as `67c79ec`; the old refs were already removed. |
+| `solvecraft-kdev4` | The earlier robustness, shell, blends, wasm and measurement work is already present. Ported the remaining `9f98449` stacked-prism sewing and repaired curved-boundary face picking. |
+| `solvecraft-params(-build)` | Previously landed as `517b7a9`. |
+
+The source WIP refs are retained until this batch merges. Delete them only after the merged
+main contains the reconciled changes and passes CI.
+
+Regression coverage includes root sketches on translated and rotated components, subsequent
+component moves, canvas save/reopen, joint origins during pending moves, moved feature dialog
+refill, Browser chevrons, sample building, and the UI scenarios. `cargo xtask ci` covers native
+tests, wasm, layering and asset attribution.

examples/regressions/loft_cut_beside_round_hole.json

@@ -0,0 +1,24 @@
+{
+ "description": "A loft cut from a pocket floor beside a round hole it never touches (the hole made first). Slab 900 x 480 x 160, a 557.68 x 100 pocket 120 deep, a 35 mm hole 25 deep 66 mm from the pocket, then a loft cut from a rectangle on the pocket floor (0.5 mm inside its walls) down 4 mm to an 80 x 80 square. The loft's top lies in the pocket floor, and the hole's cylinder kept the exact planar boolean from taking it: the cut failed with a kernel panic. Result: the same body as with the hole made after the loft.",
+ "commands": [
+  {"command": "sketch.create", "params": {"plane": "XY", "offset": 690, "name": "Outline"}},
+  {"command": "sketch.rectangle.two_point", "params": {"p0": [0, -480], "p1": [900, 0]}},
+  {"command": "sketch.finish", "params": {}},
+  {"command": "solid.extrude", "params": {"distance": 160, "name": "Slab"}},
+  {"command": "sketch.create", "params": {"plane": "XY", "offset": 850, "name": "BowlTop"}},
+  {"command": "sketch.rectangle.two_point", "params": {"p0": [171.16, -151.16], "p1": [728.84, -51.16]}},
+  {"command": "sketch.finish", "params": {}},
+  {"command": "solid.extrude", "params": {"distance": -120, "operation": "cut", "name": "BowlPocket"}},
+  {"command": "sketch.create", "params": {"plane": "XY", "offset": 850, "name": "TapHole"}},
+  {"command": "sketch.circle.center", "params": {"center": [795, -101.16], "radius": 17.5}},
+  {"command": "sketch.finish", "params": {}},
+  {"command": "solid.extrude", "params": {"distance": -25, "operation": "cut", "name": "TapCut"}},
+  {"command": "sketch.create", "params": {"plane": "XY", "offset": 730, "name": "TroughInset"}},
+  {"command": "sketch.rectangle.two_point", "params": {"p0": [171.66, -150.66], "p1": [728.34, -51.66]}},
+  {"command": "sketch.finish", "params": {}},
+  {"command": "sketch.create", "params": {"plane": "XY", "offset": 726, "name": "DrainSeat"}},
+  {"command": "sketch.rectangle.two_point", "params": {"p0": [410, -141.16], "p1": [490, -61.16]}},
+  {"command": "sketch.finish", "params": {}},
+  {"command": "solid.loft", "params": {"sections": [{"sketch": "TroughInset"}, {"sketch": "DrainSeat"}], "operation": "cut", "name": "TroughFall"}}
+ ]
+}

examples/regressions/oblique_cut_of_cylinder.json

@@ -0,0 +1,15 @@
+{
+ "description": "A thin 437 mm bar whose profile has a 3 mm concave arc, cut by a long prism whose top is tilted 21 degrees to the bar (an elliptical cut through the arc's cylinder). The check on the result meshed both bodies at a step from the 920 mm prism, which faceted the arc so coarsely that a correct cut failed the membership test. Result: the bar with its end trimmed by the tilted plane, as a split by that plane gives.",
+ "commands": [
+  {"command": "sketch.create", "params": {"plane": "XZ", "offset": -462, "name": "Profile"}},
+  {"command": "sketch.line", "params": {"points": [[147.4407, -849.95], [147.4407, -851.0], [151.3952, -851.0], [151.3952, -847.4709], [150.3952, -847.4709]]}},
+  {"command": "sketch.arc.center_point", "params": {"center": [147.4407, -846.95], "start": "l1.start", "end": "l4.end"}},
+  {"command": "sketch.finish", "params": {}},
+  {"command": "solid.extrude", "params": {"sketch": "Profile", "profiles": "all", "direction": "positive", "start_offset": -1, "distance": 437.52, "operation": "new", "body_name": "Tool"}},
+  {"command": "sketch.create", "params": {"plane": "YZ", "name": "Clip"}},
+  {"command": "sketch.line", "params": {"points": [[-472, 853.91], [-432, 838.47], [-432, 820], [-472, 820]], "closed": true}},
+  {"command": "sketch.finish", "params": {}},
+  {"command": "solid.extrude", "params": {"sketch": "Clip", "profiles": "all", "start_offset": -10, "distance": 920, "operation": "new", "body_name": "ClipBody"}},
+  {"command": "solid.combine", "params": {"target": "Tool", "tools": ["ClipBody"], "operation": "cut", "keep_tools": true}}
+ ]
+}

examples/regressions/oblique_cut_of_cylinder_hang.json

@@ -0,0 +1,15 @@
+{
+ "description": "The oblique cut of oblique_cut_of_cylinder.json with the prism running past the bar's end. Moving a boolean result back after a shifted retry computed a matrix norm whose root refinement never ended: the app hung at full CPU. Result: the same trimmed bar.",
+ "commands": [
+  {"command": "sketch.create", "params": {"plane": "XZ", "offset": -462, "name": "Profile"}},
+  {"command": "sketch.line", "params": {"points": [[147.4407, -849.95], [147.4407, -851.0], [151.3952, -851.0], [151.3952, -847.4709], [150.3952, -847.4709]]}},
+  {"command": "sketch.arc.center_point", "params": {"center": [147.4407, -846.95], "start": "l1.start", "end": "l4.end"}},
+  {"command": "sketch.finish", "params": {}},
+  {"command": "solid.extrude", "params": {"sketch": "Profile", "profiles": "all", "direction": "positive", "start_offset": -1, "distance": 437.52, "operation": "new", "body_name": "Tool"}},
+  {"command": "sketch.create", "params": {"plane": "YZ", "name": "Clip"}},
+  {"command": "sketch.line", "params": {"points": [[-480, 856.9979999999999], [-432, 838.47], [-432, 820], [-480, 820]], "closed": true}},
+  {"command": "sketch.finish", "params": {}},
+  {"command": "solid.extrude", "params": {"sketch": "Clip", "profiles": "all", "start_offset": -10, "distance": 920, "operation": "new", "body_name": "ClipBody"}},
+  {"command": "solid.combine", "params": {"target": "Tool", "tools": ["ClipBody"], "operation": "cut", "keep_tools": true}}
+ ]
+}

examples/regressions/shallow_loft_cut_from_top_face.json

@@ -0,0 +1,16 @@
+{
+ "description": "A shallow, wide loft cut starting in a body's top face: slab 900 x 480 x 160, loft cut from a 556.68 x 99 rectangle on the top face down 4 mm to an 80 x 80 square (sides about 0.9 degrees from horizontal). Healing an intermediate boolean result panicked outside the boolean's guard and stopped every later attempt. Result: the slab less the loft, 69 003 015.31 mm³.",
+ "commands": [
+  {"command": "sketch.create", "params": {"plane": "XY", "name": "Base"}},
+  {"command": "sketch.rectangle.two_point", "params": {"p0": [0, 0], "p1": [900, 480]}},
+  {"command": "sketch.finish", "params": {}},
+  {"command": "solid.extrude", "params": {"distance": 160, "name": "Slab"}},
+  {"command": "sketch.create", "params": {"plane": "XY", "offset": 160, "name": "LoftTop"}},
+  {"command": "sketch.rectangle.two_point", "params": {"p0": [171.66, 329.34], "p1": [728.34, 428.34]}},
+  {"command": "sketch.finish", "params": {}},
+  {"command": "sketch.create", "params": {"plane": "XY", "offset": 156, "name": "LoftBottom"}},
+  {"command": "sketch.rectangle.two_point", "params": {"p0": [410, 338.84], "p1": [490, 418.84]}},
+  {"command": "sketch.finish", "params": {}},
+  {"command": "solid.loft", "params": {"sections": [{"sketch": "LoftTop"}, {"sketch": "LoftBottom"}], "operation": "cut", "name": "LoftCut"}}
+ ]
+}

vendor/README.md

@@ -49,3 +49,15 @@ Changes:
   direction (long triangles from a trim loop to the grid's far ends cut through cylinders).
 - `lib.rs`: compiler warnings no longer fail the build. Example, test and bench targets are
   dropped (their sources are not vendored).
+
+## matext4cgmath 0.1.0 (Apache-2.0, © RICOS Co. Ltd., https://github.com/ricosjp/matext4cgmath)
+
+truck-geometry uses it for a matrix's operator norm (an intersection curve scales its tolerance
+by it whenever it is moved).
+
+Changes:
+- `solver.rs`: the Newton refinement of cubic and quartic roots stops after 100 steps. Near a
+  double root it could cycle forever: moving a body whose edges a boolean made (the retries
+  move both bodies and the result back) hung the app.
+- `lib.rs`: compiler warnings no longer fail the build. Test targets are dropped (their sources
+  are not vendored).

vendor/matext4cgmath/Cargo.toml

@@ -0,0 +1,40 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies.
+#
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
+
+[package]
+edition = "2021"
+name = "matext4cgmath"
+version = "0.1.0"
+authors = ["Yoshinori Tanimura <tanimura@ricos.co.jp>"]
+description = "Unofficial third-party cgmath extensions for calculate eigenvalues, operator norms and Iwasawa decomposition."
+homepage = "https://github.com/ricosjp/matext4cgmath"
+keywords = [
+    "cgmath",
+    "graphics",
+    "linear-algebra",
+]
+categories = ["graphics"]
+license = "Apache-2.0"
+repository = "https://github.com/ricosjp/matext4cgmath"
+resolver = "2"
+autotests = false
+autoexamples = false
+autobenches = false
+
+[dependencies.cgmath]
+version = "0.18.0"
+
+[dependencies.katexit]
+version = "0.1.2"
+
+[dependencies.num-complex]
+version = "0.4.0"
+