Open .solidcraft designs: rebuild, persistent face names, geometry commands (#4)

* geometry: open .solidcraft designs, rebuild them and keep persistent face names

open_design(bytes) reads a design (container or JSON) with solidcraft-io, rebuilds its
timeline with solidcraft-doc and returns its bodies; each Shape carries SolidCraft's
persistent face names by B-rep face index, so a face keeps its name through a parameter
edit. sample::plate_design builds a parametric test plate in code.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

* engine: geometry.open, geometry.bodies and geometry.tessellate

The session holds the open design (shared, restored on a failed command, journalled when
it changes). Hostile-params coverage includes non-files, missing files, oversized paths and
extreme tolerances against an open design.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

* docs: opening SolidCraft designs in the architecture and roadmap

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

* geometry: open_design_file reads through SolidCraft's bounded file access; simplify

The engine's hand-rolled capped read is replaced by open_design_file, which uses
solidcraft_io::vfs::read (refuses non-regular files before opening, works on the browser's
in-memory files). Drops the duplicate size check, simplifies the sample sketch and the
design-change test in Session::execute.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

---------

Co-authored-by: jyviko <2501648+jyviko@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

crates/engine/src/cmd/geometry.rs

@@ -0,0 +1,79 @@
+use std::sync::Arc;
+
+use modelcraft_geometry::{Shape, open_design_file};
+use serde_json::{Value, json};
+
+use crate::{CommandSpec, EngineError, Result, Session};
+
+pub const OPEN: CommandSpec = CommandSpec {
+    id: "geometry.open",
+    label: "Open Design",
+    params: r#"{"path": "part.solidcraft"} — rebuilds the SolidCraft design and makes its bodies the geometry; opening it again after an edit picks up the change"#,
+    run: open,
+};
+
+pub const BODIES: CommandSpec = CommandSpec {
+    id: "geometry.bodies",
+    label: "Bodies",
+    params: "{} — the open design's bodies: measures and persistent face names (by face index)",
+    run: bodies,
+};
+
+pub const TESSELLATE: CommandSpec = CommandSpec {
+    id: "geometry.tessellate",
+    label: "Tessellate Body",
+    params: r#"{"body": "Body1", "tolerance": 0.05} — triangulates the body's boundary within the chordal tolerance (mm); reports triangles per face"#,
+    run: tessellate,
+};
+
+fn open(s: &mut Session, p: &Value) -> Result<Value> {
+    let path = p
+        .get("path")
+        .and_then(Value::as_str)
+        .filter(|v| !v.is_empty())
+        .ok_or_else(|| EngineError::Params("`path` must be the design file's path".into()))?;
+    let design = open_design_file(path)?;
+    let out = json!({
+        "name": design.name,
+        "bodies": design.bodies.iter().map(|b| b.name.as_str()).collect::<Vec<_>>(),
+        "errors": design.errors.iter().map(|e| json!({"feature": e.feature, "message": e.message})).collect::<Vec<_>>(),
+    });
+    s.design = Some(Arc::new(design));
+    Ok(out)
+}
+
+fn bodies(s: &mut Session, _: &Value) -> Result<Value> {
+    let Some(design) = &s.design else { return Ok(json!([])) };
+    let mut out = Vec::with_capacity(design.bodies.len());
+    for b in &design.bodies {
+        let m = b.measure()?;
+        out.push(json!({
+            "name": b.name,
+            "volume": m.volume,
+            "area": m.area,
+            "centroid": m.centroid,
+            "bbox": [m.bbox_min, m.bbox_max],
+            "faces": b.faces().iter().map(|f| json!({"name": f.name, "exact": f.exact})).collect::<Vec<_>>(),
+        }));
+    }
+    Ok(Value::Array(out))
+}
+
+fn body<'a>(s: &'a Session, p: &Value) -> Result<&'a Shape> {
+    let name = p.get("body").and_then(Value::as_str).ok_or_else(|| EngineError::Params("`body` must be a body name".into()))?;
+    s.design.as_deref().and_then(|d| d.body(name)).ok_or_else(|| EngineError::Params(format!("no body `{name}` (open a design first)")))
+}
+
+fn tessellate(s: &mut Session, p: &Value) -> Result<Value> {
+    let shape = body(s, p)?;
+    let tolerance = p.get("tolerance").and_then(Value::as_f64).ok_or_else(|| EngineError::Params("`tolerance` must be a number (mm)".into()))?;
+    let mesh = shape.tessellate(tolerance)?;
+    let mut per_face = vec![0usize; shape.faces().len()];
+    for &f in &mesh.tri_face {
+        if let Some(n) = per_face.get_mut(f as usize) {
+            *n += 1;
+        }
+    }
+    let faces: Vec<Value> = shape.faces().iter().zip(per_face).map(|(f, n)| json!({"name": f.name, "triangles": n})).collect();
+    Ok(json!({"body": shape.name, "vertices": mesh.positions.len(), "triangles": mesh.triangles.len(), "faces": faces}))
+}

crates/engine/src/cmd/mod.rs

@@ -1,5 +1,6 @@
 //! The command registry. Each area has its own module; [`ALL`] lists every command.
 
+mod geometry;
 mod mesh;
 mod model;
 
@@ -7,7 +8,16 @@ use serde_json::Value;
 
 use crate::{CommandSpec, EngineError, Result};
 
-pub static ALL: &[CommandSpec] = &[model::INFO, mesh::NODE_ADD, mesh::NODE_REMOVE, mesh::ELEMENT_ADD, mesh::ELEMENT_REMOVE];
+pub static ALL: &[CommandSpec] = &[
+    model::INFO,
+    geometry::OPEN,
+    geometry::BODIES,
+    geometry::TESSELLATE,
+    mesh::NODE_ADD,
+    mesh::NODE_REMOVE,
+    mesh::ELEMENT_ADD,
+    mesh::ELEMENT_REMOVE,
+];
 
 /// A required label parameter (1..=u32::MAX; the model checks its own range).
 pub(crate) fn label(p: &Value, key: &str) -> Result<u32> {

crates/engine/src/lib.rs

@@ -9,6 +9,9 @@
 
 pub mod cmd;
 
+use std::sync::Arc;
+
+use modelcraft_geometry::Design;
 use modelcraft_model::Model;
 use serde_json::Value;
 
@@ -20,6 +23,8 @@ pub enum EngineError {
     Params(String),
     #[error(transparent)]
     Model(#[from] modelcraft_model::Error),
+    #[error(transparent)]
+    Geometry(#[from] modelcraft_geometry::Error),
     /// A command panicked; the model is unchanged.
     #[error("internal error in {command}: {message}")]
     Internal { command: String, message: String },
@@ -46,19 +51,22 @@ pub fn find_command(id: &str) -> Option<&'static CommandSpec> {
     commands().iter().find(|c| c.id == id)
 }
 
-/// The model being edited and the commands that built it.
+/// The model being edited, the geometry it is built on and the commands that built it.
 #[derive(Debug, Clone, Default)]
 pub struct Session {
     pub model: Model,
+    /// The open SolidCraft design (`geometry.open`); shared, so a snapshot costs nothing.
+    pub design: Option<Arc<Design>>,
     /// Commands that changed the model, in order (a script that rebuilds it).
     pub journal: Vec<(String, Value)>,
 }
 
 impl Session {
-    /// Run a command. On an error or a panic the model is left as it was.
+    /// Run a command. On an error or a panic the model and the design are left as they were.
     pub fn execute(&mut self, id: &str, params: &Value) -> Result<Value> {
         let spec = find_command(id).ok_or_else(|| EngineError::UnknownCommand(id.to_string()))?;
         let before = self.model.clone();
+        let design_before = self.design.clone();
         let outcome = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| (spec.run)(self, params)));
         let result = match outcome {
             Ok(r) => r,
@@ -68,10 +76,14 @@ impl Session {
                 Err(EngineError::Internal { command: id.to_string(), message })
             }
         };
+        let design_changed = self.design.as_ref().map(Arc::as_ptr) != design_before.as_ref().map(Arc::as_ptr);
         match &result {
-            Ok(_) if self.model != before => self.journal.push((id.to_string(), params.clone())),
+            Ok(_) if self.model != before || design_changed => self.journal.push((id.to_string(), params.clone())),
             Ok(_) => {}
-            Err(_) => self.model = before,
+            Err(_) => {
+                self.model = before;
+                self.design = design_before;
+            }
         }
         result
     }
@@ -91,6 +103,7 @@ impl Session {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use modelcraft_geometry::sample::{Plate, plate_design};
     use serde_json::json;
 
     #[test]
@@ -143,6 +156,14 @@ mod tests {
             json!({"label": 1, "kind": "nope", "nodes": [1]}),
             json!({"label": 1, "kind": "tet4", "nodes": [1, 1, 1, 1]}),
             json!({"label": 1, "kind": "hex20", "nodes": vec![u32::MAX; 20]}),
+            json!({"path": ""}),
+            json!({"path": "/"}),
+            json!({"path": "/dev/zero"}),
+            json!({"path": "/no/such/design.solidcraft"}),
+            json!({"path": "x".repeat(100_000)}),
+            json!({"path": 7}),
+            json!({"body": "Body1", "tolerance": 0.05}),
+            json!({"body": null, "tolerance": "fine"}),
         ];
         for spec in commands() {
             for p in &hostile {
@@ -151,5 +172,83 @@ mod tests {
             }
         }
         assert!(Session::default().execute("no.such", &json!({})).is_err());
+
+        // The same against an open design.
+        let (_dir, path) = sample_design_file(&Plate::default());
+        let mut opened = Session::default();
+        opened.execute("geometry.open", &json!({"path": path})).unwrap();
+        let tess = [
+            json!({"body": "Body1"}),
+            json!({"body": "Body1", "tolerance": 0}),
+            json!({"body": "Body1", "tolerance": -1}),
+            json!({"body": "Body1", "tolerance": 1e-300}),
+            json!({"body": "Body1", "tolerance": 1e300}),
+            json!({"body": "Body2", "tolerance": 0.1}),
+        ];
+        for p in tess.iter().chain(&hostile) {
+            for spec in commands() {
+                let mut s = opened.clone();
+                let _ = s.execute(spec.id, p);
+            }
+        }
+    }
+
+    /// A design file in a fresh temporary directory (removed when the guard drops).
+    fn sample_design_file(plate: &Plate) -> (TempDir, String) {
+        let dir = TempDir::new();
+        let path = dir.0.join("plate.solidcraft");
+        std::fs::write(&path, plate_design(plate).unwrap()).unwrap();
+        (dir, path.to_string_lossy().into_owned())
+    }
+
+    struct TempDir(std::path::PathBuf);
+    impl TempDir {
+        fn new() -> Self {
+            static N: std::sync::atomic::AtomicUsize = std::sync::atomic::AtomicUsize::new(0);
+            let n = N.fetch_add(1, std::sync::atomic::Ordering::Relaxed);
+            let dir = std::env::temp_dir().join(format!("modelcraft-engine-{}-{n}", std::process::id()));
+            std::fs::create_dir_all(&dir).unwrap();
+            TempDir(dir)
+        }
+    }
+    impl Drop for TempDir {
+        fn drop(&mut self) {
+            let _ = std::fs::remove_dir_all(&self.0);
+        }
+    }
+
+    #[test]
+    fn open_a_design_list_its_bodies_and_tessellate_one() {
+        let (_dir, path) = sample_design_file(&Plate::default());
+        let mut s = Session::default();
+        let opened = s.execute("geometry.open", &json!({"path": path})).unwrap();
+        assert_eq!(opened["bodies"], json!(["Body1"]));
+        assert_eq!(opened["errors"], json!([]));
+        assert_eq!(s.journal.len(), 1);
+
+        let bodies = s.execute("geometry.bodies", &json!({})).unwrap();
+        let volume = bodies[0]["volume"].as_f64().unwrap();
+        let expect = (40.0 * 30.0 - std::f64::consts::PI * 25.0) * 10.0;
+        assert!((volume - expect).abs() < 1e-3 * expect, "{volume}");
+        let faces = bodies[0]["faces"].as_array().unwrap();
+        assert_eq!(faces.len(), 8);
+
+        let t = s.execute("geometry.tessellate", &json!({"body": "Body1", "tolerance": 0.05})).unwrap();
+        let per_face: Vec<u64> = t["faces"].as_array().unwrap().iter().map(|f| f["triangles"].as_u64().unwrap()).collect();
+        assert!(per_face.iter().all(|&n| n > 0), "{t}");
+        assert_eq!(per_face.iter().sum::<u64>(), t["triangles"].as_u64().unwrap());
+
+        // A failed open keeps the design that was open.
+        assert!(s.execute("geometry.open", &json!({"path": "/no/such/design.solidcraft"})).is_err());
+        assert!(s.design.is_some());
+        assert_eq!(s.journal.len(), 1);
+
+        // Re-opening the edited design rebuilds it with the same face names.
+        std::fs::write(&path, plate_design(&Plate { width: 60.0, ..Plate::default() }).unwrap()).unwrap();
+        s.execute("geometry.open", &json!({"path": path})).unwrap();
+        let wider = s.execute("geometry.bodies", &json!({})).unwrap();
+        assert!(wider[0]["volume"].as_f64().unwrap() > volume);
+        assert_eq!(wider[0]["faces"], bodies[0]["faces"]);
+        assert_eq!(s.journal.len(), 2);
     }
 }