feat(wasm): compile the library for wasm32 (issue #45 groundwork)

First step toward a web build: the library now compiles for
wasm32-unknown-unknown with --no-default-features.

- Add a `solid3d` feature (default on) gating truck-meshalgo /
  truck-shapeops / lzma-sys. These pull vtkio → xz2 → lzma-sys (C),
  which cannot cross-compile to wasm. Without the feature the 3-D
  solid path (tessellation, booleans, ACIS import) becomes no-ops;
  2-D CAD is unaffected. Native builds keep the feature by default.
- Move native-only crates (ureq, open) to non-wasm target deps and
  add cfg shims: update-check is a no-op on wasm, and a new `sys`
  module provides open_url + handle_path (rfd FileHandle → PathBuf;
  synthesizes a name-based path on the web).

Native build + all 75 tests unchanged. Browser runtime wiring
(entry point, trunk, real file I/O) is a follow-up.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Cargo.toml

@@ -12,6 +12,15 @@ members = ["crates/ocs_plugin_api"]
 [target.'cfg(windows)'.build-dependencies]
 winresource = "0.1"
 
+[features]
+default = ["solid3d"]
+# 3-D solid modelling: B-rep tessellation (truck-meshalgo) and booleans
+# (truck-shapeops). Disabled for wasm builds — truck-meshalgo pulls
+# vtkio → xz2 → lzma-sys (a C library) that does not cross-compile to
+# wasm32. Without this feature the app is a 2-D CAD editor; the Model tab,
+# solid tessellation and ACIS import become no-ops.
+solid3d = ["dep:truck-meshalgo", "dep:truck-shapeops", "dep:lzma-sys"]
+
 [dependencies]
 # Stable, dependency-free add-on contract (manifest + ribbon/CadModule types).
 # Plugin authors target this crate's semver, not OpenCADStudio internals.
@@ -22,23 +31,21 @@ ocs_plugin_api = { path = "crates/ocs_plugin_api" }
 # the .app crashes on launch on machines without that exact library (#56).
 # Forcing the `static` feature builds liblzma from the bundled source, making
 # the binary self-contained on every platform.
-lzma-sys = { version = "0.1", features = ["static"] }
+lzma-sys = { version = "0.1", features = ["static"], optional = true }
 iced = { version = "0.14", features = ["image", "svg", "advanced", "canvas", "smol"] }
 bytemuck = { version = "1.25", features = ["derive"] }
 glam = { version = "0.33", features = ["bytemuck"] }
 truck-modeling = "0.6"
-truck-meshalgo = { version = "0.4", default-features = false, features = ["tessellation"] }
+truck-meshalgo = { version = "0.4", default-features = false, features = ["tessellation"], optional = true }
 truck-polymesh = "0.6"
 rfd = "0.17"
 acadrust = "0.3.4"
-open = "5"
 printpdf = "0.9.1"
 flate2 = "1"
 image = { version = "0.25", default-features = false, features = ["png", "jpeg", "bmp", "tiff"] }
 rayon = "1"
-ureq = { version = "3", default-features = false, features = ["rustls"] }
 inventory = "0.3"
-truck-shapeops = "0.4"
+truck-shapeops = { version = "0.4", optional = true }
 # Fast non-cryptographic hasher. Handle/u64 keys dominate the hot block,
 # hatch, draw-depth and wire caches; the default SipHash is overkill there.
 rustc-hash = "2"
@@ -68,3 +75,7 @@ windows-sys = { version = "0.61", features = ["Win32_UI_Shell", "Win32_UI_Window
 # Z-decode fix, and CANNOSCALE/CANNOSCALEVALUE header support on top of
 # upstream. Revert to upstream once those PRs land.
 acadrust = { git = "https://github.com/HakanSeven12/acadrust", branch = "main" }
+
+[target.'cfg(not(target_arch = "wasm32"))'.dependencies]
+open = "5"
+ureq = { version = "3", default-features = false, features = ["rustls"] }

src/app/commands.rs

@@ -2489,7 +2489,7 @@ impl OpenCADStudio {
             }
 
             "DONATE" => {
-                let _ = open::that("https://patreon.com/HakanSeven12");
+                crate::sys::open_url("https://patreon.com/HakanSeven12");
                 self.command_line.push_info("Opening Patreon page...");
             }
 
@@ -2669,7 +2669,7 @@ impl OpenCADStudio {
             }
 
             "REPORT" => {
-                let _ = open::that("https://github.com/HakanSeven12/OpenCADStudio/issues/new");
+                crate::sys::open_url("https://github.com/HakanSeven12/OpenCADStudio/issues/new");
                 self.command_line.push_info("Opening feedback page...");
             }
 
@@ -2682,7 +2682,7 @@ impl OpenCADStudio {
             }
 
             "CHANGELOG" => {
-                let _ = open::that("https://github.com/HakanSeven12/OpenCADStudio/releases");
+                crate::sys::open_url("https://github.com/HakanSeven12/OpenCADStudio/releases");
                 self.command_line.push_info("Opening release notes...");
             }
 

src/app/update.rs

@@ -408,7 +408,7 @@ impl OpenCADStudio {
                         .pick_file()
                         .await;
                     match handle {
-                        Some(h) => Ok(h.path().to_path_buf()),
+                        Some(h) => Ok(crate::sys::handle_path(&h)),
                         None => Err("Cancelled".to_string()),
                     }
                 },
@@ -443,7 +443,7 @@ impl OpenCADStudio {
                             .add_filter("DWG Files", &["dwg"])
                             .save_file()
                             .await
-                            .map(|h| h.path().to_path_buf());
+                            .map(|h| crate::sys::handle_path(&h));
                         (name, path)
                     },
                     |(name, path)| Message::WblockSaveResult(name, path),
@@ -497,7 +497,7 @@ impl OpenCADStudio {
                             .add_filter("All Files", &["*"])
                             .save_file()
                             .await
-                            .map(|h| h.path().to_path_buf());
+                            .map(|h| crate::sys::handle_path(&h));
                         (csv_clone, path)
                     },
                     |(csv, path)| Message::DataExtractionSaveResult(csv, path),
@@ -540,7 +540,7 @@ impl OpenCADStudio {
                             .add_filter("All Files", &["*"])
                             .save_file()
                             .await
-                            .map(|h| h.path().to_path_buf())
+                            .map(|h| crate::sys::handle_path(&h))
                     },
                     Message::StlExportPath,
                 )
@@ -594,7 +594,7 @@ impl OpenCADStudio {
                             .add_filter("All Files", &["*"])
                             .save_file()
                             .await
-                            .map(|h| h.path().to_path_buf())
+                            .map(|h| crate::sys::handle_path(&h))
                     },
                     Message::StepExportPath,
                 )
@@ -637,7 +637,7 @@ impl OpenCADStudio {
                         .add_filter("All Files", &["*"])
                         .pick_file()
                         .await
-                        .map(|h| h.path().to_path_buf())
+                        .map(|h| crate::sys::handle_path(&h))
                 },
                 Message::ObjImportPath,
             ),
@@ -5730,7 +5730,7 @@ impl OpenCADStudio {
                 }
             }
             Message::UpdateNoticeOpenRelease => {
-                let _ = open::that(crate::update_check::RELEASES_PAGE);
+                crate::sys::open_url(crate::update_check::RELEASES_PAGE);
                 if let Some(id) = self.update_notice_window.take() {
                     window::close(id)
                 } else {
@@ -6313,7 +6313,7 @@ impl OpenCADStudio {
                             .add_filter("All Files", &["*"])
                             .save_file()
                             .await
-                            .map(|h| h.path().to_path_buf())
+                            .map(|h| crate::sys::handle_path(&h))
                     },
                     Message::PlotStylePanelSavePath,
                 )

src/io/mod.rs

@@ -40,7 +40,7 @@ pub async fn pick_open_path() -> Option<(PathBuf, u64)> {
         .add_filter("All Files", &["*"])
         .pick_file()
         .await?;
-    let path = handle.path().to_path_buf();
+    let path = crate::sys::handle_path(&handle);
     let size = std::fs::metadata(&path).map(|m| m.len()).unwrap_or(0);
     Some((path, size))
 }
@@ -250,7 +250,7 @@ pub async fn pick_plot_style() -> Option<plot_style::PlotStyleTable> {
         .add_filter("All Files", &["*"])
         .pick_file()
         .await?;
-    plot_style::PlotStyleTable::load(handle.path()).ok()
+    plot_style::PlotStyleTable::load(&crate::sys::handle_path(&handle)).ok()
 }
 
 // ── Image file picker ─────────────────────────────────────────────────────
@@ -267,7 +267,7 @@ pub async fn pick_image_file() -> Result<(PathBuf, u32, u32), String> {
         .pick_file()
         .await
         .ok_or_else(|| "Cancelled".to_string())?;
-    let path = handle.path().to_path_buf();
+    let path = crate::sys::handle_path(&handle);
     let img = image::open(&path).map_err(|e| e.to_string())?;
     let (w, h) = image::GenericImageView::dimensions(&img);
     Ok((path, w, h))

src/io/pdf_export.rs

@@ -62,7 +62,7 @@ pub async fn pick_pdf_path_owned(stem: String) -> Option<std::path::PathBuf> {
         .add_filter("All Files", &["*"])
         .save_file()
         .await
-        .map(|h| h.path().to_path_buf())
+        .map(|h| crate::sys::handle_path(&h))
 }
 
 // ── PDF builder ───────────────────────────────────────────────────────────

src/lib.rs

@@ -11,4 +11,5 @@ pub mod patterns;
 pub mod scene;
 pub mod snap;
 pub mod ui;
+pub mod sys;
 pub mod update_check;

src/main.rs

@@ -15,6 +15,7 @@ mod patterns;
 mod scene;
 mod snap;
 mod ui;
+mod sys;
 mod update_check;
 
 fn main() -> iced::Result {

src/scene/convert/mod.rs

@@ -1,5 +1,21 @@
 pub mod acad_to_truck;
+#[cfg(feature = "solid3d")]
 pub mod acis_to_truck;
+/// Without `solid3d` (e.g. wasm) ACIS/SAT meshing is unavailable; the entry
+/// point stays so callers compile, returning no mesh.
+#[cfg(not(feature = "solid3d"))]
+pub mod acis_to_truck {
+    use crate::scene::model::mesh_model::MeshLodSet;
+    use acadrust::entities::acis::SatDocument;
+    pub fn tessellate_sat_truck(
+        _sat: &SatDocument,
+        _name: String,
+        _color: [f32; 4],
+        _facet_res: f64,
+    ) -> Option<MeshLodSet> {
+        None
+    }
+}
 pub mod truck_tess;
 pub mod tessellate;
 pub mod tess_util;

src/scene/convert/truck_tess.rs

@@ -8,9 +8,11 @@
 // The caller (acad_to_truck / tessellate) decides which function to call based on
 // the truck topology level of the object.
 
+#[cfg(feature = "solid3d")]
 use truck_meshalgo::tessellation::{MeshableShape, MeshedShape};
 use truck_modeling::base::{BoundedCurve, ParameterDivision1D};
 use truck_modeling::{Edge, Shell, Solid, Vertex, Wire};
+#[cfg(feature = "solid3d")]
 use truck_polymesh::PolygonMesh;
 
 
@@ -140,21 +142,45 @@ pub fn tessellate_wire(w: &Wire, offset: [f64; 3]) -> TruckTessResult {
 // ── Shell ─────────────────────────────────────────────────────────────────
 
 #[allow(dead_code)]
+#[cfg(feature = "solid3d")]
 pub fn tessellate_shell(s: &Shell, offset: [f64; 3]) -> TruckTessResult {
     let meshed = s.triangulation(MESH_TOL);
     polygon_to_result(meshed.to_polygon(), offset)
 }
 
+/// Without `solid3d` (e.g. wasm) there is no mesher; a shell yields no mesh.
+#[cfg(not(feature = "solid3d"))]
+pub fn tessellate_shell(_s: &Shell, _offset: [f64; 3]) -> TruckTessResult {
+    TruckTessResult::Mesh {
+        verts: Vec::new(),
+        normals: Vec::new(),
+        indices: Vec::new(),
+    }
+}
+
 // ── Solid ─────────────────────────────────────────────────────────────────
 
 #[allow(dead_code)]
+#[cfg(feature = "solid3d")]
 pub fn tessellate_solid(s: &Solid, offset: [f64; 3]) -> TruckTessResult {
     let meshed = s.triangulation(MESH_TOL);
     polygon_to_result(meshed.to_polygon(), offset)
 }
 
+/// Without `solid3d` (e.g. wasm) there is no mesher; a solid yields no mesh.
+#[allow(dead_code)]
+#[cfg(not(feature = "solid3d"))]
+pub fn tessellate_solid(_s: &Solid, _offset: [f64; 3]) -> TruckTessResult {
+    TruckTessResult::Mesh {
+        verts: Vec::new(),
+        normals: Vec::new(),
+        indices: Vec::new(),
+    }
+}
+
 // ── Internal ─────────────────────────────────────────────────────────────
 
+#[cfg(feature = "solid3d")]
 fn polygon_to_result(mesh: PolygonMesh, offset: [f64; 3]) -> TruckTessResult {
     let verts: Vec<[f32; 3]> = mesh
         .positions()

src/scene/model/solid_model.rs

@@ -130,10 +130,12 @@ pub enum Bool {
     Intersect,
 }
 
+#[cfg(feature = "solid3d")]
 const BOOL_TOL: f64 = 0.05;
 
 /// Combine two solids. `Subtract` removes `b` from `a`. Returns `None` when the
 /// operation fails (e.g. the solids don't actually overlap).
+#[cfg(feature = "solid3d")]
 pub fn boolean(op: Bool, a: &Solid, b: &Solid) -> Option<Solid> {
     match op {
         Bool::Union => truck_shapeops::or(a, b, BOOL_TOL),
@@ -146,6 +148,12 @@ pub fn boolean(op: Bool, a: &Solid, b: &Solid) -> Option<Solid> {
     }
 }
 
+/// Without `solid3d` (e.g. wasm) there is no boolean kernel.
+#[cfg(not(feature = "solid3d"))]
+pub fn boolean(_op: Bool, _a: &Solid, _b: &Solid) -> Option<Solid> {
+    None
+}
+
 // ── Tessellation ────────────────────────────────────────────────────────────
 
 /// Tessellate a truck `Solid` into a single-LOD `MeshLodSet` (world-space,

src/sys.rs

@@ -0,0 +1,31 @@
+// Small platform shims for things the desktop build does natively but the web
+// (wasm) build must handle differently or skip.
+
+/// Open a URL in the user's browser. On the desktop this launches the default
+/// handler; on the web the app already *is* in a browser, so for now this is a
+/// no-op (a real implementation would call `window.open`).
+#[cfg(not(target_arch = "wasm32"))]
+pub fn open_url(url: &str) {
+    let _ = open::that(url);
+}
+
+#[cfg(target_arch = "wasm32")]
+pub fn open_url(_url: &str) {
+    // TODO(web): web_sys::window().open_with_url(_url)
+}
+
+/// Turn an `rfd` file handle into a `PathBuf` the rest of the app keys on.
+///
+/// Desktop returns the real filesystem path. The browser has no path, so we
+/// synthesize one from the file name — enough for the app to compile and track
+/// the document name; actual byte I/O on the web reads the handle directly
+/// (a follow-up).
+#[cfg(not(target_arch = "wasm32"))]
+pub fn handle_path(h: &rfd::FileHandle) -> std::path::PathBuf {
+    h.path().to_path_buf()
+}
+
+#[cfg(target_arch = "wasm32")]
+pub fn handle_path(h: &rfd::FileHandle) -> std::path::PathBuf {
+    std::path::PathBuf::from(h.file_name())
+}

src/update_check.rs

@@ -28,6 +28,7 @@ pub struct UpdateInfo {
     pub body: String,
 }
 
+#[cfg(not(target_arch = "wasm32"))]
 pub async fn check_for_update() -> Option<UpdateInfo> {
     std::thread::spawn(fetch_latest_if_outdated)
         .join()
@@ -35,6 +36,14 @@ pub async fn check_for_update() -> Option<UpdateInfo> {
         .flatten()
 }
 
+/// On wasm there is no background thread or blocking HTTP client; the web build
+/// skips the self-update check (the page is always served fresh).
+#[cfg(target_arch = "wasm32")]
+pub async fn check_for_update() -> Option<UpdateInfo> {
+    None
+}
+
+#[cfg(not(target_arch = "wasm32"))]
 fn fetch_latest_if_outdated() -> Option<UpdateInfo> {
     let agent: ureq::Agent = ureq::Agent::config_builder()
         .timeout_global(Some(std::time::Duration::from_secs(5)))