Add design containers with deduplicated blobs and JSON compatibility (#327)

* Add fast design containers with lossless deduplicated payloads

* Keep display caching opt-in to avoid default save overhead

apps/solidcraft-cli/src/main.rs

@@ -123,7 +123,14 @@ pub fn load(path: &str) -> Result<Session, String> {
         s.execute("doc.open", &json!({"path": path})).map_err(|e| e.to_string())?;
         return Ok(s);
     }
-    let v = read_json(path)?;
+    let bytes = solidcraft_engine::io::vfs::read(path, solidcraft_engine::io::MAX_DESIGN_BYTES).map_err(|e| format!("{path}: {e}"))?;
+    if solidcraft_engine::io::is_design_container(&bytes) {
+        let doc = solidcraft_engine::io::read_design(&bytes).map_err(|e| format!("{path}: {e}"))?;
+        let mut session = Session::new(doc);
+        session.path = Some(path.to_owned());
+        return Ok(session);
+    }
+    let v: Value = serde_json::from_slice(&bytes).map_err(|e| format!("{path}: {e}"))?;
     if v.get("format").and_then(Value::as_str).is_some_and(|f| solidcraft_engine::doc::format::version_of(f).is_some()) {
         s.execute("doc.open", &json!({"path": path})).map_err(|e| e.to_string())?;
     } else if v.get("features").is_some() && v.get("commands").is_none() {

apps/solidcraft-cli/tests/design_corpus.rs

@@ -86,6 +86,9 @@ fn old_designs_open_and_evaluate_as_saved() {
         // Saved again, it reads back the same.
         let again = solidcraft_engine::doc::Document::from_json(&s.doc.to_json()).unwrap();
         assert_eq!(again, *s.doc, "{name}: round trip");
+        let package = solidcraft_engine::io::write_design_container(&s.doc).unwrap();
+        let packaged = solidcraft_engine::io::read_design(&package).unwrap();
+        assert_eq!(packaged, *s.doc, "{name}: container round trip after migration");
     }
     assert!(problems.is_empty(), "{}", problems.join("\n"));
 }

apps/solidcraft-cli/tests/run_results.rs

@@ -43,10 +43,27 @@ fn body_count(path: &Path) -> Value {
     json_output(cli().arg("eval").arg(path).output().unwrap())["body_count"].clone()
 }
 
+#[test]
+fn cli_loads_both_design_encodings_by_contents() {
+    let dir = Scratch::new();
+    for extension in ["solidcraft", "solvecraft", "json"] {
+        let saved = dir.0.join(format!("box.{extension}"));
+        json_output(cli().arg("run").arg(dir.script()).arg("--save").arg(&saved).output().unwrap());
+        let bytes = std::fs::read(&saved).unwrap();
+        assert_eq!(solidcraft_engine::io::is_design_container(&bytes), extension != "json");
+        let renamed = dir.0.join(format!("{extension}.unusual"));
+        std::fs::write(&renamed, bytes).unwrap();
+        let measured = json_output(cli().arg("eval").arg(&renamed).output().unwrap());
+        assert_eq!(measured["body_count"], 1);
+        assert!((measured["bodies"][0]["volume_mm3"].as_f64().unwrap() - 24.0).abs() < 1e-6);
+    }
+}
+
 #[test]
 fn results_still_save_and_export_the_script_once() {
     let dir = Scratch::new();
-    let saved = dir.0.join("box.solidcraft");
+    // JSON is explicit here because the fixture edits its saved format tag.
+    let saved = dir.0.join("box.json");
     let stl = dir.0.join("box.stl");
     let obj = dir.0.join("box.obj");
     let result = json_output(
@@ -101,7 +118,8 @@ fn results_without_script_still_fail() {
 #[test]
 fn legacy_extension_and_format_tag_still_open() {
     let dir = Scratch::new();
-    let saved = dir.0.join("box.solidcraft");
+    // JSON is explicit here because the fixture edits its saved format tag.
+    let saved = dir.0.join("box.json");
     json_output(cli().arg("run").arg(dir.script()).arg("--save").arg(&saved).output().unwrap());
     let text = std::fs::read_to_string(&saved).unwrap();
     assert!(text.contains("\"solidcraft/"), "new designs carry the current tag");
@@ -111,5 +129,6 @@ fn legacy_extension_and_format_tag_still_open() {
     let resaved = dir.0.join("resaved.solidcraft");
     json_output(cli().args(["run", "--in"]).arg(&legacy).arg(dir.script()).arg("--save").arg(&resaved).output().unwrap());
     assert_eq!(body_count(&resaved), 2);
-    assert!(std::fs::read_to_string(&resaved).unwrap().contains("\"solidcraft/"));
+    let reopened = solidcraft_engine::io::read_design(&std::fs::read(&resaved).unwrap()).unwrap();
+    assert!(reopened.to_json().contains("\"solidcraft/"));
 }

apps/solidcraft-web/src/files.rs

@@ -376,7 +376,13 @@ pub fn autosave(files: &Rc<Files>, doc: Option<(&solidcraft_engine::doc::Documen
     let files = files.clone();
     match doc {
         Some((d, path)) => {
-            let bytes = solidcraft_engine::io::write_design(d);
+            let bytes = match solidcraft_engine::io::write_design_container(d) {
+                Ok(bytes) => bytes,
+                Err(e) => {
+                    files.say(format!("autosave: {e}"), true);
+                    return;
+                }
+            };
             let meta = serde_json::json!({"name": d.name, "path": path, "saved_at": js_sys::Date::now()}).to_string();
             spawn_local(async move {
                 let r = async {
@@ -452,7 +458,7 @@ fn input_picker(files: &Rc<Files>, intent: Intent) {
     let Some(doc) = web_sys::window().and_then(|w| w.document()) else { return };
     let Ok(input) = doc.create_element("input").map(|e| e.unchecked_into::<web_sys::HtmlInputElement>()) else { return };
     input.set_type("file");
-    input.set_accept(".solidcraft,.solvecraft,.step,.stp,.3mf,.stl");
+    input.set_accept(".solidcraft,.solvecraft,.json,.step,.stp,.3mf,.stl");
     // Attached (hidden) while it is open: some browsers ignore a click on a detached input.
     let _ = input.set_attribute("style", "display:none");
     if let Some(body) = doc.body() {

apps/solidcraft-web/src/main.rs

@@ -251,8 +251,10 @@ mod web {
                 },
                 "download_open" => {
                     let d = &self.app.session.doc;
-                    let bytes = solidcraft_engine::io::write_design(d);
-                    if let Err(e) = files::download(&format!("{}.{}", d.name, solidcraft_engine::io::DESIGN_EXT), &bytes) {
+                    let result = solidcraft_engine::io::write_design_container(d)
+                        .map_err(|e| e.to_string())
+                        .and_then(|bytes| files::download(&format!("{}.{}", d.name, solidcraft_engine::io::DESIGN_EXT), &bytes));
+                    if let Err(e) = result {
                         self.app.set_status(e, true);
                     }
                 }

apps/solidcraft/src/main.rs

@@ -19,7 +19,7 @@ mod control_server;
 #[cfg(any(target_os = "windows", target_os = "linux"))]
 mod space_mouse;
 
-use solidcraft_engine::Session;
+use solidcraft_engine::{Session, io};
 use solidcraft_ui_egui::{Services, SolveApp};
 
 struct App {
@@ -66,10 +66,25 @@ fn services() -> Services {
             rfd::FileDialog::new()
                 .add_filter(
                     "Designs, STEP, IGES and meshes",
-                    &["solidcraft", "solvecraft", "step", "stp", "STEP", "STP", "igs", "iges", "IGS", "IGES", "3mf", "3MF", "stl", "STL"],
+                    &[
+                        io::DESIGN_EXT,
+                        io::LEGACY_DESIGN_EXT,
+                        "json",
+                        "step",
+                        "stp",
+                        "STEP",
+                        "STP",
+                        "igs",
+                        "iges",
+                        "IGS",
+                        "IGES",
+                        "3mf",
+                        "3MF",
+                        "stl",
+                        "STL",
+                    ],
                 )
-                // The legacy extension is a compatibility shim (docs/compatibility.md).
-                .add_filter("SolidCraft design", &solidcraft_engine::io::DESIGN_EXTS)
+                .add_filter("SolidCraft design (container or JSON)", &[io::DESIGN_EXT, io::LEGACY_DESIGN_EXT, "json"])
                 .add_filter("STEP", &["step", "stp", "STEP", "STP"])
                 .add_filter("IGES", &["igs", "iges", "IGS", "IGES"])
                 .add_filter("Mesh (3MF, STL)", &["3mf", "3MF", "stl", "STL"])
@@ -79,7 +94,17 @@ fn services() -> Services {
                 .map(|p| p.to_string_lossy().to_string())
         })),
         pick_save: Some(Box::new(|name: &str, exts: &[&str]| {
-            rfd::FileDialog::new().set_file_name(name).add_filter("File", exts).save_file().map(|p| p.to_string_lossy().to_string())
+            let dialog = rfd::FileDialog::new().set_file_name(name);
+            let dialog = if exts == [io::DESIGN_EXT, "json"] {
+                if name.ends_with(".json") {
+                    dialog.add_filter("Plain JSON design", &["json"]).add_filter("SolidCraft container", &[io::DESIGN_EXT])
+                } else {
+                    dialog.add_filter("SolidCraft container", &[io::DESIGN_EXT]).add_filter("Plain JSON design", &["json"])
+                }
+            } else {
+                dialog.add_filter("File", exts)
+            };
+            dialog.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| {