Avoid clone in src/syncback/file_names.rs

Co-authored-by: krakow10 <krakow20@gmail.com>

CHANGELOG.md

@@ -30,6 +30,9 @@ Making a new release? Simply add the new header with the version and date undern
 -->
 
 ## Unreleased
+* Fixed a bug caused by having reference properties (such as `ObjectValue.Value`) that point to an Instance not included in syncback. ([#1179])
+
+[#1179]: https://github.com/rojo-rbx/rojo/pull/1179
 
 ## [7.7.0-rc.1] (November 27th, 2025)
 

Cargo.lock

@@ -1313,7 +1313,7 @@ checksum = "f52b00d39961fc5b2736ea853c9cc86238e165017a493d1d5c8eac6bdc4cc273"
 
 [[package]]
 name = "memofs"
-version = "0.3.0"
+version = "0.3.1"
 dependencies = [
  "crossbeam-channel",
  "fs-err",

Cargo.toml

@@ -46,7 +46,7 @@ name = "build"
 harness = false
 
 [dependencies]
-memofs = { version = "0.3.0", path = "crates/memofs" }
+memofs = { version = "0.3.1", path = "crates/memofs" }
 
 # These dependencies can be uncommented when working on rbx-dom simultaneously
 # rbx_binary = { path = "../rbx-dom/rbx_binary", features = [

crates/memofs/CHANGELOG.md

@@ -1,6 +1,8 @@
 # memofs Changelog
 
 ## Unreleased Changes
+
+## 0.3.1 (2025-11-27)
 * Added `Vfs::exists`. [#1169]
 * Added `create_dir` and `create_dir_all` to allow creating directories. [#937]
 

crates/memofs/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "memofs"
 description = "Virtual filesystem with configurable backends."
-version = "0.3.0"
+version = "0.3.1"
 authors = [
     "Lucien Greathouse <me@lpghatguy.com>",
     "Micah Reid <git@dekkonot.com>",

crates/memofs/src/noop_backend.rs

@@ -31,17 +31,11 @@ impl VfsBackend for NoopBackend {
     }
 
     fn create_dir(&mut self, _path: &Path) -> io::Result<()> {
-        Err(io::Error::new(
-            io::ErrorKind::Other,
-            "NoopBackend doesn't do anything",
-        ))
+        Err(io::Error::other("NoopBackend doesn't do anything"))
     }
 
     fn create_dir_all(&mut self, _path: &Path) -> io::Result<()> {
-        Err(io::Error::new(
-            io::ErrorKind::Other,
-            "NoopBackend doesn't do anything",
-        ))
+        Err(io::Error::other("NoopBackend doesn't do anything"))
     }
 
     fn remove_file(&mut self, _path: &Path) -> io::Result<()> {

rojo-test/build-test-snapshots/end_to_end__tests__build__json_model_legacy_name.snap

@@ -1,16 +0,0 @@
----
-source: tests/tests/build.rs
-expression: contents
----
-<roblox version="4">
-  <Item class="Folder" referent="0">
-    <Properties>
-      <string name="Name">json_model_legacy_name</string>
-    </Properties>
-    <Item class="Folder" referent="1">
-      <Properties>
-        <string name="Name">Expected Name</string>
-      </Properties>
-    </Item>
-  </Item>
-</roblox>

rojo-test/build-test-snapshots/end_to_end__tests__build__model_json_name_input.snap

@@ -0,0 +1,23 @@
+---
+source: tests/tests/build.rs
+assertion_line: 109
+expression: contents
+---
+<roblox version="4">
+  <Item class="DataModel" referent="0">
+    <Properties>
+      <string name="Name">model_json_name_input</string>
+    </Properties>
+    <Item class="Workspace" referent="1">
+      <Properties>
+        <string name="Name">Workspace</string>
+        <bool name="NeedsPivotMigration">false</bool>
+      </Properties>
+      <Item class="StringValue" referent="2">
+        <Properties>
+          <string name="Name">/Bar</string>
+        </Properties>
+      </Item>
+    </Item>
+  </Item>
+</roblox>

rojo-test/build-test-snapshots/end_to_end__tests__build__slugified_name_roundtrip.snap

@@ -0,0 +1,20 @@
+---
+source: tests/tests/build.rs
+assertion_line: 108
+expression: contents
+---
+<roblox version="4">
+  <Item class="Folder" referent="0">
+    <Properties>
+      <string name="Name">slugified_name_roundtrip</string>
+    </Properties>
+    <Item class="Script" referent="1">
+      <Properties>
+        <string name="Name">/Script</string>
+        <token name="RunContext">0</token>
+        <string name="Source"><![CDATA[print("Hello world!")
+]]></string>
+      </Properties>
+    </Item>
+  </Item>
+</roblox>

rojo-test/build-tests/json_model_legacy_name/default.project.json

@@ -1,6 +0,0 @@
-{
-  "name": "json_model_legacy_name",
-  "tree": {
-    "$path": "folder"
-  }
-}

rojo-test/build-tests/json_model_legacy_name/folder/Expected Name.model.json

@@ -1,4 +0,0 @@
-{
-  "Name": "Overridden Name",
-  "ClassName": "Folder"
-}

rojo-test/build-tests/model_json_name_input/default.project.json

@@ -0,0 +1,11 @@
+{
+  "name": "model_json_name_input",
+  "tree": {
+    "$className": "DataModel",
+    "Workspace": {
+      "$className": "Workspace",
+      "$path": "src"
+    }
+  }
+}
+

rojo-test/build-tests/model_json_name_input/src/Bar.model.json

@@ -0,0 +1,5 @@
+{
+  "name": "/Bar",
+  "className": "StringValue"
+}
+

rojo-test/build-tests/slugified_name_roundtrip/_Script/init.meta.json

@@ -0,0 +1,4 @@
+{
+  "name": "/Script"
+}
+

rojo-test/build-tests/slugified_name_roundtrip/_Script/init.server.luau

@@ -0,0 +1,2 @@
+print("Hello world!")
+

rojo-test/build-tests/slugified_name_roundtrip/default.project.json

@@ -0,0 +1,6 @@
+{
+  "name": "slugified_name_roundtrip",
+  "tree": {
+    "$path": "src"
+  }
+}

rojo-test/build-tests/slugified_name_roundtrip/src/_Script/init.meta.json

@@ -0,0 +1,3 @@
+{
+  "name": "/Script"
+}

rojo-test/build-tests/slugified_name_roundtrip/src/_Script/init.server.luau

@@ -0,0 +1 @@
+print("Hello world!")

rojo-test/syncback-test-snapshots/end_to_end__rojo_test__syncback_util__model_json_name-stdout.snap

@@ -0,0 +1,6 @@
+---
+source: tests/rojo_test/syncback_util.rs
+assertion_line: 101
+expression: "String::from_utf8_lossy(&output.stdout)"
+---
+

rojo-test/syncback-test-snapshots/end_to_end__rojo_test__syncback_util__ref_properties_pruned-stdout.snap

@@ -0,0 +1,7 @@
+---
+source: tests/rojo_test/syncback_util.rs
+expression: "String::from_utf8_lossy(&output.stdout)"
+---
+Writing src/Pointer1.model.json
+Writing src/Pointer2.model.json
+Writing src/Pointer3.model.json

rojo-test/syncback-test-snapshots/end_to_end__rojo_test__syncback_util__slugified_name-stdout.snap

@@ -0,0 +1,13 @@
+---
+source: tests/rojo_test/syncback_util.rs
+assertion_line: 101
+expression: "String::from_utf8_lossy(&output.stdout)"
+---
+Writing default.project.json
+Writing src/Camera.rbxm
+Writing src/Terrain.rbxm
+Writing src/_Folder/init.meta.json
+Writing src/_Script.meta.json
+Writing src/_Script.server.luau
+Writing src
+Writing src/_Folder

rojo-test/syncback-test-snapshots/end_to_end__tests__syncback__model_json_name-src__foo.model.json.snap

@@ -0,0 +1,9 @@
+---
+source: tests/tests/syncback.rs
+assertion_line: 31
+expression: src/foo.model.json
+---
+{
+  "name": "/Bar",
+  "className": "StringValue"
+}

rojo-test/syncback-test-snapshots/end_to_end__tests__syncback__ref_properties_pruned-src__Pointer1.model.json.snap

@@ -0,0 +1,7 @@
+---
+source: tests/tests/syncback.rs
+expression: src/Pointer1.model.json
+---
+{
+  "className": "ObjectValue"
+}

rojo-test/syncback-test-snapshots/end_to_end__tests__syncback__ref_properties_pruned-src__Pointer2.model.json.snap

@@ -0,0 +1,7 @@
+---
+source: tests/tests/syncback.rs
+expression: src/Pointer2.model.json
+---
+{
+  "className": "ObjectValue"
+}

rojo-test/syncback-test-snapshots/end_to_end__tests__syncback__ref_properties_pruned-src__Pointer3.model.json.snap

@@ -0,0 +1,7 @@
+---
+source: tests/tests/syncback.rs
+expression: src/Pointer3.model.json
+---
+{
+  "className": "ObjectValue"
+}

rojo-test/syncback-test-snapshots/end_to_end__tests__syncback__slugified_name-src___Folder.model.json.snap

@@ -0,0 +1,8 @@
+---
+source: tests/tests/syncback.rs
+assertion_line: 31
+expression: src/_Folder.model.json
+---
+{
+  "className": "Folder"
+}

rojo-test/syncback-test-snapshots/end_to_end__tests__syncback__slugified_name-src___Folder__init.meta.json.snap

@@ -0,0 +1,8 @@
+---
+source: tests/tests/syncback.rs
+assertion_line: 31
+expression: src/_Folder/init.meta.json
+---
+{
+  "name": "/Folder"
+}

rojo-test/syncback-test-snapshots/end_to_end__tests__syncback__slugified_name-src___Script.meta.json.snap

@@ -0,0 +1,8 @@
+---
+source: tests/tests/syncback.rs
+assertion_line: 31
+expression: src/_Script.meta.json
+---
+{
+  "name": "/Script"
+}

rojo-test/syncback-test-snapshots/end_to_end__tests__syncback__slugified_name-src___Script.server.luau.snap

@@ -0,0 +1,6 @@
+---
+source: tests/tests/syncback.rs
+assertion_line: 31
+expression: src/_Script.server.luau
+---
+print("Hello world!")

rojo-test/syncback-test-snapshots/end_to_end__tests__syncback__slugified_name-src___Script__init.meta.json.snap

@@ -0,0 +1,8 @@
+---
+source: tests/tests/syncback.rs
+assertion_line: 31
+expression: src/_Script/init.meta.json
+---
+{
+  "name": "/Script"
+}

rojo-test/syncback-test-snapshots/end_to_end__tests__syncback__slugified_name-src___Script__init.server.luau.snap

@@ -0,0 +1,6 @@
+---
+source: tests/tests/syncback.rs
+assertion_line: 31
+expression: src/_Script/init.server.luau
+---
+print("Hello world!")

rojo-test/syncback-tests/model_json_name/input-project/default.project.json

@@ -0,0 +1,11 @@
+{
+  "name": "model_json_name",
+  "tree": {
+    "$className": "DataModel",
+    "Workspace": {
+      "$className": "Workspace",
+      "$path": "src"
+    }
+  }
+}
+

rojo-test/syncback-tests/model_json_name/input-project/src/foo.model.json

@@ -0,0 +1,5 @@
+{
+  "name": "/Bar",
+  "className": "StringValue"
+}
+

rojo-test/syncback-tests/ref_properties_pruned/input-project/default.project.json

@@ -0,0 +1,9 @@
+{
+  "name": "ref_properties_pruned",
+  "tree": {
+    "$className": "DataModel",
+    "ServerScriptService": {
+      "$path": "src"
+    }
+  }
+}

rojo-test/syncback-tests/slugified_name/input-project/default.project.json

@@ -0,0 +1,10 @@
+{
+  "name": "slugified_name",
+  "tree": {
+    "$className": "DataModel",
+    "Workspace": {
+      "$className": "Workspace",
+      "$path": "src"
+    }
+  }
+}

src/snapshot/metadata.rs

@@ -70,6 +70,12 @@ pub struct InstanceMetadata {
     /// A schema provided via a JSON file, if one exists. Will be `None` for
     /// all non-JSON middleware.
     pub schema: Option<String>,
+
+    /// A custom name specified via meta.json or model.json files. If present,
+    /// this name will be used for the instance while the filesystem name will
+    /// be slugified to remove illegal characters.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub specified_name: Option<String>,
 }
 
 impl InstanceMetadata {
@@ -82,6 +88,7 @@ impl InstanceMetadata {
             specified_id: None,
             middleware: None,
             schema: None,
+            specified_name: None,
         }
     }
 
@@ -130,6 +137,13 @@ impl InstanceMetadata {
     pub fn schema(self, schema: Option<String>) -> Self {
         Self { schema, ..self }
     }
+
+    pub fn specified_name(self, specified_name: Option<String>) -> Self {
+        Self {
+            specified_name,
+            ..self
+        }
+    }
 }
 
 impl Default for InstanceMetadata {

src/snapshot_middleware/json_model.rs

@@ -35,20 +35,14 @@ pub fn snapshot_json_model(
         format!("File is not a valid JSON model: {}", path.display())
     })?;
 
-    if let Some(top_level_name) = &instance.name {
-        let new_name = format!("{}.model.json", top_level_name);
+    // If the JSON has a name property, preserve it in metadata for syncback
+    let specified_name = instance.name.clone();
 
-        log::warn!(
-            "Model at path {} had a top-level Name field. \
-            This field has been ignored since Rojo 6.0.\n\
-            Consider removing this field and renaming the file to {}.",
-            new_name,
-            path.display()
-        );
+    // Use the name from JSON if present, otherwise fall back to filename-derived name
+    if instance.name.is_none() {
+        instance.name = Some(name.to_owned());
     }
 
-    instance.name = Some(name.to_owned());
-
     let id = instance.id.take().map(RojoRef::new);
     let schema = instance.schema.take();
 
@@ -62,7 +56,8 @@ pub fn snapshot_json_model(
         .relevant_paths(vec![path.to_path_buf()])
         .context(context)
         .specified_id(id)
-        .schema(schema);
+        .schema(schema)
+        .specified_name(specified_name);
 
     Ok(Some(snapshot))
 }
@@ -81,6 +76,7 @@ pub fn syncback_json_model<'sync>(
         // schemas will ever exist in one project for it to matter, but it
         // could have a performance cost.
         model.schema = old_inst.metadata().schema.clone();
+        model.name = old_inst.metadata().specified_name.clone();
     }
 
     Ok(SyncbackReturn {

src/snapshot_middleware/lua.rs

@@ -158,8 +158,16 @@ pub fn syncback_lua<'sync>(
 
         if !meta.is_empty() {
             let parent_location = snapshot.path.parent_err()?;
+            let instance_name = &snapshot.new_inst().name;
+            let slugified;
+            let meta_name = if crate::syncback::validate_file_name(instance_name).is_err() {
+                slugified = crate::syncback::slugify_name(instance_name);
+                &slugified
+            } else {
+                instance_name
+            };
             fs_snapshot.add_file(
-                parent_location.join(format!("{}.meta.json", new_inst.name)),
+                parent_location.join(format!("{}.meta.json", meta_name)),
                 serde_json::to_vec_pretty(&meta).context("cannot serialize metadata")?,
             );
         }

src/snapshot_middleware/meta_file.rs

@@ -10,7 +10,10 @@ use rbx_dom_weak::{
 use serde::{Deserialize, Serialize};
 
 use crate::{
-    json, resolution::UnresolvedValue, snapshot::InstanceSnapshot, syncback::SyncbackSnapshot,
+    json,
+    resolution::UnresolvedValue,
+    snapshot::InstanceSnapshot,
+    syncback::{validate_file_name, SyncbackSnapshot},
     RojoRef,
 };
 
@@ -36,6 +39,9 @@ pub struct AdjacentMetadata {
     #[serde(default, skip_serializing_if = "IndexMap::is_empty")]
     pub attributes: IndexMap<String, UnresolvedValue>,
 
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub name: Option<String>,
+
     #[serde(skip)]
     pub path: PathBuf,
 }
@@ -144,6 +150,24 @@ impl AdjacentMetadata {
             }
         }
 
+        let name = snapshot
+            .old_inst()
+            .and_then(|inst| inst.metadata().specified_name.clone())
+            .or_else(|| {
+                // If this is a new instance and its name is invalid for the filesystem,
+                // we need to specify the name in meta.json so it can be preserved
+                if snapshot.old_inst().is_none() {
+                    let instance_name = &snapshot.new_inst().name;
+                    if validate_file_name(instance_name).is_err() {
+                        Some(instance_name.clone())
+                    } else {
+                        None
+                    }
+                } else {
+                    None
+                }
+            });
+
         Ok(Some(Self {
             ignore_unknown_instances: if ignore_unknown_instances {
                 Some(true)
@@ -155,6 +179,7 @@ impl AdjacentMetadata {
             path,
             id: None,
             schema,
+            name,
         }))
     }
 
@@ -213,11 +238,26 @@ impl AdjacentMetadata {
         Ok(())
     }
 
+    fn apply_name(&mut self, snapshot: &mut InstanceSnapshot) -> anyhow::Result<()> {
+        if self.name.is_some() && snapshot.metadata.specified_name.is_some() {
+            anyhow::bail!(
+                "cannot specify a name using {} (instance has a name from somewhere else)",
+                self.path.display()
+            );
+        }
+        if let Some(name) = &self.name {
+            snapshot.name = name.clone().into();
+        }
+        snapshot.metadata.specified_name = self.name.take();
+        Ok(())
+    }
+
     pub fn apply_all(&mut self, snapshot: &mut InstanceSnapshot) -> anyhow::Result<()> {
         self.apply_ignore_unknown_instances(snapshot);
         self.apply_properties(snapshot)?;
         self.apply_id(snapshot)?;
         self.apply_schema(snapshot)?;
+        self.apply_name(snapshot)?;
         Ok(())
     }
 
@@ -226,11 +266,13 @@ impl AdjacentMetadata {
     ///
     /// - The number of properties and attributes is 0
     /// - `ignore_unknown_instances` is None
+    /// - `name` is None
     #[inline]
     pub fn is_empty(&self) -> bool {
         self.attributes.is_empty()
             && self.properties.is_empty()
             && self.ignore_unknown_instances.is_none()
+            && self.name.is_none()
     }
 
     // TODO: Add method to allow selectively applying parts of metadata and
@@ -262,6 +304,9 @@ pub struct DirectoryMetadata {
     #[serde(skip_serializing_if = "Option::is_none")]
     pub class_name: Option<Ustr>,
 
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub name: Option<String>,
+
     #[serde(skip)]
     pub path: PathBuf,
 }
@@ -372,6 +417,24 @@ impl DirectoryMetadata {
             }
         }
 
+        let name = snapshot
+            .old_inst()
+            .and_then(|inst| inst.metadata().specified_name.clone())
+            .or_else(|| {
+                // If this is a new instance and its name is invalid for the filesystem,
+                // we need to specify the name in meta.json so it can be preserved
+                if snapshot.old_inst().is_none() {
+                    let instance_name = &snapshot.new_inst().name;
+                    if validate_file_name(instance_name).is_err() {
+                        Some(instance_name.clone())
+                    } else {
+                        None
+                    }
+                } else {
+                    None
+                }
+            });
+
         Ok(Some(Self {
             ignore_unknown_instances: if ignore_unknown_instances {
                 Some(true)
@@ -384,6 +447,7 @@ impl DirectoryMetadata {
             path,
             id: None,
             schema,
+            name,
         }))
     }
 
@@ -393,6 +457,7 @@ impl DirectoryMetadata {
         self.apply_properties(snapshot)?;
         self.apply_id(snapshot)?;
         self.apply_schema(snapshot)?;
+        self.apply_name(snapshot)?;
 
         Ok(())
     }
@@ -464,17 +529,33 @@ impl DirectoryMetadata {
         snapshot.metadata.schema = self.schema.take();
         Ok(())
     }
+
+    fn apply_name(&mut self, snapshot: &mut InstanceSnapshot) -> anyhow::Result<()> {
+        if self.name.is_some() && snapshot.metadata.specified_name.is_some() {
+            anyhow::bail!(
+                "cannot specify a name using {} (instance has a name from somewhere else)",
+                self.path.display()
+            );
+        }
+        if let Some(name) = &self.name {
+            snapshot.name = name.clone().into();
+        }
+        snapshot.metadata.specified_name = self.name.take();
+        Ok(())
+    }
     /// Returns whether the metadata is 'empty', meaning it doesn't have anything
     /// worth persisting in it. Specifically:
     ///
     /// - The number of properties and attributes is 0
     /// - `ignore_unknown_instances` is None
     /// - `class_name` is either None or not Some("Folder")
+    /// - `name` is None
     #[inline]
     pub fn is_empty(&self) -> bool {
         self.attributes.is_empty()
             && self.properties.is_empty()
             && self.ignore_unknown_instances.is_none()
+            && self.name.is_none()
             && if let Some(class) = &self.class_name {
                 class == "Folder"
             } else {

src/syncback/file_names.rs

@@ -8,11 +8,11 @@ use rbx_dom_weak::Instance;
 
 use crate::{snapshot::InstanceWithMeta, snapshot_middleware::Middleware};
 
-pub fn name_for_inst<'old>(
+pub fn name_for_inst<'a>(
     middleware: Middleware,
-    new_inst: &Instance,
-    old_inst: Option<InstanceWithMeta<'old>>,
-) -> anyhow::Result<Cow<'old, str>> {
+    new_inst: &'a Instance,
+    old_inst: Option<InstanceWithMeta<'a>>,
+) -> anyhow::Result<Cow<'a, str>> {
     if let Some(old_inst) = old_inst {
         if let Some(source) = old_inst.metadata().relevant_paths.first() {
             source
@@ -35,14 +35,24 @@ pub fn name_for_inst<'old>(
             | Middleware::CsvDir
             | Middleware::ServerScriptDir
             | Middleware::ClientScriptDir
-            | Middleware::ModuleScriptDir => Cow::Owned(new_inst.name.clone()),
+            | Middleware::ModuleScriptDir => {
+                if validate_file_name(&new_inst.name).is_err() {
+                    Cow::Owned(slugify_name(&new_inst.name))
+                } else {
+                    Cow::Borrowed(&new_inst.name)
+                }
+            }
             _ => {
                 let extension = extension_for_middleware(middleware);
-                let name = &new_inst.name;
-                validate_file_name(name).with_context(|| {
-                    format!("name '{name}' is not legal to write to the file system")
-                })?;
-                Cow::Owned(format!("{name}.{extension}"))
+                let slugified;
+                let final_name = if validate_file_name(&new_inst.name).is_err() {
+                    slugified = slugify_name(&new_inst.name);
+                    &slugified
+                } else {
+                    &new_inst.name
+                };
+
+                Cow::Owned(format!("{final_name}.{extension}"))
             }
         })
     }
@@ -94,6 +104,39 @@ const INVALID_WINDOWS_NAMES: [&str; 22] = [
 /// in a file's name.
 const FORBIDDEN_CHARS: [char; 9] = ['<', '>', ':', '"', '/', '|', '?', '*', '\\'];
 
+/// Slugifies a name by replacing forbidden characters with underscores
+/// and ensuring the result is a valid file name
+pub fn slugify_name(name: &str) -> String {
+    let mut result = String::with_capacity(name.len());
+
+    for ch in name.chars() {
+        if FORBIDDEN_CHARS.contains(&ch) {
+            result.push('_');
+        } else {
+            result.push(ch);
+        }
+    }
+
+    // Handle Windows reserved names by appending an underscore
+    let result_lower = result.to_lowercase();
+    for forbidden in INVALID_WINDOWS_NAMES {
+        if result_lower == forbidden.to_lowercase() {
+            result.push('_');
+            break;
+        }
+    }
+
+    while result.ends_with(' ') || result.ends_with('.') {
+        result.pop();
+    }
+
+    if result.is_empty() || result.chars().all(|c| c == '_') {
+        result = "instance".to_string();
+    }
+
+    result
+}
+
 /// Validates a provided file name to ensure it's allowed on the file system. An
 /// error is returned if the name isn't allowed, indicating why.
 /// This takes into account rules for Windows, MacOS, and Linux.

src/syncback/mod.rs

@@ -28,7 +28,7 @@ use crate::{
     Project,
 };
 
-pub use file_names::{extension_for_middleware, name_for_inst, validate_file_name};
+pub use file_names::{extension_for_middleware, name_for_inst, slugify_name, validate_file_name};
 pub use fs_snapshot::FsSnapshot;
 pub use hash::*;
 pub use property_filter::{filter_properties, filter_properties_preallocated};
@@ -301,6 +301,7 @@ pub fn get_best_middleware(snapshot: &SyncbackSnapshot) -> Middleware {
     static JSON_MODEL_CLASSES: OnceLock<HashSet<&str>> = OnceLock::new();
     let json_model_classes = JSON_MODEL_CLASSES.get_or_init(|| {
         [
+            "Actor",
             "Sound",
             "SoundGroup",
             "Sky",
@@ -333,8 +334,6 @@ pub fn get_best_middleware(snapshot: &SyncbackSnapshot) -> Middleware {
         return override_middleware;
     } else if let Some(old_middleware) = old_middleware {
         return old_middleware;
-    } else if json_model_classes.contains(inst.class.as_str()) {
-        middleware = Middleware::JsonModel;
     } else {
         middleware = match inst.class.as_str() {
             "Folder" | "Configuration" | "Tool" => Middleware::Dir,
@@ -345,6 +344,7 @@ pub fn get_best_middleware(snapshot: &SyncbackSnapshot) -> Middleware {
             "LocalizationTable" => Middleware::Csv,
             // This isn't the ideal way to handle this but it works.
             name if name.ends_with("Value") => Middleware::JsonModel,
+            _ if json_model_classes.contains(inst.class.as_str()) => Middleware::JsonModel,
             _ => Middleware::Rbxm,
         }
     }
@@ -360,6 +360,28 @@ pub fn get_best_middleware(snapshot: &SyncbackSnapshot) -> Middleware {
         }
     }
 
+    // If the name is invalid but the instance has no descendants and isn't a
+    // folder/config/tool, prefer slugified files over creating a directory.
+    // Only promote to directory when there are children (or dir-like classes).
+    if crate::syncback::file_names::validate_file_name(&inst.name).is_err() {
+        middleware = match middleware {
+            Middleware::ServerScript | Middleware::ClientScript | Middleware::ModuleScript
+                if inst.children().is_empty() =>
+            {
+                middleware
+            }
+            Middleware::JsonModel | Middleware::Text if inst.children().is_empty() => middleware,
+            _ => match middleware {
+                Middleware::ServerScript => Middleware::ServerScriptDir,
+                Middleware::ClientScript => Middleware::ClientScriptDir,
+                Middleware::ModuleScript => Middleware::ModuleScriptDir,
+                Middleware::Csv => Middleware::CsvDir,
+                Middleware::JsonModel | Middleware::Text => Middleware::Dir,
+                _ => middleware,
+            },
+        }
+    }
+
     if middleware == Middleware::Rbxm {
         middleware = match env::var(DEBUG_MODEL_FORMAT_VAR) {
             Ok(value) if value == "1" => Middleware::Rbxmx,

src/syncback/ref_properties.rs

@@ -8,7 +8,10 @@ use rbx_dom_weak::{
     ustr, Instance, Ustr, WeakDom,
 };
 
-use crate::{multimap::MultiMap, REF_ID_ATTRIBUTE_NAME, REF_POINTER_ATTRIBUTE_PREFIX};
+use crate::{
+    multimap::MultiMap, syncback::snapshot::inst_path, REF_ID_ATTRIBUTE_NAME,
+    REF_POINTER_ATTRIBUTE_PREFIX,
+};
 
 pub struct RefLinks {
     /// A map of referents to each of their Ref properties.
@@ -50,6 +53,22 @@ pub fn collect_referents(dom: &WeakDom) -> RefLinks {
                 continue;
             }
 
+            let target = match dom.get_by_ref(*prop_value) {
+                Some(inst) => inst,
+                None => {
+                    // Properties that are Some but point to nothing may as
+                    // well be `nil`. Roblox and us never produce these values
+                    // but syncback prunes trees without adjusting ref
+                    // properties for performance reasons.
+                    log::warn!(
+                        "Property {}.{} will be `nil` on the disk because the actual value is not being included in syncback",
+                        inst_path(dom, inst_ref),
+                        prop_name
+                    );
+                    continue;
+                }
+            };
+
             links.insert(
                 inst_ref,
                 RefLink {
@@ -58,10 +77,6 @@ pub fn collect_referents(dom: &WeakDom) -> RefLinks {
                 },
             );
 
-            let target = dom
-                .get_by_ref(*prop_value)
-                .expect("Refs in DOM should point to valid Instances");
-
             // 1. Check if target has an ID
             if let Some(id) = get_existing_id(target) {
                 // If it does, we need to check whether that ID is a duplicate

tests/tests/build.rs

@@ -41,7 +41,6 @@ gen_build_tests! {
     issue_546,
     json_as_lua,
     json_model_in_folder,
-    json_model_legacy_name,
     module_in_folder,
     module_init,
     nested_runcontext,
@@ -55,6 +54,8 @@ gen_build_tests! {
     script_meta_disabled,
     server_in_folder,
     server_init,
+    slugified_name_roundtrip,
+    model_json_name_input,
     txt,
     txt_in_folder,
     unresolved_values,

tests/tests/syncback.rs

@@ -71,8 +71,13 @@ syncback_tests! {
     ref_properties_conflict => ["src/Pointer_2.model.json", "src/Target_2.model.json"],
     // Ensures that having multiple pointers that are aimed at the same target doesn't trigger ref rewrites.
     ref_properties_duplicate => [],
+    // Ensures that ref properties that point to nothing after the prune both
+    // do not leave any trace of themselves
+    ref_properties_pruned => ["src/Pointer1.model.json", "src/Pointer2.model.json", "src/Pointer3.model.json"],
     // Ensures that the old middleware is respected during syncback
     respect_old_middleware => ["default.project.json", "src/model_json.model.json", "src/rbxm.rbxm", "src/rbxmx.rbxmx"],
+    // Ensures that the `$schema` field roundtrips with syncback
+    schema_roundtrip => ["default.project.json", "src/model.model.json", "src/init/init.meta.json", "src/adjacent.meta.json"],
     // Ensures that StringValues inside project files are written to the
     // project file, but only if they don't have `$path` set
     string_value_project => ["default.project.json"],
@@ -81,5 +86,9 @@ syncback_tests! {
     sync_rules => ["src/module.modulescript", "src/text.text"],
     // Ensures that the `syncUnscriptable` setting works
     unscriptable_properties => ["default.project.json"],
-    schema_roundtrip => ["default.project.json", "src/model.model.json", "src/init/init.meta.json", "src/adjacent.meta.json"]
+    // Ensures that instances with names containing illegal characters get slugified filenames
+    // and preserve their original names in meta.json without forcing directories for leaf scripts
+    slugified_name => ["src/_Script.meta.json", "src/_Script.server.luau", "src/_Folder/init.meta.json"],
+    // Ensures that .model.json files preserve the name property
+    model_json_name => ["src/foo.model.json"],
 }