Add audit plan for slugify branch pass 3 and implement critical fixes

- Introduced a comprehensive audit plan for the slugify branch, detailing findings from a holistic review of 110 files, including 1 critical bug and 2 correctness issues.
- Completed todos addressing model JSON renaming, syncback updates, and test enhancements for roundtrip fidelity.
- Added tests for reserved names and ensured correct handling of slugified instances, preserving compound extensions in model files.
- Refactored change processing logic to correctly manage the `name` field in model files, enhancing metadata handling and ensuring compliance with round-trip identity standards.

src/syncback/file_names.rs

@@ -323,7 +323,9 @@ pub fn validate_file_name<S: AsRef<str>>(name: S) -> anyhow::Result<()> {
 
 /// Known script suffixes that appear between the base name and file extension.
 /// For example, in `MyScript.server.luau`, `.server` is the suffix.
-const KNOWN_SCRIPT_SUFFIXES: &[&str] = &[".server", ".client", ".plugin", ".local", ".legacy"];
+const KNOWN_SCRIPT_SUFFIXES: &[&str] = &[
+    ".server", ".client", ".plugin", ".local", ".legacy", ".model",
+];
 
 /// Strips a known script suffix from a file stem.
 ///

src/syncback/meta.rs

@@ -46,6 +46,50 @@ pub enum RemoveNameOutcome {
     FileDeleted,
 }
 
+/// Upsert the `name` field inside a `.model.json5` / `.model.json` file.
+///
+/// Parses the existing JSON, sets/replaces the `name` key, and rewrites.
+/// Unlike `upsert_meta_name`, this modifies the model file in-place.
+pub fn upsert_model_name(model_path: &Path, real_name: &str) -> anyhow::Result<()> {
+    let bytes = fs::read(model_path)?;
+    let mut obj = match crate::json::from_slice::<serde_json::Value>(&bytes) {
+        Ok(serde_json::Value::Object(map)) => map,
+        _ => anyhow::bail!("model file is not a JSON object: {}", model_path.display()),
+    };
+    obj.insert(
+        "name".to_string(),
+        serde_json::Value::String(real_name.to_string()),
+    );
+    let content = crate::json::to_vec_pretty_sorted(&serde_json::Value::Object(obj))?;
+    fs::write(model_path, &content)?;
+    Ok(())
+}
+
+/// Remove the `name` field from a `.model.json5` / `.model.json` file.
+///
+/// Unlike meta files, model files are never deleted when they become "empty"
+/// (they always have at least `className`). Returns `RemoveNameOutcome` for
+/// consistency with the meta helpers.
+pub fn remove_model_name(model_path: &Path) -> anyhow::Result<RemoveNameOutcome> {
+    if !model_path.exists() {
+        return Ok(RemoveNameOutcome::NoOp);
+    }
+    let bytes = match fs::read(model_path) {
+        Ok(b) => b,
+        Err(_) => return Ok(RemoveNameOutcome::NoOp),
+    };
+    let mut obj = match crate::json::from_slice::<serde_json::Value>(&bytes) {
+        Ok(serde_json::Value::Object(map)) => map,
+        _ => return Ok(RemoveNameOutcome::NoOp),
+    };
+    if obj.remove("name").is_none() {
+        return Ok(RemoveNameOutcome::NoOp);
+    }
+    let content = crate::json::to_vec_pretty_sorted(&serde_json::Value::Object(obj))?;
+    fs::write(model_path, &content)?;
+    Ok(RemoveNameOutcome::FieldRemoved)
+}
+
 /// Remove the `name` field from a `.meta.json5` file.
 ///
 /// If the file becomes an empty object after removal, deletes it entirely.