Support $schema in JSON structures (#974)

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Rojo Changelog
 
 ## Unreleased Changes
+* Support for a `$schema` field in all special JSON files (`.project.json`, `.model.json`, and `.meta.json`) ([#974])
 * Projects may now manually link `Ref` properties together using `Attributes`. ([#843])
  	This has two parts: using `id` or `$id` in JSON files or a `Rojo_Target` attribute, an Instance
     is given an ID. Then, that ID may be used elsewhere in the project to point to an Instance
@@ -85,6 +86,7 @@
 [#886]: https://github.com/rojo-rbx/rojo/pull/886
 [#911]: https://github.com/rojo-rbx/rojo/pull/911
 [#915]: https://github.com/rojo-rbx/rojo/pull/915
+[#974]: https://github.com/rojo-rbx/rojo/pull/974
 
 ## [7.4.3] - August 6th, 2024
 * Fixed issue with building binary files introduced in 7.4.2

src/project.rs

@@ -51,6 +51,9 @@ enum Error {
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(deny_unknown_fields, rename_all = "camelCase")]
 pub struct Project {
+    #[serde(rename = "$schema", skip_serializing_if = "Option::is_none")]
+    schema: Option<String>,
+
     /// The name of the top-level instance described by the project.
     pub name: Option<String>,
 

src/snapshot_middleware/json_model.rs

@@ -61,6 +61,9 @@ pub fn snapshot_json_model(
 #[derive(Debug, Deserialize)]
 #[serde(rename_all = "camelCase")]
 struct JsonModel {
+    #[serde(rename = "$schema", skip_serializing_if = "Option::is_none")]
+    schema: Option<String>,
+
     #[serde(alias = "Name")]
     name: Option<String>,
 

src/snapshot_middleware/meta_file.rs

@@ -13,6 +13,9 @@ use crate::{resolution::UnresolvedValue, snapshot::InstanceSnapshot, RojoRef};
 #[derive(Debug, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct AdjacentMetadata {
+    #[serde(rename = "$schema", skip_serializing_if = "Option::is_none")]
+    schema: Option<String>,
+
     #[serde(skip_serializing_if = "Option::is_none")]
     pub id: Option<String>,
 
@@ -104,6 +107,9 @@ impl AdjacentMetadata {
 #[derive(Debug, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct DirectoryMetadata {
+    #[serde(rename = "$schema", skip_serializing_if = "Option::is_none")]
+    schema: Option<String>,
+
     #[serde(skip_serializing_if = "Option::is_none")]
     pub id: Option<String>,