Add exact saved-project comparison for native Arrange checks

crates/oa-core/examples/arrange_reset_native_probe.rs

@@ -208,10 +208,27 @@ fn source_bytes(p: &Project) -> Vec<u8> {
 
 fn main() -> Result<(), Box<dyn Error>> {
     let mut args = std::env::args_os().skip(1);
-    let output = PathBuf::from(
-        args.next()
-            .ok_or("Usage: arrange_reset_native_probe NEW_DIRECTORY")?,
-    );
+    let first = args.next().ok_or(
+        "Usage: arrange_reset_native_probe NEW_DIRECTORY | --compare ACTUAL EXPECTED",
+    )?;
+    if first == "--compare" {
+        let actual_path = args.next().ok_or("Missing ACTUAL path")?;
+        let expected_path = args.next().ok_or("Missing EXPECTED path")?;
+        if args.next().is_some() {
+            return Err("Unexpected comparison argument".into());
+        }
+        let actual = persistence::decode(&fs::read(actual_path)?)?;
+        let expected = persistence::decode(&fs::read(expected_path)?)?;
+        let equal = actual == expected;
+        println!("{}", json!({"complete_project_equal": equal,
+            "actual_diagrams": actual.diagrams.len(),
+            "expected_diagrams": expected.diagrams.len()}));
+        if !equal {
+            return Err("Complete typed Projects differ".into());
+        }
+        return Ok(());
+    }
+    let output = PathBuf::from(first);
     if args.next().is_some() || output.exists() {
         return Err("Require exactly one output directory that does not already exist".into());
     }