Add format (roundtrip) button

src/main.rs

@@ -1,5 +1,7 @@
 use eframe::egui;
+use myc::ast::compiler::emitter;
 use myc::ast::environment::Environment;
+use myc::ast::parser::Parser;
 use std::path::PathBuf;
 
 fn main() -> eframe::Result {
@@ -171,6 +173,25 @@ impl CompilerApp {
         }
     }
 
+    fn roundtrip(&mut self) {
+        let mut parser = Parser::new(&self.source_code);
+        let ast = parser.parse_expression();
+        if parser.diagnostics.has_errors() {
+            let errors: Vec<_> = parser
+                .diagnostics
+                .items
+                .iter()
+                .map(|d| d.message.clone())
+                .collect();
+            self.output_log = format!("Roundtrip failed — parse errors:\n{}", errors.join("\n"));
+            self.active_tab = AppTab::Output;
+            return;
+        }
+        self.source_code = emitter::emit(&ast);
+        self.output_log = "Roundtrip complete — source reformatted.".to_string();
+        self.active_tab = AppTab::Output;
+    }
+
     fn save(&mut self) {
         if let Some(path) = &self.current_example_path {
             match std::fs::write(path, &self.source_code) {
@@ -334,6 +355,10 @@ impl eframe::App for CompilerApp {
                         self.dump_ast();
                         ui.close();
                     }
+                    if ui.button("Format (Roundtrip)").clicked() {
+                        self.roundtrip();
+                        ui.close();
+                    }
                     ui.separator();
                     ui.checkbox(&mut self.debug_enabled, "Debug Mode");
                 });
@@ -410,6 +435,14 @@ impl eframe::App for CompilerApp {
                     self.dump_ast();
                 }
 
+                if ui
+                    .button("🔄 Format")
+                    .on_hover_text("Format/Roundtrip source code")
+                    .clicked()
+                {
+                    self.roundtrip();
+                }
+
                 ui.separator();
 
                 ui.toggle_value(&mut self.debug_enabled, "🐛 Debug");