feat: added upgradeToV3 upgrader

src/core/project-upgrader/KGProjectUpgrader.ts

@@ -1,6 +1,7 @@
 import { KGProject } from '../KGProject';
 import { upgradeToV1 } from './upgradeToV1';
 import { upgradeToV2 } from './upgradeToV2';
+import { upgradeToV3 } from './upgradeToV3';
 
 /**
  * Upgrade the given project to the latest structure version, one version at a time.
@@ -28,6 +29,10 @@ export function upgradeProjectToLatest(project: KGProject): KGProject {
         workingProject = upgradeToV2(workingProject);
         break;
       }
+      case 3: {
+        workingProject = upgradeToV3(workingProject);
+        break;
+      }
       default: {
         // If an upgrader is missing, throw to prevent loading incompatible structures
         throw new Error(`No upgrader found for project structure version ${nextVersion}`);

src/core/project-upgrader/upgradeToV3.ts

@@ -0,0 +1,26 @@
+import { KGProject } from '../KGProject';
+
+/**
+ * Upgrade a project from structure version 2 to 3.
+ * Adds the isLooping and loopingRange fields with default values.
+ */
+export function upgradeToV3(project: KGProject): KGProject {
+  try {
+    // Set default isLooping to false if not already set
+    const currentIsLooping = project.getIsLooping?.();
+    if (currentIsLooping === undefined) {
+      project.setIsLooping(false);
+    }
+
+    // Set default loopingRange to [0, 0] if not already set
+    const currentLoopingRange = project.getLoopingRange?.();
+    if (!currentLoopingRange) {
+      project.setLoopingRange([0, 0]);
+    }
+  } finally {
+    // Always set the project structure version to 3 to mark migration complete
+    project.setProjectStructureVersion(3);
+  }
+
+  return project;
+}