feat: add audio region trimming with non-destructive clip offset

src/core/project-upgrader/KGProjectUpgrader.ts

@@ -4,6 +4,7 @@ import { upgradeToV2 } from './upgradeToV2';
 import { upgradeToV3 } from './upgradeToV3';
 import { upgradeToV4 } from './upgradeToV4';
 import { upgradeToV5 } from './upgradeToV5';
+import { upgradeToV6 } from './upgradeToV6';
 
 /**
  * Upgrade the given project to the latest structure version, one version at a time.
@@ -43,6 +44,10 @@ export function upgradeProjectToLatest(project: KGProject): KGProject {
         workingProject = upgradeToV5(workingProject);
         break;
       }
+      case 6: {
+        workingProject = upgradeToV6(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/upgradeToV6.ts

@@ -0,0 +1,21 @@
+import { KGProject } from '../KGProject';
+import { KGAudioRegion } from '../region/KGAudioRegion';
+
+export function upgradeToV6(project: KGProject): KGProject {
+  try {
+    // Ensure all audio regions have clipStartOffsetSeconds initialized
+    for (const track of project.getTracks()) {
+      for (const region of track.getRegions()) {
+        if (region instanceof KGAudioRegion) {
+          const current = region.getClipStartOffsetSeconds?.();
+          if (current === undefined || current === null) {
+            region.setClipStartOffsetSeconds(0);
+          }
+        }
+      }
+    }
+  } finally {
+    project.setProjectStructureVersion(6);
+  }
+  return project;
+}