fix: tempo-driven audio region resizing and playhead clamping

src/core/commands/global-region/UpdateTempoRegionCommand.ts

@@ -2,13 +2,23 @@ import { KGCommand } from '../KGCommand';
 import { KGCore } from '../../KGCore';
 import { GlobalTrackType } from '../../global-track';
 import { KGTempoRegion } from '../../region/KGTempoRegion';
-import { findGlobalTrackByType } from '../../../util/globalTrackUtil';
+import {
+  findGlobalTrackByType,
+  getRequiredMaxBarsForAudioRegions,
+  normalizeTempoRegionsForProject,
+  restoreAudioRegionLengths,
+  syncAudioRegionLengthsToPlaybackDuration,
+  type AudioRegionLengthSnapshot,
+} from '../../../util/globalTrackUtil';
 
 export class UpdateTempoRegionCommand extends KGCommand {
   private readonly regionId: string;
   private readonly nextBpm: number;
   private previousBpm: number | null = null;
+  private previousMaxBars: number | null = null;
+  private nextMaxBars: number | null = null;
   private targetRegion: KGTempoRegion | null = null;
+  private audioRegionLengthSnapshots: AudioRegionLengthSnapshot[] = [];
 
   constructor(regionId: string, nextBpm: number) {
     super();
@@ -30,15 +40,32 @@ export class UpdateTempoRegionCommand extends KGCommand {
 
     this.targetRegion = region;
     this.previousBpm = region.getBpm();
+    this.previousMaxBars = project.getMaxBars();
     region.setBpm(this.nextBpm);
+    this.audioRegionLengthSnapshots = syncAudioRegionLengthsToPlaybackDuration(project);
+
+    const requiredMaxBars = getRequiredMaxBarsForAudioRegions(project);
+    this.nextMaxBars = Math.max(project.getMaxBars(), requiredMaxBars);
+    if (this.nextMaxBars > project.getMaxBars()) {
+      project.setMaxBars(this.nextMaxBars);
+      normalizeTempoRegionsForProject(project);
+    }
   }
 
   undo(): void {
-    if (!this.targetRegion || this.previousBpm === null) {
+    if (!this.targetRegion || this.previousBpm === null || this.previousMaxBars === null) {
       throw new Error('Cannot undo tempo update without previous state');
     }
 
+    const project = KGCore.instance().getCurrentProject();
     this.targetRegion.setBpm(this.previousBpm);
+    if (project.getMaxBars() !== this.previousMaxBars) {
+      project.setMaxBars(this.previousMaxBars);
+      normalizeTempoRegionsForProject(project);
+    }
+    if (this.audioRegionLengthSnapshots.length > 0) {
+      restoreAudioRegionLengths(this.audioRegionLengthSnapshots);
+    }
   }
 
   getDescription(): string {