feat: enhanced the note scheduling logic to support loop mode

pending cases: user disabled the loop mode or updated the loop range during playback.

src/core/KGCore.ts

@@ -270,6 +270,26 @@ export class KGCore {
 
   // High-level playback control methods
   public async startPlaying(): Promise<void> {
+    // Handle loop mode initialization
+    if (this.currentProject.getIsLooping()) {
+      const [startBar, endBar] = this.currentProject.getLoopingRange();
+
+      // Handle [0, 0] case - set to full project
+      if (startBar === 0 && endBar === 0) {
+        const maxBars = this.currentProject.getMaxBars();
+        const { ChangeLoopSettingsCommand } = await import('./commands');
+        this.executeCommand(new ChangeLoopSettingsCommand({
+          loopingRange: [0, maxBars]
+        }));
+      }
+
+      // Move playhead to loop start (use updated range if [0,0] was just set)
+      const updatedRange = this.currentProject.getLoopingRange();
+      const beatsPerBar = this.currentProject.getTimeSignature().numerator;
+      const loopStartBeats = updatedRange[0] * beatsPerBar;
+      this.setPlayheadPosition(loopStartBeats);
+    }
+
     // Prepare playback first
     await this.preparePlay();
 
@@ -336,12 +356,36 @@ export class KGCore {
 
     const bpm = this.currentProject.getBpm();
     const beatsPerMs = bpm / (60 * 1000);
-    const newPosition = this.playbackStartPosition + (adjustedElapsedMs * beatsPerMs);
+    let newPosition = this.playbackStartPosition + (adjustedElapsedMs * beatsPerMs);
 
-    // Stop playback at the end of project (maxBars)
-    const maxBars = this.currentProject.getMaxBars();
+    // Handle looping or end-of-project
     const beatsPerBar = this.currentProject.getTimeSignature().numerator;
+
+    if (this.currentProject.getIsLooping()) {
+      // Loop mode: wrap playhead when it reaches loop end
+      const [startBar, endBarOriginal] = this.currentProject.getLoopingRange();
+      const endBar = (startBar === 0 && endBarOriginal === 0) ? this.currentProject.getMaxBars() : endBarOriginal;
+
+      const loopStartBeats = startBar * beatsPerBar;
+      const loopEndBeats = (endBar + 1) * beatsPerBar; // +1 because endBar is inclusive
+      const loopLengthBeats = loopEndBeats - loopStartBeats;
+
+      // Wrap playhead position within loop range
+      if (newPosition >= loopEndBeats) {
+        // Calculate how far we've overshot and wrap back
+        const overshot = newPosition - loopEndBeats;
+        newPosition = loopStartBeats + (overshot % loopLengthBeats);
+
+        // Reset timing reference to prevent drift accumulation
+        const newElapsedBeats = newPosition - loopStartBeats;
+        this.playbackStartTime = performance.now() - (newElapsedBeats / beatsPerMs) - playbackDelayMs;
+        this.playbackStartPosition = loopStartBeats;
+      }
+    } else {
+      // Non-looping mode: stop at project end
+      const maxBars = this.currentProject.getMaxBars();
       const maxBeats = maxBars * beatsPerBar;
+
       if (newPosition >= maxBeats) {
         // Clamp to max and stop
         this.setPlayheadPosition(maxBeats);
@@ -349,6 +393,7 @@ export class KGCore {
         this.stopPlaying();
         return;
       }
+    }
 
     // Update playhead position
     this.setPlayheadPosition(newPosition);
@@ -357,7 +402,6 @@ export class KGCore {
     // - Sync with Tone.Transport position for more accurate timing
     // - Handle tempo changes mid-playback
     // - Account for latency compensation
-    // - Support for loop regions
   }
 
   // selected items

src/core/audio-interface/KGAudioInterface.ts

@@ -267,6 +267,38 @@ export class KGAudioInterface {
 
       console.log(`Setting Tone.js BPM to ${project.getBpm()}, actual value: ${Tone.Transport.bpm.value}`);
 
+      // Configure loop settings
+      const isLooping = project.getIsLooping();
+      let scheduleStartBeat = 0;
+      let scheduleEndBeat = Infinity;
+
+      if (isLooping) {
+        const [startBar, endBarOriginal] = project.getLoopingRange();
+        const beatsPerBar = timeSignature.numerator;
+
+        // Handle [0, 0] case - use full project
+        const endBar = (startBar === 0 && endBarOriginal === 0) ? project.getMaxBars() : endBarOriginal;
+
+        scheduleStartBeat = startBar * beatsPerBar;
+        scheduleEndBeat = (endBar + 1) * beatsPerBar; // +1 because endBar is inclusive
+
+        // Configure Tone.Transport loop boundaries
+        const loopStartTime = this.beatsToToneTime(scheduleStartBeat);
+        const loopEndTime = this.beatsToToneTime(scheduleEndBeat);
+        Tone.Transport.setLoopPoints(loopStartTime, loopEndTime);
+        Tone.Transport.loop = true;
+
+        console.log(`Loop mode enabled: bars [${startBar}, ${endBar}], beats [${scheduleStartBeat}, ${scheduleEndBeat}]`);
+
+        // Adjust start position to loop start if before loop range
+        if (startPosition < scheduleStartBeat) {
+          startPosition = scheduleStartBeat;
+        }
+      } else {
+        Tone.Transport.loop = false;
+        console.log("Loop mode disabled");
+      }
+
       // Set transport position (convert beats to Tone.js format)
       this.setTransportPosition(startPosition);
       
@@ -290,8 +322,14 @@ export class KGAudioInterface {
                   // Calculate absolute note timing in beats (note position + region start position)
                   const regionStartBeat = region.getStartFromBeat();
                   const noteStartBeat = note.getStartBeat() + regionStartBeat;
+                  const noteEndBeat = note.getEndBeat() + regionStartBeat;
                   const noteDurationBeats = note.getEndBeat() - note.getStartBeat();
 
+                  // Skip notes outside loop range when looping
+                  if (noteStartBeat >= scheduleEndBeat || noteEndBeat <= scheduleStartBeat) {
+                    return; // Skip notes outside the loop range
+                  }
+
                   // Only schedule notes that start at or after the playback start position
                   if (noteStartBeat < startPosition) {
                     return; // Skip notes that would have already finished before playback starts