fix: preserve 7sus4 chord canonicalization for global chord MIDI import

src/util/chordUtil.test.ts

@@ -44,11 +44,17 @@ describe('chordUtil', () => {
     expect(parseChordSymbol('Dm11')?.symbol).toBe('Dm11');
     expect(parseChordSymbol('G13')?.symbol).toBe('G13');
     expect(parseChordSymbol('Bbmaj9')?.symbol).toBe('Bbmaj9');
+    expect(parseChordSymbol('E7sus4')?.symbol).toBe('E7sus4');
     expect(buildChordSymbol({
       root: 'C',
       quality: 'sus4',
       extensions: ['9'],
     })).toBe('Csus4add9');
+    expect(buildChordSymbol({
+      root: 'E',
+      quality: 'sus4',
+      extensions: ['7'],
+    })).toBe('E7sus4');
   });
 
   it('rejects unsupported symbols deterministically', () => {
@@ -84,6 +90,7 @@ describe('chordUtil', () => {
     expect(convertChordSymbolToMidiPitches('Am')).toEqual([45, 57, 60, 64]);
     expect(convertChordSymbolToMidiPitches('Dm')).toEqual([50, 62, 65, 69]);
     expect(convertChordSymbolToMidiPitches('E7')).toEqual([52, 64, 68, 71, 74]);
+    expect(convertChordSymbolToMidiPitches('E7sus4')).toEqual([52, 64, 69, 71, 74]);
     expect(convertChordSymbolToMidiPitches('Bm7b5')).toEqual([47, 59, 62, 65, 69]);
   });
 
@@ -156,6 +163,25 @@ describe('chordUtil', () => {
     ]);
   });
 
+  it('builds an import plan for a suspended dominant chord', () => {
+    const chord = new KGChordRegion('chord-1', 'global-chord', 3, 'E7sus4', 0, 4);
+    const result = buildChordRegionImportPlan([chord]);
+
+    expect(result.ok).toBe(true);
+    if (!result.ok) {
+      return;
+    }
+
+    expect(result.plan.sourceRegionIds).toEqual(['chord-1']);
+    expect(result.plan.notes).toEqual([
+      { startBeat: 0, endBeat: 4, pitch: 52, velocity: 127 },
+      { startBeat: 0, endBeat: 4, pitch: 64, velocity: 127 },
+      { startBeat: 0, endBeat: 4, pitch: 69, velocity: 127 },
+      { startBeat: 0, endBeat: 4, pitch: 71, velocity: 127 },
+      { startBeat: 0, endBeat: 4, pitch: 74, velocity: 127 },
+    ]);
+  });
+
   it('builds an import plan for extended chord progressions', () => {
     const chordA = new KGChordRegion('chord-1', 'global-chord', 3, 'Am9', 0, 4);
     const chordB = new KGChordRegion('chord-2', 'global-chord', 3, 'Dm9', 4, 4);

src/util/chordUtil.ts

@@ -82,6 +82,25 @@ interface CollapsedNaturalExtension {
   consumed: ChordExtension[];
 }
 
+function getSuspendedSeventhSuffix(
+  quality: ChordQuality,
+  extensions: ChordExtension[],
+): string | null {
+  if (!extensions.includes('7')) {
+    return null;
+  }
+
+  if (quality === 'sus2') {
+    return '7sus2';
+  }
+
+  if (quality === 'sus4') {
+    return '7sus4';
+  }
+
+  return null;
+}
+
 function getCollapsedNaturalExtension(
   quality: ChordQuality,
   extensions: ChordExtension[],
@@ -309,7 +328,15 @@ function parseCustomChordSymbol(symbol: string): ChordDescriptor | null {
   let quality: ChordQuality = 'maj';
   const extensions = new Set<ChordExtension>();
 
-  if (remainder.startsWith('m7b5')) {
+  if (remainder.startsWith('7sus2')) {
+    quality = 'sus2';
+    extensions.add('7');
+    remainder = remainder.slice(5);
+  } else if (remainder.startsWith('7sus4')) {
+    quality = 'sus4';
+    extensions.add('7');
+    remainder = remainder.slice(5);
+  } else if (remainder.startsWith('m7b5')) {
     quality = 'dim';
     extensions.add('b5');
     extensions.add('7');
@@ -473,43 +500,49 @@ export function buildChordSymbol(descriptor: Pick<ChordDescriptor, 'root' | 'qua
       symbol += collapsedNaturalExtension.suffix;
       collapsedNaturalExtension.consumed.forEach(extension => remainingExtensions.delete(extension));
     } else {
-      switch (descriptor.quality) {
-        case 'maj':
-          break;
-        case 'min':
-          symbol += 'm';
-          break;
-        case 'sus2':
-          symbol += 'sus2';
-          break;
-        case 'sus4':
-          symbol += 'sus4';
-          break;
-        case 'power':
-          symbol += '5';
-          break;
-        case 'aug':
-          symbol += 'aug';
-          remainingExtensions.delete('#5');
-          break;
-        case 'dim':
-          symbol += 'dim';
-          remainingExtensions.delete('b5');
-          break;
-      }
-
-      if (has('dim7')) {
-        symbol += 'dim7';
-        remainingExtensions.delete('dim7');
-      } else if (has('maj7')) {
-        symbol += 'maj7';
-        remainingExtensions.delete('maj7');
-      } else if (has('7')) {
-        symbol += '7';
+      const suspendedSeventhSuffix = getSuspendedSeventhSuffix(descriptor.quality, extensions);
+      if (suspendedSeventhSuffix) {
+        symbol += suspendedSeventhSuffix;
         remainingExtensions.delete('7');
-      } else if (has('6')) {
-        symbol += '6';
-        remainingExtensions.delete('6');
+      } else {
+        switch (descriptor.quality) {
+          case 'maj':
+            break;
+          case 'min':
+            symbol += 'm';
+            break;
+          case 'sus2':
+            symbol += 'sus2';
+            break;
+          case 'sus4':
+            symbol += 'sus4';
+            break;
+          case 'power':
+            symbol += '5';
+            break;
+          case 'aug':
+            symbol += 'aug';
+            remainingExtensions.delete('#5');
+            break;
+          case 'dim':
+            symbol += 'dim';
+            remainingExtensions.delete('b5');
+            break;
+        }
+
+        if (has('dim7')) {
+          symbol += 'dim7';
+          remainingExtensions.delete('dim7');
+        } else if (has('maj7')) {
+          symbol += 'maj7';
+          remainingExtensions.delete('maj7');
+        } else if (has('7')) {
+          symbol += '7';
+          remainingExtensions.delete('7');
+        } else if (has('6')) {
+          symbol += '6';
+          remainingExtensions.delete('6');
+        }
       }
     }
   }
@@ -589,10 +622,14 @@ export function formatChordSymbolForDisplay(symbol: string): string {
   }
   const collapsedNaturalExtension = getCollapsedNaturalExtension(quality, extensions);
   const consumedCollapsedExtensions = new Set(collapsedNaturalExtension?.consumed ?? []);
+  const suspendedSeventhSuffix = getSuspendedSeventhSuffix(quality, extensions);
   const baseQuality = (() => {
     if (collapsedNaturalExtension) {
       return '';
     }
+    if (suspendedSeventhSuffix) {
+      return '';
+    }
 
     switch (quality) {
       case 'maj':
@@ -634,6 +671,8 @@ export function formatChordSymbolForDisplay(symbol: string): string {
 
   const inlineText = collapsedNaturalExtension
     ? collapsedNaturalExtension.suffix
+    : suspendedSeventhSuffix
+      ? suspendedSeventhSuffix
     : inlineExtensions.join('');
   const parentheticalText = parentheticalExtensions.length > 0
     ? `(${parentheticalExtensions.join(', ')})`