Fix LilyPond melody/guide tones staff overlap and web UI null checks

internal/jazz/musicxml_read.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"sort"
 	"strconv"
 	"strings"
 	"unicode/utf8"
@@ -421,6 +422,21 @@ func ParseMusicXML(r io.Reader) (*Tune, error) {
 
 		numHarmonies := len(harmonyEvents)
 		if numHarmonies > 0 {
+			sort.SliceStable(harmonyEvents, func(i, j int) bool {
+				return harmonyEvents[i].division < harmonyEvents[j].division
+			})
+
+			// Deduplicate harmonies that fall on the exact same division
+			var deduped []harmonyAt
+			for _, h := range harmonyEvents {
+				if len(deduped) > 0 && deduped[len(deduped)-1].division == h.division {
+					continue
+				}
+				deduped = append(deduped, h)
+			}
+			harmonyEvents = deduped
+			numHarmonies = len(harmonyEvents)
+
 			hasNoteTiming := maxCursor > 0 && divisions > 0
 
 			for i, h := range harmonyEvents {

internal/server/api.go

@@ -193,15 +193,22 @@ func (s *Server) handleAnalyze(w http.ResponseWriter, r *http.Request) {
 	// Run tonal center analysis and device detection
 	jazz.AnalyzeTonalCenters(tune)
 	devices := jazz.DetectHarmonicDevices(tune)
+	if devices == nil {
+		devices = []jazz.HarmonicDevice{}
+	}
 	journeySpans := jazz.GetHarmonicJourneySpans(tune)
+	if journeySpans == nil {
+		journeySpans = []jazz.JourneySpan{}
+	}
 	journeyStr := jazz.HarmonicJourney(tune)
 
-	var measuresDTO []MeasureDTO
+	measuresDTO := make([]MeasureDTO, 0, len(tune.Measures))
 	pairIdx := 0
 
 	for _, m := range tune.Measures {
 		mDTO := MeasureDTO{
 			Number: m.Number,
+			Chords: make([]ChordDTO, 0, len(m.Chords)),
 		}
 		for _, tc := range m.Chords {
 			var p jazz.GuideTonePair

internal/server/server_test.go

@@ -157,4 +157,18 @@ func TestAnalyzeEndpoint_StandardAutumnLeaves(t *testing.T) {
 	if len(resp.Measures) == 0 {
 		t.Errorf("expected measures in Autumn Leaves, got 0")
 	}
+
+	rawJSON := rec.Body.String()
+	if strings.Contains(rawJSON, `"chords":null`) {
+		t.Errorf("expected non-null chords in JSON, but found '\"chords\":null'")
+	}
+	if resp.Measures[0].Chords == nil {
+		t.Errorf("expected Measure[0].Chords to be non-nil empty slice, got nil")
+	}
+	if resp.Devices == nil {
+		t.Errorf("expected Devices to be non-nil slice, got nil")
+	}
+	if resp.JourneySpans == nil {
+		t.Errorf("expected JourneySpans to be non-nil slice, got nil")
+	}
 }

web/dist/index.html

@@ -5,7 +5,7 @@
     <link rel="icon" type="image/svg+xml" href="data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 100 100'><text y='.9em' font-size='90'>🎷</text></svg>" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>jazz-tools - Harmonic Analysis & Companion Generator</title>
-    <script type="module" crossorigin src="/assets/index-BU2UpVYr.js"></script>
+    <script type="module" crossorigin src="/assets/index-BEh0cyCH.js"></script>
     <link rel="stylesheet" crossorigin href="/assets/index-DK9tBSLp.css">
   </head>
   <body class="bg-slate-50 text-slate-900 min-h-screen">

web/src/App.tsx

@@ -490,7 +490,7 @@ export const App: React.FC = () => {
                     Key: {analysis.key || 'Modal/C'}
                   </span>
                   <span className="px-2.5 py-1 rounded-md bg-slate-100 text-slate-700 text-xs font-semibold">
-                    Time: {analysis.timeSignature[0]}/{analysis.timeSignature[1]}
+                    Time: {analysis.timeSignature ? `${analysis.timeSignature[0]}/${analysis.timeSignature[1]}` : '4/4'}
                   </span>
                   <span className="px-2.5 py-1 rounded-md bg-slate-100 text-slate-700 text-xs font-semibold">
                     {analysis.measureCount} Measures

web/src/components/ChordsTable.tsx

@@ -4,6 +4,9 @@ import { MeasureDTO } from '../types';
 export const ChordsTable: React.FC<{ measures: MeasureDTO[] }> = ({ measures }) => {
   if (!measures || measures.length === 0) return null;
 
+  const hasAnyChords = measures.some((m) => m.chords && m.chords.length > 0);
+  if (!hasAnyChords) return null;
+
   return (
     <div className="bg-white rounded-xl shadow-sm border border-slate-200 overflow-hidden">
       <div className="px-5 py-3 border-b border-slate-100 bg-slate-50/50 flex justify-between items-center">
@@ -25,7 +28,7 @@ export const ChordsTable: React.FC<{ measures: MeasureDTO[] }> = ({ measures })
           </thead>
           <tbody className="divide-y divide-slate-100 font-mono">
             {measures.flatMap((m) =>
-              m.chords.map((c, cIdx) => (
+              (m.chords || []).map((c, cIdx) => (
                 <tr key={`${m.number}-${cIdx}`} className="hover:bg-slate-50/80 transition-colors">
                   <td className="py-2 px-4 font-semibold text-slate-700">
                     {cIdx === 0 ? m.number : ''}

web/src/components/ScoreViewer.tsx

@@ -26,11 +26,16 @@ export const ScoreViewer: React.FC<Props> = ({ xmlContent, hasMelody }) => {
       });
     }
 
-    osmdRef.current.load(xmlContent).then(() => {
-      osmdRef.current?.render();
-    }).catch(err => {
-      console.error("OSMD render error:", err);
-    });
+    try {
+      osmdRef.current.clear();
+      osmdRef.current.load(xmlContent).then(() => {
+        osmdRef.current?.render();
+      }).catch(err => {
+        console.error("OSMD render error:", err);
+      });
+    } catch (err) {
+      console.error("OSMD load error:", err);
+    }
   }, [xmlContent]);
 
   return (

web/src/types.ts

@@ -43,7 +43,7 @@ export interface ChordDTO {
 
 export interface MeasureDTO {
   number: number;
-  chords: ChordDTO[];
+  chords?: ChordDTO[];
   melody?: MelodyNoteDTO[];
 }