exporter: remove stage voice entries for deleted instruments

static/exporter.js

@@ -246,6 +246,66 @@ function _patchInstrumentHeader(text, instruments) {
 }
 
 
+// Remove stage voice entries whose referenced instrument is no longer in the model.
+// String form: `  voicename: LEFT|RIGHT DIST [Instrument]` — 3rd token is instrument.
+// Mapping form: `  voicename:\n    instrument: Name` — look for `instrument:` child.
+// When no explicit instrument is present, the voice name is the implicit instrument name.
+
+function _patchStageSection(text, instruments) {
+    const instrNames = new Set(instruments.flatMap(i => {
+        const names = [i.name];
+        if (i.name.includes('/')) names.push(i.name.split('/').pop());
+        return names;
+    }));
+    const lines = text.split('\n');
+    const stageIdx = lines.findIndex(l => /^stage\s*:/.test(l));
+    if (stageIdx === -1) return text;
+
+    let stageEnd = lines.length;
+    for (let j = stageIdx + 1; j < lines.length; j++) {
+        if (lines[j] !== '' && !/^\s/.test(lines[j])) { stageEnd = j; break; }
+    }
+
+    const stageLines = lines.slice(stageIdx + 1, stageEnd);
+    const firstIndented = stageLines.find(l => l !== '' && /^\s/.test(l));
+    if (!firstIndented) return text;
+    const voiceIndentLen = firstIndented.match(/^(\s+)/)[1].length;
+
+    // Group stageLines into per-voice entries
+    const entries = [];
+    let cur = null;
+    for (const line of stageLines) {
+        if (line === '') { if (cur) cur.lines.push(line); continue; }
+        const indentLen = (line.match(/^(\s+)/) ?? ['', ''])[1].length;
+        if (indentLen === voiceIndentLen) {
+            if (cur) entries.push(cur);
+            const m = line.match(/^\s+(\w[\w./]*)\s*:(.*)/);
+            cur = m ? { lines: [line], name: m[1], rest: m[2].trim() } : { lines: [line], name: null };
+        } else if (cur) {
+            cur.lines.push(line);
+        }
+    }
+    if (cur) entries.push(cur);
+
+    const keptLines = [];
+    for (const entry of entries) {
+        if (!entry.name || entry.name === '_space') { keptLines.push(...entry.lines); continue; }
+        let instrRef = null;
+        if (entry.rest) {
+            const parts = entry.rest.split(/\s+/);
+            if (parts.length >= 3) instrRef = parts[2];
+        } else {
+            for (const l of entry.lines.slice(1)) {
+                const im = l.match(/^\s+instrument\s*:\s*(\S+)/);
+                if (im) { instrRef = im[1]; break; }
+            }
+        }
+        if (instrNames.has(instrRef ?? entry.name)) keptLines.push(...entry.lines);
+    }
+
+    return [...lines.slice(0, stageIdx + 1), ...keptLines, ...lines.slice(stageEnd)].join('\n');
+}
+
 function _patchBarMeta(doc, bar) {
     const props = [];
     const sp = stressorToString(bar.stressor);
@@ -304,6 +364,7 @@ export function patchScore(rawScoreText, instruments, bars = [], info = null, ar
     }
 
     patchedHeader = _patchInstrumentHeader(patchedHeader, instruments);
+    patchedHeader = _patchStageSection(patchedHeader, instruments);
     instruments.forEach(i => {
         if (!(i.isLinked && !i._modified)) log.push({ level: 'changed', path: `instrument / ${i.name}` });
     });