fix: score against the chart's effective tuning and capo

screen.js

@@ -13628,8 +13628,19 @@ function createNoteDetector(options = {}) {
         const info = (hw && hw.getSongInfo) ? hw.getSongInfo() : null;
         if (!info) return;
         if (info.arrangement) currentArrangement = _ndArrangementKindFromName(info.arrangement);
-        if (Array.isArray(info.tuning)) tuningOffsets = info.tuning;
-        if (Number.isFinite(info.capo)) capo = info.capo;
+        // Tuning and capo of the chart as the highway shows it. A chart-
+        // transform provider (core #952) can re-fret the notes and change the
+        // tuning to match, e.g. a drop tuning shown as standard shapes;
+        // getSongInfo() keeps the ORIGINAL metadata, so scoring the transformed
+        // frets against it would expect the wrong pitch on re-fretted strings.
+        // Older hosts without the effective getters fall back to songInfo.
+        let effTuning = null, effCapo = null;
+        try { effTuning = (hw && typeof hw.getTuning === 'function') ? hw.getTuning() : null; } catch (_) {}
+        try { effCapo = (hw && typeof hw.getCapo === 'function') ? hw.getCapo() : null; } catch (_) {}
+        const tuning = Array.isArray(effTuning) && effTuning.length ? effTuning : info.tuning;
+        if (Array.isArray(tuning)) tuningOffsets = tuning;
+        if (Number.isFinite(effCapo)) capo = effCapo;
+        else if (Number.isFinite(info.capo)) capo = info.capo;
 
         // String-count resolution, in precedence order:
         //   1. hw.getStringCount() — host's authoritative count. Asked
@@ -13654,7 +13665,7 @@ function createNoteDetector(options = {}) {
         if (Number.isFinite(hostStringCount)) {
             currentStringCount = hostStringCount;
         } else if (info.arrangement) {
-            const tuneLen = Array.isArray(info.tuning) ? info.tuning.length : null;
+            const tuneLen = Array.isArray(tuning) ? tuning.length : null;
             const consistent = currentArrangement === 'bass'
                 ? (tuneLen === 4 || tuneLen === 5)
                 : (tuneLen === 6 || tuneLen === 7 || tuneLen === 8);
@@ -13663,8 +13674,8 @@ function createNoteDetector(options = {}) {
             } else {
                 currentStringCount = currentArrangement === 'bass' ? 4 : 6;
             }
-        } else if (Array.isArray(info.tuning)) {
-            currentStringCount = info.tuning.length;
+        } else if (Array.isArray(tuning)) {
+            currentStringCount = tuning.length;
         }
     }
 

test/chart_state_sync.test.js

@@ -230,3 +230,54 @@ test('older host without getStringCount: bass with arrangement XML-padded 6-entr
         'bass + tuning.length=6 (arrangement XML pad) must fall back to bass-4');
     det.destroy();
 });
+
+test('a chart transform\'s effective tuning and capo win over the original song info', () => {
+    // A provider re-fretted a Drop D chart into D-standard shapes: the
+    // highway's getTuning() reports the uniform tuning the frets now match,
+    // while getSongInfo() keeps the original Drop D metadata.
+    const core = loadDetectionCore();
+    const det = mountDetectorWithSong(core, {
+        arrangement: 'Lead', tuning: [-2, 0, 0, 0, 0, 0], capo: 0, stringCount: 6,
+    });
+    core.highway.getTuning = () => [-2, -2, -2, -2, -2, -2];
+    core.highway.getCapo = () => 0;
+    det._syncChartStateFromHw();
+    let state = det._getChartState();
+    assert.deepEqual([...state.tuningOffsets], [-2, -2, -2, -2, -2, -2]);
+    assert.equal(state.capo, 0);
+
+    // A transform that moves the capo is honoured too.
+    core.highway.getCapo = () => 3;
+    det._syncChartStateFromHw();
+    state = det._getChartState();
+    assert.equal(state.capo, 3);
+    det.destroy();
+});
+
+test('older hosts without getTuning/getCapo keep using the song info', () => {
+    const core = loadDetectionCore();
+    const det = mountDetectorWithSong(core, {
+        arrangement: 'Lead', tuning: [-2, 0, 0, 0, 0, 0], capo: 2, stringCount: 6,
+    });
+    delete core.highway.getTuning;
+    delete core.highway.getCapo;
+    det._syncChartStateFromHw();
+    const state = det._getChartState();
+    assert.deepEqual([...state.tuningOffsets], [-2, 0, 0, 0, 0, 0]);
+    assert.equal(state.capo, 2);
+    det.destroy();
+});
+
+test('an empty or throwing effective tuning falls back to the song info', () => {
+    const core = loadDetectionCore();
+    const det = mountDetectorWithSong(core, {
+        arrangement: 'Bass', tuning: [-1, -1, -1, -1], capo: 0, stringCount: 4,
+    });
+    core.highway.getTuning = () => [];
+    core.highway.getCapo = () => { throw new Error('boom'); };
+    det._syncChartStateFromHw();
+    const state = det._getChartState();
+    assert.deepEqual([...state.tuningOffsets], [-1, -1, -1, -1]);
+    assert.equal(state.capo, 0);
+    det.destroy();
+});