Add octave offset for play-freq, adjustable via UI input

webapp/path_navigator.html

@@ -281,6 +281,8 @@
             <button id="loadFileBtn">Load</button>
             <span style="margin-left: 20px;">Fundamental (Hz):</span>
             <input type="number" id="fundamentalInput" value="110" style="width: 60px;">
+            <span style="margin-left: 15px;">Octave:</span>
+            <input type="number" id="octaveInput" value="2" style="width: 40px;">
         </div>
         
         <div class="controls">
@@ -466,7 +468,8 @@
                     headers: {'Content-Type': 'application/json'},
                     body: JSON.stringify({
                         chordIndex: chordIndex,
-                        nodeIndex: localId
+                        nodeIndex: localId,
+                        octave: parseInt(document.getElementById('octaveInput').value) || 0
                     })
                 }).then(r => r.json()).then(data => {
                     console.log('Playing on', destination + ':', data.frequency.toFixed(2), 'Hz on voice', data.voice);

webapp/server.py

@@ -99,6 +99,7 @@ def play_freq():
     data = request.json
     chord_index = data.get("chordIndex")
     node_index = data.get("nodeIndex")
+    octave = data.get("octave", 0)
 
     if chord_index < 0 or chord_index >= len(chords):
         return jsonify({"error": "Invalid chord index"}), 400
@@ -109,7 +110,7 @@ def play_freq():
 
     pitch = chord[node_index]
     fraction = Fraction(pitch.get("fraction", "1"))
-    frequency = fundamental * float(fraction)
+    frequency = fundamental * float(fraction) * (2**octave)
     voice = node_index + 1  # 1-indexed
 
     osc_sender.send_single(frequency, voice)