Add batch API endpoints for cents calculation, client fetches cents from server

webapp/path_navigator.html

@@ -581,13 +581,37 @@
         // Load from Flask API - get chords and compute graphs client-side
         async function loadAllGraphs() {
             try {
+                // Step 1: Get raw chord data
                 const response = await fetch("/api/chords");
                 if (!response.ok) throw new Error("API not available");
                 const data = await response.json();
                 
-                // Compute graphs from raw chord data client-side
+                // Step 2: Collect all fractions from all chords
+                const allFractions = [];
+                const chordFractions = []; // Track which fractions belong to which chord
+                
+                for (const chord of data.chords) {
+                    const fractions = [];
+                    for (const pitch of chord) {
+                        fractions.push(pitch.fraction || "1");
+                    }
+                    chordFractions.push(fractions);
+                    allFractions.push(...fractions);
+                }
+                
+                // Step 3: Batch fetch cents from server (avoid N+1 problem)
+                const centsResponse = await fetch("/api/batch-calculate-cents", {
+                    method: "POST",
+                    headers: {"Content-Type": "application/json"},
+                    body: JSON.stringify({ fractions: allFractions })
+                });
+                const centsData = await centsResponse.json();
+                const allCents = centsData.results.map(r => r.cents);
+                
+                // Step 4: Build graphs with cached cents values
+                let centsIndex = 0;
                 const graphs = data.chords.map((chord, index) => {
-                    return calculateGraph(chord, index);
+                    return calculateGraph(chord, index, () => allCents[centsIndex++]);
                 });
                 
                 allGraphsData = {
@@ -611,18 +635,17 @@
             }
         }
         
-        // Compute graph (nodes + edges) from raw chord data - client-side version
-        function calculateGraph(chord, index) {
+        // Compute graph (nodes + edges) from raw chord data - using API for cents
+        function calculateGraph(chord, index, getNextCent) {
             if (!chord) return { nodes: [], edges: [] };
             
             const nodes = [];
             const dims = [2, 3, 5, 7];
             
-            // Calculate cents for each pitch
+            // Calculate cents for each pitch (fetched from server)
             for (let i = 0; i < chord.length; i++) {
                 const pitch = chord[i];
-                const fraction = parseFraction(pitch.fraction || "1");
-                const cents = fraction > 0 ? 1200 * Math.log2(fraction) : 0;
+                const cents = getNextCent();
                 
                 nodes.push({
                     id: i,
@@ -689,18 +712,6 @@
             return { nodes, edges, index };
         }
         
-        // Parse fraction string to number
-        function parseFraction(fracStr) {
-            if (typeof fracStr === 'number') return fracStr;
-            if (!fracStr) return 1;
-            
-            if (fracStr.includes('/')) {
-                const [num, den] = fracStr.split('/').map(Number);
-                return num / den;
-            }
-            return Number(fracStr);
-        }
-        
         // Update UI elements
         function updateUI() {
             hasPrev = currentIndex > 0;

webapp/server.py

@@ -406,6 +406,45 @@ def load_file():
         return jsonify({"error": f"Invalid JSON in: {filepath}"}), 400
 
 
+@app.route("/api/parse-fraction", methods=["POST"])
+def parse_fraction_api():
+    """Parse a fraction string to float."""
+    data = request.json
+    fraction = data.get("fraction", "1")
+    try:
+        value = parse_fraction(fraction)
+        return jsonify({"fraction": fraction, "value": value})
+    except Exception as e:
+        return jsonify({"error": str(e)}), 400
+
+
+@app.route("/api/calculate-cents", methods=["POST"])
+def calculate_cents_api():
+    """Calculate cents from fraction string."""
+    data = request.json
+    fraction = data.get("fraction", "1")
+    try:
+        cents = calculate_cents(fraction)
+        return jsonify({"fraction": fraction, "cents": cents})
+    except Exception as e:
+        return jsonify({"error": str(e)}), 400
+
+
+@app.route("/api/batch-calculate-cents", methods=["POST"])
+def batch_calculate_cents_api():
+    """Calculate cents for multiple fractions at once."""
+    data = request.json
+    fractions = data.get("fractions", [])
+    try:
+        results = []
+        for fraction in fractions:
+            cents = calculate_cents(fraction)
+            results.append({"fraction": fraction, "cents": cents})
+        return jsonify({"results": results})
+    except Exception as e:
+        return jsonify({"error": str(e)}), 400
+
+
 if __name__ == "__main__":
     print("Starting Path Navigator server...")
     print(f"Loading chords from: {get_chords_file()}")