enable model fetching mechanism

app/static/index.html

@@ -139,6 +139,7 @@
       orig_sample_rate = context.sampleRate;
 
       ws.onopen = () => {
+        sendConfig();
         console.log("[DEBUG client] WebSocket.onopen fired!");
         ws.send(JSON.stringify({ 
           type: "config", 
@@ -147,6 +148,22 @@
           precision: precisionSelect.value
         }));
       };
+
+      // factor out sending config
+      function sendConfig() {
+        ws.send(JSON.stringify({
+          type: "config",
+          sampleRate: orig_sample_rate,
+          model:    modelSelect.value,
+          precision: precisionSelect.value
+        }));
+      }
+
+      // send a new config when dropdowns change
+      modelSelect.addEventListener("change", sendConfig);
+      precisionSelect.addEventListener("change", sendConfig);
+
+
       ws.onerror = err => {
         console.error("[DEBUG client] WebSocket.onerror:", err);
       };