feat: add diagnostics page and functionality, enhance transport settings in index.html

- Introduced a new diagnostics page (diagnostics.html) with real-time monitoring for Art-Net, sACN, MQTT, and KNX.
- Added JavaScript functionality (diagnostics.js) to handle diagnostics data and render updates.
- Enhanced index.html with new transport settings including timeline length, beat snap options, and diagnostics button.
- Updated styles.css to accommodate new diagnostics layout and transport settings.
- Added splash screen (splash.html) for improved user experience during startup.
- Included new assets: Time4Midi.psd and updated executable files for version 0.3.6.

preload.js

@@ -69,6 +69,28 @@ function addStatusApi(target, handler) {
   };
 }
 
+function normalizeDiagnosticsChannelValues(values) {
+  if (!Array.isArray(values)) {
+    return [];
+  }
+
+  return values.slice(0, 512).map((value) => {
+    const safeValue = Math.round(Number(value) || 0);
+    return Math.max(0, Math.min(255, safeValue));
+  });
+}
+
+function recordDiagnostics(record) {
+  try {
+    ipcRenderer.send("diagnostics:record", {
+      ...record,
+      timestamp: Date.now()
+    });
+  } catch (_error) {
+    // Ignore diagnostics forwarding issues to avoid blocking output.
+  }
+}
+
 const artnet = {
   ...createStatusEmitter(),
   sendSocket: null,
@@ -297,7 +319,13 @@ function closeUdpSocket(target, key, signatureKey) {
 }
 
 async function ensureUdpSocket(target, key, signatureKey, label, config, options = {}) {
-  const signature = `${config.localAddress || ""}|${options.broadcast ? "1" : "0"}`;
+  const signature = [
+    config.localAddress || "",
+    options.broadcast ? "1" : "0",
+    options.multicast ? "1" : "0",
+    options.multicastInterface || "",
+    Number.isFinite(Number(options.multicastTtl)) ? String(Number(options.multicastTtl)) : ""
+  ].join("|");
   if (target[key] && target[signatureKey] === signature) {
     return target[key];
   }
@@ -308,8 +336,14 @@ async function ensureUdpSocket(target, key, signatureKey, label, config, options
   target[signatureKey] = signature;
 
   const bindAddress = config.localAddress || "0.0.0.0";
-  const requiresBinding = Boolean(config.localAddress || options.broadcast);
+  const requiresBinding = Boolean(
+    config.localAddress
+    || options.broadcast
+    || options.multicast
+    || options.forceBind
+  );
   if (!requiresBinding) {
+    emitStatus(target, "");
     return socket;
   }
 
@@ -346,6 +380,14 @@ async function ensureUdpSocket(target, key, signatureKey, label, config, options
   if (options.broadcast) {
     socket.setBroadcast(true);
   }
+  if (options.multicast) {
+    if (Number.isFinite(Number(options.multicastTtl))) {
+      socket.setMulticastTTL(Number(options.multicastTtl));
+    }
+    if (options.multicastInterface) {
+      socket.setMulticastInterface(options.multicastInterface);
+    }
+  }
 
   emitStatus(target, "");
   return socket;
@@ -453,6 +495,7 @@ async function sendArtNetDmx(payload) {
 
   const universe = Math.max(0, Math.min(32767, Number(payload.universe) || 0));
   const values = Array.isArray(payload.values) ? payload.values : [];
+  const diagnosticsValues = normalizeDiagnosticsChannelValues(values);
   const length = Math.max(2, Math.min(512, values.length || 512));
   const evenLength = length % 2 === 0 ? length : length + 1;
   const packet = Buffer.alloc(18 + evenLength);
@@ -487,6 +530,12 @@ async function sendArtNetDmx(payload) {
         return;
       }
       emitStatus(artnet, "");
+      recordDiagnostics({
+        kind: "dmx-frame",
+        transport: "artnet",
+        universe,
+        values: diagnosticsValues
+      });
       resolve(true);
     });
   });
@@ -550,8 +599,12 @@ async function sendOsc(payload) {
 
 function configureSacn(nextConfig) {
   const previousLocalAddress = sacn.config.localAddress;
+  const previousMulticast = sacn.config.multicast;
   sacn.config = normalizeSacnConfig(nextConfig);
-  if (previousLocalAddress !== sacn.config.localAddress) {
+  if (
+    previousLocalAddress !== sacn.config.localAddress
+    || previousMulticast !== sacn.config.multicast
+  ) {
     closeUdpSocket(sacn, "socket", "socketSignature");
   }
   emitStatus(sacn, "");
@@ -588,6 +641,7 @@ async function sendSacnDmx(payload) {
 
   const universe = clampSacnUniverse(payload.universe);
   const values = Array.isArray(payload.values) ? payload.values : [];
+  const diagnosticsValues = normalizeDiagnosticsChannelValues(values);
   const slotCount = Math.max(1, Math.min(512, values.length || 512));
   const packetLength = 126 + slotCount;
   const propertyValueCount = slotCount + 1;
@@ -624,7 +678,19 @@ async function sendSacnDmx(payload) {
 
   sacn.sequence = sacn.sequence >= 255 ? 1 : sacn.sequence + 1;
   const host = sacnDestination(universe);
-  const socket = await ensureUdpSocket(sacn, "socket", "socketSignature", "sACN", sacn.config);
+  const socket = await ensureUdpSocket(
+    sacn,
+    "socket",
+    "socketSignature",
+    "sACN",
+    sacn.config,
+    {
+      multicast: sacn.config.multicast,
+      multicastInterface: sacn.config.localAddress || "",
+      multicastTtl: 32,
+      forceBind: sacn.config.multicast
+    }
+  );
 
   return new Promise((resolve, reject) => {
     socket.send(packet, 0, packet.length, sacn.config.port, host, (error) => {
@@ -634,6 +700,12 @@ async function sendSacnDmx(payload) {
         return;
       }
       emitStatus(sacn, "");
+      recordDiagnostics({
+        kind: "dmx-frame",
+        transport: "sacn",
+        universe,
+        values: diagnosticsValues
+      });
       resolve(true);
     });
   });
@@ -707,6 +779,11 @@ function publishMqtt(payload) {
         return;
       }
       emitStatus(mqttState, "");
+      recordDiagnostics({
+        kind: "mqtt-publish",
+        topic: String(payload.topic || ""),
+        value: String(payload.value ?? "")
+      });
       resolve(true);
     });
   });
@@ -1104,6 +1181,12 @@ async function sendKnx(payload) {
           return;
         }
         emitStatus(knxState, "");
+        recordDiagnostics({
+          kind: "knx-write",
+          groupAddress: String(payload.groupAddress || "1/1/1"),
+          dpt,
+          value
+        });
         resolve(true);
       });
     } catch (error) {
@@ -1134,6 +1217,19 @@ contextBridge.exposeInMainWorld("time4midi", {
     importFile: (defaultPath) => importMappingLibrary(defaultPath),
     exportFile: (defaultPath, data) => exportMappingLibrary(defaultPath, data)
   },
+  diagnostics: {
+    openWindow: () => ipcRenderer.invoke("diagnostics:openWindow"),
+    getSnapshot: () => ipcRenderer.invoke("diagnostics:getSnapshot"),
+    subscribe: (handler) => {
+      const listener = (_event, record) => {
+        handler(record);
+      };
+      ipcRenderer.on("diagnostics:update", listener);
+      return () => {
+        ipcRenderer.removeListener("diagnostics:update", listener);
+      };
+    }
+  },
   network: {
     listInterfaces: () => listNetworkInterfaces()
   },