Fix corner cases in connect/disconnect lifecycle and resource cleanup

1. Move TS6 handler patch to after client.connect() — the library's
   connect() internally replaces handler via #S(), discarding any
   patch applied beforehand. Patching after connect() is safe because
   clientinit is sent in async message callbacks after Init1 round-trips.

2. Preserve detectedProtocol across reconnect — disconnect() resets it
   to "unknown", causing the TS6 patch to be skipped on reconnect.

3. Prevent double "disconnected" event in BotInstance — disconnect()
   emitted it directly AND the async TS3Client disconnect triggered
   another through the event chain.

4. Guard playNext() against running after disconnect — check connected
   flag to avoid ghost queue processing.

5. Fix UDP error timer leak — clear previous timer before setting a new
   one to prevent accumulation.

6. Fix isPortFree() FD leak — close the test server on error path.

https://claude.ai/code/session_01QzvMLUT3UkhsffShcY1qzD

src/bot/instance.ts

@@ -105,6 +105,9 @@ export class BotInstance extends EventEmitter {
     });
 
     this.tsClient.on("disconnected", () => {
+      // Avoid duplicate event if disconnect() was called explicitly
+      // (it already set connected = false and emitted "disconnected").
+      if (!this.connected) return;
       this.connected = false;
       this.player.stop();
       this.emit("disconnected");
@@ -119,8 +122,10 @@ export class BotInstance extends EventEmitter {
 
   disconnect(): void {
     this.player.stop();
-    this.tsClient.disconnect();
+    // Set connected = false BEFORE tsClient.disconnect() so that the
+    // "disconnected" event handler (setupTsEvents) won't emit a duplicate.
     this.connected = false;
+    this.tsClient.disconnect();
     this.emit("disconnected");
   }
 
@@ -488,7 +493,7 @@ export class BotInstance extends EventEmitter {
   }
 
   private async playNext(): Promise<void> {
-    if (this.isAdvancing) return;
+    if (this.isAdvancing || !this.connected) return;
     this.isAdvancing = true;
     try {
       this.voteSkipUsers.clear();
@@ -497,7 +502,7 @@ export class BotInstance extends EventEmitter {
         let started = await this.resolveAndPlay(next);
         if (!started) {
           // Skip to next if URL resolve fails (up to 3 retries)
-          for (let i = 0; i < 3; i++) {
+          for (let i = 0; i < 3 && this.connected; i++) {
             const retry = this.queue.next();
             if (!retry) break;
             if (await this.resolveAndPlay(retry)) {

src/music/api-server.ts

@@ -17,7 +17,9 @@ export interface ApiServerManager {
 function isPortFree(port: number): Promise<boolean> {
   return new Promise((resolve) => {
     const server = net.createServer();
-    server.once("error", () => resolve(false));
+    server.once("error", () => {
+      server.close(() => resolve(false));
+    });
     server.once("listening", () => {
       server.close(() => resolve(true));
     });

src/ts-protocol/client.ts

@@ -119,10 +119,15 @@ export class TS3Client extends EventEmitter {
       });
     }
 
-    // Guard against calling connect() while already connected
+    // Guard against calling connect() while already connected.
+    // Save detectedProtocol first because disconnect() resets it.
     if (this.client) {
       this.logger.warn("connect() called while already connected, disconnecting first");
+      const savedProtocol = this.detectedProtocol;
+      const savedHttpQuery = this.httpQuery;
       this.disconnect();
+      this.detectedProtocol = savedProtocol;
+      this.httpQuery = savedHttpQuery;
       // Give the old client a moment to tear down
       await new Promise((r) => setTimeout(r, 100));
     }
@@ -139,7 +144,9 @@ export class TS3Client extends EventEmitter {
         udpErrorCount++;
         if (udpErrorCount === 1) {
           this.logger.warn(msg);
-          // After 2 seconds, log a summary and reset
+          // After 2 seconds, log a summary and reset.
+          // Clear any previous timer to avoid leaking it.
+          if (this.udpErrorTimer) clearTimeout(this.udpErrorTimer);
           this.udpErrorTimer = setTimeout(() => {
             if (udpErrorCount > 1) {
               this.logger.warn(`udp send error (repeated ${udpErrorCount} times, connection may be lost)`);
@@ -162,28 +169,6 @@ export class TS3Client extends EventEmitter {
       },
     });
 
-    // Patch handler.sendPacket to intercept clientinit during handshake for TS6.
-    // The library's commandMiddleware only applies to post-connection commands
-    // (sendCommandNoWait/execCommand), but the handshake's clientinit is sent
-    // directly via handler.sendPacket, bypassing middleware entirely.
-    // This monkey-patch ensures the version is upgraded for TS6 servers.
-    if (this.detectedProtocol === "ts6") {
-      this.logger.info("Applying TS6 compatibility: upgrading client_version to 3.6.2");
-      const origSendPacket = this.client.handler.sendPacket.bind(this.client.handler);
-      this.client.handler.sendPacket = (pType: number, data: Uint8Array, flags: number) => {
-        // PacketType.Command = 2
-        if (pType === 2) {
-          const str = Buffer.from(data).toString("utf-8");
-          if (str.startsWith("clientinit ")) {
-            const patched = patchClientInitVersion(str);
-            origSendPacket(pType, Buffer.from(patched), flags);
-            return;
-          }
-        }
-        origSendPacket(pType, data, flags);
-      };
-    }
-
     this.client.on("textMessage", (msg: TextMessage) => {
       const tsMsg: TS3TextMessage = {
         invokerName: msg.invokerName,
@@ -209,6 +194,37 @@ export class TS3Client extends EventEmitter {
     });
 
     await this.client.connect();
+
+    // Patch handler.sendPacket to intercept clientinit during handshake for TS6.
+    //
+    // Why after connect(): The library's connect() internally calls #S() which
+    // replaces this.handler with a fresh PacketHandler. Any patch applied before
+    // connect() would be discarded. Patching here is safe because connect() only
+    // establishes the UDP socket and sends the first Init1 packet — the actual
+    // clientinit command is sent later in async message callbacks (after Init1
+    // round-trips complete), which cannot fire before this sync continuation.
+    //
+    // Why not commandMiddleware: The library's middleware chain only applies to
+    // post-connection commands (sendCommandNoWait/execCommand). The handshake's
+    // clientinit is sent directly via handler.sendPacket(), bypassing middleware.
+    if (this.detectedProtocol === "ts6") {
+      this.logger.info("Applying TS6 compatibility: upgrading client_version to 3.6.2");
+      const handler = this.client.handler;
+      const origSendPacket = handler.sendPacket.bind(handler);
+      handler.sendPacket = (pType: number, data: Uint8Array, flags: number) => {
+        // PacketType.Command = 2
+        if (pType === 2) {
+          const str = Buffer.from(data).toString("utf-8");
+          if (str.startsWith("clientinit ")) {
+            const patched = patchClientInitVersion(str);
+            origSendPacket(pType, Buffer.from(patched), flags);
+            return;
+          }
+        }
+        origSendPacket(pType, data, flags);
+      };
+    }
+
     await this.client.waitConnected();
     this.clientId = this.client.clientID();
     this.voiceFramesSent = 0;