diff --git a/browser-ext/proxy/proxy.js b/browser-ext/proxy/proxy.js
index e31c5f98b..b30968979 100644
--- a/browser-ext/proxy/proxy.js
+++ b/browser-ext/proxy/proxy.js
@@ -74,7 +74,7 @@ wss.on('connection', (ws, req) => {
     port: config.dapPort,
   });
 
-  let tcpBuffer = '';
+  let tcpBuffer = Buffer.alloc(0);
   let tcpConnected = false;
 
   tcp.on('connect', () => {
@@ -135,33 +135,45 @@ wss.on('connection', (ws, req) => {
   });
 
   // TCP → WebSocket: Parse Content-Length framing
+  // IMPORTANT: We use Buffer (byte-based) operations because DAP's Content-Length
+  // header specifies the message length in bytes, not characters. Using string
+  // operations would cause buffer misalignment when the JSON contains multi-byte
+  // UTF-8 characters.
   tcp.on('data', (chunk) => {
-    tcpBuffer += chunk.toString();
+    // Append chunk to buffer (chunk is already a Buffer)
+    tcpBuffer = Buffer.concat([tcpBuffer, chunk]);
 
     // Process complete DAP messages from buffer
+    const headerEndMarker = Buffer.from('\r\n\r\n');
+
     while (true) {
-      // Look for Content-Length header
-      const headerEnd = tcpBuffer.indexOf('\r\n\r\n');
+      // Look for header end (\r\n\r\n)
+      const headerEnd = tcpBuffer.indexOf(headerEndMarker);
       if (headerEnd === -1) break;
 
-      const header = tcpBuffer.substring(0, headerEnd);
+      // Extract header as string to parse Content-Length
+      const header = tcpBuffer.slice(0, headerEnd).toString('utf8');
       const match = header.match(/Content-Length:\s*(\d+)/i);
       if (!match) {
         console.error(`[Proxy] Invalid DAP header: ${header}`);
-        tcpBuffer = tcpBuffer.substring(headerEnd + 4);
+        // Skip past the invalid header
+        tcpBuffer = tcpBuffer.slice(headerEnd + 4);
         continue;
       }
 
-      const contentLength = parseInt(match[1]);
-      const messageStart = headerEnd + 4;
+      const contentLength = parseInt(match[1], 10);
+      const messageStart = headerEnd + 4; // After \r\n\r\n
       const messageEnd = messageStart + contentLength;
 
-      // Check if we have the complete message
+      // Check if we have the complete message (in bytes)
       if (tcpBuffer.length < messageEnd) break;
 
-      // Extract the JSON message
-      const json = tcpBuffer.substring(messageStart, messageEnd);
-      tcpBuffer = tcpBuffer.substring(messageEnd);
+      // Extract the JSON message (as bytes, then decode to string)
+      const jsonBuffer = tcpBuffer.slice(messageStart, messageEnd);
+      const json = jsonBuffer.toString('utf8');
+
+      // Remove processed message from buffer
+      tcpBuffer = tcpBuffer.slice(messageEnd);
 
       // Send to WebSocket
       try {
@@ -175,6 +187,7 @@ wss.on('connection', (ws, req) => {
         }
       } catch (err) {
         console.error(`[Proxy] Invalid JSON from TCP: ${err.message}`);
+        console.error(`[Proxy] JSON content (first 200 chars): ${json.substring(0, 200)}`);
       }
     }
   });