diff --git a/dist/components/proxy-middleware/index.js b/dist/components/proxy-middleware/index.js
index f178de8..032f7a3 100644
--- a/dist/components/proxy-middleware/index.js
+++ b/dist/components/proxy-middleware/index.js
@@ -103,7 +103,9 @@ class ProxyMiddlewareManager {
                     if (modifyResponseActionExist) {
                         const statusCode = ctx.rq_response_status_code || 404;
                         const responseHeaders = (0, proxy_ctx_helper_1.getResponseHeaders)(ctx) || {};
-                        ctx.proxyToClientResponse.writeHead(statusCode, http_1.default.STATUS_CODES[statusCode], responseHeaders);
+                        if (!ctx.proxyToClientResponse.headersSent) {
+                            ctx.proxyToClientResponse.writeHead(statusCode, http_1.default.STATUS_CODES[statusCode], responseHeaders);
+                        }
                         ctx.proxyToClientResponse.end(ctx.rq_response_body);
                         ctx.rq.set_final_response({
                             status_code: statusCode,
@@ -121,10 +123,12 @@ class ProxyMiddlewareManager {
                         // Serve a clear SSL error instead of a misleading ERR_NAME_NOT_RESOLVED.
                         if ((0, handleUnreachableAddress_1.isCertificateError)(err)) {
                             const { status, contentType, body, errorToken } = (0, handleUnreachableAddress_1.dataToServeCertErrorPage)(host, err === null || err === void 0 ? void 0 : err.code);
-                            ctx.proxyToClientResponse.writeHead(status, http_1.default.STATUS_CODES[status], {
-                                "Content-Type": contentType,
-                                "x-rq-error": errorToken,
-                            });
+                            if (!ctx.proxyToClientResponse.headersSent) {
+                                ctx.proxyToClientResponse.writeHead(status, http_1.default.STATUS_CODES[status], {
+                                    "Content-Type": contentType,
+                                    "x-rq-error": errorToken,
+                                });
+                            }
                             ctx.proxyToClientResponse.end(body);
                             ctx.rq.set_final_response({
                                 status_code: status,
@@ -150,10 +154,12 @@ class ProxyMiddlewareManager {
                             const isAddressUnreachable = await (0, handleUnreachableAddress_1.isAddressUnreachableError)(hostname);
                             if (isAddressUnreachable) {
                                 const { status, contentType, body } = (0, handleUnreachableAddress_1.dataToServeUnreachablePage)(host);
-                                ctx.proxyToClientResponse.writeHead(status, http_1.default.STATUS_CODES[status], {
-                                    "Content-Type": contentType,
-                                    "x-rq-error": "ERR_NAME_NOT_RESOLVED"
-                                });
+                                if (!ctx.proxyToClientResponse.headersSent) {
+                                    ctx.proxyToClientResponse.writeHead(status, http_1.default.STATUS_CODES[status], {
+                                        "Content-Type": contentType,
+                                        "x-rq-error": "ERR_NAME_NOT_RESOLVED"
+                                    });
+                                }
                                 ctx.proxyToClientResponse.end(body);
                                 ctx.rq.set_final_response({
                                     status_code: status,
@@ -246,7 +252,11 @@ class ProxyMiddlewareManager {
                         delete responseHeaders['transfer-encoding'];
                         delete responseHeaders['Transfer-Encoding'];
                     }
-                    ctx.proxyToClientResponse.writeHead(statusCode, http_1.default.STATUS_CODES[statusCode], responseHeaders);
+                    // Node 24 commits headers on writeHead and throws on a second call;
+                    // guard so a re-entrant write can't crash the response pipeline.
+                    if (!ctx.proxyToClientResponse.headersSent) {
+                        ctx.proxyToClientResponse.writeHead(statusCode, http_1.default.STATUS_CODES[statusCode], responseHeaders);
+                    }
                     ctx.proxyToClientResponse.write(ctx.rq_response_body);
                     ctx.rq.set_final_response({
                         ...(0, proxy_ctx_helper_1.get_response_options)(ctx),
diff --git a/dist/components/proxy-middleware/rule_action_processor/index.js b/dist/components/proxy-middleware/rule_action_processor/index.js
index 8947148..4276fac 100644
--- a/dist/components/proxy-middleware/rule_action_processor/index.js
+++ b/dist/components/proxy-middleware/rule_action_processor/index.js
@@ -44,7 +44,9 @@ class RuleActionProcessor {
                 if (typeof (body) !== 'string') {
                     body = JSON.stringify(body);
                 }
-                ctx.proxyToClientResponse.writeHead(status_code, headers).end(body);
+                if (!ctx.proxyToClientResponse.headersSent) {
+                    ctx.proxyToClientResponse.writeHead(status_code, headers).end(body);
+                }
                 ctx.rq.request_finished = true;
                 ctx.rq.set_final_response({
                     status_code: status_code,
diff --git a/dist/lib/proxy/lib/proxy.js b/dist/lib/proxy/lib/proxy.js
index 7d6a4be..a36247e 100644
--- a/dist/lib/proxy/lib/proxy.js
+++ b/dist/lib/proxy/lib/proxy.js
@@ -915,7 +915,19 @@ Proxy.prototype._onHttpServerRequest = function (isSSL, clientToProxyRequest, pr
                 if (err) {
                     return self._onError("ON_RESPONSEHEADERS_ERROR", ctx, err);
                 }
-                ctx.proxyToClientResponse.writeHead(ctx.serverToProxyResponse.statusCode, Proxy.filterAndCanonizeHeaders(ctx.serverToProxyResponse.headers));
+                // NOTE (RQ / Node 24 + Electron 42 compat): do NOT writeHead eagerly here.
+                // The Requestly response middleware buffers the whole body (onResponseData
+                // returns no chunk) and writes the FINAL response — status, rule-modified
+                // headers, and body — in its onResponseEnd handler. Sending headers here
+                // caused a double writeHead: harmless on Node 18 (the later call overrode),
+                // but Node 24 commits headers on the first writeHead and throws
+                // ERR_HTTP_HEADERS_SENT on the second, breaking interception. Eager headers
+                // were also wrong — they predate the rule modifications computed at response
+                // end. The guard keeps the generic streaming path working when no
+                // response-end handler will write.
+                if (!ctx.proxyToClientResponse.headersSent && !ctx.onResponseEndHandlers.length) {
+                    ctx.proxyToClientResponse.writeHead(ctx.serverToProxyResponse.statusCode, Proxy.filterAndCanonizeHeaders(ctx.serverToProxyResponse.headers));
+                }
                 ctx.responseFilters.push(new ProxyFinalResponseFilter(self, ctx));
                 var prevResponsePipeElem = ctx.serverToProxyResponse;
                 ctx.responseFilters.forEach(function (filter) {
diff --git a/src/components/proxy-middleware/index.js b/src/components/proxy-middleware/index.js
index 19c461b..d47a8e4 100644
--- a/src/components/proxy-middleware/index.js
+++ b/src/components/proxy-middleware/index.js
@@ -158,11 +158,13 @@ class ProxyMiddlewareManager {
         if (modifyResponseActionExist) {
           const statusCode = ctx.rq_response_status_code || 404;
           const responseHeaders = getResponseHeaders(ctx) || {}
-          ctx.proxyToClientResponse.writeHead(
-              statusCode,
-              http.STATUS_CODES[statusCode],
-              responseHeaders
-            );
+          if (!ctx.proxyToClientResponse.headersSent) {
+            ctx.proxyToClientResponse.writeHead(
+                statusCode,
+                http.STATUS_CODES[statusCode],
+                responseHeaders
+              );
+          }
           ctx.proxyToClientResponse.end(ctx.rq_response_body);
 
           ctx.rq.set_final_response({
@@ -185,14 +187,16 @@ class ProxyMiddlewareManager {
           // Serve a clear SSL error instead of a misleading ERR_NAME_NOT_RESOLVED.
           if (isCertificateError(err)) {
             const { status, contentType, body, errorToken } = dataToServeCertErrorPage(host, err?.code);
-            ctx.proxyToClientResponse.writeHead(
-              status,
-              http.STATUS_CODES[status],
-              {
-                "Content-Type": contentType,
-                "x-rq-error": errorToken,
-              }
-            );
+            if (!ctx.proxyToClientResponse.headersSent) {
+              ctx.proxyToClientResponse.writeHead(
+                status,
+                http.STATUS_CODES[status],
+                {
+                  "Content-Type": contentType,
+                  "x-rq-error": errorToken,
+                }
+              );
+            }
             ctx.proxyToClientResponse.end(body);
             ctx.rq.set_final_response({
               status_code: status,
@@ -222,14 +226,16 @@ class ProxyMiddlewareManager {
             const isAddressUnreachable = await isAddressUnreachableError(hostname);
             if (isAddressUnreachable) {
               const { status, contentType, body } = dataToServeUnreachablePage(host);
-              ctx.proxyToClientResponse.writeHead(
-                status,
-                http.STATUS_CODES[status],
-                { 
-                  "Content-Type": contentType ,
-                  "x-rq-error": "ERR_NAME_NOT_RESOLVED"
-                }
-              );
+              if (!ctx.proxyToClientResponse.headersSent) {
+                ctx.proxyToClientResponse.writeHead(
+                  status,
+                  http.STATUS_CODES[status],
+                  {
+                    "Content-Type": contentType ,
+                    "x-rq-error": "ERR_NAME_NOT_RESOLVED"
+                  }
+                );
+              }
               ctx.proxyToClientResponse.end(body);
               ctx.rq.set_final_response({
                 status_code: status,
@@ -348,11 +354,15 @@ class ProxyMiddlewareManager {
           delete responseHeaders['Transfer-Encoding'];
         }
 
-        ctx.proxyToClientResponse.writeHead(
-          statusCode,
-          http.STATUS_CODES[statusCode],
-          responseHeaders,
-        );
+        // Node 24 commits headers on writeHead and throws on a second call;
+        // guard so a re-entrant write can't crash the response pipeline.
+        if (!ctx.proxyToClientResponse.headersSent) {
+          ctx.proxyToClientResponse.writeHead(
+            statusCode,
+            http.STATUS_CODES[statusCode],
+            responseHeaders,
+          );
+        }
 
         ctx.proxyToClientResponse.write(ctx.rq_response_body);
 
diff --git a/src/components/proxy-middleware/rule_action_processor/index.js b/src/components/proxy-middleware/rule_action_processor/index.js
index 8f8baa3..f1224e3 100644
--- a/src/components/proxy-middleware/rule_action_processor/index.js
+++ b/src/components/proxy-middleware/rule_action_processor/index.js
@@ -48,7 +48,9 @@ class RuleActionProcessor {
         body = JSON.stringify(body);
       }
 
-      ctx.proxyToClientResponse.writeHead(status_code, headers).end(body);
+      if (!ctx.proxyToClientResponse.headersSent) {
+        ctx.proxyToClientResponse.writeHead(status_code, headers).end(body);
+      }
       ctx.rq.request_finished = true;
 
       ctx.rq.set_final_response({
diff --git a/src/lib/proxy/lib/proxy.ts b/src/lib/proxy/lib/proxy.ts
index de79fd4..d315cd0 100644
--- a/src/lib/proxy/lib/proxy.ts
+++ b/src/lib/proxy/lib/proxy.ts
@@ -1080,10 +1080,22 @@ Proxy.prototype._onHttpServerRequest = function (
         if (err) {
           return self._onError("ON_RESPONSEHEADERS_ERROR", ctx, err);
         }
-        ctx.proxyToClientResponse.writeHead(
-          ctx.serverToProxyResponse.statusCode,
-          Proxy.filterAndCanonizeHeaders(ctx.serverToProxyResponse.headers)
-        );
+        // NOTE (RQ / Node 24 + Electron 42 compat): do NOT writeHead eagerly here.
+        // The Requestly response middleware buffers the whole body (onResponseData
+        // returns no chunk) and writes the FINAL response — status, rule-modified
+        // headers, and body — in its onResponseEnd handler. Sending headers here
+        // caused a double writeHead: harmless on Node 18 (the later call overrode),
+        // but Node 24 commits headers on the first writeHead and throws
+        // ERR_HTTP_HEADERS_SENT on the second, breaking interception. Eager headers
+        // were also wrong — they predate the rule modifications computed at response
+        // end. The guard keeps the generic streaming path working when no
+        // response-end handler will write.
+        if (!ctx.proxyToClientResponse.headersSent && !ctx.onResponseEndHandlers.length) {
+          ctx.proxyToClientResponse.writeHead(
+            ctx.serverToProxyResponse.statusCode,
+            Proxy.filterAndCanonizeHeaders(ctx.serverToProxyResponse.headers)
+          );
+        }
         ctx.responseFilters.push(new ProxyFinalResponseFilter(self, ctx));
         var prevResponsePipeElem = ctx.serverToProxyResponse;
         ctx.responseFilters.forEach(function (filter) {