diff --git a/src/gateway/client.ts b/src/gateway/client.ts
index a29fa284c..3867b1f1c 100644
--- a/src/gateway/client.ts
+++ b/src/gateway/client.ts
@@ -8,7 +8,9 @@ import {
   type HelloOk,
   PROTOCOL_VERSION,
   type RequestFrame,
+  validateEventFrame,
   validateRequestFrame,
+  validateResponseFrame,
 } from "./protocol/index.js";
 
 type Pending = {
@@ -125,7 +127,7 @@ export class GatewayClient {
   private handleMessage(raw: string) {
     try {
       const parsed = JSON.parse(raw);
-      if (parsed?.type === "event") {
+      if (validateEventFrame(parsed)) {
         const evt = parsed as EventFrame;
         const seq = typeof evt.seq === "number" ? evt.seq : null;
         if (seq !== null) {
@@ -140,7 +142,7 @@ export class GatewayClient {
         this.opts.onEvent?.(evt);
         return;
       }
-      if (parsed?.type === "res") {
+      if (validateResponseFrame(parsed)) {
         const pending = this.pending.get(parsed.id);
         if (!pending) return;
         // If the payload is an ack with status accepted, keep waiting for final.
diff --git a/src/gateway/protocol/index.ts b/src/gateway/protocol/index.ts
index 42a46160a..02c7306b4 100644
--- a/src/gateway/protocol/index.ts
+++ b/src/gateway/protocol/index.ts
@@ -121,6 +121,9 @@ export const validateConnectParams =
   ajv.compile<ConnectParams>(ConnectParamsSchema);
 export const validateRequestFrame =
   ajv.compile<RequestFrame>(RequestFrameSchema);
+export const validateResponseFrame =
+  ajv.compile<ResponseFrame>(ResponseFrameSchema);
+export const validateEventFrame = ajv.compile<EventFrame>(EventFrameSchema);
 export const validateSendParams = ajv.compile(SendParamsSchema);
 export const validateAgentParams = ajv.compile(AgentParamsSchema);
 export const validateWakeParams = ajv.compile<WakeParams>(WakeParamsSchema);