diff --git a/src/gateway/call.ts b/src/gateway/call.ts
index 001410a739e..582810c24d0 100644
--- a/src/gateway/call.ts
+++ b/src/gateway/call.ts
@@ -800,6 +800,11 @@ async function executeGatewayRequestWithScopes<T>(params: {
 }): Promise<T> {
   const { opts, scopes, url, token, password, tlsFingerprint, timeoutMs, safeTimerTimeoutMs } =
     params;
+  // Yield to the event loop before starting the WebSocket connection.
+  // On Windows with large dist bundles, heavy synchronous module loading
+  // can starve the event loop, preventing timely processing of the
+  // connect.challenge frame and causing handshake timeouts (#48736).
+  await new Promise<void>((r) => setImmediate(r));
   return await new Promise<T>((resolve, reject) => {
     let settled = false;
     let ignoreClose = false;
diff --git a/src/gateway/client.ts b/src/gateway/client.ts
index 7a22cae41b6..eeedc4e562a 100644
--- a/src/gateway/client.ts
+++ b/src/gateway/client.ts
@@ -727,12 +727,18 @@ export class GatewayClient {
 
   private armConnectChallengeTimeout() {
     const connectChallengeTimeoutMs = resolveGatewayClientConnectChallengeTimeoutMs(this.opts);
+    const armedAt = Date.now();
     this.clearConnectChallengeTimeout();
     this.connectTimer = setTimeout(() => {
       if (this.connectSent || this.ws?.readyState !== WebSocket.OPEN) {
         return;
       }
-      this.opts.onConnectError?.(new Error("gateway connect challenge timeout"));
+      const elapsedMs = Date.now() - armedAt;
+      this.opts.onConnectError?.(
+        new Error(
+          `gateway connect challenge timeout (waited ${elapsedMs}ms, limit ${connectChallengeTimeoutMs}ms)`,
+        ),
+      );
       this.ws?.close(1008, "connect challenge timeout");
     }, connectChallengeTimeoutMs);
   }
diff --git a/src/gateway/handshake-timeouts.test.ts b/src/gateway/handshake-timeouts.test.ts
index 13fe14ea746..9feccdab8ef 100644
--- a/src/gateway/handshake-timeouts.test.ts
+++ b/src/gateway/handshake-timeouts.test.ts
@@ -2,6 +2,7 @@ import { describe, expect, test } from "vitest";
 import {
   clampConnectChallengeTimeoutMs,
   DEFAULT_PREAUTH_HANDSHAKE_TIMEOUT_MS,
+  getConnectChallengeTimeoutMsFromEnv,
   getPreauthHandshakeTimeoutMsFromEnv,
   MAX_CONNECT_CHALLENGE_TIMEOUT_MS,
   MIN_CONNECT_CHALLENGE_TIMEOUT_MS,
@@ -34,4 +35,30 @@ describe("gateway handshake timeouts", () => {
       }),
     ).toBe(20);
   });
+
+  test("getConnectChallengeTimeoutMsFromEnv reads OPENCLAW_CONNECT_CHALLENGE_TIMEOUT_MS", () => {
+    expect(getConnectChallengeTimeoutMsFromEnv({})).toBeUndefined();
+    expect(
+      getConnectChallengeTimeoutMsFromEnv({ OPENCLAW_CONNECT_CHALLENGE_TIMEOUT_MS: "15000" }),
+    ).toBe(15_000);
+    expect(
+      getConnectChallengeTimeoutMsFromEnv({ OPENCLAW_CONNECT_CHALLENGE_TIMEOUT_MS: "garbage" }),
+    ).toBeUndefined();
+  });
+
+  test("resolveConnectChallengeTimeoutMs falls back to env override", () => {
+    const original = process.env.OPENCLAW_CONNECT_CHALLENGE_TIMEOUT_MS;
+    try {
+      process.env.OPENCLAW_CONNECT_CHALLENGE_TIMEOUT_MS = "5000";
+      expect(resolveConnectChallengeTimeoutMs()).toBe(5_000);
+      // Explicit value still takes precedence over env
+      expect(resolveConnectChallengeTimeoutMs(3_000)).toBe(3_000);
+    } finally {
+      if (original === undefined) {
+        delete process.env.OPENCLAW_CONNECT_CHALLENGE_TIMEOUT_MS;
+      } else {
+        process.env.OPENCLAW_CONNECT_CHALLENGE_TIMEOUT_MS = original;
+      }
+    }
+  });
 });
diff --git a/src/gateway/handshake-timeouts.ts b/src/gateway/handshake-timeouts.ts
index 1911db22658..545d3e72d65 100644
--- a/src/gateway/handshake-timeouts.ts
+++ b/src/gateway/handshake-timeouts.ts
@@ -9,10 +9,28 @@ export function clampConnectChallengeTimeoutMs(timeoutMs: number): number {
   );
 }
 
+export function getConnectChallengeTimeoutMsFromEnv(
+  env: NodeJS.ProcessEnv = process.env,
+): number | undefined {
+  const raw = env.OPENCLAW_CONNECT_CHALLENGE_TIMEOUT_MS;
+  if (raw) {
+    const parsed = Number(raw);
+    if (Number.isFinite(parsed) && parsed > 0) {
+      return parsed;
+    }
+  }
+  return undefined;
+}
+
 export function resolveConnectChallengeTimeoutMs(timeoutMs?: number | null): number {
-  return typeof timeoutMs === "number" && Number.isFinite(timeoutMs)
-    ? clampConnectChallengeTimeoutMs(timeoutMs)
-    : DEFAULT_PREAUTH_HANDSHAKE_TIMEOUT_MS;
+  if (typeof timeoutMs === "number" && Number.isFinite(timeoutMs)) {
+    return clampConnectChallengeTimeoutMs(timeoutMs);
+  }
+  const envOverride = getConnectChallengeTimeoutMsFromEnv();
+  if (envOverride !== undefined) {
+    return clampConnectChallengeTimeoutMs(envOverride);
+  }
+  return DEFAULT_PREAUTH_HANDSHAKE_TIMEOUT_MS;
 }
 
 export function getPreauthHandshakeTimeoutMsFromEnv(env: NodeJS.ProcessEnv = process.env): number {