diff --git a/.changeset/disable-headers-timeout.md b/.changeset/disable-headers-timeout.md
new file mode 100644
index 00000000..428394fe
--- /dev/null
+++ b/.changeset/disable-headers-timeout.md
@@ -0,0 +1,5 @@
+---
+"@vercel/sandbox": patch
+---
+
+Disable `headersTimeout` on the default undici Agent so long-running `cmd.wait()` long-polls don't abort at undici's 5-minute default. Previously `bodyTimeout` was disabled but `headersTimeout` was left at the default, which cut off `cmd.wait()` when a sandbox command took longer than 5 minutes — even though the sandbox itself was still alive.
diff --git a/packages/vercel-sandbox/src/api-client/base-client.ts b/packages/vercel-sandbox/src/api-client/base-client.ts
index 42f83424..209997a7 100644
--- a/packages/vercel-sandbox/src/api-client/base-client.ts
+++ b/packages/vercel-sandbox/src/api-client/base-client.ts
@@ -15,6 +15,7 @@ export interface RequestParams extends RequestInit {
 
 const DEFAULT_AGENT = new Agent({
   bodyTimeout: 0, // disable body timeout to allow long logs streaming
+  headersTimeout: 0, // disable headers timeout so long-poll cmd.wait() doesn't abort after undici's 5-min default
 });
 
 /**