diff --git a/SANDBOX_DEMO.md b/SANDBOX_DEMO.md
new file mode 100644
index 0000000..3171099
--- /dev/null
+++ b/SANDBOX_DEMO.md
@@ -0,0 +1,4 @@
+# gVisor sandbox demo
+
+This file was created by an AI agent running inside a gVisor-isolated pod
+(kernel 4.19.0-gvisor) on browserstack-euc1-stag-001, as a PoC of sandboxed agent execution.