diff --git a/codex-rs/core/tests/suite/input_validation.rs b/codex-rs/core/tests/suite/input_validation.rs
new file mode 100644
index 0000000000..3a284f1071
--- /dev/null
+++ b/codex-rs/core/tests/suite/input_validation.rs
@@ -0,0 +1,37 @@
+use codex_core::protocol::EventMsg;
+use codex_core::protocol::Op;
+use codex_protocol::user_input::UserInput;
+use core_test_support::responses::start_mock_server;
+use core_test_support::test_codex::test_codex;
+use core_test_support::wait_for_event_with_timeout;
+use std::sync::Arc;
+use std::time::Duration;
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn interrupt_tool_records_history_entries() {
+    let server = start_mock_server().await;
+
+    let fixture = test_codex().build(&server).await.unwrap();
+    let codex = Arc::clone(&fixture.codex);
+
+    let wait_timeout = Duration::from_millis(100);
+
+    let input_300_tokens = "token ".repeat(300_000);
+
+    codex
+        .submit(Op::UserInput {
+            items: vec![UserInput::Text {
+                text: input_300_tokens,
+            }],
+        })
+        .await
+        .unwrap();
+
+    let error_event =
+        wait_for_event_with_timeout(&codex, |ev| matches!(ev, EventMsg::Error(_)), wait_timeout)
+            .await;
+    let EventMsg::Error(error_event) = error_event else {
+        unreachable!("wait_for_event_with_timeout returned unexpected payload");
+    };
+    assert_eq!(error_event.message, "invalid input: input too large");
+}