diff --git a/server/src/agents/pty/mod.rs b/server/src/agents/pty/mod.rs
index a672b496..f81a40fc 100644
--- a/server/src/agents/pty/mod.rs
+++ b/server/src/agents/pty/mod.rs
@@ -208,21 +208,19 @@ mod tests {
     /// by the backoff duration so the watchdog doesn't kill the agent while
     /// it's legitimately waiting for the limit to clear.
     ///
-    /// Script emits a hard-block event with reset_at = now + 3s, then sleeps
-    /// 3s, then exits.  With inactivity_timeout_secs = 1, the run would fail
-    /// without the extension; with it, the deadline is bumped to ~4s and the
-    /// script gets to complete cleanly.
+    /// Script emits a hard-block event with reset_at in the far future, then
+    /// sleeps 3s, then exits.  With inactivity_timeout_secs = 1, the run
+    /// would normally fail at the 1s mark; with the extension the deadline
+    /// is bumped past the sleep and the script completes cleanly.  The
+    /// far-future reset_at avoids wall-clock races under cargo-test load.
     #[tokio::test]
     async fn rate_limit_hard_block_extends_inactivity_deadline() {
         use std::os::unix::fs::PermissionsExt;
 
         let tmp = tempfile::tempdir().unwrap();
         let script = tmp.path().join("emit_then_wait.sh");
-        let reset_at = chrono::Utc::now() + chrono::Duration::seconds(3);
-        let reset_at_str = reset_at.to_rfc3339_opts(chrono::SecondsFormat::Secs, true);
-        let body = format!(
-            "#!/bin/sh\nprintf '%s\\n' '{{\"type\":\"rate_limit_event\",\"rate_limit_info\":{{\"status\":\"hard_block\",\"reset_at\":\"{reset_at_str}\"}}}}'\nsleep 3\n"
-        );
+        let body =
+            "#!/bin/sh\nprintf '%s\\n' '{\"type\":\"rate_limit_event\",\"rate_limit_info\":{\"status\":\"hard_block\",\"reset_at\":\"2099-01-01T12:00:00Z\"}}'\nsleep 3\n";
         std::fs::write(&script, body).unwrap();
         std::fs::set_permissions(&script, std::fs::Permissions::from_mode(0o755)).unwrap();