diff --git a/codex-rs/protocol/src/protocol.rs b/codex-rs/protocol/src/protocol.rs
index f103357074..b8c81c3491 100644
--- a/codex-rs/protocol/src/protocol.rs
+++ b/codex-rs/protocol/src/protocol.rs
@@ -500,6 +500,7 @@ pub struct Event {
     pub id: String,
     /// Optional agent identifier associated with this event.
     #[serde(default, skip_serializing_if = "Option::is_none")]
+    #[ts(optional)]
     pub agent_id: Option<AgentId>,
     /// Payload
     pub msg: EventMsg,