diff --git a/agent/chat_completion_helpers.py b/agent/chat_completion_helpers.py
index 4b000372b39..d2dc4745c03 100644
--- a/agent/chat_completion_helpers.py
+++ b/agent/chat_completion_helpers.py
@@ -1525,8 +1525,10 @@ def handle_max_iterations(agent, messages: list, api_call_count: int) -> str:
             # hand-builds messages and calls chat.completions.create() directly,
             # bypassing the transport — so mirror that sanitization here:
             # tool_name (SQLite FTS bookkeeping), the codex_* reasoning carriers,
+            # timestamp (preserved on gateway user replay entries for the
+            # stale-confirmation expiry check — #47868 rejection class),
             # and every Hermes-internal underscore-prefixed scaffolding key.
-            for schema_foreign in ("tool_name", "codex_reasoning_items", "codex_message_items"):
+            for schema_foreign in ("tool_name", "codex_reasoning_items", "codex_message_items", "timestamp"):
                 api_msg.pop(schema_foreign, None)
             for internal_key in [k for k in api_msg if isinstance(k, str) and k.startswith("_")]:
                 api_msg.pop(internal_key, None)