diff --git a/loopx/attached_session.py b/loopx/attached_session.py
index 9a5715e7a9..cc77c6f776 100644
--- a/loopx/attached_session.py
+++ b/loopx/attached_session.py
@@ -181,9 +181,10 @@ def _require_attached_host(
     session_id: str,
     host_surface: str,
     host_session_id: str,
+    allow_closed: bool = False,
 ) -> dict[str, Any]:
     session = store.load_session(session_id)
-    if session is None or session.get("status") == "closed":
+    if session is None or (session.get("status") == "closed" and not allow_closed):
         raise KeyError("attached Agent session was not found")
     if session.get("session_mode") != CHAT_SESSION_MODE_ATTACHED:
         raise ValueError("the selected Session is not an attached host session")
@@ -273,6 +274,7 @@ def complete_attached_agent_turn(
         session_id=session_id,
         host_surface=host_surface,
         host_session_id=host_session_id,
+        allow_closed=True,
     )
     normalized_response = normalize_agent_response(
         response,
diff --git a/tests/test_attached_session_broker.py b/tests/test_attached_session_broker.py
index 29b429d2cf..46b3873eaa 100644
--- a/tests/test_attached_session_broker.py
+++ b/tests/test_attached_session_broker.py
@@ -608,6 +608,43 @@ def test_attached_close_rejects_active_claim_and_preserves_completion(
     assert runtime.wait_for_turn(session_id=session_id, turn_id=turn_id)["status"] == "completed"
     assert runtime.close_session(session_id) is True
     assert store.load_session(session_id)["status"] == "closed"  # type: ignore[index]
+    with pytest.raises(KeyError, match="attached Agent session was not found"):
+        claim_attached_agent_turn(
+            store=store,
+            session_id=session_id,
+            host_surface=HOST_SURFACE,
+            host_session_id=HOST_SESSION_ID,
+            claim_id="claim-after-close",
+        )
+
+    replay = complete_attached_agent_turn(
+        store=store,
+        session_id=session_id,
+        turn_id=turn_id,
+        host_surface=HOST_SURFACE,
+        host_session_id=HOST_SESSION_ID,
+        claim_id="close-active-claim",
+        completion_id="close-active-completion",
+        response={"message": "retry payload"},
+    )
+
+    assert replay["created"] is False
+    assert [
+        message["text"]
+        for message in store.messages(session_id)
+        if message["role"] == "agent"
+    ] == ["completed before close"]
+    with pytest.raises(ValueError, match="already completed by another receipt"):
+        complete_attached_agent_turn(
+            store=store,
+            session_id=session_id,
+            turn_id=turn_id,
+            host_surface=HOST_SURFACE,
+            host_session_id=HOST_SESSION_ID,
+            claim_id="close-active-claim",
+            completion_id="different-receipt",
+            response={"message": "conflicting retry"},
+        )
 
 
 def test_attached_close_rejects_pending_queue_and_preserves_claimability(