fix(webui): deliver late subagent results as new turns (#4992)

tests/agent/test_turn_delivery.py

@@ -0,0 +1,60 @@
+from pathlib import Path
+
+from nanobot.agent.turn_delivery import TurnDeliveryFactory
+from nanobot.bus.events import InboundMessage
+from nanobot.bus.queue import MessageBus
+from nanobot.bus.runtime_events import RuntimeEventBus
+from nanobot.session.manager import SessionManager
+from nanobot.session.webui_turns import WebuiTurnRoutePolicy
+from nanobot.webui.metadata import WEBUI_TURN_METADATA_KEY
+
+
+def test_late_subagent_route_requires_webui_owned_session(tmp_path: Path) -> None:
+    sessions = SessionManager(tmp_path)
+    factory = TurnDeliveryFactory(
+        MessageBus(),
+        RuntimeEventBus(),
+        route_policy=WebuiTurnRoutePolicy(sessions),
+    )
+    session_key = "websocket:chat-a"
+    msg = InboundMessage(
+        channel="system",
+        sender_id="subagent",
+        chat_id=session_key,
+        content="Background research completed",
+        session_key_override=session_key,
+        metadata={
+            "injected_event": "subagent_result",
+            "subagent_task_id": "sub-1",
+        },
+    )
+
+    hidden_route = factory.create(msg, session_key).route
+
+    assert hidden_route.channel == "websocket"
+    assert hidden_route.chat_id == "chat-a"
+    assert hidden_route.metadata == {}
+    assert hidden_route.publish_lifecycle is False
+
+    session = sessions.get_or_create(session_key)
+    session.metadata["webui"] = True
+    first_visible_route = factory.create(msg, session_key).route
+    second_visible_route = factory.create(msg, session_key).route
+
+    assert first_visible_route.publish_lifecycle is True
+    assert set(first_visible_route.metadata) == {
+        "webui",
+        "_wants_stream",
+        WEBUI_TURN_METADATA_KEY,
+    }
+    assert first_visible_route.metadata["webui"] is True
+    assert first_visible_route.metadata["_wants_stream"] is True
+    first_turn_id = first_visible_route.metadata[WEBUI_TURN_METADATA_KEY]
+    second_turn_id = second_visible_route.metadata[WEBUI_TURN_METADATA_KEY]
+    assert first_turn_id.startswith("subagent:")
+    assert second_turn_id.startswith("subagent:")
+    assert first_turn_id != second_turn_id
+    assert msg.metadata == {
+        "injected_event": "subagent_result",
+        "subagent_task_id": "sub-1",
+    }