diff --git a/nanobot/nanobot.py b/nanobot/nanobot.py
index 6c9951ed8..3c1654cb0 100644
--- a/nanobot/nanobot.py
+++ b/nanobot/nanobot.py
@@ -302,7 +302,7 @@ class Nanobot:
                 ))
                 raise
             finally:
-                emitter.close()
+                await emitter.close()
 
         task = asyncio.create_task(_run())
         return RunStream(task, queue)
diff --git a/nanobot/sdk/streaming.py b/nanobot/sdk/streaming.py
index 1abfd64fc..b8036bd67 100644
--- a/nanobot/sdk/streaming.py
+++ b/nanobot/sdk/streaming.py
@@ -158,15 +158,11 @@ class SDKStreamEmitter:
             resuming=resuming,
         ))
 
-    def close(self) -> None:
+    async def close(self) -> None:
         if self._closed:
             return
         self._closed = True
-        if self._queue.full():
-            with suppress(asyncio.QueueEmpty):
-                self._queue.get_nowait()
-        with suppress(asyncio.QueueFull):
-            self._queue.put_nowait(_STREAM_SENTINEL)
+        await self._queue.put(_STREAM_SENTINEL)
 
 
 class SDKStreamingHook(AgentHook):
diff --git a/tests/test_sdk_streaming.py b/tests/test_sdk_streaming.py
new file mode 100644
index 000000000..a292315d8
--- /dev/null
+++ b/tests/test_sdk_streaming.py
@@ -0,0 +1,24 @@
+"""Tests for SDK streaming primitives."""
+
+import asyncio
+
+import pytest
+
+from nanobot.sdk.streaming import SDKStreamEmitter
+from nanobot.sdk.types import STREAM_EVENT_TEXT_DELTA, StreamEvent
+
+
+@pytest.mark.asyncio
+async def test_close_preserves_events_when_queue_is_full():
+    queue: asyncio.Queue[StreamEvent | object] = asyncio.Queue(maxsize=1)
+    emitter = SDKStreamEmitter(queue)
+    event = StreamEvent(type=STREAM_EVENT_TEXT_DELTA, delta="kept")
+    await emitter.emit(event)
+
+    close_task = asyncio.create_task(emitter.close())
+    await asyncio.sleep(0)
+
+    assert not close_task.done()
+    assert queue.get_nowait() is event
+    await close_task
+    assert queue.qsize() == 1