fix(agent): address session and streaming concurrency bugs

tests/agent/test_runner_injections.py

@@ -554,6 +554,31 @@ async def test_pending_queue_cleanup_on_dispatch(tmp_path):
     assert msg.session_key not in loop._pending_queues
 
 
+@pytest.mark.asyncio
+async def test_waiting_dispatch_does_not_replace_active_pending_queue(tmp_path):
+    """A queued dispatch must not steal the active task's injection queue."""
+    from nanobot.bus.events import InboundMessage
+
+    loop = _make_loop(tmp_path)
+    session_key = "cli:c"
+    lock = loop._session_locks.setdefault(session_key, asyncio.Lock())
+    await lock.acquire()
+    active_pending = asyncio.Queue(maxsize=1)
+    loop._pending_queues[session_key] = active_pending
+
+    waiting = asyncio.create_task(
+        loop._dispatch(InboundMessage(channel="cli", sender_id="u", chat_id="c", content="queued"))
+    )
+    await asyncio.sleep(0.05)
+
+    assert loop._pending_queues[session_key] is active_pending
+
+    waiting.cancel()
+    with pytest.raises(asyncio.CancelledError):
+        await waiting
+    lock.release()
+
+
 @pytest.mark.asyncio
 async def test_followup_routed_to_pending_queue(tmp_path):
     """Unified-session follow-ups should route into the active pending queue."""