test: improve deterministic unit test coverage

tests/agent/test_task_cancel.py

@@ -27,8 +27,8 @@ def _make_loop(*, tools_config=None):
 
     with patch("nanobot.agent.loop.ContextBuilder"), \
          patch("nanobot.agent.loop.SessionManager"), \
-         patch("nanobot.agent.loop.SubagentManager") as MockSubMgr:
-        MockSubMgr.return_value.cancel_by_session = AsyncMock(return_value=0)
+         patch("nanobot.agent.loop.SubagentManager") as mock_sub_mgr:
+        mock_sub_mgr.return_value.cancel_by_session = AsyncMock(return_value=0)
         loop = AgentLoop(bus=bus, provider=provider, workspace=workspace, tools_config=tools_config)
     return loop, bus
 
@@ -103,8 +103,8 @@ class TestHandleStop:
 
 class TestDispatch:
     def test_exec_tool_not_registered_when_disabled(self):
-        from nanobot.config.schema import ToolsConfig
         from nanobot.agent.tools.shell import ExecToolConfig
+        from nanobot.config.schema import ToolsConfig
 
         loop, _bus = _make_loop(tools_config=ToolsConfig(exec=ExecToolConfig(enable=False)))
 
@@ -166,10 +166,14 @@ class TestDispatch:
 
         loop, bus = _make_loop()
         order = []
+        first_started = asyncio.Event()
+        release_first = asyncio.Event()
 
         async def mock_process(m, **kwargs):
             order.append(f"start-{m.content}")
-            await asyncio.sleep(0.05)
+            if m.content == "a":
+                first_started.set()
+                await release_first.wait()
             order.append(f"end-{m.content}")
             return OutboundMessage(channel="test", chat_id="c1", content=m.content)
 
@@ -178,7 +182,12 @@ class TestDispatch:
         msg2 = InboundMessage(channel="test", sender_id="u1", chat_id="c1", content="b")
 
         t1 = asyncio.create_task(loop._dispatch(msg1))
+        await asyncio.wait_for(first_started.wait(), timeout=1.0)
         t2 = asyncio.create_task(loop._dispatch(msg2))
+        await asyncio.sleep(0)
+        assert order == ["start-a"]
+
+        release_first.set()
         await asyncio.gather(t1, t2)
         assert order == ["start-a", "end-a", "start-b", "end-b"]
 
@@ -286,8 +295,8 @@ class TestSubagentCancellation:
     @pytest.mark.asyncio
     async def test_subagent_exec_tool_not_registered_when_disabled(self, tmp_path):
         from nanobot.agent.subagent import SubagentManager
-        from nanobot.bus.queue import MessageBus
         from nanobot.agent.tools.shell import ExecToolConfig
+        from nanobot.bus.queue import MessageBus
         from nanobot.config.schema import ToolsConfig
 
         bus = MessageBus()