test: align MCP transient reconnect coverage

maintainer edit: update the existing transient retry tests for reconnect-first behavior and keep structured retry-failure coverage in the focused MCP transient suite.

tests/agent/test_mcp_transient_retry.py

@@ -16,6 +16,7 @@ from nanobot.agent.tools.mcp import (
     _is_session_terminated,
     _is_transient,
 )
+from nanobot.agent.tools.registry import is_tool_error_result
 
 # ---------------------------------------------------------------------------
 # _is_transient helper
@@ -134,6 +135,7 @@ async def test_tool_fails_after_retry_exhausted():
 
     assert "failed after retry" in output
     assert "ClosedResourceError" in output
+    assert is_tool_error_result(wrapper.name, output)
     assert session.call_tool.call_count == 2
 
 
@@ -237,12 +239,10 @@ async def test_tool_retry_on_end_of_stream():
 
 
 @pytest.mark.asyncio
-async def test_tool_reconnects_when_transient_retry_reveals_terminated_session():
-    """Tool should reconnect if a stale session reports termination after transient retry."""
+async def test_tool_reconnects_on_transient_failure():
+    """Tool should reconnect when a stale session reports a transient stream failure."""
     old_session = AsyncMock()
-    old_session.call_tool = AsyncMock(
-        side_effect=[_FakeClosedResourceError("closed"), _session_terminated_error()]
-    )
+    old_session.call_tool = AsyncMock(side_effect=_FakeClosedResourceError("closed"))
     new_session = AsyncMock()
     new_session.call_tool = AsyncMock(return_value=_make_tool_result("fresh"))
 
@@ -257,12 +257,13 @@ async def test_tool_reconnects_when_transient_retry_reveals_terminated_session()
 
     wrapper.set_reconnect_handler(reconnect)
 
-    with patch("nanobot.agent.tools.mcp.asyncio.sleep", new_callable=AsyncMock):
+    with patch("nanobot.agent.tools.mcp.asyncio.sleep", new_callable=AsyncMock) as mock_sleep:
         output = await wrapper.execute(foo="bar")
 
     assert output == "fresh"
-    assert old_session.call_tool.call_count == 2
+    assert old_session.call_tool.call_count == 1
     assert new_session.call_tool.call_count == 1
+    mock_sleep.assert_not_called()
 
 
 # ---------------------------------------------------------------------------