diff --git a/tests/protocol/test_conn_writer.py b/tests/protocol/test_conn_writer.py
index c3c25b8..254a168 100644
--- a/tests/protocol/test_conn_writer.py
+++ b/tests/protocol/test_conn_writer.py
@@ -11,8 +11,8 @@
 import threading
 
 from tests.protocol._fakes import FakeTransport
-from trpc_sdk.protocol import ConnWriter
-from trpc_sdk.protocol import _conn_writer
+from trpc_sdk.transport import ConnWriter
+from trpc_sdk.transport._server import _conn_writer
 
 
 def test_still_importable_from_runtime_package():
diff --git a/tests/protocol/test_session_id.py b/tests/protocol/test_session_id.py
index 9c5a7a3..0a58ae9 100644
--- a/tests/protocol/test_session_id.py
+++ b/tests/protocol/test_session_id.py
@@ -17,8 +17,8 @@
 from tests.protocol._fakes import stream_frame
 from tests.protocol._fakes import unary_frame
 from trpc_sdk.abc import get_message
-from trpc_sdk.protocol import TCPConnection
-from trpc_sdk.protocol._cython import _tcp_protocol
+from trpc_sdk.transport import TCPConnection
+from trpc_sdk.transport._server._cython import _tcp_protocol
 from trpc_sdk.transport import TcpConnectionOption
 
 
diff --git a/tests/server/test_stream_thread_model.py b/tests/server/test_stream_thread_model.py
index 621f146..760e7cd 100644
--- a/tests/server/test_stream_thread_model.py
+++ b/tests/server/test_stream_thread_model.py
@@ -17,8 +17,8 @@
 from tests.protocol._fakes import stream_frame
 from tests.protocol._fakes import unary_frame
 from trpc_sdk.abc import STREAM_WRITER_CTX_KEY
-from trpc_sdk.protocol import ConnWriter
-from trpc_sdk.protocol import TCPConnection
+from trpc_sdk.transport import ConnWriter
+from trpc_sdk.transport import TCPConnection
 from trpc_sdk.server._server import Server
 from trpc_sdk.transport import TcpConnectionOption
 
diff --git a/tests/transport/test_default_io_connection.py b/tests/transport/test_default_io_connection.py
index 9d79016..f9b9b34 100644
--- a/tests/transport/test_default_io_connection.py
+++ b/tests/transport/test_default_io_connection.py
@@ -13,7 +13,7 @@
 from tests.protocol._fakes import ParserFactory
 from tests.protocol._fakes import FakeTransport
 from trpc_sdk.abc import BaseServerTransportOption
-from trpc_sdk.protocol import TCPConnection
+from trpc_sdk.transport import TCPConnection
 from trpc_sdk.transport import ConnectionOption
 from trpc_sdk.transport import DefaultIoConnection
 from trpc_sdk.transport import TrpcServerTransport
diff --git a/trpc_sdk/protocol/__init__.py b/trpc_sdk/protocol/__init__.py
deleted file mode 100644
index 12dba0f..0000000
--- a/trpc_sdk/protocol/__init__.py
+++ /dev/null
@@ -1,43 +0,0 @@
-# Tencent is pleased to support the open source community by making tRPC-Python available.
-#
-# Copyright (C) 2026 Tencent. All rights reserved.
-#
-# tRPC-Python is licensed under Apache-2.0.
-
-"""tRPC-Python protocol package: asyncio Protocol bound to a listen socket.
-
-Public symbols are re-exported here. Callers should ``from trpc.protocol
-import ...``.
-
-This package owns the **in-process TCP Protocol** used by merge workers
-and multi-listener executors: the Protocol is attached to the accepted
-client socket, a per-connection parser splits the byte stream into
-frames, and each complete frame is scheduled as an asyncio task that
-runs the service handler and writes the response on the same
-connection.
-
-It is not the codec (what a frame means) and not the transport process
-model (how frames travel between dispatcher / worker / task). Those
-live in :mod:`trpc.codec` and :mod:`trpc.transport`. The UDP counterpart
-on the same listen path is
-:class:`trpc.transport.DefaultDatagramConnection`.
-
-Modules:
-
-- :mod:`~trpc_sdk.protocol._cython._tcp_protocol` — :class:`TCPConnection` and
-  :func:`handle_request`
-- :mod:`~trpc_sdk.protocol._conn_writer` — :class:`ConnWriter`, the handle
-  that writes on a connection's transport from any thread
-"""
-
-from __future__ import annotations
-
-from ._conn_writer import ConnWriter
-from ._cython import TCPConnection  # pylint: disable=no-name-in-module
-from ._cython import handle_request  # pylint: disable=no-name-in-module
-
-__all__ = [
-    "ConnWriter",
-    "TCPConnection",
-    "handle_request",
-]
diff --git a/trpc_sdk/runtime/__init__.py b/trpc_sdk/runtime/__init__.py
index 7f14cf9..69497e4 100644
--- a/trpc_sdk/runtime/__init__.py
+++ b/trpc_sdk/runtime/__init__.py
@@ -54,7 +54,7 @@
   :class:`~trpc_sdk.runtime._threadmodel._separate_thread.SeparateThread`
   for merge mode with the separate thread model (trpc-cpp
   ``runtime/threadmodel`` and ``separate_runtime``); responses cross back
-  to the I/O loops through :class:`~trpc_sdk.protocol.ConnWriter`,
+  to the I/O loops through :class:`~trpc_sdk.transport.ConnWriter`,
   re-exported here
 - :mod:`~trpc_sdk.runtime._common` — SIGTERM callbacks, process metadata and the exit template every mode shares (trpc-cpp
   ``runtime/common``)
@@ -77,7 +77,7 @@
 re-exports :func:`register_protocol_handle`.
 """
 
-from trpc_sdk.protocol import ConnWriter
+from trpc_sdk.transport import ConnWriter
 from trpc_sdk.transport import register_protocol_handle
 
 from ._common import ProcessInfo
diff --git a/trpc_sdk/runtime/_threadmodel/_loop_thread.py b/trpc_sdk/runtime/_threadmodel/_loop_thread.py
index 30147fd..c7e32ea 100644
--- a/trpc_sdk/runtime/_threadmodel/_loop_thread.py
+++ b/trpc_sdk/runtime/_threadmodel/_loop_thread.py
@@ -27,7 +27,7 @@
 ``transport.write()`` from another thread is not safe. That is why every
 serving loop opens its own connections to the task processes, and why the
 separate thread model hands responses back through
-:class:`~trpc_sdk.protocol.ConnWriter`.
+:class:`~trpc_sdk.transport.ConnWriter`.
 
 A loop thread that dies while the worker is serving is not left behind
 silently: its ``on_exit`` callback tells the worker, which shuts the process
diff --git a/trpc_sdk/runtime/_threadmodel/_separate_thread.py b/trpc_sdk/runtime/_threadmodel/_separate_thread.py
index f063e48..441fdea 100644
--- a/trpc_sdk/runtime/_threadmodel/_separate_thread.py
+++ b/trpc_sdk/runtime/_threadmodel/_separate_thread.py
@@ -23,7 +23,7 @@
 thread through
 :class:`~trpc_sdk.runtime._threadmodel._handler_pool.SharedHandlerPool`, and
 the handle thread hands the response back through the connection's
-:class:`~trpc_sdk.protocol.ConnWriter`. Requests of one connection
+:class:`~trpc_sdk.transport.ConnWriter`. Requests of one connection
 may therefore run on several handle threads and complete out of order, which
 tRPC already allows: responses are matched by request id.
 
diff --git a/trpc_sdk/transport/__init__.py b/trpc_sdk/transport/__init__.py
index 73e9697..e95f512 100644
--- a/trpc_sdk/transport/__init__.py
+++ b/trpc_sdk/transport/__init__.py
@@ -21,11 +21,10 @@
   accepts the client TCP, splits frames, and writes them to an rpc task
   pipe; :class:`RpcTaskConnection` on the rpc task runs the handler and
   writes the response back
-- merge mode: :class:`DefaultDatagramConnection` and the re-exported
-  :class:`TCPConnection` listen on the merge worker. The TCP Protocol is
-  owned by :mod:`trpc_sdk.protocol`; this package only forwards the name
-  so :class:`~trpc_sdk.runtime.MergeWorker` can import both listen
-  protocols from here.
+- merge mode: :class:`DefaultDatagramConnection` and
+  :class:`TCPConnection` listen on the merge worker. Both live in
+  :mod:`trpc_sdk.transport._server`, so a merge worker imports them from
+  here.
 
 The package is split by responsibility:
 
@@ -44,9 +43,11 @@
   ``UserProtocolTransport`` with the ``register_protocol_handle`` registry,
   the plugin factory (``DefaultServerTransport*``,
   :func:`get_server_transport`), and the accepted connections:
-  ``TcpConnectionOption`` for the Cython ``TCPConnection``,
-  ``DefaultIoConnection`` with its ``ConnectionOption`` for subclasses
-  calling ``set_io_connection``, ``DefaultDatagramConnection`` for UDP listen
+  ``TcpConnectionOption`` and the Cython ``TCPConnection``
+  (:mod:`~trpc_sdk.transport._server._cython`), ``ConnWriter`` for
+  cross-thread writes, ``DefaultIoConnection`` with its ``ConnectionOption``
+  for subclasses calling ``set_io_connection``,
+  ``DefaultDatagramConnection`` for UDP listen
   sockets (built from the same ``ConnectionOption``), and
   ``ServerConnection``, the peer view both hand to ``_msg_handler``
 - :mod:`~trpc_sdk.transport._separate` — the asyncio protocols on both ends
@@ -68,8 +69,6 @@
 
 from __future__ import annotations
 
-from importlib import import_module
-
 from trpc_sdk.abc import BaseServerTransportOption
 
 from ._cython import InnerStreamParser  # pylint: disable=no-name-in-module
@@ -103,6 +102,7 @@
 from ._client import get_client_transport
 from ._client import get_default_client_transport
 from ._client import open_datagram_endpoint
+from ._server import ConnWriter
 from ._server import ConnectionCloseHandler
 from ._server import ConnectionIdleCleanHandler
 from ._server import ConnectionInitHandler
@@ -115,6 +115,7 @@
 from ._server import MsgHandler
 from ._server import ProtocolStarter
 from ._server import ServerConnection
+from ._server import TCPConnection
 from ._server import TcpConnectionOption
 from ._server import TrpcServerStreamTransport
 from ._server import TrpcServerTransport
@@ -152,6 +153,8 @@
     "TrpcServerStreamTransport",
     "UserProtocolTransport",
     "IpcStreamWriter",
+    "ConnWriter",
+    "TCPConnection",
     "TcpConnectionOption",
     "DefaultIoConnection",
     "ConnectionOption",
@@ -177,8 +180,6 @@
     "SeparateRpczConnection",
     # Separate-mode rpc task protocol
     "RpcTaskConnection",
-    # Executor / merge-worker listen protocols
-    "TCPConnection",
     # Shared types and hooks
     "ClientConnectionInfo",
     "SchedulerParams",
@@ -192,24 +193,3 @@
     "InnerStreamParser",
     "encode_worker_msg_req",
 ]
-
-
-_LAZY_EXPORTS = {
-    "TCPConnection": ("trpc_sdk.protocol", "TCPConnection"),
-}
-
-
-def __getattr__(name: str):
-    """Lazily export symbols that would otherwise load too early.
-
-    :class:`TCPConnection` is owned by :mod:`trpc_sdk.protocol` and is only
-    needed once a merge worker is already serving. Resolving it on first
-    access is enough.
-    """
-    spec = _LAZY_EXPORTS.get(name)
-    if spec is None:
-        raise AttributeError(f"module {__name__!r} has no attribute {name!r}")
-    module_name, attr_name = spec
-    value = getattr(import_module(module_name, package=__name__), attr_name)
-    globals()[name] = value
-    return value
diff --git a/trpc_sdk/transport/_server/__init__.py b/trpc_sdk/transport/_server/__init__.py
index a9a766e..ca4be9e 100644
--- a/trpc_sdk/transport/_server/__init__.py
+++ b/trpc_sdk/transport/_server/__init__.py
@@ -33,6 +33,11 @@
   ``set_io_connection``, with its :class:`ConnectionOption` and the
   ``MsgHandler`` / ``Connection*Handler`` callback types it holds; and
   :class:`ServerConnection`, the peer view ``_msg_handler`` reads
+- :mod:`~trpc_sdk.transport._server._cython` — :class:`TCPConnection`, the
+  Cython asyncio Protocol for one accepted client TCP socket, and
+  :func:`handle_request`
+- :mod:`~trpc_sdk.transport._server._conn_writer` — :class:`ConnWriter`, the
+  handle that writes on a connection's transport from any thread
 - :mod:`~trpc_sdk.transport._server._datagram_connection` —
   :class:`DefaultDatagramConnection`, the datagram protocol of a
   tRPC-over-UDP listen socket, which builds one peer view per datagram
@@ -53,6 +58,8 @@
 from ._acceptor import Acceptor
 from ._acceptor import StreamListener
 from ._acceptor import serve_stream
+from ._conn_writer import ConnWriter
+from ._cython import TCPConnection  # pylint: disable=no-name-in-module
 from ._datagram_connection import DefaultDatagramConnection
 from ._stream_connection import BaseConnection
 from ._stream_connection import ConnectionCloseHandler
@@ -81,6 +88,7 @@
     "AcceptTarget",
     "Acceptor",
     "BaseConnection",
+    "ConnWriter",
     "ConnectionCloseHandler",
     "ConnectionIdleCleanHandler",
     "ConnectionInitHandler",
@@ -92,6 +100,7 @@
     "MsgHandler",
     "ServerConnection",
     "StreamListener",
+    "TCPConnection",
     "TcpConnectionOption",
     "TrpcServerTransport",
     "TrpcServerStreamTransport",
diff --git a/trpc_sdk/protocol/_conn_writer.py b/trpc_sdk/transport/_server/_conn_writer.py
similarity index 95%
rename from trpc_sdk/protocol/_conn_writer.py
rename to trpc_sdk/transport/_server/_conn_writer.py
index dacea6d..2a3c9cf 100644
--- a/trpc_sdk/protocol/_conn_writer.py
+++ b/trpc_sdk/transport/_server/_conn_writer.py
@@ -22,8 +22,10 @@
   keep writing (DATA, CLOSE, RESET) after the client left, and the writer's
   ``closed`` flag is what drops those writes.
 
-It lives in the protocol package because the TCP protocol builds it itself;
-the protocol package does not import the server package.
+It lives beside the TCP protocol because that protocol builds the writer
+itself. The Cython module imports it with a relative import and does not
+import :mod:`trpc_sdk.transport`: that package's ``__init__`` loads this
+module.
 
 Every cross-thread write costs one ``call_soon_threadsafe``; wake-ups are not
 coalesced in this version.
diff --git a/trpc_sdk/protocol/_cython/__init__.py b/trpc_sdk/transport/_server/_cython/__init__.py
similarity index 100%
rename from trpc_sdk/protocol/_cython/__init__.py
rename to trpc_sdk/transport/_server/_cython/__init__.py
diff --git a/trpc_sdk/protocol/_cython/_tcp_protocol.pxd b/trpc_sdk/transport/_server/_cython/_tcp_protocol.pxd
similarity index 100%
rename from trpc_sdk/protocol/_cython/_tcp_protocol.pxd
rename to trpc_sdk/transport/_server/_cython/_tcp_protocol.pxd
diff --git a/trpc_sdk/protocol/_cython/_tcp_protocol.pyi b/trpc_sdk/transport/_server/_cython/_tcp_protocol.pyi
similarity index 100%
rename from trpc_sdk/protocol/_cython/_tcp_protocol.pyi
rename to trpc_sdk/transport/_server/_cython/_tcp_protocol.pyi
diff --git a/trpc_sdk/protocol/_cython/_tcp_protocol.pyx b/trpc_sdk/transport/_server/_cython/_tcp_protocol.pyx
similarity index 98%
rename from trpc_sdk/protocol/_cython/_tcp_protocol.pyx
rename to trpc_sdk/transport/_server/_cython/_tcp_protocol.pyx
index f85f1c3..5632cc4 100644
--- a/trpc_sdk/protocol/_cython/_tcp_protocol.pyx
+++ b/trpc_sdk/transport/_server/_cython/_tcp_protocol.pyx
@@ -43,7 +43,7 @@ from trpc_sdk.abc import TrpcContext
 from trpc_sdk.abc import get_message
 from trpc_sdk.exceptions import ServerDecodeError
 from trpc_sdk.log import logger
-from trpc_sdk.protocol._conn_writer import ConnWriter
+from .._conn_writer import ConnWriter
 from trpc_sdk.rpcz import RPCZ_SERVER_REQ_SIZE_CTX_KEY
 from trpc_sdk.rpcz import RPCZ_SERVER_RSP_SIZE_CTX_KEY
 from trpc_sdk.rpcz import submit_server_span_on_executor_post_io
@@ -178,8 +178,9 @@ cdef class TCPConnection:
         """Copy the listener's options into this connection's C-level slots.
 
         ``option`` is read by attribute name only, so this module does not
-        import :mod:`trpc_sdk.transport`. It is not kept: the hot path reads
-        the copied slots.
+        import :mod:`trpc_sdk.transport`. That package's ``__init__`` loads
+        this module; a back-import would run while it is still loading.
+        The option is not kept: the hot path reads the copied slots.
 
         Args:
             option: A :class:`~trpc_sdk.transport.ConnectionOption`.
diff --git a/trpc_sdk/transport/_server/_datagram_connection.py b/trpc_sdk/transport/_server/_datagram_connection.py
index 7579085..c6928fb 100644
--- a/trpc_sdk/transport/_server/_datagram_connection.py
+++ b/trpc_sdk/transport/_server/_datagram_connection.py
@@ -28,9 +28,9 @@
 
 from trpc_sdk.exceptions import ServerDecodeError
 from trpc_sdk.log import logger
-from trpc_sdk.protocol import ConnWriter
 from trpc_sdk.telemetry import report_attr
 
+from ._conn_writer import ConnWriter
 from ._stream_connection import ConnectionOption
 from ._stream_connection import _to_host_port
 
diff --git a/trpc_sdk/transport/_server/_stream_transport.py b/trpc_sdk/transport/_server/_stream_transport.py
index de163ab..ea623d0 100644
--- a/trpc_sdk/transport/_server/_stream_transport.py
+++ b/trpc_sdk/transport/_server/_stream_transport.py
@@ -15,7 +15,7 @@
 business:
 
 - merge mode (every thread model): the connection's
-  :class:`~trpc_sdk.protocol.ConnWriter`, which writes the raw frame on the
+  :class:`~trpc_sdk.transport.ConnWriter`, which writes the raw frame on the
   client TCP from whichever thread the stream runs on, and drops writes once
   the connection is closed;
 - ``server.mode: separate``: an :class:`IpcStreamWriter` on the rpc task's
diff --git a/trpc_sdk/transport/_server/_trpc_transport.py b/trpc_sdk/transport/_server/_trpc_transport.py
index 715cc1d..12cf045 100644
--- a/trpc_sdk/transport/_server/_trpc_transport.py
+++ b/trpc_sdk/transport/_server/_trpc_transport.py
@@ -47,7 +47,6 @@
 from trpc_sdk.abc import TrpcContext
 from trpc_sdk.abc import get_message
 from trpc_sdk.log import logger
-from trpc_sdk.protocol import TCPConnection
 from trpc_sdk.rpcz import RPCZ_SERVER_REQ_SIZE_CTX_KEY
 from trpc_sdk.rpcz import RPCZ_SERVER_RSP_SIZE_CTX_KEY
 from trpc_sdk.rpcz import submit_server_span_on_executor_post_io
@@ -63,6 +62,7 @@
 from ._acceptor import StreamListener
 from ._acceptor import serve_stream
 from ._constants import SERVER_CONN_KEY
+from ._cython import TCPConnection  # pylint: disable=no-name-in-module
 from ._datagram_connection import DefaultDatagramConnection
 from ._stream_connection import ConnectionOption
 from ._stream_connection import DefaultIoConnection