diff --git a/docs/client/callbacks.md b/docs/client/callbacks.md
index 6b4e934cf9..53f6e563ee 100644
--- a/docs/client/callbacks.md
+++ b/docs/client/callbacks.md
@@ -135,7 +135,7 @@ Two more. Neither declares anything.
 
 `logging_callback` receives every `notifications/message` a server sends, as `LoggingMessageNotificationParams` (`level`, `logger`, `data`). Protocol logging is itself deprecated by the 2026-07-28 spec (**[Logging](../handlers/logging.md)** has what to do instead), so this callback exists for the servers that still emit it.
 
-`message_handler` is the catch-all: every server notification reaches it (as well as its specific callback), and on a stream-backed transport so does every transport-level `Exception`. The one pattern worth knowing is `if isinstance(message, Exception): raise message`, so a broken connection fails loudly instead of vanishing.
+`message_handler` is the catch-all: every server notification the session surfaces reaches it (as well as its specific callback), and on a stream-backed transport so does every transport-level `Exception`. Two never do: `notifications/cancelled` is applied by the SDK rather than surfaced, and a subscription acknowledgment for a live `listen()` stream is consumed by that stream. Annotate the parameter with `IncomingMessage` (`ServerNotification | Exception`, exported from `mcp.client`). The one pattern worth knowing is `if isinstance(message, Exception): raise message`, so a broken connection fails loudly instead of vanishing.
 
 ## Recap
 
diff --git a/docs/migration.md b/docs/migration.md
index afe0953631..c2ffe1e6c9 100644
--- a/docs/migration.md
+++ b/docs/migration.md
@@ -1651,7 +1651,9 @@ Behavior changes:
 - **`send_notification` no longer takes `related_request_id`, and `send_request` no longer accepts `ServerMessageMetadata`.** No client transport ever serialized these hints; progress and response correlation via `progressToken` and the request id is unaffected.
 - **Client callbacks now receive `mcp.client.ClientRequestContext`** (its `request_id` is always populated); the `mcp.shared.context.RequestContext` generic is deleted. Annotations spelled `RequestContext[ClientSession, Any]` become `ClientRequestContext` (details in [`RequestContext` type parameters simplified](#requestcontext-type-parameters-simplified)).
 
-`mcp.shared.session` is now a compatibility module: `ProgressFnT` is re-exported (its home is `mcp.shared.dispatcher`), and `RequestResponder` remains as a typing-only stub so `MessageHandlerFnT` annotations keep importing. `RequestResponder.respond()` no longer exists, and neither do the cancellation-tracking members (`cancel()`, the `cancelled` and `in_flight` properties, the `on_complete` constructor argument) or `BaseSession._in_flight`; inbound cancellation is handled by `JSONRPCDispatcher`.
+- **`message_handler` no longer receives requests.** Server-initiated requests are answered by the typed callbacks (`sampling_callback`, `elicitation_callback`, `list_roots_callback`), so the handler's parameter is now `IncomingMessage = ServerNotification | Exception`, exported from `mcp.client`. Replace the hand-written v1 union `RequestResponder[ServerRequest, ClientResult] | ServerNotification | Exception` with `IncomingMessage`; `RequestResponder` is gone (below), so the old annotation no longer imports.
+
+The `mcp.shared.session` module is gone. `RequestResponder` is removed — `respond()`, the cancellation-tracking members (`cancel()`, the `cancelled` and `in_flight` properties, the `on_complete` constructor argument) and `BaseSession._in_flight` have no replacement; inbound cancellation is handled by `JSONRPCDispatcher`. `ProgressFnT` now lives only in `mcp.shared.dispatcher`, and `RequestId` in `mcp_types`.
 
 ### Experimental Tasks support removed
 
diff --git a/docs/whats-new.md b/docs/whats-new.md
index 3f1188f8fc..4ae0de2bcb 100644
--- a/docs/whats-new.md
+++ b/docs/whats-new.md
@@ -146,7 +146,7 @@ Each of these is a section in the **[Migration Guide](migration.md)**:
 
 * The **WebSocket transport**, both sides, and the `mcp[ws]` extra. It was never part of the MCP specification.
 * The **experimental Tasks** API (`mcp.*.experimental`). 2026-07-28 moves tasks out of the core protocol and into an official extension ([SEP-2663](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2663)), which this SDK does not implement yet.
-* `mcp.types`, `mcp.shared.version`, and `mcp.shared.progress` as import paths.
+* `mcp.types`, `mcp.shared.version`, `mcp.shared.progress`, and `mcp.shared.session` (with the `RequestResponder` stub v1 `message_handler` annotations imported) as import paths.
 * The deprecated `streamablehttp_client` spelling, and the `get_session_id` callback from `streamable_http_client` (which now yields exactly two streams).
 * `McpError`, renamed **`MCPError`** with a direct `(code, message, data)` constructor.
 * `MCPServer.get_context()`, `mount_path=`, and the lowlevel `Server`'s decorator methods, ContextVar, and handler dicts.
diff --git a/examples/stories/standalone_get/client.py b/examples/stories/standalone_get/client.py
index aaf870f0e7..d2054ca8df 100644
--- a/examples/stories/standalone_get/client.py
+++ b/examples/stories/standalone_get/client.py
@@ -3,7 +3,7 @@
 import anyio
 import mcp_types as types
 
-from mcp.client import Client
+from mcp.client import Client, IncomingMessage
 from stories._harness import Target, run_client
 
 
@@ -13,7 +13,7 @@ async def main(target: Target, *, mode: str = "auto") -> None:
     received: list[types.ResourceListChangedNotification] = []
     seen = anyio.Event()
 
-    async def on_message(message: object) -> None:
+    async def on_message(message: IncomingMessage) -> None:
         if isinstance(message, types.ResourceListChangedNotification):
             received.append(message)
             seen.set()
diff --git a/examples/stories/stickynotes/client.py b/examples/stories/stickynotes/client.py
index 56ca10f551..a5b0e41dad 100644
--- a/examples/stories/stickynotes/client.py
+++ b/examples/stories/stickynotes/client.py
@@ -4,7 +4,7 @@
 import mcp_types as types
 from mcp_types.version import HANDSHAKE_PROTOCOL_VERSIONS
 
-from mcp.client import Client, ClientRequestContext
+from mcp.client import Client, ClientRequestContext, IncomingMessage
 from stories._harness import Target, run_client
 
 
@@ -18,7 +18,7 @@ async def on_elicit(context: ClientRequestContext, params: types.ElicitRequestPa
             return types.ElicitResult(action="cancel")
         return types.ElicitResult(action="accept", content={"confirm": answer == "confirm"})
 
-    async def on_message(message: object) -> None:
+    async def on_message(message: IncomingMessage) -> None:
         if isinstance(message, types.ResourceListChangedNotification):
             list_changed.set()
 
diff --git a/src/mcp/client/__init__.py b/src/mcp/client/__init__.py
index 21581749d0..d6b07045ce 100644
--- a/src/mcp/client/__init__.py
+++ b/src/mcp/client/__init__.py
@@ -20,7 +20,7 @@
     UnexpectedClaimedResult,
     advertise,
 )
-from mcp.client.session import ClientSession
+from mcp.client.session import ClientSession, IncomingMessage
 
 __all__ = [
     "CacheConfig",
@@ -32,6 +32,7 @@
     "ClientExtension",
     "ClientRequestContext",
     "ClientSession",
+    "IncomingMessage",
     "InMemoryResponseCacheStore",
     "InputRequiredRoundsExceededError",
     "NotificationBinding",
diff --git a/src/mcp/client/__main__.py b/src/mcp/client/__main__.py
index 5fa3ce109b..60e3b02390 100644
--- a/src/mcp/client/__main__.py
+++ b/src/mcp/client/__main__.py
@@ -9,11 +9,10 @@
 import mcp_types as types
 
 from mcp.client._transport import ReadStream, WriteStream
-from mcp.client.session import ClientSession
+from mcp.client.session import ClientSession, IncomingMessage
 from mcp.client.sse import sse_client
 from mcp.client.stdio import StdioServerParameters, stdio_client
 from mcp.shared.message import SessionMessage
-from mcp.shared.session import RequestResponder
 
 if not sys.warnoptions:
     warnings.simplefilter("ignore")
@@ -22,9 +21,7 @@
 logger = logging.getLogger("client")
 
 
-async def message_handler(
-    message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
-) -> None:
+async def message_handler(message: IncomingMessage) -> None:
     if isinstance(message, Exception):
         logger.error("Error: %s", message)
         return
diff --git a/src/mcp/client/client.py b/src/mcp/client/client.py
index 9e26d40859..aaf7c83b0b 100644
--- a/src/mcp/client/client.py
+++ b/src/mcp/client/client.py
@@ -52,6 +52,7 @@
     ClientRequestContext,
     ClientSession,
     ElicitationFnT,
+    IncomingMessage,
     ListRootsFnT,
     LoggingFnT,
     MessageHandlerFnT,
@@ -68,7 +69,6 @@
 from mcp.shared.exceptions import MCPDeprecationWarning, MCPError
 from mcp.shared.extension import validate_extension_identifier
 from mcp.shared.jsonrpc_dispatcher import JSONRPCDispatcher
-from mcp.shared.session import RequestResponder
 from mcp.shared.subscriptions import event_to_notification
 
 logger = logging.getLogger(__name__)
@@ -155,9 +155,7 @@ def _strip_userinfo(url: str) -> str:
 def _evicting_message_handler(cache: ClientResponseCache, user_handler: MessageHandlerFnT | None) -> MessageHandlerFnT:
     """Wrap the session message handler with cache eviction on server notifications."""
 
-    async def handler(
-        message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
-    ) -> None:
+    async def handler(message: IncomingMessage) -> None:
         if isinstance(message, types.ServerNotification):
             try:
                 await cache.evict_for_notification(message)
diff --git a/src/mcp/client/session.py b/src/mcp/client/session.py
index 36cb78df5d..1ef4ddf3a3 100644
--- a/src/mcp/client/session.py
+++ b/src/mcp/client/session.py
@@ -6,7 +6,7 @@
 from functools import reduce
 from operator import or_
 from types import TracebackType
-from typing import Annotated, Any, Final, Literal, Protocol, cast, overload
+from typing import Annotated, Any, Final, Literal, Protocol, TypeAlias, cast, overload
 
 import anyio
 import anyio.abc
@@ -53,7 +53,6 @@
 )
 from mcp.shared.jsonrpc_dispatcher import JSONRPCDispatcher, cancelled_request_id_from_params
 from mcp.shared.message import ClientMessageMetadata, SessionMessage
-from mcp.shared.session import RequestResponder
 from mcp.shared.subscriptions import SUBSCRIPTION_ID_META_KEY, event_from_wire
 from mcp.shared.transport_context import TransportContext
 
@@ -172,16 +171,20 @@ class LoggingFnT(Protocol):
     async def __call__(self, params: types.LoggingMessageNotificationParams) -> None: ...  # pragma: no branch
 
 
+IncomingMessage: TypeAlias = types.ServerNotification | Exception
+"""What `message_handler` receives: the server notifications the session surfaces, plus transport-level exceptions.
+
+`notifications/cancelled` is applied by the dispatcher and never surfaced, and a
+`notifications/subscriptions/acknowledged` for a live `listen()` stream is consumed by that
+stream, so neither reaches the handler.
+"""
+
+
 class MessageHandlerFnT(Protocol):
-    async def __call__(
-        self,
-        message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
-    ) -> None: ...  # pragma: no branch
+    async def __call__(self, message: IncomingMessage) -> None: ...  # pragma: no branch
 
 
-async def _default_message_handler(
-    message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
-) -> None:
+async def _default_message_handler(message: IncomingMessage) -> None:
     await anyio.lowlevel.checkpoint()
 
 
@@ -331,8 +334,10 @@ class ClientSession:
     `dispatcher=`), enter as an async context manager, then call
     `initialize()`. The dispatcher owns the receive loop and request
     correlation; this class owns the typed MCP layer and the constructor
-    callbacks. Transport `Exception` items reach `message_handler` only when
-    the session builds its own dispatcher from a stream pair.
+    callbacks. Transport `Exception` items reach `message_handler` on any
+    stream-backed dispatcher (`JSONRPCDispatcher`), whether built here from a
+    stream pair or supplied without a stream-exception hook of its own; an
+    in-process `DirectDispatcher` carries none.
 
     Extension `result_claims` fold into tools/call parsing at `adopt()`;
     `notification_bindings` observe vendor notifications via bounded FIFOs.
diff --git a/src/mcp/client/session_group.py b/src/mcp/client/session_group.py
index 5f26a43365..a544cecbe8 100644
--- a/src/mcp/client/session_group.py
+++ b/src/mcp/client/session_group.py
@@ -25,8 +25,8 @@
 from mcp.client.stdio import StdioServerParameters
 from mcp.client.streamable_http import streamable_http_client
 from mcp.shared._httpx_utils import create_mcp_http_client
+from mcp.shared.dispatcher import ProgressFnT
 from mcp.shared.exceptions import MCPError
-from mcp.shared.session import ProgressFnT
 
 
 class SseServerParameters(BaseModel):
diff --git a/src/mcp/shared/session.py b/src/mcp/shared/session.py
deleted file mode 100644
index f8f0a6d416..0000000000
--- a/src/mcp/shared/session.py
+++ /dev/null
@@ -1,22 +0,0 @@
-"""Compatibility names that outlived the removed v1 session layer (`BaseSession`)."""
-
-from typing import Generic, TypeVar
-
-from mcp_types import RequestParamsMeta
-
-from mcp.shared.dispatcher import ProgressFnT as ProgressFnT
-from mcp.shared.message import MessageMetadata
-
-RequestId = str | int
-
-ReceiveRequestT = TypeVar("ReceiveRequestT")
-SendResultT = TypeVar("SendResultT")
-
-
-class RequestResponder(Generic[ReceiveRequestT, SendResultT]):
-    """Typing stub for the v1 responder; the SDK never instantiates it."""
-
-    request_id: RequestId
-    request_meta: RequestParamsMeta | None
-    request: ReceiveRequestT
-    message_metadata: MessageMetadata
diff --git a/tests/client/test_client_caching.py b/tests/client/test_client_caching.py
index aa6ed22e20..30f752eb6c 100644
--- a/tests/client/test_client_caching.py
+++ b/tests/client/test_client_caching.py
@@ -42,7 +42,7 @@
 )
 from mcp_types.version import LATEST_MODERN_VERSION
 
-from mcp.client import Client
+from mcp.client import Client, IncomingMessage
 from mcp.client._transport import TransportStreams
 from mcp.client.caching import (
     CacheConfig,
@@ -57,13 +57,10 @@
 from mcp.shared.exceptions import MCPError
 from mcp.shared.memory import MessageStream, create_client_server_memory_streams
 from mcp.shared.message import SessionMessage
-from mcp.shared.session import RequestResponder
 from tests.interaction._connect import BASE_URL, mounted_app
 
 pytestmark = pytest.mark.anyio
 
-IncomingMessage = RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception
-
 
 def _coordinator(client: Client) -> ClientResponseCache:
     cache = client._response_cache
diff --git a/tests/client/test_logging_callback.py b/tests/client/test_logging_callback.py
index d62b7e19b3..7ccdae3530 100644
--- a/tests/client/test_logging_callback.py
+++ b/tests/client/test_logging_callback.py
@@ -1,6 +1,5 @@
 from typing import Literal
 
-import mcp_types as types
 import pytest
 from mcp_types import (
     LoggingMessageNotificationParams,
@@ -8,8 +7,8 @@
 )
 
 from mcp import Client
+from mcp.client import IncomingMessage
 from mcp.server.mcpserver import Context, MCPServer
-from mcp.shared.session import RequestResponder
 
 
 class LoggingCollector:
@@ -55,9 +54,7 @@ async def test_tool_with_log_dict(
         return True
 
     # Create a message handler to catch exceptions
-    async def message_handler(
-        message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
-    ) -> None:
+    async def message_handler(message: IncomingMessage) -> None:
         if isinstance(message, Exception):  # pragma: no cover
             raise message
 
diff --git a/tests/client/test_notification_response.py b/tests/client/test_notification_response.py
index 6724dfaf1b..b21e734fa3 100644
--- a/tests/client/test_notification_response.py
+++ b/tests/client/test_notification_response.py
@@ -16,8 +16,8 @@
 from starlette.routing import Route
 
 from mcp import ClientSession, MCPError
+from mcp.client import IncomingMessage
 from mcp.client.streamable_http import streamable_http_client
-from mcp.shared.session import RequestResponder
 
 pytestmark = pytest.mark.anyio
 
@@ -82,9 +82,7 @@ async def test_non_compliant_notification_response() -> None:
     """
     returned_exception = None
 
-    async def message_handler(  # pragma: no cover
-        message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
-    ) -> None:
+    async def message_handler(message: IncomingMessage) -> None:  # pragma: no cover
         nonlocal returned_exception
         if isinstance(message, Exception):
             returned_exception = message
diff --git a/tests/client/test_session.py b/tests/client/test_session.py
index 9c935ef18a..12fab4c8c9 100644
--- a/tests/client/test_session.py
+++ b/tests/client/test_session.py
@@ -37,7 +37,7 @@
 from pydantic import FileUrl, ValidationError
 
 from mcp import MCPError
-from mcp.client import ClientRequestContext
+from mcp.client import ClientRequestContext, IncomingMessage
 from mcp.client.client import Client
 from mcp.client.session import DEFAULT_CLIENT_INFO, ClientSession
 from mcp.client.subscriptions import ToolsListChanged, listen
@@ -45,7 +45,6 @@
 from mcp.shared.direct_dispatcher import create_direct_dispatcher_pair
 from mcp.shared.dispatcher import CallOptions, DispatchContext, OnNotify, OnNotifyIntercept, OnRequest
 from mcp.shared.message import SessionMessage
-from mcp.shared.session import RequestResponder
 from mcp.shared.subscriptions import SUBSCRIPTION_ID_META_KEY
 from mcp.shared.transport_context import TransportContext
 
@@ -123,9 +122,7 @@ async def mock_server():
             )
 
     # Create a message handler to catch exceptions
-    async def message_handler(  # pragma: no cover
-        message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
-    ) -> None:
+    async def message_handler(message: IncomingMessage) -> None:  # pragma: no cover
         if isinstance(message, Exception):
             raise message
 
@@ -1228,10 +1225,8 @@ async def test_raising_notification_callbacks_over_direct_dispatch_cost_only_tha
     async def logging_callback(params: types.LoggingMessageNotificationParams) -> None:
         raise ValueError("logging callback boom")
 
-    async def message_handler(
-        message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
-    ) -> None:
-        assert not isinstance(message, RequestResponder | Exception)
+    async def message_handler(message: IncomingMessage) -> None:
+        assert not isinstance(message, Exception)
         teed.append(message)
         raise ValueError("message handler boom")
 
diff --git a/tests/interaction/README.md b/tests/interaction/README.md
index 89be3d3abf..3060a240c1 100644
--- a/tests/interaction/README.md
+++ b/tests/interaction/README.md
@@ -40,7 +40,7 @@ flows — with a single subprocess test for stdio.
 ```text
 tests/interaction/
   _requirements.py      the requirements manifest (see below)
-  _helpers.py           shared type aliases + the wire-recording transport
+  _helpers.py           the wire-recording transport
   _connect.py           the transport-parametrized connection factories
   conftest.py           the connect fixture (the transport matrix)
   test_coverage.py      enforces the manifest ↔ test contract
diff --git a/tests/interaction/_helpers.py b/tests/interaction/_helpers.py
index 0641aeab97..b335def7d0 100644
--- a/tests/interaction/_helpers.py
+++ b/tests/interaction/_helpers.py
@@ -1,28 +1,16 @@
 """Shared helpers for the interaction suite.
 
-Keep this module small: it exists only for (a) types that every test would otherwise have to
-assemble from the SDK's internals to annotate a client callback, and (b) the recording transport
-used by the wire-level tests. Server fixtures and assertion helpers belong in the test that uses
-them.
+Keep this module small: it exists only for the recording transport used by the wire-level
+tests. Server fixtures and assertion helpers belong in the test that uses them.
 """
 
 from types import TracebackType
 
 import anyio
-from mcp_types import ClientResult, ServerNotification, ServerRequest
 from typing_extensions import Self
 
 from mcp.client._transport import ReadStream, Transport, TransportStreams, WriteStream
 from mcp.shared.message import SessionMessage
-from mcp.shared.session import RequestResponder
-
-# TODO: this union is the parameter type of every client message handler (MessageHandlerFnT),
-# but the SDK does not export a name for it -- writing a correctly-typed handler requires
-# importing RequestResponder from mcp.shared.session and assembling the union by hand. It
-# should be a named, exported alias next to MessageHandlerFnT (like ClientRequestContext is
-# for the request callbacks), at which point this alias can be deleted.
-IncomingMessage = RequestResponder[ServerRequest, ClientResult] | ServerNotification | Exception
-"""Everything a client message handler can receive."""
 
 
 class _RecordingReadStream:
diff --git a/tests/interaction/lowlevel/test_cancellation.py b/tests/interaction/lowlevel/test_cancellation.py
index 8361865db0..ecbf1a088d 100644
--- a/tests/interaction/lowlevel/test_cancellation.py
+++ b/tests/interaction/lowlevel/test_cancellation.py
@@ -29,13 +29,12 @@
 )
 
 from mcp import MCPError
-from mcp.client import ClientRequestContext, ClientSession
+from mcp.client import ClientRequestContext, ClientSession, IncomingMessage
 from mcp.server import Server, ServerRequestContext
 from mcp.shared.memory import MessageStream, create_client_server_memory_streams
 from mcp.shared.message import SessionMessage
 from tests._stamp import Unstamp
 from tests.interaction._connect import Connect
-from tests.interaction._helpers import IncomingMessage
 from tests.interaction._requirements import requirement
 
 pytestmark = pytest.mark.anyio
diff --git a/tests/interaction/lowlevel/test_elicitation.py b/tests/interaction/lowlevel/test_elicitation.py
index b8393dd316..7024ef9e0f 100644
--- a/tests/interaction/lowlevel/test_elicitation.py
+++ b/tests/interaction/lowlevel/test_elicitation.py
@@ -28,12 +28,11 @@
 )
 
 from mcp import MCPError, UrlElicitationRequiredError
-from mcp.client import ClientRequestContext, ClientSession
+from mcp.client import ClientRequestContext, ClientSession, IncomingMessage
 from mcp.server import Server, ServerRequestContext
 from mcp.shared.memory import MessageStream, create_client_server_memory_streams
 from mcp.shared.message import SessionMessage
 from tests.interaction._connect import Connect
-from tests.interaction._helpers import IncomingMessage
 from tests.interaction._requirements import requirement
 
 pytestmark = pytest.mark.anyio
diff --git a/tests/interaction/lowlevel/test_flows.py b/tests/interaction/lowlevel/test_flows.py
index 9a6db1a45a..78ca716021 100644
--- a/tests/interaction/lowlevel/test_flows.py
+++ b/tests/interaction/lowlevel/test_flows.py
@@ -29,12 +29,11 @@
 )
 
 from mcp import MCPError, UrlElicitationRequiredError
-from mcp.client import ClientRequestContext
+from mcp.client import ClientRequestContext, IncomingMessage
 from mcp.server import Server, ServerRequestContext
 from mcp.server.session import ServerSession
 from tests._stamp import Unstamp
 from tests.interaction._connect import Connect
-from tests.interaction._helpers import IncomingMessage
 from tests.interaction._requirements import requirement
 
 pytestmark = pytest.mark.anyio
diff --git a/tests/interaction/lowlevel/test_list_changed.py b/tests/interaction/lowlevel/test_list_changed.py
index e7d497ba2d..d978c0db51 100644
--- a/tests/interaction/lowlevel/test_list_changed.py
+++ b/tests/interaction/lowlevel/test_list_changed.py
@@ -26,9 +26,9 @@
     ToolListChangedNotification,
 )
 
+from mcp.client import IncomingMessage
 from mcp.server import Server, ServerRequestContext
 from tests.interaction._connect import Connect
-from tests.interaction._helpers import IncomingMessage
 from tests.interaction._requirements import requirement
 
 pytestmark = pytest.mark.anyio
diff --git a/tests/interaction/lowlevel/test_progress.py b/tests/interaction/lowlevel/test_progress.py
index 025dded156..4d1f0d42af 100644
--- a/tests/interaction/lowlevel/test_progress.py
+++ b/tests/interaction/lowlevel/test_progress.py
@@ -15,12 +15,12 @@
 from inline_snapshot import snapshot
 from mcp_types import CallToolResult, ProgressNotification, ProgressNotificationParams, ProgressToken, TextContent
 
+from mcp.client import IncomingMessage
 from mcp.server import Server, ServerRequestContext
 from mcp.server.session import ServerSession
-from mcp.shared.session import ProgressFnT
+from mcp.shared.dispatcher import ProgressFnT
 from tests._stamp import Unstamp
 from tests.interaction._connect import Connect
-from tests.interaction._helpers import IncomingMessage
 from tests.interaction._requirements import requirement
 
 pytestmark = pytest.mark.anyio
diff --git a/tests/interaction/lowlevel/test_resources.py b/tests/interaction/lowlevel/test_resources.py
index e911c65876..9e18393707 100644
--- a/tests/interaction/lowlevel/test_resources.py
+++ b/tests/interaction/lowlevel/test_resources.py
@@ -26,10 +26,10 @@
 )
 
 from mcp import MCPError
+from mcp.client import IncomingMessage
 from mcp.server import Server, ServerRequestContext
 from tests._stamp import Unstamp
 from tests.interaction._connect import Connect
-from tests.interaction._helpers import IncomingMessage
 from tests.interaction._requirements import requirement
 
 pytestmark = pytest.mark.anyio
diff --git a/tests/interaction/mcpserver/test_context.py b/tests/interaction/mcpserver/test_context.py
index 24728e2da8..0f07a128b7 100644
--- a/tests/interaction/mcpserver/test_context.py
+++ b/tests/interaction/mcpserver/test_context.py
@@ -17,12 +17,11 @@
 from pydantic import BaseModel
 
 from mcp import MCPError
-from mcp.client import ClientRequestContext
+from mcp.client import ClientRequestContext, IncomingMessage
 from mcp.server.elicitation import AcceptedElicitation
 from mcp.server.mcpserver import Context, MCPServer
 from tests._stamp import Unstamp
 from tests.interaction._connect import Connect
-from tests.interaction._helpers import IncomingMessage
 from tests.interaction._requirements import requirement
 
 pytestmark = pytest.mark.anyio
diff --git a/tests/interaction/mcpserver/test_tools.py b/tests/interaction/mcpserver/test_tools.py
index ad5db520b9..21a7163360 100644
--- a/tests/interaction/mcpserver/test_tools.py
+++ b/tests/interaction/mcpserver/test_tools.py
@@ -17,12 +17,12 @@
 from pydantic import BaseModel, Field
 
 from mcp import MCPError
+from mcp.client import IncomingMessage
 from mcp.server.mcpserver import Context, MCPServer
 from mcp.server.mcpserver.exceptions import ToolError
 from mcp.shared.exceptions import UrlElicitationRequiredError
 from tests._stamp import Unstamp
 from tests.interaction._connect import Connect
-from tests.interaction._helpers import IncomingMessage
 from tests.interaction._requirements import requirement
 
 pytestmark = pytest.mark.anyio
diff --git a/tests/interaction/transports/test_streamable_http.py b/tests/interaction/transports/test_streamable_http.py
index bb6dec5695..cb22e7ab87 100644
--- a/tests/interaction/transports/test_streamable_http.py
+++ b/tests/interaction/transports/test_streamable_http.py
@@ -23,12 +23,11 @@
 )
 from pydantic import BaseModel
 
-from mcp.client import ClientRequestContext
+from mcp.client import ClientRequestContext, IncomingMessage
 from mcp.server.elicitation import AcceptedElicitation
 from mcp.server.mcpserver import Context, MCPServer
 from mcp.shared.exceptions import MCPError
 from tests.interaction._connect import connect_over_streamable_http
-from tests.interaction._helpers import IncomingMessage
 from tests.interaction._requirements import requirement
 
 pytestmark = pytest.mark.anyio
diff --git a/tests/server/mcpserver/test_integration.py b/tests/server/mcpserver/test_integration.py
index f6361f7574..2c57aab086 100644
--- a/tests/server/mcpserver/test_integration.py
+++ b/tests/server/mcpserver/test_integration.py
@@ -14,7 +14,6 @@
 import pytest
 from inline_snapshot import snapshot
 from mcp_types import (
-    ClientResult,
     CreateMessageRequestParams,
     CreateMessageResult,
     ElicitRequestParams,
@@ -30,7 +29,6 @@
     ResourceListChangedNotification,
     ResourceTemplateReference,
     ServerNotification,
-    ServerRequest,
     TextContent,
     TextResourceContents,
     ToolListChangedNotification,
@@ -48,8 +46,7 @@
     structured_output,
     tool_progress,
 )
-from mcp.client import Client, ClientRequestContext
-from mcp.shared.session import RequestResponder
+from mcp.client import Client, ClientRequestContext, IncomingMessage
 
 pytestmark = pytest.mark.anyio
 
@@ -63,9 +60,7 @@ def __init__(self):
         self.resource_notifications: list[NotificationParams | None] = []
         self.tool_notifications: list[NotificationParams | None] = []
 
-    async def handle_generic_notification(
-        self, message: RequestResponder[ServerRequest, ClientResult] | ServerNotification | Exception
-    ) -> None:
+    async def handle_generic_notification(self, message: IncomingMessage) -> None:
         """Handle any server notification and route to appropriate handler."""
         if isinstance(message, ServerNotification):  # pragma: no branch
             if isinstance(message, ProgressNotification):
@@ -180,7 +175,7 @@ async def test_tool_progress() -> None:
     """Test tool progress reporting."""
     collector = NotificationCollector()
 
-    async def message_handler(message: RequestResponder[ServerRequest, ClientResult] | ServerNotification | Exception):
+    async def message_handler(message: IncomingMessage):
         await collector.handle_generic_notification(message)
         if isinstance(message, Exception):  # pragma: no cover
             raise message
@@ -259,7 +254,7 @@ async def test_notifications() -> None:
     """Test notifications and logging functionality."""
     collector = NotificationCollector()
 
-    async def message_handler(message: RequestResponder[ServerRequest, ClientResult] | ServerNotification | Exception):
+    async def message_handler(message: IncomingMessage):
         await collector.handle_generic_notification(message)
         if isinstance(message, Exception):  # pragma: no cover
             raise message
diff --git a/tests/shared/test_streamable_http.py b/tests/shared/test_streamable_http.py
index d7eeccdfdb..aeef25a278 100644
--- a/tests/shared/test_streamable_http.py
+++ b/tests/shared/test_streamable_http.py
@@ -43,7 +43,7 @@
 from starlette.types import Message, Scope
 
 from mcp import MCPError
-from mcp.client import ClientRequestContext
+from mcp.client import ClientRequestContext, IncomingMessage
 from mcp.client.session import ClientSession
 from mcp.client.streamable_http import StreamableHTTPTransport, streamable_http_client
 from mcp.server import Server, ServerRequestContext
@@ -64,7 +64,6 @@
 from mcp.shared._compat import resync_tracer
 from mcp.shared._context_streams import create_context_streams
 from mcp.shared.message import ClientMessageMetadata, ServerMessageMetadata, SessionMessage
-from mcp.shared.session import RequestResponder
 from tests.interaction.transports import StreamingASGITransport
 
 # Test constants
@@ -968,9 +967,7 @@ async def test_streamable_http_client_get_stream(basic_app: Starlette) -> None:
     notifications_received: list[types.ServerNotification] = []
 
     # Define message handler to capture notifications
-    async def message_handler(  # pragma: no branch
-        message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
-    ) -> None:
+    async def message_handler(message: IncomingMessage) -> None:  # pragma: no branch
         if isinstance(message, types.ServerNotification):  # pragma: no branch
             notifications_received.append(message)
 
@@ -1128,9 +1125,7 @@ async def test_streamable_http_client_resumption(event_app: tuple[SimpleEventSto
     first_notification_received = anyio.Event()
     resumption_token_received = anyio.Event()
 
-    async def message_handler(  # pragma: no branch
-        message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
-    ) -> None:
+    async def message_handler(message: IncomingMessage) -> None:  # pragma: no branch
         if isinstance(message, types.ServerNotification):  # pragma: no branch
             captured_notifications.append(message)
             # Look for our first notification
@@ -1798,14 +1793,11 @@ async def test_streamable_http_client_auto_reconnects(
     _, app = event_app
     captured_notifications: list[str] = []
 
-    async def message_handler(
-        message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
-    ) -> None:
+    async def message_handler(message: IncomingMessage) -> None:
         if isinstance(message, Exception):  # pragma: no branch
             return  # pragma: no cover
-        if isinstance(message, types.ServerNotification):  # pragma: no branch
-            if isinstance(message, types.LoggingMessageNotification):  # pragma: no branch
-                captured_notifications.append(str(message.params.data))
+        if isinstance(message, types.LoggingMessageNotification):  # pragma: no branch
+            captured_notifications.append(str(message.params.data))
 
     async with (
         make_client(app) as http_client,
@@ -1866,14 +1858,11 @@ async def test_streamable_http_sse_polling_full_cycle(
     _, app = event_app
     all_notifications: list[str] = []
 
-    async def message_handler(
-        message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
-    ) -> None:
+    async def message_handler(message: IncomingMessage) -> None:
         if isinstance(message, Exception):  # pragma: no branch
             return  # pragma: no cover
-        if isinstance(message, types.ServerNotification):  # pragma: no branch
-            if isinstance(message, types.LoggingMessageNotification):  # pragma: no branch
-                all_notifications.append(str(message.params.data))
+        if isinstance(message, types.LoggingMessageNotification):  # pragma: no branch
+            all_notifications.append(str(message.params.data))
 
     async with (
         make_client(app) as http_client,
@@ -1909,14 +1898,11 @@ async def test_streamable_http_events_replayed_after_disconnect(
     _, app = event_app
     notification_data: list[str] = []
 
-    async def message_handler(
-        message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
-    ) -> None:
+    async def message_handler(message: IncomingMessage) -> None:
         if isinstance(message, Exception):  # pragma: no branch
             return  # pragma: no cover
-        if isinstance(message, types.ServerNotification):  # pragma: no branch
-            if isinstance(message, types.LoggingMessageNotification):  # pragma: no branch
-                notification_data.append(str(message.params.data))
+        if isinstance(message, types.LoggingMessageNotification):  # pragma: no branch
+            notification_data.append(str(message.params.data))
 
     async with (
         make_client(app) as http_client,
@@ -2042,14 +2028,11 @@ async def test_standalone_get_stream_reconnection(event_app: tuple[SimpleEventSt
     _, app = event_app
     received_notifications: list[str] = []
 
-    async def message_handler(
-        message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
-    ) -> None:
+    async def message_handler(message: IncomingMessage) -> None:
         if isinstance(message, Exception):
             return  # pragma: no cover
-        if isinstance(message, types.ServerNotification):  # pragma: no branch
-            if isinstance(message, types.ResourceUpdatedNotification):  # pragma: no branch
-                received_notifications.append(str(message.params.uri))
+        if isinstance(message, types.ResourceUpdatedNotification):  # pragma: no branch
+            received_notifications.append(str(message.params.uri))
 
     async with (
         make_client(app) as http_client,
@@ -2183,9 +2166,7 @@ async def test_standalone_stream_teardown_mid_listen_is_not_an_error(caplog: pyt
     app = Starlette(routes=[Mount("/mcp", app=session_manager.handle_request)])
     notified = anyio.Event()
 
-    async def message_handler(
-        message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
-    ) -> None:
+    async def message_handler(message: IncomingMessage) -> None:
         # Only the standalone-stream notification is teed to the handler here.
         assert isinstance(message, types.ResourceUpdatedNotification)
         notified.set()