modelcontextprotocol/python-sdk
Watch
1
0
Fork
You've already forked python-sdk
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Add a pluggable server extension API with MCP Apps (#3003)

Browse source 
Co-authored-by: Max Isbey <224885523+maxisbey@users.noreply.github.com>
This commit is contained in:
Marcelo Trylesinski 2026-06-29 11:58:05 +02:00 • committed by GitHub
commit 4b519782f1
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
2 changed files with 2598 additions and 24 deletions
Download patch file Download diff file Expand all files Collapse all files

5
src/mcp/client/client.py
View file

@ -217,6 +217,10 @@ class Client:
`read_resource` give up. Use `client.session.<method>(..., allow_input_required=True)`
to drive the loop manually instead."""
extensions: dict[str, dict[str, Any]] | None = None
"""SEP-2133 extension support to advertise under `ClientCapabilities.extensions`
(identifier -> settings), e.g. `{"io.modelcontextprotocol/ui": {"mimeTypes": [...]}}`."""
_entered: bool = field(init=False, default=False)
_session: ClientSession | None = field(init=False, default=None)
_exit_stack: AsyncExitStack | None = field(init=False, default=None)
@ -255,6 +259,7 @@ class Client:
message_handler=self.message_handler,
client_info=self.client_info,
elicitation_callback=self.elicitation_callback,
extensions=self.extensions,
)
async def __aenter__(self) -> Client:

6
src/mcp/client/session.py
View file

@ -224,12 +224,14 @@ class ClientSession:
client_info: types.Implementation | None = None,
*,
sampling_capabilities: types.SamplingCapability | None = None,
extensions: dict[str, dict[str, Any]] | None = None,
dispatcher: Dispatcher[Any] | None = None,
) -> None:
self._session_read_timeout_seconds = read_timeout_seconds
self._client_info = client_info or DEFAULT_CLIENT_INFO
self._sampling_callback = sampling_callback or _default_sampling_callback
self._sampling_capabilities = sampling_capabilities
self._extensions = extensions
self._elicitation_callback = elicitation_callback or _default_elicitation_callback
self._list_roots_callback = list_roots_callback or _default_list_roots_callback
self._logging_callback = logging_callback or _default_logging_callback
@ -369,7 +371,9 @@ class ClientSession:
if self._list_roots_callback is not _default_list_roots_callback
else None
)
return types.ClientCapabilities(sampling=sampling, elicitation=elicitation, experimental=None, roots=roots)
return types.ClientCapabilities(
sampling=sampling, elicitation=elicitation, experimental=None, extensions=self._extensions, roots=roots
)
async def initialize(self) -> types.InitializeResult:
if self._initialize_result is not None: