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Merge pull request #440 from koic/mcp_2026_07_28_spec_associate_server_requests

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Associate server-to-client requests with the originating client request per SEP-2260
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Koichi ITO 2026-07-12 02:17:04 +09:00 • committed by GitHub
commit a793dde6cd
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2 changed files with 323 additions and 16 deletions
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12
lib/mcp/server_context.rb
View file

@ -54,6 +54,9 @@ module MCP
end
# Delegates to the session so the request is scoped to the originating client.
# The originating request id is stamped as `related_request_id`, satisfying
# SEP-2260's requirement that server-to-client requests be associated with
# the client request being processed.
# @deprecated MCP Roots (`roots/list` and
# `notifications/roots/list_changed`) is deprecated as of MCP protocol
# version 2026-07-28 (SEP-2577). Use tool parameters, resource URIs,
@ -91,6 +94,11 @@ module MCP
# Delegates to the session so the request is scoped to the originating client.
# Falls back to `@context` (via `method_missing`) when `@notification_target`
# does not support sampling.
#
# The originating request id is stamped as `related_request_id` and cannot be
# overridden by callers (the literal keyword after `**kwargs` wins),
# satisfying SEP-2260's requirement that server-to-client requests be
# associated with the client request being processed.
# @deprecated MCP Sampling (`sampling/createMessage`) is deprecated as of
# MCP protocol version 2026-07-28 (SEP-2577). Use direct LLM provider
# APIs instead.
@ -107,6 +115,8 @@ module MCP
# Delegates to the session so the request is scoped to the originating client.
# Falls back to `@context` (via `method_missing`) when `@notification_target`
# does not support elicitation.
# The originating request id is stamped as a non-overridable
# `related_request_id`, as with `create_sampling_message` (SEP-2260).
def create_form_elicitation(**kwargs)
if @notification_target.respond_to?(:create_form_elicitation)
@notification_target.create_form_elicitation(**kwargs, related_request_id: @related_request_id)
@ -119,6 +129,8 @@ module MCP
# Delegates to the session so the request is scoped to the originating client.
# Falls back to `@context` when `@notification_target` does not support URL mode elicitation.
# The originating request id is stamped as a non-overridable `related_request_id`,
# as with `create_sampling_message` (SEP-2260).
def create_url_elicitation(**kwargs)
if @notification_target.respond_to?(:create_url_elicitation)
@notification_target.create_url_elicitation(**kwargs, related_request_id: @related_request_id)

40
lib/mcp/server_session.rb
View file

@ -98,11 +98,17 @@ module MCP
end
# Sends a `roots/list` request scoped to this session.
#
# Per SEP-2260, the request must be associated with an originating client
# request; prefer `server_context.list_roots` inside a handler, which stamps
# the association automatically.
# @deprecated MCP Roots (`roots/list` and
# `notifications/roots/list_changed`) is deprecated as of MCP protocol
# version 2026-07-28 (SEP-2577). Use tool parameters, resource URIs,
# server configuration, or environment variables instead.
def list_roots(related_request_id: nil)
warn_unassociated_request(__method__, related_request_id)
unless client_capabilities&.dig(:roots)
raise "Client does not support roots."
end
@ -119,16 +125,28 @@ module MCP
end
# Sends a `sampling/createMessage` request scoped to this session.
#
# Per SEP-2260, the request must be associated with an originating client
# request; prefer `server_context.create_sampling_message` inside a handler,
# which stamps the association automatically.
# @deprecated MCP Sampling (`sampling/createMessage`) is deprecated as of
# MCP protocol version 2026-07-28 (SEP-2577). Use direct LLM provider
# APIs instead.
def create_sampling_message(related_request_id: nil, **kwargs)
warn_unassociated_request(__method__, related_request_id)
params = @server.build_sampling_params(client_capabilities, **kwargs)
send_to_transport_request(Methods::SAMPLING_CREATE_MESSAGE, params, related_request_id: related_request_id)
end
# Sends an `elicitation/create` request (form mode) scoped to this session.
#
# Per SEP-2260, the request must be associated with an originating client
# request; prefer `server_context.create_form_elicitation` inside a handler,
# which stamps the association automatically.
def create_form_elicitation(message:, requested_schema:, related_request_id: nil)
warn_unassociated_request(__method__, related_request_id)
unless client_capabilities&.dig(:elicitation)
raise "Client does not support elicitation. " \
"The client must declare the `elicitation` capability during initialization."
@ -139,7 +157,13 @@ module MCP
end
# Sends an `elicitation/create` request (URL mode) scoped to this session.
#
# Per SEP-2260, the request must be associated with an originating client
# request; prefer `server_context.create_url_elicitation` inside a handler,
# which stamps the association automatically.
def create_url_elicitation(message:, url:, elicitation_id:, related_request_id: nil)
warn_unassociated_request(__method__, related_request_id)
unless client_capabilities&.dig(:elicitation, :url)
raise "Client does not support URL mode elicitation. " \
"The client must declare the `elicitation.url` capability during initialization."
@ -264,5 +288,21 @@ module MCP
# The explicit splat suppresses that conversion and is a no-op when `supported` is empty.
transport_method.call(method, params, **supported)
end
# Per SEP-2260, servers MUST send `roots/list`, `sampling/createMessage`, and `elicitation/create` only
# in association with an originating client request (`ping` is exempt). A request without `related_request_id:` is
# delivered on the standalone GET stream by the Streamable HTTP transport, which the 2026-07-28 spec forbids;
# warn so callers migrate to the `server_context` helpers before this becomes an error.
# https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2260
def warn_unassociated_request(method_name, related_request_id)
return if related_request_id
warn(
"Calling `ServerSession##{method_name}` without `related_request_id:` is deprecated (SEP-2260): " \
"server-to-client #{method_name} requests must be associated with an originating client request. " \
"Use `server_context.#{method_name}` inside a handler, or pass `related_request_id:` explicitly.",
uplevel: 2,
)
end
end
end