From e6b5a9b5e3c451bed575a3f76404461c31f2af26 Mon Sep 17 00:00:00 2001 From: Koichi ITO Date: Thu, 2 Jul 2026 14:40:20 +0900 Subject: [PATCH] Add opt-in `requestState` sealing via `RequestStateSecurity` ## Motivation and Context The SEP-2322 `requestState` continuation string leaves the server, sits in the client's hands, and comes back as client-controlled input. Without protection a client can read the server's continuation state, tamper with it (for example forging an already-answered elicitation), or replay a state issued for one call against another tool, other arguments, or another server. The multi-round-trip documentation of the Python SDK is explicit that the echo must be treated as untrusted input; its high-level server seals the state by default via `RequestStateBoundary`. New `MCP::Server::RequestStateSecurity` (OpenSSL standard library only) brings that protection to this SDK as an opt-in: - `seal` encrypts the plaintext state with AES-256-GCM (clients cannot read it, not merely verify it) inside a claims envelope binding an expiry window (`ttl:`, default 300 seconds, re-sealed each round), the originating method and target (tool/prompt name or resource URI), a digest of the originating arguments (stringified and sorted recursively, so symbol/string parses of identical JSON digest identically), and an optional `audience:`. The token format is `v1.` with the version prefix bound as GCM associated data, following the Python SDK's `AESGCMRequestStateCodec`. - `unseal` verifies every claim fail-closed and raises `InvalidStateError` on tampering, expiry, or any mismatch. Passing an instance via `Server.new(request_state_security:)` makes the seal/unseal transparent: issuance seals the `requestState` of an outgoing `input_required` result, and dispatch unseals the echoed token for `tools/call`, `prompts/get`, and `resources/read` before any handler runs, so `server_context.request_state` always reads the plaintext the handler wrote. A tampered, expired, or cross-call echo is rejected as `-32602` with "Invalid or expired requestState", matching the Python SDK's frozen error. Without the option the state crosses the wire exactly as the handler wrote it (the Python low-level Server behavior); the README documents that this is then the handler author's responsibility, and that multi-process deployments must share the key across workers. The conformance fixture opts in with a random per-boot key, both to dogfood the feature and because the tampered-state scenario of the 2026-07-28 conformance requirements retries an MRTR request with a corrupted `requestState` and requires a JSON-RPC error; without integrity-checked state the fixture cannot detect the corruption. Every MRTR round trip completes within one server process, so no key persistence is needed. Sealing is transparent to the fixture tools, whose `requestState` plaintext round-trips unchanged, and the new `test_input_required_result_tampered_state` tool is therefore a plain MRTR elicitation flow; the tampered echo is rejected with `-32602` by the server-level unsealing before dispatch ever reaches it. Refs #382. ## How Has This Been Tested? New `test/mcp/server/request_state_security_test.rb` covers constructor validation, the seal/unseal round trip (opaque `v1.` token, plaintext not visible), expiry via time travel, fail-closed rejection of method/target/digest/audience mismatches, tampered and malformed tokens, and tokens sealed under a different key. New tests in `test/mcp/server_test.rb` drive `Server#handle` with the modern envelope: transparent sealing on issuance and plaintext restoration on the retry leg, `-32602` for tampered echoes and for echoes replayed against different arguments, and the pass-through default when `request_state_security:` is not set. Against the fixture server at `--spec-version 2026-07-28` (run with `@modelcontextprotocol/conformance@alpha`; the 2026-07-28 scenarios are not yet in a stable conformance release), `sep-2322-reject-tampered-state` reports SUCCESS, and the other 13 `input-required-result-*` scenarios stay green with sealing active, confirming that sealed states round-trip through the suite's retries without false rejections (the seal binds `method`, target, and an arguments digest, and the suite echoes all three unchanged). The `--requirements 2025-11-25` server leg still passes. ## Breaking Changes None. The feature is opt-in via a new keyword argument that defaults to `nil`, in which case behavior is byte-identical to before. --- README.md | 7 +- conformance/server.rb | 39 ++++++ lib/mcp/server.rb | 82 ++++++++++- lib/mcp/server/request_state_security.rb | 131 ++++++++++++++++++ .../mcp/server/request_state_security_test.rb | 90 ++++++++++++ test/mcp/server_test.rb | 74 ++++++++++ 6 files changed, 417 insertions(+), 6 deletions(-) create mode 100644 lib/mcp/server/request_state_security.rb create mode 100644 test/mcp/server/request_state_security_test.rb diff --git a/README.md b/README.md index f83cdaa5..d563a541 100644 --- a/README.md +++ b/README.md @@ -60,8 +60,11 @@ It implements the Model Context Protocol specification, handling model context r which the modern lifecycle forbids. On the retried request the handler re-runs from the start and reads the answers via `server_context.input_responses` / `server_context.input_response(key)` and the echoed opaque `server_context.request_state` (deterministic replay; the server holds no memory between rounds). The SDK rejects issuance on legacy requests and returns `-32021` - when an embedded request needs a client capability the request did not declare. Note that the echoed `requestState` arrives as - client-controlled input; treat it accordingly + when an embedded request needs a client capability the request did not declare. The echoed `requestState` arrives as + client-controlled input: pass `MCP::Server::RequestStateSecurity.new(key:)` (a 32-byte key) via `Server.new(request_state_security:)` to + have it sealed with AES-256-GCM and bound to a TTL plus the originating method, target, and arguments, all transparently to handlers. + Multi-process deployments must share the key across workers; without `request_state_security:` the state crosses the wire exactly as + the handler wrote it and protecting it is the handler author's responsibility - `ping` - Simple health check - `logging/setLevel` - Configures the minimum log level for the server - `tools/list` - Lists all registered tools and their schemas diff --git a/conformance/server.rb b/conformance/server.rb index dca807db..ef138d0e 100644 --- a/conformance/server.rb +++ b/conformance/server.rb @@ -575,6 +575,40 @@ def second_round(name) end end + class TestInputRequiredResultTamperedState < MCP::Tool + tool_name "test_input_required_result_tampered_state" + description "A tool whose sealed requestState rejects tampered echoes (SEP-2322)" + + class << self + # A tampered `requestState` never reaches this handler: the server-level unsealing rejects it with -32602 + # before dispatch, so the tool body is a plain MRTR flow. + def call(server_context:, **_args) + state = Mrtr.parse_state(server_context.request_state) + confirmed = Mrtr.accepted_content(server_context.input_response("confirm")) + + if state && state["kind"] == "tamper-check" && confirmed + return MCP::Tool::Response.new([MCP::Content::Text.new("requestState integrity verified").to_h]) + end + + MCP::Server::InputRequiredResult.new( + input_requests: { + confirm: { + method: "elicitation/create", + params: { + message: "Confirm to continue", + requestedSchema: { + type: "object", + properties: { ok: { type: "boolean" } }, + }, + }, + }, + }, + request_state: JSON.generate({ kind: "tamper-check", nonce: SecureRandom.hex(8) }), + ) + end + end + end + class TestInputRequiredResultCapabilities < MCP::Tool tool_name "test_input_required_result_capabilities" description "A tool that only embeds input requests the client's declared capabilities can fulfill (SEP-2322)" @@ -869,6 +903,7 @@ def build_server Tools::TestInputRequiredResultRequestState, Tools::TestInputRequiredResultMultipleInputs, Tools::TestInputRequiredResultMultiRound, + Tools::TestInputRequiredResultTamperedState, Tools::TestInputRequiredResultCapabilities, Tools::TestStreamingElicitation, Tools::TestLoggingTool, @@ -882,6 +917,10 @@ def build_server ], resources: resources, resource_templates: resource_templates, + # A per-boot random key is enough for conformance: every MRTR round trip completes + # within one server process, and sealing keeps the fixture's `requestState` values + # tamper-evident without any tool-level verification code. + request_state_security: MCP::Server::RequestStateSecurity.new(key: SecureRandom.bytes(32)), capabilities: { tools: { listChanged: true }, prompts: { listChanged: true }, diff --git a/lib/mcp/server.rb b/lib/mcp/server.rb index 262352f6..eaca0def 100644 --- a/lib/mcp/server.rb +++ b/lib/mcp/server.rb @@ -12,6 +12,7 @@ require_relative "server/capabilities" require_relative "server/input_required_result" require_relative "server/pagination" +require_relative "server/request_state_security" require_relative "server/transports" module MCP @@ -145,7 +146,7 @@ class ValidationError < StandardError; end CACHE_SCOPES = ["public", "private"].freeze attr_accessor :description, :icons, :name, :title, :version, :website_url, :instructions, :tools, :prompts, :resource_templates, :server_context, :configuration, :capabilities, :transport, :logging_message_notification - attr_reader :resources, :page_size, :client_capabilities, :ttl_ms, :cache_scope + attr_reader :resources, :page_size, :client_capabilities, :ttl_ms, :cache_scope, :request_state_security def initialize( description: nil, @@ -165,6 +166,7 @@ def initialize( page_size: nil, ttl_ms: nil, cache_scope: nil, + request_state_security: nil, transport: nil ) @description = description @@ -184,6 +186,7 @@ def initialize( self.page_size = page_size self.ttl_ms = ttl_ms self.cache_scope = cache_scope + @request_state_security = request_state_security @configuration = MCP.configuration.merge(configuration) @client = nil @client_protocol_version = nil @@ -594,6 +597,8 @@ def handle_request(request, method, session: nil, related_request_id: nil) session.configure_logging(request_logging) if request_logging.valid_level? end + params = unseal_request_state(params, method: method) if @request_state_security + result = case method when Methods::INITIALIZE init(params, session: session) @@ -628,7 +633,7 @@ def handle_request(request, method, session: nil, related_request_id: nil) # Runs after the cancellation check so a cancelled request stays suppressed # instead of turning into a gate error response. if result.is_a?(InputRequiredResult) - result = serialize_input_required_result(result, envelope: envelope, request: params) + result = serialize_input_required_result(result, envelope: envelope, request: params, method: method) end # SEP-2322 makes `resultType` REQUIRED on every result a 2026-07-28 server returns; @@ -707,7 +712,7 @@ def lift_request_envelope(params, method:, session:) # a final result. The capability gate enforces the SEP-2575 rule that servers MUST NOT rely on # (or embed requests for) capabilities the client did not declare, and reports every missing capability at # once so the client sees the full set. - def serialize_input_required_result(result, envelope:, request:) + def serialize_input_required_result(result, envelope:, request:, method:) if envelope.nil? raise RequestHandlerError.new( "input_required results require the 2026-07-28 stateless lifecycle (SEP-2322)", @@ -720,7 +725,76 @@ def serialize_input_required_result(result, envelope:, request:) raise MissingRequiredClientCapabilityError.new(missing, request) unless missing.empty? add_instrumentation_data(input_required: true) - result.to_h + serialized = result.to_h + + if @request_state_security && serialized[:requestState] + serialized = serialized.merge(requestState: @request_state_security.seal( + serialized[:requestState], + method: method, + target: mrtr_target(request), + arguments_digest: mrtr_arguments_digest(request), + )) + end + + serialized + end + + # Methods whose results may be `input_required` and whose retried requests carry + # `inputResponses`/`requestState` (SEP-2322). + MRTR_METHODS = [Methods::TOOLS_CALL, Methods::PROMPTS_GET, Methods::RESOURCES_READ].freeze + + # Replaces a sealed client-echoed `requestState` with its verified plaintext before dispatch, + # so handlers always read the state they wrote. A tampered, expired, or cross-request token is + # rejected as invalid params, matching the Python SDK's "Invalid or expired requestState" behavior. + def unseal_request_state(params, method:) + return params unless MRTR_METHODS.include?(method) + return params unless params.is_a?(Hash) + + sealed = params[:requestState] || params["requestState"] + return params unless sealed + + plaintext = @request_state_security.unseal( + sealed, + method: method, + target: mrtr_target(params), + arguments_digest: mrtr_arguments_digest(params), + ) + key = params.key?("requestState") ? "requestState" : :requestState + params.merge(key => plaintext) + rescue RequestStateSecurity::InvalidStateError => e + raise RequestHandlerError.new( + "Invalid or expired requestState", + params, + error_type: :invalid_params, + error_code: JsonRpcHandler::ErrorCode::INVALID_PARAMS, + original_error: e, + ) + end + + def mrtr_target(params) + return "" unless params.is_a?(Hash) + + params[:name] || params["name"] || params[:uri] || params["uri"] || "" + end + + # Digest of the originating arguments, binding a sealed state to retries of + # the same call with the same inputs. Keys are stringified and sorted recursively + # so symbol/string parses of identical JSON digest identically. + def mrtr_arguments_digest(params) + arguments = params.is_a?(Hash) ? params[:arguments] || params["arguments"] : nil + OpenSSL::Digest::SHA256.hexdigest(canonical_json(arguments || {})) + end + + def canonical_json(value) + case value + when Hash + pairs = value.map { |key, nested| [key.to_s, nested] }.sort_by(&:first) + "{#{pairs.map { |key, nested| "#{key.to_json}:#{canonical_json(nested)}" }.join(",")}}" + when Array + "[#{value.map { |element| canonical_json(element) }.join(",")}]" + else + value.to_json + end end # Extracts the SEP-2322 retry fields a client sends when re-issuing a request: diff --git a/lib/mcp/server/request_state_security.rb b/lib/mcp/server/request_state_security.rb new file mode 100644 index 00000000..bc96a858 --- /dev/null +++ b/lib/mcp/server/request_state_security.rb @@ -0,0 +1,131 @@ +# frozen_string_literal: true + +require "json" +require "openssl" + +module MCP + class Server + # Opt-in protection for the SEP-2322 `requestState` echo. The opaque continuation string leaves the server, + # sits in the client's hands, and comes back as client-controlled input, so it must be treated like + # any other untrusted data. Sealing encrypts the state with AES-256-GCM (clients cannot read it) and binds + # a claims envelope that unsealing verifies fail-closed: + # + # - `exp`: a TTL window (re-sealed each round) + # - `m` / `t`: the originating method and target (tool/prompt name or resource URI) + # - `a`: a digest of the originating arguments, so the state only resumes the same call with the same inputs + # - `aud`: an optional audience, so tokens cannot cross servers sharing a key + # + # Pass an instance via `Server.new(request_state_security:)` and the seal/unseal happens transparently; + # handlers keep reading plaintext through `server_context.request_state`. Without it, the state crosses + # the wire exactly as the handler wrote it (the author's responsibility, matching the Python SDK's low-level Server). + # The key must be shared across workers in multi-process + # + # deployments; a per-process random key makes retries that land on another worker fail with an invalid-state error, + # forcing clients to restart the flow. + # + # The token format is `v1.`, with the version prefix bound as GCM associated data, + # following the Python SDK's `AESGCMRequestStateCodec`. + class RequestStateSecurity + class InvalidStateError < StandardError; end + + VERSION_PREFIX = "v1." + KEY_BYTES = 32 + IV_BYTES = 12 + TAG_BYTES = 16 + DEFAULT_TTL = 300 + + def initialize(key:, ttl: DEFAULT_TTL, audience: nil) + unless key.is_a?(String) && key.bytesize == KEY_BYTES + raise ArgumentError, "key must be a #{KEY_BYTES}-byte String" + end + unless ttl.is_a?(Numeric) && ttl.positive? + raise ArgumentError, "ttl must be a positive number of seconds" + end + + @key = key.dup.force_encoding(Encoding::BINARY).freeze + @ttl = ttl + @audience = audience + end + + # Seals a plaintext state into an opaque token bound to the originating request. + def seal(state, method:, target:, arguments_digest:) + claims = { + v: 1, + exp: Time.now.to_i + @ttl, + m: method, + t: target, + a: arguments_digest, + aud: @audience, + s: state, + }.compact + + cipher = OpenSSL::Cipher.new("aes-256-gcm").encrypt + cipher.key = @key + iv = cipher.random_iv + cipher.auth_data = VERSION_PREFIX + ciphertext = cipher.update(JSON.generate(claims)) + cipher.final + + VERSION_PREFIX + base64url_encode(iv + ciphertext + cipher.auth_tag) + end + + # Unseals a client-echoed token and verifies every claim, failing closed with + # `InvalidStateError` on tampering, expiry, or a claims mismatch. + def unseal(sealed, method:, target:, arguments_digest:) + unless sealed.is_a?(String) && sealed.start_with?(VERSION_PREFIX) + raise InvalidStateError, "malformed token" + end + + blob = base64url_decode(sealed.delete_prefix(VERSION_PREFIX)) + raise InvalidStateError, "malformed token" if blob.bytesize < IV_BYTES + TAG_BYTES + + iv = blob.byteslice(0, IV_BYTES) + tag = blob.byteslice(-TAG_BYTES, TAG_BYTES) + ciphertext = blob.byteslice(IV_BYTES, blob.bytesize - IV_BYTES - TAG_BYTES) + + cipher = OpenSSL::Cipher.new("aes-256-gcm").decrypt + cipher.key = @key + cipher.iv = iv + cipher.auth_tag = tag + cipher.auth_data = VERSION_PREFIX + plaintext = begin + cipher.update(ciphertext) + cipher.final + rescue OpenSSL::Cipher::CipherError + raise InvalidStateError, "authentication failed" + end + + claims = begin + JSON.parse(plaintext, symbolize_names: true) + rescue JSON::ParserError + raise InvalidStateError, "malformed claims" + end + + verify!(claims, method: method, target: target, arguments_digest: arguments_digest) + claims[:s] + end + + private + + def verify!(claims, method:, target:, arguments_digest:) + raise InvalidStateError, "unsupported version" unless claims[:v] == 1 + raise InvalidStateError, "expired" unless claims[:exp].is_a?(Integer) && Time.now.to_i <= claims[:exp] + raise InvalidStateError, "method mismatch" unless claims[:m] == method + raise InvalidStateError, "target mismatch" unless claims[:t] == target + raise InvalidStateError, "arguments mismatch" unless claims[:a] == arguments_digest + raise InvalidStateError, "audience mismatch" unless claims[:aud] == @audience + raise InvalidStateError, "missing state" unless claims[:s].is_a?(String) + end + + def base64url_encode(data) + [data].pack("m0").tr("+/", "-_").delete("=") + end + + def base64url_decode(encoded) + padded = encoded.tr("-_", "+/") + padded += "=" * ((4 - padded.length % 4) % 4) + padded.unpack1("m0") + rescue ArgumentError + raise InvalidStateError, "malformed token" + end + end + end +end diff --git a/test/mcp/server/request_state_security_test.rb b/test/mcp/server/request_state_security_test.rb new file mode 100644 index 00000000..29b7d794 --- /dev/null +++ b/test/mcp/server/request_state_security_test.rb @@ -0,0 +1,90 @@ +# frozen_string_literal: true + +require "test_helper" + +module MCP + class Server + class RequestStateSecurityTest < ActiveSupport::TestCase + include ActiveSupport::Testing::TimeHelpers + + KEY = ("k" * 32).freeze + + test "validates constructor arguments" do + assert_raises(ArgumentError) { RequestStateSecurity.new(key: "short") } + assert_raises(ArgumentError) { RequestStateSecurity.new(key: KEY, ttl: 0) } + end + + test "seals and unseals a state bound to the originating request" do + security = RequestStateSecurity.new(key: KEY, audience: "my_server") + sealed = security.seal("plain-state", method: "tools/call", target: "my_tool", arguments_digest: "digest") + + assert sealed.start_with?("v1.") + refute_includes sealed, "plain-state" + assert_equal "plain-state", + security.unseal(sealed, method: "tools/call", target: "my_tool", arguments_digest: "digest") + end + + test "rejects expired tokens" do + security = RequestStateSecurity.new(key: KEY, ttl: 60) + sealed = security.seal("state", method: "tools/call", target: "t", arguments_digest: "d") + + travel 120 do + assert_raises(RequestStateSecurity::InvalidStateError) do + security.unseal(sealed, method: "tools/call", target: "t", arguments_digest: "d") + end + end + end + + test "rejects claims mismatches fail-closed" do + security = RequestStateSecurity.new(key: KEY, audience: "my_server") + sealed = security.seal("state", method: "tools/call", target: "my_tool", arguments_digest: "digest") + + assert_raises(RequestStateSecurity::InvalidStateError) do + security.unseal(sealed, method: "prompts/get", target: "my_tool", arguments_digest: "digest") + end + assert_raises(RequestStateSecurity::InvalidStateError) do + security.unseal(sealed, method: "tools/call", target: "other_tool", arguments_digest: "digest") + end + assert_raises(RequestStateSecurity::InvalidStateError) do + security.unseal(sealed, method: "tools/call", target: "my_tool", arguments_digest: "other") + end + + other_audience = RequestStateSecurity.new(key: KEY, audience: "other_server") + assert_raises(RequestStateSecurity::InvalidStateError) do + other_audience.unseal(sealed, method: "tools/call", target: "my_tool", arguments_digest: "digest") + end + end + + test "rejects tampered and malformed tokens" do + security = RequestStateSecurity.new(key: KEY) + sealed = security.seal("state", method: "tools/call", target: "t", arguments_digest: "d") + + tampered = sealed.dup + tampered[-1] = tampered[-1] == "A" ? "B" : "A" + assert_raises(RequestStateSecurity::InvalidStateError) do + security.unseal(tampered, method: "tools/call", target: "t", arguments_digest: "d") + end + + assert_raises(RequestStateSecurity::InvalidStateError) do + security.unseal("not-a-token", method: "tools/call", target: "t", arguments_digest: "d") + end + assert_raises(RequestStateSecurity::InvalidStateError) do + security.unseal("v1.!!!", method: "tools/call", target: "t", arguments_digest: "d") + end + assert_raises(RequestStateSecurity::InvalidStateError) do + security.unseal(nil, method: "tools/call", target: "t", arguments_digest: "d") + end + end + + test "rejects tokens sealed under a different key" do + sealed = RequestStateSecurity.new(key: KEY) + .seal("state", method: "tools/call", target: "t", arguments_digest: "d") + other = RequestStateSecurity.new(key: "x" * 32) + + assert_raises(RequestStateSecurity::InvalidStateError) do + other.unseal(sealed, method: "tools/call", target: "t", arguments_digest: "d") + end + end + end + end +end diff --git a/test/mcp/server_test.rb b/test/mcp/server_test.rb index 69d9b8cb..162bdfb3 100644 --- a/test/mcp/server_test.rb +++ b/test/mcp/server_test.rb @@ -505,6 +505,80 @@ class ServerTest < ActiveSupport::TestCase assert_equal "input_required", response.dig(:result, :resultType) end + test "#handle seals and unseals requestState transparently when request_state_security is set" do + security = Server::RequestStateSecurity.new(key: "k" * 32) + server = Server.new(name: "mrtr_test", tools: [], request_state_security: security) + seen_state = nil + server.define_tool(name: "mrtr_tool") do |server_context:| + if server_context.request_state + seen_state = server_context.request_state + Tool::Response.new([{ type: "text", text: "done" }]) + else + Server::InputRequiredResult.new(request_state: "plain-state") + end + end + + first = server.handle(modern_request("tools/call", { name: "mrtr_tool", arguments: {} })) + sealed = first.dig(:result, :requestState) + + assert sealed.start_with?("v1.") + refute_equal "plain-state", sealed + + retry_response = server.handle(modern_request("tools/call", { + name: "mrtr_tool", + arguments: {}, + requestState: sealed, + })) + + refute_nil retry_response[:result] + # The handler reads the plaintext it originally wrote. + assert_equal "plain-state", seen_state + end + + test "#handle rejects a tampered or cross-call requestState echo with -32602" do + security = Server::RequestStateSecurity.new(key: "k" * 32) + server = Server.new(name: "mrtr_test", tools: [], request_state_security: security) + server.define_tool(name: "mrtr_tool") do |server_context:| + if server_context.request_state + Tool::Response.new([{ type: "text", text: "done" }]) + else + Server::InputRequiredResult.new(request_state: "plain-state") + end + end + + first = server.handle(modern_request("tools/call", { name: "mrtr_tool", arguments: {} })) + sealed = first.dig(:result, :requestState) + + tampered = server.handle(modern_request("tools/call", { + name: "mrtr_tool", + arguments: {}, + requestState: sealed.sub("v1.", "v1.x"), + })) + # Different arguments than the sealing call: the digest claim no longer matches. + cross_call = server.handle(modern_request("tools/call", { + name: "mrtr_tool", + arguments: { other: true }, + requestState: sealed, + })) + + assert_equal JsonRpcHandler::ErrorCode::INVALID_PARAMS, tampered.dig(:error, :code) + assert_equal "Invalid or expired requestState", tampered.dig(:error, :message) + assert_equal JsonRpcHandler::ErrorCode::INVALID_PARAMS, cross_call.dig(:error, :code) + end + + test "#handle passes requestState through untouched without request_state_security" do + server = Server.new(name: "mrtr_test", tools: []) + seen_state = nil + server.define_tool(name: "mrtr_tool") do |server_context:| + seen_state = server_context.request_state + Tool::Response.new([{ type: "text", text: "done" }]) + end + + server.handle(modern_request("tools/call", { name: "mrtr_tool", requestState: "raw-state" })) + + assert_equal "raw-state", seen_state + end + test "#handle prompts/get serializes an input_required result on a modern request" do server = Server.new(name: "mrtr_test") server.define_prompt(name: "mrtr_prompt", arguments: []) do |_args, server_context:|