Track Mcp-Session-Id and protocol version in HTTP client
Per the Streamable HTTP spec, if the server returns an Mcp-Session-Id header during `initialize`, the client MUST include it on subsequent requests. Capture the session ID and protocol version from the `initialize` response and attach them automatically on subsequent POSTs. Per the Protocol Version Header section of the spec, the client MUST also include `MCP-Protocol-Version` on all subsequent requests so the server can respond based on the negotiated protocol version. Map 404 responses to a new `SessionExpiredError` (a subclass of `RequestHandlerError` for backward compatibility) and clear local session state so callers can start a fresh session with a new `initialize` request, as required by the spec. - https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#session-management - https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#protocol-version-header Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
This commit is contained in:
Ates Goral
parent
baa093dfd5
commit
07226b7cf1
1 changed files with 275 additions and 10 deletions
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@ -203,7 +203,7 @@ module MCP
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assert_equal({ method: "tools/list", params: nil }, error.request)
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end
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def test_send_request_raises_not_found_error
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def test_send_request_raises_not_found_error_on_404_without_session
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request = {
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jsonrpc: "2.0",
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id: "test_id",
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@ -218,11 +218,56 @@ module MCP
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client.send_request(request: request)
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end
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refute_kind_of(SessionExpiredError, error)
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assert_equal("The tools/list request is not found", error.message)
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assert_equal(:not_found, error.error_type)
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assert_equal({ method: "tools/list", params: nil }, error.request)
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end
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def test_send_request_raises_session_expired_error_on_404_with_session
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stub_request(:post, url)
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.to_return(
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status: 200,
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headers: {
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"Content-Type" => "application/json",
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"Mcp-Session-Id" => "session-abc",
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},
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body: { result: { protocolVersion: "2025-11-25" } }.to_json,
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)
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client.send_request(request: { jsonrpc: "2.0", id: "1", method: "initialize" })
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stub_request(:post, url).to_return(status: 404)
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error = assert_raises(SessionExpiredError) do
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client.send_request(request: { jsonrpc: "2.0", id: "2", method: "tools/list" })
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end
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assert_equal(:not_found, error.error_type)
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end
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def test_session_expired_error_is_a_request_handler_error
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stub_request(:post, url)
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.to_return(
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status: 200,
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headers: {
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"Content-Type" => "application/json",
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"Mcp-Session-Id" => "session-abc",
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},
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body: { result: { protocolVersion: "2025-11-25" } }.to_json,
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)
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client.send_request(request: { jsonrpc: "2.0", id: "1", method: "initialize" })
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stub_request(:post, url).to_return(status: 404)
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error = assert_raises(RequestHandlerError) do
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client.send_request(request: { jsonrpc: "2.0", id: "2", method: "tools/list" })
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end
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assert_kind_of(SessionExpiredError, error)
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end
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def test_send_request_raises_unprocessable_entity_error
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request = {
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jsonrpc: "2.0",
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@ -413,6 +458,149 @@ module MCP
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assert_equal(:parse_error, error.error_type)
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end
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def test_captures_session_id_and_protocol_version_on_initialize
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stub_request(:post, url)
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.to_return(
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status: 200,
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headers: {
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"Content-Type" => "application/json",
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"Mcp-Session-Id" => "session-abc",
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},
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body: { result: { protocolVersion: "2025-11-25" } }.to_json,
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)
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client.send_request(request: { jsonrpc: "2.0", id: "1", method: "initialize" })
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assert_equal("session-abc", client.session_id)
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assert_equal("2025-11-25", client.protocol_version)
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end
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def test_includes_session_and_protocol_version_headers_after_initialize
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stub_request(:post, url)
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.to_return(
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status: 200,
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headers: {
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"Content-Type" => "application/json",
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"Mcp-Session-Id" => "session-abc",
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},
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body: { result: { protocolVersion: "2025-11-25" } }.to_json,
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)
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client.send_request(request: { jsonrpc: "2.0", id: "1", method: "initialize" })
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stub_request(:post, url)
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.with(
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headers: {
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"Mcp-Session-Id" => "session-abc",
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"MCP-Protocol-Version" => "2025-11-25",
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},
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)
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.to_return(
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status: 200,
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headers: { "Content-Type" => "application/json" },
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body: { result: { tools: [] } }.to_json,
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)
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client.send_request(request: { jsonrpc: "2.0", id: "2", method: "tools/list" })
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end
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def test_does_not_send_protocol_version_header_before_initialize
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stub_request(:post, url)
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.with { |req| !req.headers.keys.map(&:downcase).include?("mcp-protocol-version") }
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.to_return(
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status: 200,
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headers: { "Content-Type" => "application/json" },
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body: { result: { protocolVersion: "2025-11-25" } }.to_json,
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)
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client.send_request(request: { jsonrpc: "2.0", id: "1", method: "initialize" })
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end
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def test_ignores_empty_session_id_header
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stub_request(:post, url)
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.to_return(
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status: 200,
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headers: {
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"Content-Type" => "application/json",
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"Mcp-Session-Id" => "",
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},
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body: { result: { protocolVersion: "2025-11-25" } }.to_json,
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)
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client.send_request(request: { jsonrpc: "2.0", id: "1", method: "initialize" })
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assert_nil(client.session_id)
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end
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def test_session_id_not_overwritten_by_subsequent_responses
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stub_request(:post, url)
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.to_return(
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status: 200,
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headers: {
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"Content-Type" => "application/json",
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"Mcp-Session-Id" => "original-session",
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},
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body: { result: { protocolVersion: "2025-11-25" } }.to_json,
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)
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client.send_request(request: { jsonrpc: "2.0", id: "1", method: "initialize" })
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assert_equal("original-session", client.session_id)
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stub_request(:post, url)
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.to_return(
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status: 200,
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headers: {
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"Content-Type" => "application/json",
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"Mcp-Session-Id" => "different-session",
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},
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body: { result: { tools: [] } }.to_json,
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)
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client.send_request(request: { jsonrpc: "2.0", id: "2", method: "tools/list" })
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assert_equal("original-session", client.session_id)
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end
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def test_stateless_server_without_session_id_header
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stub_request(:post, url)
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.to_return(
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status: 200,
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headers: { "Content-Type" => "application/json" },
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body: { result: { protocolVersion: "2025-11-25" } }.to_json,
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)
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client.send_request(request: { jsonrpc: "2.0", id: "1", method: "initialize" })
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assert_nil(client.session_id)
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assert_equal("2025-11-25", client.protocol_version)
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end
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def test_clears_session_state_on_404
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stub_request(:post, url)
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.to_return(
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status: 200,
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headers: {
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"Content-Type" => "application/json",
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"Mcp-Session-Id" => "session-abc",
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},
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body: { result: { protocolVersion: "2025-11-25" } }.to_json,
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)
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client.send_request(request: { jsonrpc: "2.0", id: "1", method: "initialize" })
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assert_equal("session-abc", client.session_id)
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stub_request(:post, url).to_return(status: 404)
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assert_raises(SessionExpiredError) do
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client.send_request(request: { jsonrpc: "2.0", id: "2", method: "tools/list" })
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end
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assert_nil(client.session_id)
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assert_nil(client.protocol_version)
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end
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private
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def stub_request(method, url)
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