2c62139154
## Motivation and Context SEP-2133 (modelcontextprotocol/modelcontextprotocol#2133, merged for the 2026-07-28 spec release) establishes the extensions framework for MCP: both `ClientCapabilities` and `ServerCapabilities` gain an optional `extensions` member keyed by reverse-DNS extension identifiers (e.g. `"io.modelcontextprotocol/tasks"`, `"com.example/feature"`), with arbitrary extension-defined configuration objects as values and an empty object meaning "supported with no settings". Official extensions such as MCP Apps (SEP-1865) and the Tasks extension (SEP-2663) are layered on this field. This mirrors the shape the TypeScript SDK merged (typescript-sdk#1630): plain declaration and passthrough, no registrar API and no key-format validation (the naming convention is documented instead). - `MCP::Server::Capabilities` gains `support_extensions` (repeated calls merge), accepts an `:extensions` key in its constructor hash, and includes `extensions` in `to_h`. The class was previously dead code: it was never required and `Server.new` only took plain hashes. It is now required by `lib/mcp/server.rb`, and `Server.new(capabilities:)` accepts either a plain Hash (as before) or a `Capabilities` instance. - Server-declared extensions appear in the `initialize` result; extensions the client declares during `initialize` were already stored verbatim and are readable via `Server#client_capabilities[:extensions]` and `ServerSession#client_capabilities[:extensions]` (now covered by tests). - `MCP::Client#connect(capabilities:)` already passes capabilities through verbatim; its documentation now covers the `extensions` member. Resolves #378. ## How Has This Been Tested? - New `test/mcp/server/capabilities_test.rb` covers the previously untested `Capabilities` class: empty default, constructor round-trip, extensions via constructor and `support_extensions`, merge semantics, nil tolerance, and omission from `to_h` when never declared. - New tests in `test/mcp/server_test.rb` assert that the `initialize` result carries declared extensions (from both a plain hash and a `Capabilities` instance) and that client-declared extensions are readable via `Server#client_capabilities` and `ServerSession#client_capabilities`. ## Breaking Changes None. `extensions` is additive and appears on the wire only when declared; servers constructed with plain capability hashes behave exactly as before.
71 lines
2.1 KiB
Ruby
71 lines
2.1 KiB
Ruby
# frozen_string_literal: true
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require "test_helper"
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module MCP
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class Server
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class CapabilitiesTest < ActiveSupport::TestCase
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test "to_h omits everything by default" do
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assert_empty(Capabilities.new.to_h)
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end
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test "constructor accepts a capabilities hash" do
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capabilities = Capabilities.new(
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completions: {},
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logging: {},
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prompts: { listChanged: true },
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resources: { listChanged: true, subscribe: true },
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tools: { listChanged: true },
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)
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assert_equal(
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{
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completions: {},
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logging: {},
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prompts: { listChanged: true },
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resources: { listChanged: true, subscribe: true },
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tools: { listChanged: true },
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},
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capabilities.to_h,
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)
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end
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test "constructor accepts extensions" do
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capabilities = Capabilities.new(
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tools: {},
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extensions: { "com.example/feature" => { enabled: true } },
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)
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assert_equal({ "com.example/feature" => { enabled: true } }, capabilities.to_h[:extensions])
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end
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test "support_extensions merges repeated declarations" do
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capabilities = Capabilities.new
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capabilities.support_extensions("com.example/feature" => { enabled: true })
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capabilities.support_extensions("io.modelcontextprotocol/tasks" => {})
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assert_equal(
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{ "com.example/feature" => { enabled: true }, "io.modelcontextprotocol/tasks" => {} },
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capabilities.to_h[:extensions],
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)
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end
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test "support_extensions with no arguments declares an empty extensions object" do
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capabilities = Capabilities.new
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capabilities.support_extensions
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assert_equal({}, capabilities.to_h[:extensions])
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end
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test "support_extensions tolerates nil" do
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capabilities = Capabilities.new(extensions: nil)
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assert_equal({}, capabilities.to_h[:extensions])
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end
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test "to_h omits extensions when never declared" do
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refute(Capabilities.new(tools: {}).to_h.key?(:extensions))
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end
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end
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end
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end
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