Add client conformance for SEP-2663 task results

examples/clients/typescript/everything-client.ts

@@ -28,8 +28,12 @@ import type {
 import { JWT_BEARER_GRANT_TYPE } from '../../../src/scenarios/client/auth/helpers/createWorkloadJwt.js';
 import { ElicitRequestSchema } from '@modelcontextprotocol/sdk/types.js';
 import { ClientConformanceContextSchema } from '../../../src/schemas/context.js';
-import { DRAFT_PROTOCOL_VERSION } from '../../../src/types.js';
+import {
+  DRAFT_PROTOCOL_VERSION,
+  type SpecVersion
+} from '../../../src/types.js';
 import { STATELESS_SPEC_VERSIONS } from '../../../src/connection/select.js';
+import { buildStandardHeaders } from '../../../src/connection/stateless.js';
 import {
   auth,
   extractWWWAuthenticateParams
@@ -100,7 +104,8 @@ const USE_STATELESS_LIFECYCLE = PROTOCOL_VERSION
 // Wire protocolVersion for stateless requests: the runner-resolved version
 // when available (so a dated stateless release is exercised under its own
 // identifier), the current draft otherwise.
-const STATELESS_PROTOCOL_VERSION = PROTOCOL_VERSION ?? DRAFT_PROTOCOL_VERSION;
+const STATELESS_PROTOCOL_VERSION = (PROTOCOL_VERSION ??
+  DRAFT_PROTOCOL_VERSION) as SpecVersion;
 
 const STATELESS_META_BASE = {
   'io.modelcontextprotocol/clientInfo': {
@@ -128,13 +133,9 @@ async function statelessRequest(
   };
   const response = await fetch(serverUrl, {
     method: 'POST',
-    headers: {
-      'Content-Type': 'application/json',
-      // Servers built on the SDK's StreamableHTTPServerTransport reject
-      // requests that don't accept both JSON and SSE responses.
-      Accept: 'application/json, text/event-stream',
-      'MCP-Protocol-Version': STATELESS_PROTOCOL_VERSION
-    },
+    headers: buildStandardHeaders(method, params, {
+      specVersion: STATELESS_PROTOCOL_VERSION
+    }),
     body: JSON.stringify({
       jsonrpc: '2.0',
       id: _nextStatelessId++,
@@ -287,7 +288,7 @@ async function runRequestMetadataClient(serverUrl: string): Promise<void> {
             serverSupported.includes(v)
           );
           if (mutuallySupported.length > 0) {
-            activeVersion = mutuallySupported[0];
+            activeVersion = mutuallySupported[0] as SpecVersion;
             logger.debug(
               `Mutually supported version found: ${activeVersion}. Retrying...`
             );
@@ -1005,6 +1006,69 @@ async function runMRTRClient(serverUrl: string): Promise<void> {
 
 registerScenario('sep-2322-client-request-state', runMRTRClient);
 
+// ============================================================================
+// Tasks extension client conformance (SEP-2663)
+// ============================================================================
+
+const TASKS_EXTENSION_ID = 'io.modelcontextprotocol/tasks';
+
+async function runTasksClientCreateHandling(serverUrl: string): Promise<void> {
+  const taskCapabilities = {
+    ...STATELESS_META_BASE['io.modelcontextprotocol/clientCapabilities'],
+    extensions: { [TASKS_EXTENSION_ID]: {} }
+  };
+  const request = (method: string, params: Record<string, unknown> = {}) =>
+    statelessRequest(serverUrl, method, {
+      ...params,
+      _meta: {
+        'io.modelcontextprotocol/clientCapabilities': taskCapabilities
+      }
+    });
+
+  const discovery = await request('server/discover');
+  if (!discovery?.capabilities?.extensions?.[TASKS_EXTENSION_ID]) {
+    throw new Error('Server did not advertise the Tasks extension');
+  }
+
+  await request('tools/list');
+  const result = await request('tools/call', {
+    name: 'long_running_echo',
+    arguments: { text: 'hello' }
+  });
+
+  if (result?.resultType !== 'task') {
+    // A standard CallToolResult is also valid after negotiating the extension.
+    return;
+  }
+
+  const taskId = result.taskId;
+  if (typeof taskId !== 'string') {
+    throw new Error('CreateTaskResult did not contain a taskId');
+  }
+
+  for (let attempt = 0; attempt < 20; attempt++) {
+    const task = await request('tasks/get', { taskId });
+    if (task?.status === 'completed') {
+      if (!task.result) {
+        throw new Error('Completed task did not include its result');
+      }
+      return;
+    }
+    if (task?.status === 'failed' || task?.status === 'cancelled') {
+      throw new Error(`Task terminated with status ${task.status}`);
+    }
+    const delay =
+      typeof task?.pollIntervalMs === 'number' ? task.pollIntervalMs : 0;
+    if (delay > 0) {
+      await new Promise((resolve) => setTimeout(resolve, delay));
+    }
+  }
+
+  throw new Error('Task did not reach a terminal status');
+}
+
+registerScenario('tasks-client-create-handling', runTasksClientCreateHandling);
+
 // ============================================================================
 // WIF JWT-bearer scenario
 // ============================================================================

examples/clients/typescript/tasks-client-no-poll.ts

@@ -0,0 +1,60 @@
+#!/usr/bin/env node
+
+/**
+ * Deliberately broken SEP-2663 client: it negotiates the Tasks extension and
+ * receives CreateTaskResult, but never follows the task with tasks/get.
+ */
+
+import { DRAFT_PROTOCOL_VERSION } from '../../../src/types.js';
+import { buildStandardHeaders } from '../../../src/connection/stateless.js';
+import { runAsCli } from './helpers/cliRunner.js';
+
+const TASKS_EXTENSION_ID = 'io.modelcontextprotocol/tasks';
+let nextId = 1;
+
+export async function runClient(serverUrl: string): Promise<void> {
+  const request = async (
+    method: string,
+    params: Record<string, unknown> = {}
+  ): Promise<Record<string, unknown>> => {
+    const id = nextId++;
+    const meta = {
+      'io.modelcontextprotocol/protocolVersion': DRAFT_PROTOCOL_VERSION,
+      'io.modelcontextprotocol/clientInfo': {
+        name: 'broken-tasks-client',
+        version: '1.0.0'
+      },
+      'io.modelcontextprotocol/clientCapabilities': {
+        extensions: { [TASKS_EXTENSION_ID]: {} }
+      }
+    };
+    const response = await fetch(serverUrl, {
+      method: 'POST',
+      headers: buildStandardHeaders(method, params, {
+        specVersion: DRAFT_PROTOCOL_VERSION
+      }),
+      body: JSON.stringify({
+        jsonrpc: '2.0',
+        id,
+        method,
+        params: { ...params, _meta: meta }
+      })
+    });
+    const body = (await response.json()) as {
+      result?: Record<string, unknown>;
+      error?: { message: string };
+    };
+    if (body.error) throw new Error(body.error.message);
+    return body.result ?? {};
+  };
+
+  await request('server/discover');
+  await request('tools/list');
+  await request('tools/call', {
+    name: 'long_running_echo',
+    arguments: { text: 'hello' }
+  });
+  // BUG: ignores CreateTaskResult and exits without tasks/get.
+}
+
+runAsCli(runClient, import.meta.url, 'tasks-client-no-poll <server-url>');

src/runner/client.test.ts

@@ -64,4 +64,14 @@ describe('runConformanceTest spec-version applicability', () => {
     expect(result.skipped).toBeUndefined();
     expect(result.clientOutput?.stdout).toContain(LATEST_SPEC_VERSION);
   }, 30000);
+
+  test('uses an extension baseSpecVersion when the scenario declares one', async () => {
+    const result = await runConformanceTest(
+      PRINT_VERSION_COMMAND,
+      'tasks-client-create-handling',
+      10000
+    );
+    expect(result.skipped).toBeUndefined();
+    expect(result.clientOutput?.stdout).toContain(DRAFT_PROTOCOL_VERSION);
+  }, 30000);
 });

src/runner/client.ts

@@ -136,9 +136,12 @@ function resolveScenarioSpecVersion(
 ): SpecVersion {
   return (
     specVersion ??
-    ('introducedIn' in source && source.introducedIn === DRAFT_PROTOCOL_VERSION
-      ? DRAFT_PROTOCOL_VERSION
-      : LATEST_SPEC_VERSION)
+    ('extensionId' in source && source.baseSpecVersion !== undefined
+      ? source.baseSpecVersion
+      : 'introducedIn' in source &&
+          source.introducedIn === DRAFT_PROTOCOL_VERSION
+        ? DRAFT_PROTOCOL_VERSION
+        : LATEST_SPEC_VERSION)
   );
 }
 

src/runner/server.ts

@@ -79,10 +79,11 @@ export async function runServerConformanceTest(
   // on draft, so they fall under the same inference.
   const resolvedSpecVersion =
     specVersion ??
-    ('extensionId' in scenario.source ||
-    scenario.source.introducedIn === DRAFT_PROTOCOL_VERSION
-      ? DRAFT_PROTOCOL_VERSION
-      : LATEST_SPEC_VERSION);
+    ('extensionId' in scenario.source
+      ? (scenario.source.baseSpecVersion ?? DRAFT_PROTOCOL_VERSION)
+      : scenario.source.introducedIn === DRAFT_PROTOCOL_VERSION
+        ? DRAFT_PROTOCOL_VERSION
+        : LATEST_SPEC_VERSION);
 
   console.log(
     `Running client scenario '${scenarioName}' against server: ${serverUrl}`

src/scenarios/client/tasks-create-handling.test.ts

@@ -0,0 +1,52 @@
+import { describe, expect, test } from 'vitest';
+import { getHandler } from '../../../examples/clients/typescript/everything-client';
+import { runClient as noPollClient } from '../../../examples/clients/typescript/tasks-client-no-poll';
+import { DRAFT_PROTOCOL_VERSION } from '../../types';
+import { listExtensionScenarios } from '../index';
+import {
+  InlineClientRunner,
+  runClientAgainstScenario
+} from './auth/test_helpers/testClient';
+
+const SCENARIO = 'tasks-client-create-handling';
+
+describe('SEP-2663 Tasks client handling', () => {
+  test('everything-client handles CreateTaskResult and retrieves the result', async () => {
+    const handler = getHandler(SCENARIO);
+    expect(handler).toBeDefined();
+
+    const checks = await runClientAgainstScenario(
+      new InlineClientRunner(handler!),
+      SCENARIO,
+      { specVersion: DRAFT_PROTOCOL_VERSION }
+    );
+
+    expect(checks).toEqual([
+      expect.objectContaining({
+        id: 'sep-2663-client-handles-polymorphic-result',
+        status: 'SUCCESS'
+      })
+    ]);
+  });
+
+  test('detects a client that ignores CreateTaskResult', async () => {
+    const checks = await runClientAgainstScenario(
+      new InlineClientRunner(noPollClient),
+      SCENARIO,
+      {
+        specVersion: DRAFT_PROTOCOL_VERSION,
+        expectedFailureSlugs: ['sep-2663-client-handles-polymorphic-result']
+      }
+    );
+
+    expect(checks[0]).toMatchObject({
+      status: 'FAILURE',
+      errorMessage:
+        'Client received CreateTaskResult but did not retrieve it with tasks/get.'
+    });
+  });
+
+  test('is selected by the extensions suite', () => {
+    expect(listExtensionScenarios()).toContain(SCENARIO);
+  });
+});