test(mcp): negotiate the non-task revision for real in the required-tool unit test (#553)

The test pinning the Codex P1 fix (required tools stay callable on a session
without the core Tasks utility) narrowed the server's negotiated version with
Object.defineProperty. The SDK client can offer an older revision through
supportedProtocolVersions, so the session is now negotiated for real at
2025-06-18 through the initialize handshake and the server's own
getNegotiatedProtocolVersion() is asserted. A 2026-07-28 session is opened
only by the SDK's serving entries (stdio/HTTP), never by a hand-connected
in-memory pair, and takes the same branch: anything but 2025-11-25 serves
every tool on the ordinary contract.

Author: ScriptedAlchemy

packages/agent-bundle/tests/mcp-tasks.test.ts

@@ -326,18 +326,22 @@ describe('task-augmented tools/call (#369)', () => {
   });
 
   it('serves every tool as an ordinary request on a revision without the core Tasks utility, required ones included', async () => {
-    // The SDK client negotiates 2025-11-25 by default; the server's own view
-    // of the session is what gates the lifecycle, so it is narrowed here to
-    // what a 2026-07-28 session reports (where the wire has no task vocabulary).
+    // Negotiated for real: the client offers only 2025-06-18, a revision whose
+    // core has no Tasks utility, and the server counter-offers it through the
+    // ordinary initialize handshake. The gate is the negotiated revision, so
+    // this is the same branch a 2026-07-28 session takes (where the SDK strips
+    // `execution.taskSupport` and `capabilities.tasks`); that era is opened
+    // only by the SDK's serving entries, never by a hand-connected in-memory
+    // pair, which is why it is not the revision driven here.
     const { declareTool, install, server, tasks } = createTaskAugmentedMcpServer({ name: 'tasks-unit', version: '0.0.0' });
     const required = server.registerTool('background-only', { inputSchema: z.object({}) }, async () => ({ content: [{ text: 'ran', type: 'text' }] }));
     declareTool(required, 'background-only', 'required');
     install();
-    Object.defineProperty(tasks, 'getNegotiatedProtocolVersion', { configurable: true, value: () => '2026-07-28' });
-    const client = new Client({ name: 'tasks-unit-client', version: '0.0.0' });
+    const client = new Client({ name: 'tasks-unit-client', version: '0.0.0' }, { supportedProtocolVersions: ['2025-06-18'] });
     const [clientTransport, serverTransport] = InMemoryTransport.createLinkedPair();
     await Promise.all([server.connect(serverTransport), client.connect(clientTransport)]);
     try {
+      expect(tasks.getNegotiatedProtocolVersion()).toBe('2025-06-18');
       // An ordinary call to the required tool is served, not refused.
       expect(await client.callTool({ arguments: {}, name: 'background-only' })).toEqual({ content: [{ text: 'ran', type: 'text' }] });
       // Task metadata is ignored: the ordinary result comes back, no task handle.