Implement MCP 2026-07-28 (#2286)

Co-authored-by: Matt <77928207+mattzcarey@users.noreply.github.com>
Co-authored-by: Konstantin Konstantinov <KKonstantinov@users.noreply.github.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

examples/dual-era/server.ts

@@ -0,0 +1,55 @@
+/**
+ * Dual-era serving from one factory, both transports.
+ *
+ * The same factory backs both protocol eras: a 2025-era client connects with
+ * the `initialize` handshake; a 2026-capable client
+ * (`versionNegotiation: { mode: 'auto' }`) probes with `server/discover`,
+ * negotiates the 2026-07-28 revision, and the SDK attaches the per-request
+ * `_meta` envelope to every outgoing request itself. Tools are defined once
+ * and served identically to either kind of client.
+ *
+ * One binary, either transport (selected from argv): stdio by default
+ * (`serveStdio(buildServer)`), or HTTP under `--http --port <N>`
+ * (`createMcpHandler(buildServer)` on its default posture — modern served per
+ * request, 2025-era traffic served stateless from the same factory).
+ */
+import { createServer } from 'node:http';
+
+import { parseExampleArgs } from '@mcp-examples/shared';
+import { toNodeHandler } from '@modelcontextprotocol/node';
+import type { CallToolResult, McpRequestContext } from '@modelcontextprotocol/server';
+import { createMcpHandler, McpServer } from '@modelcontextprotocol/server';
+import { serveStdio } from '@modelcontextprotocol/server/stdio';
+import * as z from 'zod/v4';
+
+const buildServer = (ctx: McpRequestContext): McpServer => {
+    const server = new McpServer(
+        { name: 'dual-era-server', version: '1.0.0' },
+        { capabilities: { tools: {} }, instructions: 'A small dual-era demo server.' }
+    );
+
+    server.registerTool(
+        'greet',
+        {
+            description: 'Greets the caller and reports which protocol era served the request',
+            inputSchema: z.object({ name: z.string().describe('Name to greet') })
+        },
+        async ({ name }): Promise<CallToolResult> => ({
+            content: [{ type: 'text', text: `Hello, ${name}! (served on the ${ctx.era} protocol era)` }]
+        })
+    );
+
+    return server;
+};
+
+const { transport, port } = parseExampleArgs();
+
+if (transport === 'stdio') {
+    void serveStdio(buildServer);
+    console.error('[server] serving over stdio');
+} else {
+    const handler = createMcpHandler(buildServer);
+    createServer(toNodeHandler(handler)).listen(port, () => {
+        console.error(`[server] listening on http://127.0.0.1:${port}/mcp`);
+    });
+}