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/stateless-legacy/README.md

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+# stateless-legacy
+
+The minimal `createMcpHandler` deployment, on its default posture: 2026-07-28 traffic served per request, 2025-era traffic served stateless from the same factory. This is the one-liner replacement for the 1.x "new transport + new server per POST" stateless idiom.
+
+**HTTP-only** by definition; see `dual-era/` for the stdio analogue.

examples/stateless-legacy/client.ts

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+/**
+ * Connects to the minimal `createMcpHandler` deployment as both a plain 2025
+ * client (`versionNegotiation: { mode: 'legacy' }` — the `initialize`
+ * handshake, served stateless from the factory) and a 2026-capable client
+ * (`versionNegotiation: { mode: 'auto' }`, served per request). Asserts the
+ * same `greet` tool answers identically either way.
+ *
+ * HTTP-only — `createMcpHandler`'s `legacy: 'stateless'` posture is an HTTP
+ * hosting concern; a stdio leg would bypass it. The story body drives BOTH
+ * eras itself, so only `url` is read from argv.
+ */
+import { check, parseExampleArgs } from '@mcp-examples/shared';
+import { Client, StreamableHTTPClientTransport } from '@modelcontextprotocol/client';
+
+const { url } = parseExampleArgs();
+
+for (const mode of ['legacy', 'auto'] as const) {
+    const client = new Client({ name: 'stateless-legacy-client', version: '1.0.0' }, { versionNegotiation: { mode } });
+    await client.connect(new StreamableHTTPClientTransport(new URL(url)));
+    const tools = await client.listTools();
+    check.ok(tools.tools.some(t => t.name === 'greet'));
+    const result = await client.callTool({ name: 'greet', arguments: { name: 'world' } });
+    check.equal(result.content?.[0]?.type === 'text' ? result.content[0].text : '', 'Hello, world!');
+    await client.close();
+}

examples/stateless-legacy/package.json

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+{
+    "name": "@mcp-examples/stateless-legacy",
+    "private": true,
+    "type": "module",
+    "scripts": {
+        "server": "tsx server.ts",
+        "client": "tsx client.ts"
+    },
+    "dependencies": {
+        "@mcp-examples/shared": "workspace:*",
+        "@modelcontextprotocol/client": "workspace:*",
+        "@modelcontextprotocol/node": "workspace:*",
+        "@modelcontextprotocol/server": "workspace:*",
+        "zod": "catalog:runtimeShared"
+    },
+    "devDependencies": {
+        "tsx": "catalog:devTools"
+    },
+    "example": {
+        "transports": [
+            "http"
+        ],
+        "era": "modern",
+        "//": "The story body manages its own era internally; pinned so the runner runs it once per transport."
+    }
+}

examples/stateless-legacy/server.ts

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+/**
+ * The minimal `createMcpHandler` deployment, on its default posture.
+ *
+ * One factory, one endpoint: 2026-07-28 traffic is served per request, and
+ * 2025-era (non-envelope) traffic is served stateless from the same factory
+ * (`legacy: 'stateless'`, the default). This replaces the hand-wired
+ * "new transport + new server per POST" stateless idiom of the 1.x SDK with
+ * a one-liner.
+ *
+ * HTTP-only — `createMcpHandler`'s `legacy: 'stateless'` posture is an HTTP
+ * hosting concern; a stdio leg would bypass it. See `dual-era/` for the stdio
+ * analogue.
+ */
+import { createServer } from 'node:http';
+
+import { parseExampleArgs } from '@mcp-examples/shared';
+import { toNodeHandler } from '@modelcontextprotocol/node';
+import { createMcpHandler, McpServer } from '@modelcontextprotocol/server';
+import * as z from 'zod/v4';
+
+function buildServer(): McpServer {
+    const server = new McpServer({ name: 'stateless-legacy-example', version: '1.0.0' }, { capabilities: { logging: {} } });
+    server.registerTool(
+        'greet',
+        { description: 'A simple greeting tool', inputSchema: z.object({ name: z.string() }) },
+        async ({ name }) => ({ content: [{ type: 'text', text: `Hello, ${name}!` }] })
+    );
+    return server;
+}
+
+const { port } = parseExampleArgs();
+
+const handler = createMcpHandler(buildServer);
+createServer(toNodeHandler(handler)).listen(port, () => {
+    console.error(`[server] listening on http://127.0.0.1:${port}/mcp`);
+});