docs: register validator in typedoc and document it in the testing guide

- Add src/validator/index.ts to typedoc entryPoints; export the option and
  result types it references so the JSDoc validation check passes clean
- Add a "Validate against the specification" section to testing-mcp-apps.md

Refs #673

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: RyanAlberts

docs/testing-mcp-apps.md

@@ -8,6 +8,24 @@ description: Test MCP Apps locally with the basic-host reference implementation
 
 This guide covers two approaches for testing your MCP App: using the `basic-host` reference implementation for local development, or using an MCP Apps-compatible host like Claude\.ai or VS Code.
 
+## Validate against the specification
+
+The SDK ships a validator that checks your server and app against the app-side requirements of the MCP Apps specification — resource format, tool metadata, CSP declarations, and (with [Playwright](https://playwright.dev) installed) the app's observable protocol behavior under a mock host:
+
+```bash
+# Validate a running server (streamable HTTP)
+npx mcp-app-validator http://localhost:3001/mcp
+
+# Validate a server over stdio, or a built HTML document directly
+npx mcp-app-validator --stdio node dist/server.js
+npx mcp-app-validator --html dist/mcp-app.html
+
+# CI usage: JSON report, exit code 1 on any MUST-level violation
+npx mcp-app-validator http://localhost:3001/mcp --json
+```
+
+Every finding cites the rule it violates and the spec section the rule derives from. See the {@link validator! validator} API documentation to run it programmatically.
+
 ## Test with basic-host
 
 The [`basic-host`](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-host) example in this repository is a reference host implementation that lets you select a tool, call it, and see your App UI rendered in a sandboxed iframe.

src/validator/index.ts

@@ -43,6 +43,8 @@ export {
   validateServerStatically,
   validateAppBehavior,
 };
+export type { BehavioralOptions } from "./harness.js";
+export type { FetchedUiResource, StaticValidationResult } from "./static.js";
 
 /** What to validate. Exactly one of the members must be provided. */
 export type ValidationTarget =

typedoc.config.mjs

@@ -25,6 +25,7 @@ const config = {
     "src/app-bridge.ts",
     "src/message-transport.ts",
     "src/types.ts",
+    "src/validator/index.ts",
   ],
   excludePrivate: true,
   excludeInternal: false,