feat(clerk-js): add experimental WebMCP tools for browser agents

.changeset/experimental-webmcp-tools.md

@@ -0,0 +1,6 @@
+---
+'@clerk/clerk-js': minor
+'@clerk/shared': minor
+---
+
+Add an experimental `webmcp` option (`experimental: { webmcp: true }`). In browsers that support [WebMCP](https://webmachinelearning.github.io/webmcp/), Clerk registers tools that let browser agents check auth state, sign in, submit verification codes, switch organizations and sign out, without ever taking a password or returning a token. Each tool call dispatches a `clerk:webmcp` event on `window` with the tool name, result status and sign-in strategy, so you can track agent activity in your own analytics.

packages/clerk-js/bundlewatch.config.json

@@ -1,9 +1,9 @@
 {
   "files": [
-    { "path": "./dist/clerk.js", "maxSize": "556KB" },
+    { "path": "./dist/clerk.js", "maxSize": "557KB" },
     { "path": "./dist/clerk.browser.js", "maxSize": "83KB" },
     { "path": "./dist/clerk.legacy.browser.js", "maxSize": "126KB" },
-    { "path": "./dist/clerk.no-rhc.js", "maxSize": "322.25KB" },
+    { "path": "./dist/clerk.no-rhc.js", "maxSize": "324.25KB" },
     { "path": "./dist/clerk.native.js", "maxSize": "82KB" },
     { "path": "./dist/vendors*.js", "maxSize": "7KB" },
     { "path": "./dist/coinbase*.js", "maxSize": "36KB" },

packages/clerk-js/src/core/clerk.ts

@@ -3622,6 +3622,7 @@ export class Clerk implements ClerkInterface {
     this.#clearClerkQueryParams();
     this.#handleImpersonationFab();
     this.#handleKeylessPrompt();
+    this.#handleWebMcp();
 
     this.#publicEventBus.emit(clerkEvents.Status, initializationDegradedCounter > 0 ? 'degraded' : 'ready');
   };
@@ -3853,6 +3854,14 @@ export class Clerk implements ClerkInterface {
     }
   };
 
+  #handleWebMcp = () => {
+    if (this.#options.experimental?.webmcp) {
+      void import(/* webpackChunkName: "webmcp" */ './modules/webmcp')
+        .then(({ registerWebMcpTools }) => registerWebMcpTools(this))
+        .catch(noop);
+    }
+  };
+
   #buildUrl = (
     key: 'signInUrl' | 'signUpUrl',
     options: RedirectOptions,