perf: add preloadSchemas() and warm wire schemas eagerly on workerd (#2483)

packages/client/src/index.ts

@@ -106,5 +106,11 @@ export { fromJsonSchema } from './fromJsonSchema';
 export type { InputRequiredOptions } from '@modelcontextprotocol/core-internal';
 export { withInputRequired } from '@modelcontextprotocol/core-internal';
 
+// Explicit opt-in to eager wire-schema construction, for platforms that bill
+// request CPU but not module evaluation (isolate-based edge/serverless
+// runtimes). The package's workerd build calls it automatically at module
+// scope; other builds stay lazy unless the application calls it itself.
+export { preloadSchemas } from '@modelcontextprotocol/core-internal';
+
 // re-export curated public API from core
 export * from '@modelcontextprotocol/core-internal/public';

packages/client/src/shimsWorkerd.ts

@@ -3,8 +3,17 @@
  *
  * This file is selected via package.json export conditions when running in workerd.
  */
+import { preloadSchemas } from '@modelcontextprotocol/core-internal';
+
 export { CfWorkerJsonSchemaValidator as DefaultJsonSchemaValidator } from '@modelcontextprotocol/core-internal/validators/cfWorker';
 
+// Platform asymmetry: isolate platforms like workerd evaluate module scope
+// during deployment/isolate warm-up, outside any request's billed CPU, while
+// lazy construction would land inside the first request each fresh isolate
+// serves. Node and browser shims stay lazy — there, module evaluation is
+// process/page startup and boot latency is the cost that matters.
+preloadSchemas();
+
 /**
  * Whether `fetch()` may throw `TypeError` due to CORS. CORS is a browser-only concept —
  * in Cloudflare Workers, a `TypeError` from `fetch` is always a real network/configuration