Add BYO zod version support

docs/quickstart.md

@@ -98,7 +98,7 @@ import cors from "cors";
 import express from "express";
 import fs from "node:fs/promises";
 import path from "node:path";
-import { z } from "zod";
+import * as z from "zod";
 
 const server = new McpServer({
   name: "My MCP App Server",

examples/basic-host/package.json

@@ -14,8 +14,7 @@
     "@modelcontextprotocol/ext-apps": "../..",
     "@modelcontextprotocol/sdk": "^1.22.0",
     "react": "^19.2.0",
-    "react-dom": "^19.2.0",
-    "zod": "^3.25.0"
+    "react-dom": "^19.2.0"
   },
   "devDependencies": {
     "@types/express": "^5.0.0",

examples/basic-server-react/package.json

@@ -15,7 +15,7 @@
     "@modelcontextprotocol/sdk": "^1.22.0",
     "react": "^19.2.0",
     "react-dom": "^19.2.0",
-    "zod": "^3.25.0"
+    "zod": "^4.1.13"
   },
   "devDependencies": {
     "@types/cors": "^2.8.19",

examples/basic-server-vanillajs/package.json

@@ -13,7 +13,7 @@
   "dependencies": {
     "@modelcontextprotocol/ext-apps": "../..",
     "@modelcontextprotocol/sdk": "^1.22.0",
-    "zod": "^3.25.0"
+    "zod": "^4.1.13"
   },
   "devDependencies": {
     "@types/cors": "^2.8.19",

examples/basic-server-vanillajs/server.ts

@@ -5,7 +5,7 @@ import cors from "cors";
 import express, { type Request, type Response } from "express";
 import fs from "node:fs/promises";
 import path from "node:path";
-import { z } from "zod";
+import * as z from "zod";
 import { RESOURCE_URI_META_KEY } from "../../dist/src/app";
 
 const PORT = process.env.PORT ? parseInt(process.env.PORT, 10) : 3001;

package.json

@@ -59,14 +59,17 @@
     "nodemon": "^3.1.0",
     "prettier": "^3.6.2",
     "typedoc": "^0.28.14",
-    "typescript": "^5.9.3"
+    "typescript": "^5.9.3",
+    "zod": "^4.1.13"
+  },
+  "peerDependencies": {
+    "zod": "^3.25.0 || ^4.0.0"
   },
   "dependencies": {
     "@modelcontextprotocol/sdk": "^1.23.0",
     "bun": "^1.3.2",
     "react": "^19.2.0",
-    "react-dom": "^19.2.0",
-    "zod": "^3.25"
+    "react-dom": "^19.2.0"
   },
   "optionalDependencies": {
     "@rollup/rollup-darwin-arm64": "^4.53.3",

src/app-bridge.ts

@@ -1,5 +1,5 @@
 import { Client } from "@modelcontextprotocol/sdk/client/index.js";
-import { ZodLiteral, ZodObject } from "zod/v4";
+import * as z from "zod/v4/core";
 
 import { Transport } from "@modelcontextprotocol/sdk/shared/transport.js";
 import {
@@ -773,10 +773,10 @@ export class AppBridge extends Protocol<Request, Notification, Result> {
   }
 
   private forwardRequest<
-    Req extends ZodObject<{
-      method: ZodLiteral<string>;
+    Req extends z.$ZodObject<{
+      method: z.$ZodLiteral<string>;
     }>,
-    Res extends ZodObject<{}>,
+    Res extends z.$ZodObject<{}>,
   >(requestSchema: Req, resultSchema: Res) {
     this.setRequestHandler(requestSchema, async (request, extra) => {
       console.log(`Forwarding request ${request.method} from MCP UI client`);
@@ -786,7 +786,7 @@ export class AppBridge extends Protocol<Request, Notification, Result> {
     });
   }
   private forwardNotification<
-    N extends ZodObject<{ method: ZodLiteral<string> }>,
+    N extends z.$ZodObject<{ method: z.$ZodLiteral<string> }>,
   >(notificationSchema: N) {
     this.setNotificationHandler(notificationSchema, async (notification) => {
       console.log(

src/types.ts

@@ -12,7 +12,9 @@ import {
   Tool,
   ToolSchema,
 } from "@modelcontextprotocol/sdk/types.js";
-import { z } from "zod/v4";
+import type * as z3 from "zod/v3";
+import type * as z4 from "zod/v4/core";
+import * as z from "zod";
 
 /**
  * Type-level assertion that validates a Zod schema produces the expected interface.
@@ -28,7 +30,10 @@ import { z } from "zod/v4";
  *
  * @internal
  */
-type VerifySchemaMatches<TSchema extends z.ZodTypeAny, TInterface> =
+type VerifySchemaMatches<
+  TSchema extends z3.ZodTypeAny | z4.$ZodType,
+  TInterface,
+> =
   z.infer<TSchema> extends TInterface
     ? TInterface extends z.infer<TSchema>
       ? true
@@ -66,7 +71,7 @@ export interface McpUiOpenLinkRequest {
 export const McpUiOpenLinkRequestSchema = RequestSchema.extend({
   method: z.literal("ui/open-link"),
   params: z.object({
-    url: z.string().url(),
+    url: z.url(),
   }),
 });