chore: upgrade zod to v4 (#298)

*Issue #, if available:*

closes #280 

*Description of changes:*

* Remove zod-to-json-schema
* Replace ZodSchema with ZodType
colinhacks/zod#4877
* Upgrade @hookform/resolves to
^[5.1.0](https://github.com/react-hook-form/resolvers/releases/tag/v5.1.0)

By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice.

Author: tmokmss

package-lock.json

@@ -40,12 +40,12 @@
     "@aws-sdk/client-sts": "^3.758.0",
     "@aws-sdk/credential-providers": "^3.750.0",
     "@aws-sdk/lib-dynamodb": "^3.744.0",
+    "@modelcontextprotocol/sdk": "^1.7.0",
     "@octokit/rest": "^22.0.0",
     "@slack/bolt": "^4.2.0",
     "p-retry": "^6.2.1",
     "sharp": "^0.33.5",
-    "zod": "^3.24.2",
-    "zod-to-json-schema": "^3.24.3"
+    "zod": "^4.0.0"
   },
   "devDependencies": {
     "@types/node": "^22.13.1",

packages/agent-core/package.json

@@ -1,21 +1,18 @@
 import { Tool, ToolResultContentBlock } from '@aws-sdk/client-bedrock-runtime';
-import { ZodSchema } from 'zod';
-import { zodToJsonSchema } from 'zod-to-json-schema';
+import z, { ZodType } from 'zod';
 
 export type ToolDefinition<Input> = {
   /**
    * Name of the tool. This is the identifier of the tool for the agent.
    */
   readonly name: string;
   readonly handler: (input: Input, context: { toolUseId: string }) => Promise<string | ToolResultContentBlock[]>;
-  readonly schema: ZodSchema;
+  readonly schema: ZodType<Input>;
   readonly toolSpec: () => Promise<NonNullable<Tool['toolSpec']>>;
 };
 
-export const zodToJsonSchemaBody = (schema: ZodSchema) => {
-  const key = 'mySchema';
-  const jsonSchema = zodToJsonSchema(schema, key);
-  return jsonSchema.definitions?.[key] as any;
+export const zodToJsonSchemaBody = (schema: ZodType) => {
+  return z.toJSONSchema(schema) as any;
 };
 
 export const truncate = (str: string, maxLength: number = 10 * 1e3, headRatio = 0.2) => {

packages/agent-core/src/private/common/lib.ts

@@ -24,7 +24,7 @@
     "@remote-swe-agents/agent-core": "file:../agent-core",
     "@slack/bolt": "^4.0.0",
     "@slack/web-api": "^7.8.0",
-    "zod": "^3.24.3"
+    "zod": "^4.0.0"
   },
   "devDependencies": {
     "@types/aws-lambda": "^8.10.147",