refactor: simplify zod-adapter to use Zod 4's built-in toJSONSchema

docs/docs/installation.mdx

@@ -66,12 +66,12 @@ console.log('CLI installed at:', cliPath);
 
 ## Optional Dependencies
 
-### Zod (Recommended)
+### Zod 4+ (Recommended)
 
-For structured output validation, install Zod:
+For structured output validation, install Zod 4 or later:
 
 ```bash
-npm install zod
+npm install zod@^4
 ```
 
 Then use it with the SDK:

docs/installation.mdx

@@ -63,12 +63,12 @@ console.log('CLI installed at:', cliPath);
 
 ## Optional Dependencies
 
-### Zod (Recommended)
+### Zod 4+ (Recommended)
 
-For structured output validation, install Zod:
+For structured output validation, install Zod 4 or later:
 
 ```bash
-npm install zod
+npm install zod@^4
 ```
 
 Then use it with the SDK:

package.json

@@ -64,7 +64,7 @@
     "node": ">=18.0.0"
   },
   "peerDependencies": {
-    "zod": "^3.0.0"
+    "zod": "^4.0.0"
   },
   "peerDependenciesMeta": {
     "zod": {

src/schemas/zod-adapter.ts

@@ -1,24 +1,12 @@
 import type { JsonSchema } from '../types';
 
 /**
- * Internal type representing a Zod-like schema structure.
- *
- * This type allows the SDK to work with Zod schemas without requiring
- * Zod as a direct dependency.
+ * Internal type representing a Zod schema with toJSONSchema method (Zod 4+).
  *
  * @internal
  */
-type ZodTypeLike = {
-	_def?: {
-		typeName?: string;
-		innerType?: ZodTypeLike;
-		shape?: () => Record<string, ZodTypeLike>;
-		type?: ZodTypeLike;
-		values?: readonly unknown[];
-		checks?: Array<{ kind: string; value?: unknown }>;
-		options?: ZodTypeLike[];
-	};
-	shape?: Record<string, ZodTypeLike>;
+type ZodSchemaWithJsonSchema = {
+	toJSONSchema?: () => JsonSchema;
 };
 
 /**
@@ -27,15 +15,11 @@ type ZodTypeLike = {
  * This enables the SDK to accept Zod schemas for structured output
  * validation and convert them to JSON Schema format for the CLI.
  *
- * Supported Zod types:
- * - Primitives: string, number, boolean, null, undefined
- * - Literals and enums
- * - Arrays and objects
- * - Optional, nullable, and default
- * - Union, intersection, record, tuple
+ * Requires Zod 4+ which has built-in `toJsonSchema()` support.
  *
- * @param schema - A Zod schema or Zod-like object
+ * @param schema - A Zod schema with toJsonSchema method
  * @returns Equivalent JSON Schema object
+ * @throws Error if the schema doesn't have a toJsonSchema method
  *
  * @example
  * ```typescript
@@ -61,197 +45,21 @@ type ZodTypeLike = {
  *
  * @category Schema
  */
-export function zodToJsonSchema(schema: ZodTypeLike): JsonSchema {
-	const def = schema._def;
-	if (!def) {
-		return {};
-	}
-
-	const typeName = def.typeName;
-
-	switch (typeName) {
-		case 'ZodString':
-			return buildStringSchema(def);
-
-		case 'ZodNumber':
-			return buildNumberSchema(def);
-
-		case 'ZodBoolean':
-			return { type: 'boolean' };
-
-		case 'ZodNull':
-			return { type: 'null' };
-
-		case 'ZodUndefined':
-			return {};
-
-		case 'ZodLiteral':
-			return { const: def.values };
-
-		case 'ZodEnum':
-			return { type: 'string', enum: def.values as unknown[] };
-
-		case 'ZodNativeEnum':
-			return { type: 'string', enum: Object.values(def.values as object) };
-
-		case 'ZodArray':
-			return {
-				type: 'array',
-				items: def.type ? zodToJsonSchema(def.type) : {},
-			};
-
-		case 'ZodObject':
-			return buildObjectSchema(schema, def);
-
-		case 'ZodOptional':
-			return def.innerType ? zodToJsonSchema(def.innerType) : {};
-
-		case 'ZodNullable': {
-			const inner = def.innerType ? zodToJsonSchema(def.innerType) : {};
-			return { oneOf: [inner, { type: 'null' }] };
-		}
-
-		case 'ZodDefault':
-			return def.innerType ? zodToJsonSchema(def.innerType) : {};
-
-		case 'ZodUnion':
-			return {
-				oneOf: (def.options ?? []).map((opt) => zodToJsonSchema(opt)),
-			};
-
-		case 'ZodIntersection':
-			return {
-				allOf: [def.innerType ? zodToJsonSchema(def.innerType) : {}],
-			};
-
-		case 'ZodRecord':
-			return {
-				type: 'object',
-				additionalProperties: def.type ? zodToJsonSchema(def.type) : true,
-			};
-
-		case 'ZodTuple':
-			return { type: 'array' };
-
-		case 'ZodAny':
-		case 'ZodUnknown':
-			return {};
-
-		default:
-			return {};
-	}
-}
-
-/**
- * Builds a JSON Schema for a Zod string type.
- *
- * @param def - The Zod definition object
- * @returns JSON Schema for a string type
- *
- * @internal
- */
-function buildStringSchema(def: ZodTypeLike['_def']): JsonSchema {
-	const schema: JsonSchema = { type: 'string' };
-
-	for (const check of def?.checks ?? []) {
-		switch (check.kind) {
-			case 'min':
-				schema.minLength = check.value as number;
-				break;
-			case 'max':
-				schema.maxLength = check.value as number;
-				break;
-			case 'length':
-				schema.minLength = check.value as number;
-				schema.maxLength = check.value as number;
-				break;
-			case 'email':
-				schema.format = 'email';
-				break;
-			case 'url':
-				schema.format = 'uri';
-				break;
-			case 'uuid':
-				schema.format = 'uuid';
-				break;
-			case 'regex':
-				schema.pattern = String(check.value);
-				break;
-		}
-	}
-
-	return schema;
-}
-
-/**
- * Builds a JSON Schema for a Zod number type.
- *
- * @param def - The Zod definition object
- * @returns JSON Schema for a number type
- *
- * @internal
- */
-function buildNumberSchema(def: ZodTypeLike['_def']): JsonSchema {
-	const schema: JsonSchema = { type: 'number' };
-
-	for (const check of def?.checks ?? []) {
-		switch (check.kind) {
-			case 'min':
-				schema.minimum = check.value as number;
-				break;
-			case 'max':
-				schema.maximum = check.value as number;
-				break;
-			case 'int':
-				schema.type = 'integer';
-				break;
-			case 'multipleOf':
-				schema.multipleOf = check.value as number;
-				break;
-		}
-	}
-
-	return schema;
-}
-
-/**
- * Builds a JSON Schema for a Zod object type.
- *
- * @param schema - The Zod schema object
- * @param def - The Zod definition object
- * @returns JSON Schema for an object type
- *
- * @internal
- */
-function buildObjectSchema(schema: ZodTypeLike, def: ZodTypeLike['_def']): JsonSchema {
-	const shape = def?.shape?.() ?? schema.shape ?? {};
-	const properties: Record<string, JsonSchema> = {};
-	const required: string[] = [];
-
-	for (const [key, value] of Object.entries(shape)) {
-		properties[key] = zodToJsonSchema(value as ZodTypeLike);
-
-		const valueDef = (value as ZodTypeLike)._def;
-		const isOptional = valueDef?.typeName === 'ZodOptional' || valueDef?.typeName === 'ZodDefault';
-
-		if (!isOptional) {
-			required.push(key);
-		}
+export function zodToJsonSchema(schema: ZodSchemaWithJsonSchema): JsonSchema {
+	if (typeof schema.toJSONSchema !== 'function') {
+		throw new Error(
+			'Schema does not have toJSONSchema method. Ensure you are using Zod 4+ or provide a JSON Schema directly.',
+		);
 	}
 
-	return {
-		type: 'object',
-		properties,
-		required: required.length > 0 ? required : undefined,
-		additionalProperties: false,
-	};
+	return schema.toJSONSchema();
 }
 
 /**
- * Type guard to check if a value is a Zod schema.
+ * Type guard to check if a value is a Zod schema (Zod 4+).
  *
  * @param value - Value to check
- * @returns True if the value appears to be a Zod schema
+ * @returns True if the value appears to be a Zod schema with toJsonSchema support
  *
  * @example
  * ```typescript
@@ -266,11 +74,11 @@ function buildObjectSchema(schema: ZodTypeLike, def: ZodTypeLike['_def']): JsonS
  *
  * @category Schema
  */
-export function isZodSchema(value: unknown): value is ZodTypeLike {
+export function isZodSchema(value: unknown): value is ZodSchemaWithJsonSchema {
 	return (
 		typeof value === 'object' &&
 		value !== null &&
-		'_def' in value &&
-		typeof (value as ZodTypeLike)._def === 'object'
+		'toJSONSchema' in value &&
+		typeof (value as ZodSchemaWithJsonSchema).toJSONSchema === 'function'
 	);
 }