fix: support Zod 3.25 method literals (#2368)

test/issues/test_1380_zod325_literal.test.ts

@@ -0,0 +1,73 @@
+import { Client } from '../../src/client/index.js';
+import { Server } from '../../src/server/index.js';
+import type { AnyObjectSchema, AnySchema } from '../../src/server/zod-compat.js';
+import { getLiteralValue } from '../../src/server/zod-compat.js';
+
+function requestSchemaWithValuesLiteral(method: string): AnyObjectSchema {
+    return {
+        _zod: {
+            def: {
+                type: 'object',
+                shape: {
+                    method: {
+                        _zod: {
+                            def: {
+                                type: 'literal',
+                                values: [method]
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    } as unknown as AnyObjectSchema;
+}
+
+describe('Issue #1380: Zod 3.25.x v4 literal value shape', () => {
+    test('extracts literal values stored in _zod.def.values', () => {
+        const methodSchema = {
+            _zod: {
+                def: {
+                    type: 'literal',
+                    values: ['ping']
+                }
+            }
+        } as unknown as AnySchema;
+
+        expect(getLiteralValue(methodSchema)).toBe('ping');
+    });
+
+    test('registers server request handlers when the method literal uses _zod.def.values', () => {
+        const server = new Server(
+            { name: 'test server', version: '1.0' },
+            {
+                capabilities: {
+                    tools: {}
+                }
+            }
+        );
+
+        expect(() => {
+            server.setRequestHandler(requestSchemaWithValuesLiteral('tools/call'), () => ({
+                content: []
+            }));
+        }).not.toThrow();
+    });
+
+    test('registers client request handlers when the method literal uses _zod.def.values', () => {
+        const client = new Client(
+            { name: 'test client', version: '1.0' },
+            {
+                capabilities: {
+                    elicitation: {}
+                }
+            }
+        );
+
+        expect(() => {
+            client.setRequestHandler(requestSchemaWithValuesLiteral('elicitation/create'), () => ({
+                action: 'cancel'
+            }));
+        }).not.toThrow();
+    });
+});