feat(client,server): bundle default validators, expose customisation via subpaths (#2088)

packages/client/test/client/barrelClean.test.ts

@@ -8,6 +8,8 @@ import { beforeAll, describe, expect, test } from 'vitest';
 const pkgDir = join(dirname(fileURLToPath(import.meta.url)), '../..');
 const distDir = join(pkgDir, 'dist');
 const NODE_ONLY = /\b(child_process|cross-spawn|node:stream|node:child_process)\b/;
+// Anchored at start-of-line so JSDoc-example `from 'ajv'` strings in vendored chunks don't match.
+const VALIDATOR_BACKEND_IMPORT = /^import[^\n]*?from\s+["'](?:ajv|ajv-formats|@cfworker\/json-schema)["']/m;
 
 function chunkImportsOf(entryPath: string): string[] {
     const visited = new Set<string>();
@@ -52,4 +54,17 @@ describe('@modelcontextprotocol/client root entry is browser-safe', () => {
         expect(stdio).toMatch(/\bgetDefaultEnvironment\b/);
         expect(stdio).toMatch(/\bDEFAULT_INHERITED_ENV_VARS\b/);
     });
+
+    test('runtime shims vendor default validator backends instead of requiring consumers to install them', () => {
+        for (const shim of ['shimsNode.mjs', 'shimsWorkerd.mjs', 'shimsBrowser.mjs']) {
+            const entry = join(distDir, shim);
+            expect(readFileSync(entry, 'utf8')).not.toMatch(VALIDATOR_BACKEND_IMPORT);
+
+            for (const chunk of chunkImportsOf(entry)) {
+                expect({ chunk, content: readFileSync(chunk, 'utf8') }).not.toEqual(
+                    expect.objectContaining({ content: expect.stringMatching(VALIDATOR_BACKEND_IMPORT) })
+                );
+            }
+        }
+    });
 });

packages/client/test/client/jsonSchemaValidatorOverride.test.ts

@@ -0,0 +1,110 @@
+import type { JSONRPCMessage, JsonSchemaType, JsonSchemaValidatorResult, jsonSchemaValidator } from '@modelcontextprotocol/core';
+import { InMemoryTransport, LATEST_PROTOCOL_VERSION } from '@modelcontextprotocol/core';
+import { Client } from '../../src/client/client.js';
+import { fromJsonSchema } from '../../src/fromJsonSchema.js';
+
+class RecordingValidator implements jsonSchemaValidator {
+    schemas: JsonSchemaType[] = [];
+    values: unknown[] = [];
+
+    getValidator<T>(schema: JsonSchemaType) {
+        this.schemas.push(schema);
+        return (value: unknown): JsonSchemaValidatorResult<T> => {
+            this.values.push(value);
+            return { valid: true, data: value as T, errorMessage: undefined };
+        };
+    }
+}
+
+async function connectInitializedClient(client: Client) {
+    const [clientTransport, serverTransport] = InMemoryTransport.createLinkedPair();
+    serverTransport.onmessage = async message => {
+        if ('method' in message && 'id' in message && message.method === 'initialize') {
+            await serverTransport.send({
+                jsonrpc: '2.0',
+                id: message.id,
+                result: {
+                    protocolVersion: LATEST_PROTOCOL_VERSION,
+                    capabilities: { tools: {} },
+                    serverInfo: { name: 'test-server', version: '1.0.0' }
+                }
+            });
+        } else if ('method' in message && 'id' in message && message.method === 'tools/list') {
+            await serverTransport.send({
+                jsonrpc: '2.0',
+                id: message.id,
+                result: {
+                    tools: [
+                        {
+                            name: 'structured-tool',
+                            description: 'A tool with structured output',
+                            inputSchema: { type: 'object' },
+                            outputSchema: {
+                                type: 'object',
+                                properties: { count: { type: 'number' } },
+                                required: ['count']
+                            }
+                        }
+                    ]
+                }
+            } satisfies JSONRPCMessage);
+        }
+    };
+
+    await Promise.all([client.connect(clientTransport), serverTransport.start()]);
+    return { clientTransport, serverTransport };
+}
+
+describe('client JSON Schema validator overrides', () => {
+    test('Client constructor uses a custom validator for tool output schema caching', async () => {
+        const validator = new RecordingValidator();
+        const client = new Client(
+            { name: 'test-client', version: '1.0.0' },
+            {
+                capabilities: {},
+                jsonSchemaValidator: validator
+            }
+        );
+        const { clientTransport, serverTransport } = await connectInitializedClient(client);
+
+        await expect(client.listTools()).resolves.toMatchObject({
+            tools: [
+                {
+                    name: 'structured-tool',
+                    outputSchema: {
+                        type: 'object',
+                        properties: { count: { type: 'number' } },
+                        required: ['count']
+                    }
+                }
+            ]
+        });
+
+        expect(validator.schemas).toEqual([
+            {
+                type: 'object',
+                properties: { count: { type: 'number' } },
+                required: ['count']
+            }
+        ]);
+
+        await client.close();
+        await clientTransport.close();
+        await serverTransport.close();
+    });
+
+    test('fromJsonSchema uses an explicitly supplied custom validator', async () => {
+        const validator = new RecordingValidator();
+        const schema: JsonSchemaType = {
+            type: 'object',
+            properties: { name: { type: 'string' } },
+            required: ['name']
+        };
+
+        const standardSchema = fromJsonSchema<{ name: string }>(schema, validator);
+        expect(standardSchema['~standard'].validate({ name: 123 })).toEqual({ value: { name: 123 } });
+
+        expect(validator.schemas).toEqual([schema]);
+        expect(validator.values).toEqual([{ name: 123 }]);
+    });
+});