[pei711]

Summary

Closes #3017.

AjvJsonSchemaValidator picks an AJV engine according to each schema's declared $schema dialect (Ajv2020 for 2020-12, Ajv2019 for 2019-09, and classic Draft7 Ajv for draft-07/06). Previously, the only way to configure engine options was to pass a pre-configured instance (new AjvJsonSchemaValidator(ajv)), which bypassed the $schema dialect dispatch entirely.

This PR adds support for passing validator options:

const validator = new AjvJsonSchemaValidator({ options: { useDefaults: true } });

The options are merged into the default options (strict: false, validateFormats: true, validateSchema: false, allErrors: true, plus caller options) across each dialect engine while preserving lazy construction and dialect dispatch.

Changes

• Defined AjvJsonSchemaValidatorOptions interface and exported it from @modelcontextprotocol/core-internal/validators/ajv, @modelcontextprotocol/server/validators/ajv, and @modelcontextprotocol/client/validators/ajv.
• Updated AjvJsonSchemaValidator constructor to accept ajvOrOptions?: AjvLike | AjvJsonSchemaValidatorOptions.
• Forwarded options to createDefaultAjvInstance when lazily constructing dialect engines.
• Preserved existing behavior when passing an AjvLike instance (new AjvJsonSchemaValidator(ajv)).
• Added unit tests in packages/core-internal/test/validators/ajvLazyInit.test.ts verifying that custom engine options (like useDefaults: true) work across all dialects (2020-12, 2019-09, draft-07) while maintaining lazy instantiation and dialect dispatch.
• Added JSDoc example and type-checked example in ajvProvider.examples.ts.
• Added patch changeset for @modelcontextprotocol/server and @modelcontextprotocol/client.

Testing

• Unit tests in packages/core-internal/test/validators/ajvLazyInit.test.ts: all passed.
• pnpm --filter @modelcontextprotocol/core-internal run check: typecheck, eslint, and prettier passed cleanly.
• pnpm --filter @modelcontextprotocol/client run check: passed.
• pnpm --filter @modelcontextprotocol/server run check: passed.
• pnpm --filter @modelcontextprotocol/core-internal test: 1526/1526 passed.
• pnpm --filter @modelcontextprotocol/client test: 998/998 passed.
• pnpm --filter @modelcontextprotocol/server test: 577/577 passed.
• pnpm run sync:snippets: confirmed all snippets up to date.

[changeset-bot]

🦋 Changeset detected

Latest commit: 86ee45e

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 6 packages

Name	Type
@modelcontextprotocol/server	Patch
@modelcontextprotocol/client	Patch
@modelcontextprotocol/codemod	Patch
@modelcontextprotocol/core	Patch
@modelcontextprotocol/server-legacy	Patch
@modelcontextprotocol/core-internal	Patch

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[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	⚠️ Failed 2026-10-20T18:25:24.326863Z	86ee45e	PR opened

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commit: 86ee45e

[0xamlab]

Checked the test against the merge-base (46d9c99) to confirm it guards the regression. On this branch, test/validators/ajvLazyInit.test.ts passes 7/7 and the full core-internal suite passes 1837/1837 (77 files, 6.7s). On base with only the test file overlaid, the new test fails its first assertion: the old constructor treats any argument as a caller engine, so { options: { useDefaults: true } } lands in the _ajv slot and the $schema dispatch in _engineFor would be skipped. The isAjvLike guard at packages/core-internal/src/validators/ajvProvider.ts:63 separates the two constructor forms, and the spread at line 39 applies the options to each per-dialect engine.