fix(codemod): rewrite the bare barrel subpaths sdk/client, sdk/server and sdk/validation

[n-satoshi061]

The v1-to-v2 codemod now rewrites the bare barrel subpaths @modelcontextprotocol/sdk/client, @modelcontextprotocol/sdk/server and @modelcontextprotocol/sdk/validation the same way as their /index.js forms.

Motivation and Context

• The v1-to-v2 codemod does not rewrite imports from @modelcontextprotocol/sdk/client, @modelcontextprotocol/sdk/server or @modelcontextprotocol/sdk/validation.
• It leaves the import as is and adds an @mcp-codemod-error Unknown SDK import path: ... Manual migration required. marker.
• In the same run it removes @modelcontextprotocol/sdk from package.json, so the leftover import no longer resolves.
• The /index.js forms of the same paths (sdk/client/index.js, sdk/server/index.js) are rewritten correctly.
• The same happens for re-exports (export { ... } from) and for vi.mock / vi.doMock paths.

Why these paths matter:

• v1 lists ./client, ./server and ./validation as explicit entries in the exports field of its package.json, so they are supported import paths.
• ./client and ./server were added in fix: client import & server imports #851 for the Metro bundler.
• A comment in packages/codemod/src/utils/projectAnalyzer.ts describes '@modelcontextprotocol/sdk/client' as a form the codemod already supports, and the analyzer has a test for it. The import transform had no such test.

Cause:

• IMPORT_MAP is keyed by the /index.js form.
• lookupImportMapping only ignored a trailing .js / .mjs / .cjs, so sdk/client never matched sdk/client/index.js.

The change:

• lookupImportMapping now also ignores a trailing /index, both when building the normalized map and when looking up a specifier.
• No new map entries and no new options.
• Files: packages/codemod/src/migrations/v1-to-v2/mappings/importMap.ts, two test files, one changeset (@modelcontextprotocol/codemod, patch).

How Has This Been Tested?

• New tests: four import cases (sdk/client, sdk/client/index, sdk/server, sdk/validation), one re-export case, one vi.doMock case.
• The five cases that use the bare form fail without the source change and pass with it.
• pnpm test, pnpm typecheck and pnpm lint pass in packages/codemod (651 tests).
• Ran the rebuilt CLI on a small sample project.

Input:

import { Client } from '@modelcontextprotocol/sdk/client';
import { Server } from '@modelcontextprotocol/sdk/server';
import type { jsonSchemaValidator } from '@modelcontextprotocol/sdk/validation';

Before (mcp-codemod v1-to-v2):

/* @mcp-codemod-error Unknown SDK import path: @modelcontextprotocol/sdk/client. Manual migration required. */
import { Client } from '@modelcontextprotocol/sdk/client';

After:

import { Server } from "@modelcontextprotocol/server";
import type { jsonSchemaValidator } from "@modelcontextprotocol/server";
import { Client } from "@modelcontextprotocol/client";

Breaking Changes

None. Only specifiers that were previously reported as unknown are affected.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

Not included:

• @modelcontextprotocol/sdk/experimental (without /tasks) is still reported as unknown. It would need its own map entry, and the feature it exports was removed in v2.
• @modelcontextprotocol/sdk/shared/metadataUtils.js is also still unmapped. It was noted in the review of feat(codemod): close v1-to-v2 mechanical gaps — outputSchema wrap, importMap entries; drop dead expressMiddleware transform #2361 and left out there.

[changeset-bot]

🦋 Changeset detected

Latest commit: 1fd0bc5

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

This PR includes changesets to release 6 packages

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

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commit: 1fd0bc5