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[v2] Мonorepo, sdk-client, sdk-server, sdk-core package split - #1279

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felixweinberger merged 61 commits into
modelcontextprotocol:mainfrom
KKonstantinov:feature/v2-monorepo-setup
Dec 19, 2025
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[v2] Мonorepo, sdk-client, sdk-server, sdk-core package split#1279
felixweinberger merged 61 commits into
modelcontextprotocol:mainfrom
KKonstantinov:feature/v2-monorepo-setup

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@KKonstantinov

@KKonstantinov KKonstantinov commented Dec 10, 2025 •
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Proof of Concept: v2 monorepo, package split

Motivation and Context

v1 of the sdk shipped both client and server in the same package, introducing extra dependencies to users who have a single concern (client or server only). Client and server packages are now split, depending on a shared core package.

Additionally, v1 exported all files as the public API of the SDK, limiting the SDK ability to iterate internally while keeping backwards compatibility. Barrel files are now introduced as the single entrypoint to the SDK and defining the public API of the SDK.

  • Dropped Node v18
  • Dropped CommonJS (ESM only)
  • Updated tsgo to one of the latest versions
  • Bumped the ts version
  • Added eslint import rules to tidy up imports
  • cleaned-up package.json files - client-sdk and server-sdk ship with the minimum required dependencies (as opposed to v1, which shipped server deps if you were only interested in the client and vice versa
  • introduce catalogs for reusing dep versions
  • bundling tool change - tsdown
  • updated docs

How Has This Been Tested?

Unit, integration tests

Breaking Changes

v2

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

@pkg-pr-new

pkg-pr-new Bot commented Dec 10, 2025 •
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npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/client@1279

npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/server@1279

commit: c3b1a40

@KKonstantinov KKonstantinov added the v2 Ideas, requests and plans for v2 of the SDK which will incorporate major changes and fixes label Dec 10, 2025
@KKonstantinov KKonstantinov self-assigned this Dec 10, 2025
felixweinberger
felixweinberger reviewed Dec 10, 2025
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@felixweinberger felixweinberger left a comment •
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Is there a way we can break this PR up somehow so that this is more reviewable? E.g. with using git mv to preserve history and provenance of files? As it is it'll be quite hard to verify correctness of the split.

@KKonstantinov

KKonstantinov commented Dec 12, 2025 •
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EDITs:

  • Provenance / history retained (except 3-4 files, will review them and bring it to them as well)
  • Dropped Node v18
  • Dropped CommonJS (ESM only)
  • Updated tsgo to one of the latest versions
  • Bumped the ts version
  • Added eslint import rules to tidy up imports
  • cleaned-up package.json files - client-sdk and server-sdk ship with the minimum required dependencies (as opposed to v1, which shipped server deps if you were only interested in the client and vice versa
  • introduce catalogs for reusing dep versions
  • bundling tool change - tsdown as per @mattzcarey
  • updated docs

TODOs still:

  • test(18) check - no code change, repository config -> needs to be removed as required check from branch rulesets, and replaced with test(20)

@KKonstantinov KKonstantinov added this to the v2 milestone Dec 12, 2025
@KKonstantinov KKonstantinov linked an issue Dec 12, 2025 that may be closed by this pull request
SDK V2 #809
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mozmo15 pushed a commit to mozmo15/typescript-sdk that referenced this pull request Mar 30, 2026
@KKonstantinov mozmo15
[v2] Мonorepo, sdk-client, sdk-server, sdk-core package split (m…
8ae33e3 
…odelcontextprotocol#1279)
@coderabbitai coderabbitai Bot mentioned this pull request Apr 23, 2026
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@nikolas-sapa nikolas-sapa mentioned this pull request Sep 13, 2026
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nikolas-sapa added a commit to nikolas-sapa/typescript-sdk that referenced this pull request Sep 30, 2026
@nikolas-sapa
fix(shared): stop referencing the DOM-only global HeadersInit in norm…
88d7af0 
…alizeHeaders

shared/transport.d.ts exports normalizeHeaders(headers: HeadersInit | undefined),
and HeadersInit is a web-IDL type alias that @types/node structurally cannot
bind globally (it binds Headers/Request/RequestInit/Response, but not the
HeadersInit typedef — see DefinitelyTyped PR #74414 review). Node-only
consumers compiling with skipLibCheck: false and no "DOM" lib fail with
TS2304: Cannot find name 'HeadersInit' (reported against 1.23.0-beta.0
through 1.30.0).

Use RequestInit['headers'] instead — same-behaviour, and exactly what the
v2 rewrite already does (modelcontextprotocol#1279). Runtime code is unchanged.

Verified: a Node-only consumer (lib ES2023, types node, skipLibCheck false)
fails with the reported TS2304 against @modelcontextprotocol/sdk@1.30.0 and
typechecks clean against this branch's emitted declarations. Full repo
typecheck error set is byte-identical with and without this change.

Fixes modelcontextprotocol#2568
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@mattzcarey mattzcarey mattzcarey left review comments
@felixweinberger felixweinberger felixweinberger approved these changes

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@KKonstantinov KKonstantinov

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v2 Ideas, requests and plans for v2 of the SDK which will incorporate major changes and fixes

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Successfully merging this pull request may close these issues.

ESM only (if feasible) Publish separate client and server packages SDK V2

3 participants

@KKonstantinov @mattzcarey @felixweinberger