Repository navigation
Track migration to MCP spec 2026-07-28 (stateless, MRTR, deprecated Sampling) #130
Description
Summary
The MCP spec released a new revision on 2026-07-28 (announced at https://blog.modelcontextprotocol.io/posts/2026-07-28/) that moves from the stateful bidirectional protocol to a stateless request/response model. Key changes relevant to us:
- The
initialize/initializedhandshake and session IDs are eliminated; each request is self-describing. - Server-initiated elicitation is replaced by "Multi Round-Trip Requests" (MRTR).
- Sampling is deprecated.
- Roots and Logging are also deprecated.
- Header-based routing, cacheable list results, tasks moved to an official extensions framework.
- Security: RFC 9207 issuer validation required, shift from Dynamic Client Registration toward Client ID Metadata Documents (CIMD).
- Deprecations get a 12-month minimum window; legacy HTTP+SSE transport gets a year-long offramp. No fire drill, but not indefinite either.
As of this issue, @modelcontextprotocol/sdk on npm is still on the 1.x line (1.30.0 latest) — there is no separate 2.0.0 package. The new spec appears to be supported via 1.x releases, not a major SDK version bump.
Why this needs a dedicated pass, not an incidental bump
This repo is actively building on the mechanisms this spec revision replaces/deprecates — most concretely, the in-progress add-preview-token-elicitation work (PR #57) depends on server-initiated elicitation, the exact thing MRTR replaces. Migrating means redesigning against whatever MRTR's actual API surface turns out to be, not just bumping a dependency version.
What to check before starting
- Confirm real client support for MRTR (Claude Desktop, Claude Code, VS Code Copilot) — no point redesigning against a mechanism clients can't use yet.
- Read the SDK's actual migration guide/changelog for the TypeScript SDK version(s) that implement 2026-07-28 support.
- Audit this repo for every current use of
elicitInput/Sampling beyond the in-progress PR [security] Add MCP elicitation for secure preview token handling #57 work.
Non-goals for now
- No urgency given the 12-month deprecation window.
- The routine SDK dependency bump (
1.29.0→1.30.0) is handled separately and does not itself adopt the new spec — see the corresponding PR.
See also mapbox/mcp-server#245 for the equivalent tracking issue there.
Activity
mattpodwysocki commentedon Aug 5, 2026
Correction/clarification: the "2.0" isn't a future release of `@modelcontextprotocol/sdk` — that package is being retired entirely. Per https://blog.modelcontextprotocol.io/posts/sdk-betas-2026-07-28/, TypeScript v2 splits it into separate focused packages (`@modelcontextprotocol/server`, `@modelcontextprotocol/client`), currently beta-only (`npm install @modelcontextprotocol/server@beta`), no stable release yet, with a dedicated codemod (`npx @modelcontextprotocol/codemod@beta v1-to-v2 .`) to help migrate.
So this migration is two layers, not one:
Given it's beta with no stable release and a provided codemod (a strong signal the API surface actually changed meaningfully, not just moved), this reinforces: no urgency, worth revisiting once v2 stabilizes.
SovRock commentedon Oct 21, 2026
Readiness update (2026-10-22)
The August clarification is now out of date: the TypeScript v2 packages are stable, not beta-only. npm reports
@modelcontextprotocol/serverand@modelcontextprotocol/clientat2.3.1(published Oct 5), and@modelcontextprotocol/ext-appsat2.0.3(published Sep 25). The current ext-apps package peers on@modelcontextprotocol/core,@modelcontextprotocol/client, and@modelcontextprotocol/server^2.0.0, so package-level v2 compatibility is now available. The official v1→v2 guide and 2026-07-28 protocol guide describe separate migration steps and an official codemod:Client support remains unconfirmed. The current public Claude Code MCP guide and VS Code MCP guide establish general MCP support but do not document explicit support for the 2026-07-28 revision or MRTR. The VS Code guide also notes interactive-input limitations for Copilot harness sessions. I found no version-specific MRTR confirmation for Claude Desktop in the public docs reviewed. These are gaps in public evidence, not proof that the clients do not support MRTR; test current client releases directly before relying on it.
Repository audit: the current tree still depends on
@modelcontextprotocol/sdk^1.30.0and@modelcontextprotocol/ext-apps^1.1.1. The server usesStdioServerTransport, the legacy initialize/oninitialized handshake, client-capability inspection, and Logging notifications. No active Sampling, Roots, orelicitInputAPI calls were found undersrc/ortest/;ELICITATION_TOOLSis currently an empty scaffold. SDK imports are widespread and the UI resources use ext-apps. The open #57 adds elicitation-based preview token handling and will need to be revisited for MRTR before it is merged into a migrated server.Suggested trigger: proceed with the v2/package migration when client testing confirms MRTR works in the target clients, or when this server explicitly accepts an interim legacy-only experience. Keep the v1→v2 package migration and the wire-protocol opt-in as separate, reviewable steps; for stdio, the official guide calls for the v2
serveStdioentry point to serve the new revision. No dependency or code changes were made in this readiness pass.