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SEP-2260 Require Server requests to be associated with a Client request. - #2260

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evalstate merged 25 commits into
modelcontextprotocol:mainfrom
evalstate:sep/unsolicitited-req
Mar 10, 2026
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SEP-2260 Require Server requests to be associated with a Client request.#2260
evalstate merged 25 commits into
modelcontextprotocol:mainfrom
evalstate:sep/unsolicitited-req

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@evalstate

@evalstateevalstate commented Feb 16, 2026

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Motivation and Context

This PR tightens the scoping of Server to Client requests and to server as notice of upcoming changes where this pattern may not be supported by the underlying transport layer.

How Has This Been Tested?

This PR has been supported by research by @pja-ant on current (public) usage of this pattern.

Breaking Changes

Whilst a specification only change, this stops future use of "unsolicited" server-to-client requests in anticipation of future "stateless" transports.

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

This PR has previously been reviewed by the Transports Working Group here: modelcontextprotocol/transports-wg#8

@evalstateevalstate changed the title SEP-xxxx Require Server requests to be associated with a Client request.SEP-2260 Require Server requests to be associated with a Client request.Feb 16, 2026
@PederHP

PederHP commented Feb 16, 2026•
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Maybe explicitly exclude or include pings as valid requests to associate with? They have a request id, but I suppose they're not that useful for stateless transports. It would also be a kind of workaround to not having unsolicited server-initiated requests.

@chemicLchemicL mentioned this pull request Feb 17, 2026
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CaitieM20
CaitieM20 reviewed Feb 17, 2026
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Comment threadseps/2260-Require-Server-requests-to-be-associated-with-Client-requests.md
@evalstate
evalstate requested a review from a team as a code ownerFebruary 17, 2026 23:59
evalstateand others added 9 commits February 18, 2026 00:18
@evalstate
Open SEP from transports-wg original discussion here:modelcontextpro…
755745c
…tocol/transports-wg#8
@evalstate
update title
398dbc3
@evalstate@CaitieM20
Update seps/0000-Require-Server-requests-to-be-associated-with-Client…
1c77e5a
…-requests
Co-authored-by: Caitie McCaffrey <caitiem20@github.com>
@evalstate@CaitieM20
Update seps/0000-Require-Server-requests-to-be-associated-with-Client…
808f545
…-requests
Co-authored-by: Caitie McCaffrey <caitiem20@github.com>
@evalstate
Use .md extension
551acc6
@evalstate
Rename to include PR# in name
709e7b8
@evalstate
Fix markdown formatting issues in SEP-2260
54cd446
- Fixed missing closing backtick in Abstract (sampling/createMessage, elicitation/create)
- Fixed typo: 'Reqeusts' -> 'Requests' in Design Intent section
@evalstate
Fix markdown formatting and generate SEP documentation
4d23496
- Fixed Prettier formatting in SEP-2260 markdown file
- Generated SEP documentation and updated docs index
- Fixed missing closing backtick and typo in Abstract and Design Intent sections
@evalstate
Fix broken anchor links in documentation
a226dc4
- Remove trailing slash from ping#implementation-considerations link
- Fix anchor reference for getting-logs-from-claude-desktop section
pcarleton
pcarleton reviewed Feb 18, 2026
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@evalstate

evalstate commented Feb 18, 2026

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I've made the wording consistent, and excluded Ping from the requirement.

This was referenced Aug 17, 2026
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@pcarletonpcarletonpcarleton left review comments
@dsp-antdsp-antdsp-ant left review comments
@CaitieM20CaitieM20CaitieM20 approved these changes
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@markdrothmarkdrothmarkdroth left review comments
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Labels

finalSEP finalized.SEPtransportRelated to MCP transports

Projects

2026-07-28 Spec Implementation
Status: Done
SEP Review Pipeline
Status: No status

Milestone

2026-07-28-RC

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8 participants

@evalstate@PederHP@qdrddr@pcarleton@CaitieM20@markdroth@dsp-ant@localden