test(mcp-adapters): verify elicitation recovery and examples

[Baihao Wang (byhow)]

What changes?

Add a runnable modern elicitation example that answers two forms and a URL request, rebuilding the adapter between resumes. Local stdio tests verify reconstruction of both the adapter and server process, and exercise accept/decline/cancel with modern and mixed legacy/modern servers.

The reference and migration guide explain checkpoint ownership, answer shapes, direct-call limits, connection-level headers and Python API differences. The example uses scripted answers and MemorySaver; applications supply their own input flow and persistent checkpoint storage for process recovery.

How was it tested?

• 404 tests passed, two existing skips; package/example and modified-test type checks, lint and formatting passed.
• Ran the HTTP example against the local modern server: two forms and a URL completed, and separate decline/cancel runs returned their expected results.
• The complete replacement stack builds for ESM and CommonJS; attw and publint passed.

Scope

Fourth replacement slice of #11615, stacked on #11644. 514 additions and 25 deletions. Tests, examples, docs and a changeset only; no library runtime, OAuth, dependency or CI changes.

The stdio test reconstructs the server process while retaining an in-process checkpointer. It does not verify a separate-process checkpoint database. The migration guide retains the public SDK validator prerequisite for the major release.

[changeset-bot]

🦋 Changeset detected

Latest commit: 83e2482

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

This PR includes changesets to release 1 package

Name	Type
@langchain/mcp-adapters	Patch

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[open-swe]

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