Version Packages (alpha)

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This PR was opened by the Changesets release GitHub action. When you're ready to do a release, you can merge this and publish to npm yourself or setup this action to publish automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated.

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main is currently in pre mode so this branch has prereleases rather than normal releases. If you want to exit prereleases, run changeset pre exit on main.

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Releases

@modelcontextprotocol/client@2.0.0-alpha.3

Minor Changes

• #1653 6bec24a Thanks @rechedev9! - Add validateClientMetadataUrl()
  utility for early validation of clientMetadataUrl

  Exports a validateClientMetadataUrl() function that OAuthClientProvider implementations can call in their constructors to fail fast on invalid URL-based client IDs, instead of discovering the error deep in the auth flow.

Patch Changes

• #1655 1eb3123 Thanks @nielskaspers! - fix(client): append custom
  Accept headers to spec-required defaults in StreamableHTTPClientTransport

  Custom Accept headers provided via requestInit.headers are now appended to the spec-mandated Accept types instead of being overwritten. This ensures the required media types (application/json, text/event-stream for POST; text/event-stream for GET SSE) are always present
  while allowing users to include additional types for proxy/gateway routing.

@modelcontextprotocol/server@2.0.0-alpha.3

Patch Changes

• #1788 df4b6cc Thanks @claygeo! - Prevent stack overflow in
  StreamableHTTPServerTransport.close() with re-entrant guard

@modelcontextprotocol/core@2.0.0-alpha.2

Patch Changes

• #1930 bdfd7f0 Thanks @Christian-Sidak! - Fix requestStream to
  call tasks/result for failed tasks instead of yielding a hardcoded ProtocolError. When a task reaches the failed terminal status, the stream now retrieves and yields the actual stored result (matching the behavior for completed tasks), as required by the spec.

• #1768 866c08d Thanks @felixweinberger! - Allow additional JSON
  Schema properties in elicitInput's requestedSchema type by adding .catchall(z.unknown()), matching the pattern used by inputSchema. This fixes type incompatibility when using Zod v4's .toJSONSchema() output which includes extra properties like $schema and additionalProperties.