v2.0.0-preview.2

This second preview of the 2.0.0 series advances the SDK's alignment with the upcoming 2026-07-28 MCP protocol revision: it adds client-side conformance diagnostics for the SEP-2549 caching hints, makes Streamable HTTP error responses echo the request id per the base protocol and SEP-2243, and fully stabilizes now-stable protocol properties so consumer-defined source generators serialize them correctly. Separately -- and unrelated to the protocol revision -- it introduces DeferChangedEvents() on McpServerPrimitiveCollection<T> for batching list_changed notifications when registering primitives in bulk. There are no breaking changes relative to v2.0.0-preview.1.

What's Changed

• Document caching behavior and warn on non-conformant draft cacheable results (SEP-2549 follow-up) #1669 by @tarekgh
• Fully stabilize now-stable protocol properties #1686 by @eiriktsarpalis (co-authored by @Copilot)
• Echo request id in post-parse Streamable HTTP error responses #1687 by @tarekgh
• Add DeferChangedEvents() to McpServerPrimitiveCollection for batched change notifications #1689 by @jeffhandley (co-authored by @Copilot)

Documentation Updates

• Update package READMEs as part of the release process #1683 by @jeffhandley (co-authored by @Copilot)

Acknowledgements

• @cclabadmin submitted issue #1677 (resolved by #1687)
• @lewing submitted issue #1688 (resolved by #1689)
• @PranavSenthilnathan @halter73 @davidortinau @jeffhandley @lewing @tarekgh reviewed pull requests

Full Changelog: v2.0.0-preview.1...v2.0.0-preview.2