v0.8.0-preview.1

The 0.8.0-preview.1 release includes new server-side capabilities including message-level filters and a distributed cache-backed event stream store, along with several bug fixes for transport reliability. This release also includes a breaking change that seals public Protocol reference types to prevent external inheritance, reinforcing the SDK's API contract as we continue refining toward a stable 1.0.0 release.

Breaking Changes

Refer to the C# SDK Versioning documentation for details on versioning and breaking change policies.

1. Seal public Protocol reference types to prevent external inheritance #1232
   • Several public classes sealed: JsonRpcMessageContext, ElicitRequestParams.RequestSchema, ElicitRequestParams.LegacyTitledEnumSchema, ContentBlock.Converter, ResourceContents.Converter, PrimitiveSchemaDefinition.Converter
   • ElicitRequestParams.EnumSchema removed; use LegacyTitledEnumSchema directly
   • Migration: Remove any inheritance from these types; replace EnumSchema references with LegacyTitledEnumSchema

What's Changed

• Add Trace-level logging for JSON-RPC payloads in transports #1191 by @stephentoub (co-authored by @halter73 @Copilot)
• Use Process.Kill(entireProcessTree: true) on .NET for faster process termination #1187 by @stephentoub
• Include response body in HttpRequestException for transport client errors #1193 by @stephentoub (co-authored by @Copilot)
• Fix race condition in SSE GET request initialization #1212 by @stephentoub
• Fix keyset pagination with monotonic UUIDv7-like task IDs #1215 by @eiriktsarpalis (co-authored by @stephentoub @Copilot)
• Add ILoggerFactory to StreamableHttpServerTransport #1213 by @stephentoub (co-authored by @Copilot)
• Add support for message-level filters to McpServer #1207 by @halter73
• Seal public Protocol reference types to prevent external inheritance #1232 by @stephentoub (co-authored by @Copilot)
• Add DistributedCacheEventStreamStore #1136 by @MackinnonBuck (co-authored by @halter73)

Documentation Updates

• Fix typo in elicitation.md #1186 by @ruyut
• Fix typo in progress.md #1189 by @ruyut
• Clarify McpMetaAttribute documentation scope #1242 by @stephentoub (co-authored by @Copilot)

Test Improvements

• Remove 10 second wait from docker tests #1188 by @stephentoub
• Fix Session_TracksActivities test #1200 by @stephentoub
• Fix StdioServerTransportTests to use Debug logging level instead of Trace #1209 by @stephentoub (co-authored by @Copilot)
• Centralize test timeout constants to fix sporadic CI failures #1210 by @ericstj (co-authored by @Copilot)
• Fix race condition in AutomaticInputRequiredStatusTests polling logic #1223 by @ericstj (co-authored by @stephentoub @Copilot)
• Centralize test timeout constants to fix CI flakiness #1224 by @ericstj (co-authored by @Copilot)
• Add test coverage for AdditionalHeaders in Streamable HTTP transport #1218 by @stephentoub (co-authored by @Copilot)
• Fix XunitLoggerProvider crash when background work logs after test disposal #1229 by @stephentoub (co-authored by @Copilot)
• Skip .NET Framework tests on non-Windows platforms #1226 by @stephentoub (co-authored by @Copilot)
• Suppress TimeProvider.Testing net472 warning #1227 by @stephentoub (co-authored by @Copilot)

Repository Infrastructure Updates

• Bump version to 0.8.0-preview.1 #1181 by @jeffhandley (co-authored by @Copilot)
• Bump actions/checkout from 6.0.1 to 6.0.2 #1173
• Bump the opentelemetry-testing group with 6 updates #1174
• Bump the other-testing group with 1 update #1233
• Bump Anthropic from 12.2.0 to 12.3.0 #1234

Acknowledgements

• @ruyut made their first contribution in #1186
• @scutuatua-crypto reviewed pull requests

Full Changelog: v0.7.0-preview.1...v0.8.0-preview.1