v0.7.0-preview.1

The 0.7.0-preview.1 release adds MCP task support, Streamable HTTP resumability with SSE event stream storage, and support for the 2025-11-25 protocol version. This release also introduces user-defined JsonSerializerOptions throughout SDK serialization APIs and includes several bug fixes for elicitation, source generator diagnostics, and URI template matching. The Streamable HTTP transport includes breaking changes to StreamableHttpServerTransport as part of the resumability implementation.

Breaking Changes

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

1. Streamable HTTP resumability + redelivery + SSE polling via server-side disconnect #1077
   • StreamableHttpServerTransport.OnInitRequestReceived property removed; replaced by EventStreamStore for resumability support
   • StreamableHttpServerTransport.SessionId setter changed from { get; set; } to { get; init; }
   • Migration: Remove OnInitRequestReceived usage; use ISseEventStreamStore via EventStreamStore for resumability. Set SessionId in the object initializer instead of post-construction assignment.

What's Changed

• Update licensing to Apache 2.0 for new contributions #1140 by @domdomegg
• Add 2025-11-25 as supported version #1130 by @stephentoub (co-authored by @Copilot)
• Streamable HTTP resumability + redelivery + SSE polling via server-side disconnect #1077 by @MackinnonBuck (co-authored by @halter73)
• Fix source generator diagnostic locations for incremental caching #1153 by @stephentoub (co-authored by @Copilot)
• Fix form mode elicitation schema check to apply for all form requests #1151 by @stephentoub (co-authored by @Copilot)
• Add support for user-defined JsonSerializerOptions throughout SDK serialization APIs #1113 by @stephentoub (co-authored by @Copilot @eiriktsarpalis)
• Fix reserved expansion (e.g. {+var}) when matching resources #1142 by @halter73
• Implement MCP task support #1170 by @eiriktsarpalis (co-authored by @halter73)

Documentation Updates

• Document MCP Server project template in README #1148 by @leslierichardson95 (co-authored by @mikekistler @jeffhandley)

Test Improvements

• Add comprehensive edge case tests for JSON-RPC payload shapes #1143 by @stephentoub (co-authored by @Copilot)
• Fix flaky test: Client_CanResumePostResponseStream_AfterDisconnection #1179 by @MackinnonBuck

Repository Infrastructure Updates

• Bump version to 0.7.0-preview.1 #1144 by @jeffhandley
• Bump actions/setup-dotnet from 5.0.1 to 5.1.0 #1157
• Bump actions/setup-node from 6.1.0 to 6.2.0 #1158
• Bump the testing-frameworks group with 1 update #1159
• Bump the other-testing group with 1 update #1160
• Update Microsoft.Extensions.AI to 10.2.0 #1165 by @eiriktsarpalis (co-authored by @Copilot @stephentoub)
• Update Anthropic SDK to 12.2.0 #1164 by @eiriktsarpalis (co-authored by @Copilot)
• Pin the MCP conformance tester package #1176 by @eiriktsarpalis

Acknowledgements

• @domdomegg made their first contribution in #1140
• @leslierichardson95 made their first contribution in #1148
• @mikekistler submitted #510 #1020 (resolved by #1077), #1129 (resolved by #1130), #943 (resolved by #1170)
• @halter73 @stephentoub @eiriktsarpalis @jeffhandley @mikekistler @MackinnonBuck @heaths @scutuatua-crypto reviewed pull requests

Full Changelog: v0.6.0-preview.1...v0.7.0-preview.1