v0.4.0-preview.2

This release includes a breaking change to the Streamable HTTP transport's Stateless mode, making it truly sessionless by removing the data protection dependency and session ID tracking. It also fixes an issue with sending server notifications from request-specific McpServer instances used outside their original scope.

Breaking Changes

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

1. Make "Stateless" mode sessionless #760
   • McpServer.ClientInfo will always be null in stateless mode because stateless mode no longer uses a session ID or relies on data protection
   • If you need ClientInfo in your handlers, use the default stateful mode

What's Changed

• Move options validation to constructor #826 by @halter73
• Make "Stateless" mode sessionless #760 by @halter73
• Update sample with URI validation #824 by @localden
• Fix support for sending server notifications with request-specific McpServer instances used outside their original scope #832 by @eiriktsarpalis

Repository Infrastructure Updates

• Bump version to 0.4.0-preview.2 #818 by @jeffhandley
• Onboard repo to the .NET 10 sdk #822 by @eiriktsarpalis
• Update .NET version in release.yml #841 by @halter73
• Bump version to 0.4.0-preview.3 by @halter73
• Bump version back down to 0.4.0-preview.2 by @halter73
• Update remaining .NET versions in release.yml by @halter73

Acknowledgements

• @sr-auto submitted issue #682 (resolved by #760)
• @mikekistler submitted issue #693 (resolved by #832)
• @stephentoub reviewed pull requests

Full Changelog: v0.4.0-preview.1...v0.4.0-preview.2