Adopt strict concurrency for project

[Overcot]

• Fix one warning related to that

Motivation and Context

If I enable strict concurrency in project that depends on swift-sdk it shows that there's a warning with :

How Has This Been Tested?

By building a framework, it shouldn't impact any runtime behavior

Breaking Changes

No

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

[mattt]

Thanks for opening this PR, @Overcot. We were so close to having everything right for strict concurrency mode 🥲.

I wanted to better understand the implications of enabling this would be for downstream consumers. Reading this article by @mattmassicotte, I came to the conclusion that it's the right thing to do here.

However, I was surprised to see CI failing on Swift 6.0.3 with this error (both Linux and macOS):

:0: error: upcoming feature 'StrictConcurrency' is already enabled as of Swift version 6

No such problems for Swift 6.1.0, though: https://github.com/modelcontextprotocol/swift-sdk/actions/runs/17327395019/job/49779583926?pr=157

It looks like we'll need to either provide a version-specific package manifest or conditionalize this setting.

[mattt]

Nice, that fixed it. Merging now.

Thanks again for your help, @Overcot.

[mattmassicotte]

Glad you all figured it out! The compiler recently downgraded the errors produced for unnecessary flags recently, but I cannot quite recall which version did that. Maybe 6.1

The issue you ran into here looks like it would affect 6.2+ only - it's caused by the introduction of SendableMetatype. I actually think you can use that instead of a full Sendable conformance if that turns out to be a problem.