Downgrade Kotlin to 2.1.21

[kpavlov]

Downgrade Kotlin to 2.1.21

Motivation and Context

Compiled iOS client is not compatible with frameworks, which are using older version of Kotlin.

• Slack thread
• KG-380 Make agents-mcp support KMP targets
• This PR is blocked: Make agents-mcp support KMP targets JetBrains/koog#756

Kotlin version should be downgraded 2.2.0->2.1.21 to make possible use native artifacts in other projects, e.g. Koog

Changes

• Downgrade Kotlin 2.2.0->2.1.21 to make broader adoption possible. Update Kotlin compiler configuration
• Breaking change: Add kotlinx-datetime dependency. Switch from kotlin.time.Instant to kotlinx.datetime.Instant.
• Downgrade atomicfu 0.29.0->0.28.0
• Downgrade kotlinx-serialization 1.9.0->1.8.1

Breaking Changes

• Switch to kotlinx-datetime is causing signature changes: kotlin.time.Instant to kotlinx.datetime.Instant.

How Has This Been Tested?

• Build project locally
• PR Validaiton

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

[devcrocod]

Breaking change: Add kotlinx-datetime dependency. Switch from kotlin.time.Instant to kotlinx.datetime.Instant.
Downgrade atomicfu 0.29.0->0.28.0
Downgrade kotlinx-serialization 1.9.0->1.8.1
 

 Why did you make these changes? 

[kpavlov]

Why did you make these changes?

Because compiled Kotlin native library can't be used in the project, which is using lower Kotlin version.

[devcrocod]

Because compiled Kotlin native library can't be used in the project, which is using lower Kotlin version.

Then we can update koog to 2.2.10 kotlin

I don’t think downgrading the Kotlin version and all the kotlinx libraries in the sdk is a good idea. On top of that, switching Instant to the library one would lead to incompatibility, and it will eventually be deprecated in favor of the stdlib

In my view, ios is not the main target to justify doing that

[kpavlov]

Let's try upgraing Koog, indeed

[kpavlov]

Closing it for now