Migrating Semantic Kernel To Agents

Semantic Kernel to Agent Framework Migration

Overview

Migrate .NET projects from Microsoft.SemanticKernel.Agents to Microsoft.Agents.AI (Agent Framework). The migration involves updating NuGet packages, namespaces, agent creation patterns, tool registration, thread management, and invocation methods.

API mappings and code examples: Read ref/api-mappings.md for detailed type/method/pattern transformations. Provider-specific patterns: Read ref/provider-patterns.md for per-provider migration (OpenAI, Azure OpenAI, Assistants, Azure AI Foundry, A2A, Responses).

Workflow

Migration Progress:
- [ ] Step 1: Execute
- [ ] Step 2: Validate

Step 1: Execute

Execute continuously without pausing unless user interaction is truly needed.

1a. Update Package References

For each project with explicit package dependencies (skip transitive-only consumers):

1. Read the project file to understand its structure and dependencies
2. Remove Semantic Kernel agent packages:
   • Microsoft.SemanticKernel.Agents.Core
   • Microsoft.SemanticKernel.Agents.OpenAI
   • Microsoft.SemanticKernel.Agents.AzureAI
   • Microsoft.SemanticKernel (only if used solely for agents)
3. Add Agent Framework packages based on provider (see ref/provider-patterns.md for the mapping):
   • Microsoft.Agents.AI.Abstractions (always required)
   • Provider-specific package (e.g., Microsoft.Agents.AI.OpenAI)
4. Never guess package versions - use available tools to determine the latest stable version

Central Package Management (CPM):

If PackageReference elements lack versions or use VersionOverride, the project uses CPM. Handle it carefully because creating a duplicate props file or using wrong paths causes silent build failures:

• Search for Directory.Packages.props starting from the project folder upward through parent directories
• Read the existing file first to understand its structure
• Edit (never recreate) the existing file: remove old PackageVersion entries, add new ones
• Add PackageReference elements without versions in project files
• Always use the full absolute path when editing Directory.Packages.props

If projects specify versions directly in PackageReference elements, make all changes in the project file only.

1b. Update Code Files

Find all code files in affected projects (including transitive dependents) that reference SK agent APIs. Use search tools and pass each project's root folder.

Apply transformations from ref/api-mappings.md:

1. Search for Microsoft.SemanticKernel.Agents in using statements, types, and API calls (skip comments and string literals)
2. Replace agent types, method calls, configuration patterns, and namespaces
3. Handle provider-specific patterns per ref/provider-patterns.md

Using statement rules:

• Replace SK agent using statements with AF equivalents
• If no other SK agent API remains in the file, remove the using instead of replacing it
• If no SK agent using statements existed originally, do not add AF using statements
• Add namespace imports for types that moved (e.g., Microsoft.Agents.AI for ChatClientAgent)

Code preservation:

• Never add placeholder code or remove existing comments
• Keep business logic as close to the original as possible
• Track files/lines where conversion is impossible or may cause behavioral changes

NuGet names are case-insensitive - account for this when searching or removing dependencies.

1c. Iterate Until Clean

Search for Microsoft.SemanticKernel.Agents in all affected projects again. If any references remain, repeat step 1b. Continue until no SK agent references exist.

Step 2: Validate

1. Run dotnet build on all modified projects - zero errors required
2. Fix all build errors without violating migration guidance
3. Verify using this checklist:
   • All using Microsoft.SemanticKernel.Agents statements replaced or removed
   • All InvokeAsync -> RunAsync, InvokeStreamingAsync -> RunStreamingAsync
   • Return types: AgentRunResponse (non-streaming), IAsyncEnumerable<AgentRunResponseUpdate> (streaming)
   • Thread creation uses agent.GetNewThread()
   • [KernelFunction] removed; AIFunctionFactory.Create() used
   • AgentRunOptions or ChatClientAgentRunOptions replaces AgentInvokeOptions
   • RawRepresentation replaces InnerContent

Key Behavioral Differences

These AF behaviors differ from SK and affect migration decisions:

• Automatic thread management: AF manages thread state automatically. SK required manual thread updates in some scenarios (e.g., OpenAI Responses).
• Simplified tool registration: AF uses direct AIFunction registration via AIFunctionFactory.Create() instead of the KernelPlugin/KernelFunction system.
• Unified return types: Non-streaming returns AgentRunResponse; streaming returns IAsyncEnumerable<AgentRunResponseUpdate>.
• Two-level breaking glass: For ChatClient-based agents, access underlying SDK objects by casting RawRepresentation to ChatResponse, then casting ChatResponse.RawRepresentation to the SDK type.
• Unified usage metadata: Access via response.Usage (non-streaming) or update.Contents.OfType<UsageContent>() (streaming).