.NET: Add AgentSkillsSourceContext to AgentSkillsSource.GetSkillsAsync

[SergeyMenshykh]

Summary

Adds an AgentSkillsSourceContext (carrying Agent and optional Session) to AgentSkillsSource.GetSkillsAsync, so skill sources, filters, and caching can make context-aware decisions. The context is built by AgentSkillsProvider from the InvokingContext and flows through all sources and decorators.

Changes

• AgentSkillsSourceContext exposes Agent and Session, supplied from the invoking context.
• FilteringAgentSkillsSource predicate now receives an AgentSkillFilterContext bundling the skill and the source context.
• CachingAgentSkillsSource supports per-key cache isolation via CachingAgentSkillsSourceOptions.CacheIsolationKeySelector; a null selector keeps the existing shared-cache behavior.

Closes: #6710

[Copilot]

Pull request overview

This PR evolves the .NET “Agent Skills” pipeline to be context-aware by threading an AgentSkillsSourceContext (agent + optional session) through AgentSkillsSource.GetSkillsAsync, enabling downstream decorators (filtering/caching) and sources (including MCP) to make invocation-specific decisions.

Changes:

• Add AgentSkillsSourceContext and update all AgentSkillsSource.GetSkillsAsync implementations/callers to accept it.
• Update filtering to pass an AgentSkillFilterContext into the predicate so filters can consider both the skill and the source context.
• Extend caching to support per-key cache isolation via CachingAgentSkillsSourceOptions.CacheIsolationKeySelector, and update unit tests accordingly.

Reviewed changes

Copilot reviewed 32 out of 32 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
dotnet/src/Microsoft.Agents.AI/Skills/AgentSkillsSource.cs	Updates the core skills source abstraction to require a source context.
dotnet/src/Microsoft.Agents.AI/Skills/AgentSkillsSourceContext.cs	Introduces the new context object (agent + optional session).
dotnet/src/Microsoft.Agents.AI/Skills/AgentSkillsProvider.cs	Constructs and passes the source context from the invoking context.
dotnet/src/Microsoft.Agents.AI/Skills/AgentSkillsProviderBuilder.cs	Updates filter signature and adds caching options configuration.
dotnet/src/Microsoft.Agents.AI/Skills/AgentSkillFilterContext.cs	Adds the filter predicate context wrapper (skill + source context).
dotnet/src/Microsoft.Agents.AI/Skills/AggregatingAgentSkillsSource.cs	Threads the source context through aggregated sources.
dotnet/src/Microsoft.Agents.AI/Skills/AgentInMemorySkillsSource.cs	Updates in-memory source signature to accept the context.
dotnet/src/Microsoft.Agents.AI/Skills/File/AgentFileSkillsSource.cs	Updates file-based source signature to accept the context.
dotnet/src/Microsoft.Agents.AI/Skills/Decorators/DelegatingAgentSkillsSource.cs	Updates delegating decorator base to forward the context.
dotnet/src/Microsoft.Agents.AI/Skills/Decorators/FilteringAgentSkillsSource.cs	Updates filtering decorator to build/pass AgentSkillFilterContext.
dotnet/src/Microsoft.Agents.AI/Skills/Decorators/DeduplicatingAgentSkillsSource.cs	Updates dedup decorator to pass context through to inner source.
dotnet/src/Microsoft.Agents.AI/Skills/Decorators/CachingAgentSkillsSource.cs	Implements per-isolation-key caching using a concurrent dictionary.
dotnet/src/Microsoft.Agents.AI/Skills/Decorators/CachingAgentSkillsSourceOptions.cs	Adds options type for cache isolation key selection.
dotnet/src/Microsoft.Agents.AI/Microsoft.Agents.AI.csproj	Adds InternalsVisibleTo for MCP unit tests (to use internal context ctor).
dotnet/src/Microsoft.Agents.AI.Mcp/Skills/AgentMcpSkillsSource.cs	Updates MCP skills source signature and flows context into loaders.
dotnet/src/Microsoft.Agents.AI.Mcp/Skills/Loaders/IMcpSkillEntryLoader.cs	Updates loader interface to accept AgentSkillsSourceContext.
dotnet/src/Microsoft.Agents.AI.Mcp/Skills/Loaders/SkillMdEntryLoader.cs	Updates loader signature to accept context.
dotnet/src/Microsoft.Agents.AI.Mcp/Skills/Loaders/ArchiveEntryLoader.cs	Updates loader signature; passes context into extracted file source discovery.
dotnet/tests/Microsoft.Agents.AI.UnitTests/TestAgentSkillsSourceContextFactory.cs	Adds a test-only helper for constructing a skills source context.
dotnet/tests/Microsoft.Agents.AI.UnitTests/AgentSkills/TestSkillTypes.cs	Updates test source overrides to match the new signature.
dotnet/tests/Microsoft.Agents.AI.UnitTests/AgentSkills/FilteringAgentSkillsSourceTests.cs	Updates/extends tests for filter predicate context plumbing.
dotnet/tests/Microsoft.Agents.AI.UnitTests/AgentSkills/DeduplicatingAgentSkillsSourceTests.cs	Updates tests for new signature.
dotnet/tests/Microsoft.Agents.AI.UnitTests/AgentSkills/CachingAgentSkillsSourceTests.cs	Updates and adds tests for cache isolation keys.
dotnet/tests/Microsoft.Agents.AI.UnitTests/AgentSkills/AgentSkillsProviderTests.cs	Adds coverage ensuring agent/session flow into the source context.
dotnet/tests/Microsoft.Agents.AI.UnitTests/AgentSkills/AgentSkillsProviderBuilderTests.cs	Adds tests for caching options and updates filter signature usage.
dotnet/tests/Microsoft.Agents.AI.UnitTests/AgentSkills/AgentInMemorySkillsSourceTests.cs	Updates tests for new signature.
dotnet/tests/Microsoft.Agents.AI.UnitTests/AgentSkills/FileAgentSkillLoaderTests.cs	Updates file loader tests to pass a context.
dotnet/tests/Microsoft.Agents.AI.UnitTests/AgentSkills/AgentFileSkillsSourceScriptTests.cs	Updates script discovery/execution tests to pass a context.
dotnet/tests/Microsoft.Agents.AI.UnitTests/AgentSkills/AgentClassSkillTests.cs	Updates class-skill tests to pass a context.
dotnet/tests/Microsoft.Agents.AI.Mcp.UnitTests/TestAgentSkillsSourceContextFactory.cs	Adds a MCP-test-specific context factory (custom agent type).
dotnet/tests/Microsoft.Agents.AI.Mcp.UnitTests/Skills/AgentMcpSkillsSourceTests.cs	Updates MCP source tests for new signature.
dotnet/tests/Microsoft.Agents.AI.Mcp.UnitTests/Skills/AgentMcpSkillsSourceArchiveTests.cs	Updates MCP archive tests for new signature.

[github-actions]

Automated Code Review

Reviewers: 5 | Confidence: 89%

✓ Correctness

No actionable issues found in this dimension.

✓ Security Reliability

The PR cleanly threads AgentSkillsSourceContext through the skills pipeline. The main reliability concern is that the new CachingAgentSkillsSource uses a ConcurrentDictionary that grows without bound when CacheIsolationKeySelector produces many distinct keys (e.g., per-session), creating a potential memory leak in long-running services. The concurrency patterns are otherwise correct, and input validation is properly applied to the new context types.

✓ Test Coverage

The PR has solid test coverage for its core new behaviors: CachingAgentSkillsSource isolation keys are tested with same-key, different-key, and null-key scenarios; FilteringAgentSkillsSource has a dedicated test verifying context is passed to predicates; and AgentSkillsProviderBuilder has an integration test for cache isolation per agent. All existing tests are appropriately updated to pass the new context parameter. The only notable gap is that all test factory helpers use session: null, meaning no test exercises context-aware decisions based on a non-null Session value, though this is a minor concern given the Session property is simply a pass-through.

✓ Failure Modes

No actionable issues found in this dimension.

✗ Design Approach

That closes off direct use of AgentSkillsSource outside friend assemblies, which undercuts the extensibility this PR is trying to add.

Flagged Issues

• AgentSkillsSource.GetSkillsAsync now requires AgentSkillsSourceContext (dotnet/src/Microsoft.Agents.AI/Skills/AgentSkillsSource.cs:24), but AgentSkillsSourceContext's only constructor is internal (dotnet/src/Microsoft.Agents.AI/Skills/AgentSkillsSourceContext.cs:21). External consumers can still derive or receive an AgentSkillsSource, but they can no longer call its public API directly or write non-friend tests for it.

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Automated review by SergeyMenshykh's agents

[github-actions]

Flagged issue

AgentSkillsSource.GetSkillsAsync now requires AgentSkillsSourceContext (dotnet/src/Microsoft.Agents.AI/Skills/AgentSkillsSource.cs:24), but AgentSkillsSourceContext's only constructor is internal (dotnet/src/Microsoft.Agents.AI/Skills/AgentSkillsSourceContext.cs:21). External consumers can still derive or receive an AgentSkillsSource, but they can no longer call its public API directly or write non-friend tests for it.

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Source: automated DevFlow PR review