JD.SemanticKernel.Extensions

An extensible toolkit for Microsoft Semantic Kernel that bridges Claude Code skills, plugins, and hooks into SK applications, and adds context management primitives (compaction, semantic memory) for building production-grade AI agents.

Features

• 📝 Skills — Parse SKILL.md files (YAML frontmatter + markdown) into KernelFunction or PromptTemplate
• 🔗 Hooks — Map Claude Code lifecycle events (PreToolUse, PostToolUse, etc.) to SK's IFunctionInvocationFilter and IPromptRenderFilter
• 📦 Plugins — Load .claude-plugin/ directories with skills, hooks, and MCP configs
• 🗜️ Compaction — Transparent context window management with configurable triggers and hierarchical summarization
• 🧠 Memory — Semantic memory with MMR reranking, temporal decay scoring, and query expansion
• 💾 Memory.Sqlite — SQLite-backed persistent memory storage
• 🎯 Fluent API — UseSkills(), UseHooks(), UsePlugins(), AddCompaction(), AddSemanticMemory() extension methods

Packages

Package	Description	NuGet
JD.SemanticKernel.Extensions.Skills	SKILL.md → KernelFunction/PromptTemplate
JD.SemanticKernel.Extensions.Hooks	Claude Code hooks → SK filters
JD.SemanticKernel.Extensions.Plugins	Plugin directory loader
JD.SemanticKernel.Extensions.Compaction	Context window compaction middleware
JD.SemanticKernel.Extensions.Memory	Semantic memory with MMR + temporal decay
JD.SemanticKernel.Extensions.Memory.Sqlite	SQLite memory backend
JD.SemanticKernel.Extensions	Meta-package (all of the above)

Quick Start

dotnet add package JD.SemanticKernel.Extensions

Load Skills

using JD.SemanticKernel.Extensions.Skills; var kernel = Kernel.CreateBuilder() .AddOpenAIChatCompletion("gpt-4o", apiKey) .UseSkills("./skills/") // Scans for SKILL.md files .Build();

A SKILL.md file follows the Claude Code / AgentSkills.io format:

--- name: code-reviewer description: Reviews code for quality issues allowed-tools: [Read, Grep, Glob] --- # Code Reviewer Review the provided code for: 1. Bug risks 2. Security vulnerabilities 3. Performance issues Input: $ARGUMENTS

Configure Hooks

using JD.SemanticKernel.Extensions.Hooks; var kernel = Kernel.CreateBuilder() .AddOpenAIChatCompletion("gpt-4o", apiKey) .UseHooks(hooks => { hooks.OnFunctionInvoking("Bash|Execute", async ctx => { Console.WriteLine($"Validating: {ctx.Function.Name}"); }); hooks.OnFunctionInvoked("Write|Edit", async ctx => { Console.WriteLine($"Post-edit hook: {ctx.Function.Name}"); }); hooks.OnPromptRendering(async ctx => { Console.WriteLine("Prompt is about to render..."); }); }) .Build();

Load Plugins

using JD.SemanticKernel.Extensions.Plugins; var kernel = Kernel.CreateBuilder() .AddOpenAIChatCompletion("gpt-4o", apiKey) .UsePlugins("./my-plugin/") // Single plugin directory .UseAllPlugins("./plugins/") // All plugins in directory .Build();

Plugin directories follow the .claude-plugin/ convention:

my-plugin/ ├── .claude-plugin/ │ └── plugin.json # Manifest ├── skills/ │ └── reviewer/SKILL.md # Skills ├── hooks/ │ └── hooks.json # Hooks └── .mcp.json # MCP servers (future)

Meta-Package (All-in-One)

using JD.SemanticKernel.Extensions; var kernel = Kernel.CreateBuilder() .AddOpenAIChatCompletion("gpt-4o", apiKey) .AddClaudeCodeSkills("./skills/") .AddClaudeCodePlugin("./my-plugin/") .AddClaudeCodeHooks(hooks => hooks.OnFunctionInvoking(".*", _ => Task.CompletedTask)) .Build();

Context Compaction

Automatically compress chat history when it grows too large, preserving key context while staying within token limits.

using JD.SemanticKernel.Extensions.Compaction; var kernel = Kernel.CreateBuilder() .AddOpenAIChatCompletion("gpt-4o", apiKey) .Build(); // Register compaction as transparent middleware kernel.Services.AddCompaction(options => { options.TriggerMode = CompactionTriggerMode.ContextPercentage; options.Threshold = 0.70; // Compact at 70% of context window options.MaxContextWindowTokens = 128_000; // Model's context limit options.PreserveLastMessages = 10; // Always keep recent messages options.MinMessagesBeforeCompaction = 5; // Don't compact short conversations });

Trigger modes:

• TokenThreshold — Compact when estimated tokens exceed an absolute count
• ContextPercentage — Compact when usage exceeds a percentage of the context window

Token estimation:

var tokens = TokenEstimator.EstimateTokens("Hello world"); // ~2 tokens var historyTokens = TokenEstimator.EstimateTokens(chatHistory); // Includes overhead

Semantic Memory

Store, search, and retrieve context-relevant information with embedding-based similarity, MMR diversity reranking, and temporal decay scoring.

using JD.SemanticKernel.Extensions.Memory; // Register with in-memory backend kernel.Services.AddSemanticMemory(options => { options.DefaultSearchOptions = new MemorySearchOptions { TopK = 10, MinRelevanceScore = 0.7, UseMmrReranking = true, MmrLambda = 0.7, // Balance relevance vs diversity UseTemporalDecay = true, TemporalDecayRate = 0.01, }; });

SQLite persistence:

using JD.SemanticKernel.Extensions.Memory.Sqlite; kernel.Services.AddSqliteMemoryBackend("Data Source=memory.db");

Key capabilities:

• MMR reranking — Maximal Marginal Relevance for diverse search results
• Temporal decay — Recent memories rank higher with configurable decay rate
• Query expansion — Automatically generate alternative queries for broader recall
• Pluggable backends — InMemoryBackend (default), SqliteMemoryBackend, or implement IMemoryBackend

Hook Event Mapping

Claude Code Event	SK Filter
PreToolUse	IFunctionInvocationFilter.OnFunctionInvokingAsync
PostToolUse	IFunctionInvocationFilter.OnFunctionInvokedAsync
UserPromptSubmit	IPromptRenderFilter.OnPromptRenderingAsync
Stop / SubagentStop	IAutoFunctionInvocationFilter
SessionStart / SessionEnd	IExtensionEventBus (custom)
PreCompact / Notification	IExtensionEventBus (custom)

Related Projects

Project	Description
JD.SemanticKernel.Connectors.ClaudeCode	Claude Code authentication provider for SK
JD.SemanticKernel.Connectors.GitHubCopilot	GitHub Copilot authentication provider for SK

Building

dotnet restore dotnet build dotnet test

License

MIT © JD