Dotnet Microsoft Extensions AI

Microsoft.Extensions.AI

Trigger On

• building or reviewing .NET code that uses Microsoft.Extensions.AI, Microsoft.Extensions.AI.Abstractions, IChatClient, IEmbeddingGenerator, ChatOptions, or AIFunction
• choosing between low-level AI abstractions, provider SDKs, vector-search composition, evaluation libraries, and a fuller agent framework
• adding streaming chat, structured output, embeddings, tool calling, telemetry, caching, or DI-based AI middleware
• wiring Microsoft.Extensions.VectorData, Microsoft.Extensions.DataIngestion, MCP tooling, or evaluation packages around a provider-agnostic AI app

Workflow

1. Classify the request first: plain model access, tool calling, embeddings/vector search, evaluation, or true agent orchestration.
2. Default to Microsoft.Extensions.AI for application and service code that needs provider-agnostic chat, embeddings, middleware, structured output, and testability.
3. Reference Microsoft.Extensions.AI.Abstractions directly only when authoring provider libraries or lower-level reusable integration packages.
4. Model IChatClient and IEmbeddingGenerator composition explicitly in DI. Keep options, caching, telemetry, logging, and tool invocation inspectable in the pipeline.
5. Treat chat state deliberately. For stateless providers, resend history. For stateful providers, propagate ConversationId rather than assuming all providers behave the same way.
6. Use Microsoft.Extensions.VectorData and Microsoft.Extensions.DataIngestion as adjacent building blocks for RAG instead of hand-rolling store abstractions prematurely.
7. Escalate to dotnet-microsoft-agent-framework when the requirement becomes agent threads, multi-agent orchestration, higher-order workflows, durable execution, or remote agent hosting.
8. Validate with real providers, realistic prompts, and evaluation gates so the abstraction layer actually buys portability and reliability.

Architecture

flowchart LR
  A["Task"] --> B{"Need agent threads, multi-agent orchestration, or remote agent hosting?"}
  B -->|Yes| C["Use Microsoft Agent Framework on top of `Microsoft.Extensions.AI.Abstractions`"]
  B -->|No| D{"Need provider-agnostic chat, embeddings, tools, typed output, or evaluation?"}
  D -->|Yes| E["Use `Microsoft.Extensions.AI`"]
  E --> F["Compose `IChatClient` / `IEmbeddingGenerator` in DI"]
  F --> G["Add caching, telemetry, tools, vector data, and evaluation deliberately"]
  D -->|No| H["Use plain provider SDKs or deterministic .NET code"]

Core Knowledge

• Microsoft.Extensions.AI.Abstractions contains the core exchange contracts such as IChatClient, IEmbeddingGenerator<TInput, TEmbedding>, message/content types, and tool abstractions.
• Microsoft.Extensions.AI adds the higher-level application surface: middleware builders, automatic function invocation, caching, logging, and OpenTelemetry integration.
• Most apps and services should reference Microsoft.Extensions.AI; provider and connector libraries usually reference only the abstractions package.
• IChatClient centers on GetResponseAsync and GetStreamingResponseAsync. The returned ChatResponse or ChatResponseUpdate objects carry messages, tool-related content, metadata, and optional conversation identifiers.
• ChatOptions is the normal control plane for model ID, temperature, tools, AdditionalProperties, and provider-specific raw options.
• Tool calling is modeled with AIFunction, AIFunctionFactory, and FunctionInvokingChatClient. Ambient data can flow through closures, AdditionalProperties, AIFunctionArguments.Context, or DI.
• IEmbeddingGenerator is the standard abstraction for semantic search, vector indexing, similarity, and cache-key generation. Pair it with Microsoft.Extensions.VectorData.Abstractions for vector store operations.
• Microsoft.Extensions.AI.Evaluation.* gives you quality, NLP, safety, caching, and reporting layers for regression checks and CI gates.
• Microsoft Agent Framework builds on these abstractions. Use it when you need autonomous orchestration, threads, workflows, hosting, or multi-agent collaboration instead of just model composition.

Decision Cheatsheet

Common Failure Modes

• Referencing only Microsoft.Extensions.AI.Abstractions in an app and then rebuilding middleware, telemetry, or function invocation by hand.
• Treating IChatClient as if it already gives you durable agent threads, orchestration, or hosted-agent semantics.
• Mixing provider-specific assistants APIs with IChatClient as if they were the same runtime contract.
• Forgetting to distinguish stateless history replay from stateful ConversationId flows.
• Hiding important chat behavior in singleton service fields instead of explicit message history, options, or persistent storage.
• Adding tool calling without validating parameter binding, invalid input behavior, side effects, or DI-scoped dependencies.
• Building RAG without stable chunking, embedding-model/version tracking, or vector dimension discipline.
• Shipping AI features without evaluation baselines, safety checks, or telemetry for prompt/model drift.

Deliver

• a justified package and abstraction choice: Abstractions only vs full Microsoft.Extensions.AI
• a concrete IChatClient / IEmbeddingGenerator composition strategy
• explicit tool-calling, options, state, caching, logging, and telemetry decisions
• vector-search, evaluation, or MCP integration guidance when the scenario needs it
• a clear escalation path to Agent Framework when the problem exceeds provider abstraction

Validate

• the abstraction layer solves a real portability, testability, or composition problem
• provider registration and middleware order stay explicit in DI
• chat state management matches whether the provider is stateless or stateful
• structured output, tool invocation, and embedding flows are typed and observable
• vector store, embedding model, and chunking strategy are consistent
• evaluation or safety gates exist for important prompts and agent-like behaviors
• agentic requirements are not being under-modeled as a simple IChatClient integration

When exact wording, edge-case API behavior, or less-common examples matter, check the local official docs snapshot before relying on summaries.

References

• official-docs-index.md - Slim local snapshot map with direct links to every mirrored .NET AI docs page plus API-reference pointers
• patterns.md - Package choice, IChatClient, embeddings, DI pipelines, tool-calling, and Agent Framework escalation guidance
• examples.md - Quickstart-to-task map covering chat, structured output, function calling, vector search, local models, MCP, and assistants
• evaluation.md - Quality, NLP, safety, caching, reporting, and CI-oriented evaluation guidance