agent-framework/dotnet/samples/02-agents/Agents/Agent_Step11_Middleware

Agent Middleware

This sample demonstrates how to add middleware to intercept:

• Chat client calls (global and per‑request)
• Agent runs (guardrails and PII filtering)
• Function calling (logging/override)

What This Sample Shows

1. Azure OpenAI integration via AzureOpenAIClient and DefaultAzureCredential
2. Chat client middleware using ChatClientBuilder.Use(...)
3. Agent run middleware (PII redaction and wording guardrails)
4. Function invocation middleware (logging and overriding a tool result)
5. Per‑request chat client middleware
6. Per‑request function pipeline with approval
7. Combining agent‑level and per‑request middleware
8. MessageAIContextProvider middleware via AIAgentBuilder.Use(...) for injecting additional context messages
9. AIContextProvider middleware via ChatClientBuilder.Use(...) for enriching messages, tools, and instructions at the chat client level

Function Invocation Middleware

Not all agents support function invocation middleware.

Attempting to use function middleware on agents that do not wrap a ChatClientAgent or derives from it will throw an InvalidOperationException.

Prerequisites

1. Environment variables:
   • AZURE_OPENAI_ENDPOINT: Your Azure OpenAI endpoint
   • AZURE_OPENAI_DEPLOYMENT_NAME: Chat deployment name (optional; defaults to gpt-5.4-mini)
2. Sign in with Azure CLI (PowerShell):

   az login
   

Running the Sample

Use PowerShell:

cd dotnet/samples/02-agents/Agents/Agent_Step11_Middleware
dotnet run