docs(architect): weekly KB update — 106 files refreshed (2026-04)

Updates across all 5 skills: ms-ai-advisor, ms-ai-engineering,
ms-ai-governance, ms-ai-security, ms-ai-infrastructure.

Key changes:
- Language Services (Custom Text Classification, Text Analytics, QnA):
  retirement warning 2029-03-31, migration guides to Foundry/GPT-4o
- Agentic Retrieval: 50M free reasoning tokens/month (Public Preview)
- Computer Use: Claude Sonnet 4.5 (preview) + OpenAI CUA models
- Agent Registry: Risks column (M365 E7), user-shared/org-published types
- Declarative agents: schema v1.5 → v1.6, Store validation requirements
- MLflow 3: 13 built-in LLM judges, production monitoring, Genie Code
- AG-UI HITL: ApprovalRequiredAIFunction (C#) + @tool(approval_mode) (Python)
- Entra ID Ignite 2025: Agent ID Admin/Developer RBAC roles, Conditional Access
- Security Copilot: 400 SCU/month per 1000 M365 E5 licenses, auto-provisioned
- Fast Transcription API: phrase lists, 14-language multi-lingual transcription
- Azure Monitor Workbooks: Bicep support, RBAC specifics
- Power Platform Copilot: data residency (Norway/Europe → EU DB, Bing → USA)
- RAG security-rbac: 4-approach table (GA + 3 preview access control methods)
- IaC MLOps: Well-Architected OE:05 principles, Bicep/Terraform patterns
- Translator: image file batch translation Preview (JPEG/PNG/BMP/WebP)

All 106 files: Last updated 2026-04 | Verified: MCP 2026-04

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

skills/ms-ai-engineering/references/rag-architecture/rag-iterative-refinement.md

@@ -1,6 +1,6 @@
 # Iterative RAG and Multi-Turn Refinement
 
-**Last updated:** 2026-02
+**Last updated:** 2026-04 | Verified: MCP 2026-04
 **Status:** GA
 **Category:** RAG Architecture & Semantic Search
 
@@ -439,3 +439,25 @@ public async Task ApplyRetentionPolicyAsync()
 **Forfatter:** Cosmo Skyberg (AI Architect)
 **For:** KTG Microsoft AI Architect Plugin
 **MCP Research:** microsoft-learn (4 searches, 2 fetches), microsoft-code-samples (1 search)
+
+
+### .NET AI IChatClient-interface (oppdatert 2026-04)
+
+`IChatClient` er .NET-standarden for interaksjon med AI chat services (Microsoft.Extensions.AI). Støtter stateless og stateful samtaler, tool calling, streaming, caching, og OpenTelemetry.
+
+```csharp
+// Stateful iterativ RAG med IChatClient
+List<ChatMessage> history = [];
+while (true) {
+    history.Add(new(ChatRole.User, userInput));
+    ChatResponse response = await client.GetResponseAsync(history);
+    history.AddMessages(response); // akkumulerer kontekst
+}
+```
+
+**Viktige egenskaper:**
+- `ConversationId` støtter stateful tjenester (slipper å sende full historikk)
+- `FunctionInvokingChatClient` gir automatisk tool invocation for agentic loops
+- `DistributedCachingChatClient` wrapper cacher identiske historikker
+- `ChatHistoryTruncationReducer` / `ChatHistorySummarizationReducer` håndterer context window limits
+- Pipeline-komposisjon: `ChatClientBuilder` stacker cache, tool invocation, og telemetri