Microsoft Foundry April 2026: Foundry Local GA, GPT-5.5, CodeAct with Hyperlight

Emiliano Montesdeoca — Tue, 02 Jun 2026 00:00:00 +0000

A busy month for Microsoft Foundry. Here are the announcements that matter most.

Foundry Local Is Generally Available

Foundry Local — Microsoft’s cross-platform local AI runtime — graduates from preview to GA on Windows, macOS (Apple Silicon), and Linux x64. Production-ready local model inference with a developer-friendly SDK. The 1.1 release (detailed in a separate post) adds transcription, embeddings, and Responses API support.

GPT-5.5

The latest GPT-5 family model is now available in Foundry. Default quota for Tier 5 and Tier 6 subscriptions. If you’ve been working with earlier GPT-5 variants, this is worth evaluating for your use cases.

Agent Framework Tracing in Foundry

Two tracing features ship in preview this month:

Microsoft Agent Framework tracing — MAF agents can now emit OpenTelemetry traces into Foundry. Debug agent behavior, trace multi-step execution, surface latency and errors across tool calls. This fills a real gap: knowing what your agent actually did in production, not just what it returned.

Hosted-agent tracing — Sessions, tool calls, and run steps from hosted agents also surface in Foundry traces. Same observability story extended to the hosted tier.

CodeAct with Hyperlight (Alpha)

This is the most technically interesting addition: Agent Framework can now execute Python code inside Hyperlight micro-virtual machines.

CodeAct is the pattern where an agent generates and executes Python code as a tool. The obvious concern is security — you’re running model-generated code. Hyperlight’s micro-VMs provide process-level isolation with near-native startup time, making sandboxed code execution practical without the overhead of full containers or VMs.

For agentic workflows where code execution is necessary, this is a significant safety improvement over running code in the host process.

Agent Monitoring Dashboard (Preview)

A unified operations dashboard combining token usage, latency, run success rate, and evaluator scores in one view. The distinction from regular observability dashboards: it includes evaluation results alongside operational metrics, so you can correlate “the agent is slower” with “evaluator scores dropped” — or confirm they’re unrelated.

Continuous Evaluation Custom Evaluators (Preview)

You can now bring your own code-based or prompt-based evaluators into continuous evaluation pipelines. Previously, continuous eval was limited to built-in evaluators. Custom evaluators let you enforce team-specific quality criteria in your production monitoring loop.

Agent Inventory in Control Plane

The Foundry Control Plane Operate view now shows all supported agents across a subscription: Foundry agents, Azure SRE Agent, Logic Apps agent loops, and registered custom agents. One view to understand what’s deployed and where.

Original post: What’s new in Microsoft Foundry | April 2026

GPT-5.5 | The .NET Blog