Microsoft's Agent Framework adds agent-generated interfaces and a fatal-middleware signal

Microsoft's Agent Framework 1.15.0 for Python, released 21 August 2026, adds optional support for agent-generated user interfaces while preserving streaming tool-call indices for whatever consumes them, makes middleware failure a first-class fatal signal rather than a swallowed error, and adds steering, retry and recovery support for long-running hosted agents.

What it means An agent that renders its own interface, and a middleware failure that actually stops the run, are both about giving the operator somewhere to stand.