Validating agentic behavior when “correct” isn’t deterministic

Modern software testing is built on a fragile assumption: correct behavior is repeatable. For deterministic code, that assumption mostly holds. But for autonomous agents like Github Copilot Coding Agent (aka Agent Mode), especially as we explore the frontiers of integrated “Computer Use,” that assumption breaks down almost immediately. As agents move beyond simple code suggestions to interacting with real environments like UIs, browsers, and IDEs, correctness becomes multi-path.