GitHub Copilot adds Agent Skills in VS Code

This is a real upgrade from one-off prompting to reusable workflow engineering inside the IDE. Skills let teams codify domain workflows once and reuse them across tasks instead of rewriting long prompts. Progressive, relevance-based loading improves context efficiency versus always-on instruction blobs, while shared skill directories and slash-command invocation make adoption practical for existing repos. The strategic win is portability: one skill format that travels across Copilot surfaces and nudges a broader agent tooling ecosystem.