Visual Studio Weekly: Custom Agents, MCP Governance, and Performance Upgrades

Visual Studio 2026's March update (18.4.0) introduces custom Copilot agents defined as .agent.md files with full workspace awareness and MCP connections, along with enterprise MCP governance via GitHub allowlists to control approved servers. The release also includes smarter Copilot-powered debugging with context-aware Watch suggestions and measurable runtime performance gains in MSVC v14.51 preview.