This handles the split-view management UI where you configure agents, skills, instructions, hooks, prompts, MCP servers, and plugins across workspace, user, and extension storage. It filters by harness (Local, Copilot CLI, Claude) and follows a strict pattern: all UI behavior is driven by declarative harness descriptors, so widget code stays clean of conditionals. The architecture is interesting because it bridges VS Code's extension API down through IPC to internal interfaces, meaning any change to customization items ripples through five layers. You'll spend time in the spec at `AI_CUSTOMIZATIONS.md` and the component fixtures, which include CI-blocking screenshot tests that catch layout regressions automatically. Useful when you're wiring up new customization types or debugging why a particular harness isn't showing the storage sources you expect.
npx skills add https://github.com/microsoft/vscode --skill chat-customizations-editor