What problem does it solve? Working on the VS Code Chat Customizations editor requires navigating a multi-layer architecture spanning core workbench code, sessions-window overrides, and a proposed extension API, where changes to shared interfaces must stay synchronized across five layers and layout bugs often only reproduce in the live product. ## Core Features & Use Cases - Architecture Guidance: Maps key folders, interfaces (IHarnessDescriptor, ISectionOverride, ICustomizationItemProvider), and the five-layer sync chain for the chatSessionCustomizationProvider extension API. - Component Fixture Testing: Documents fixture IDs for screenshotting every editor tab, mock data setup per customization type, built-in grouping requirements, and CI regression gates via blocksCi labels. - Live Product Debugging: Provides Playwright CLI workflows for connecting to a running Code OSS instance, navigating the editor, and diagnosing layout issues like list rendering and overflow clipping. - Use Case: When adding a new field to ICustomizationItem, follow the documented chain to update the .d.ts API, IPC DTO, ExtHost and MainThread mappings, and internal interface so all layers compile. ## Quick Start Ask the assistant to help modify the Chat Customizations editor, such as adding a new tab fixture or syncing a field across the customization provider API layers.
