What problem does it solve? Working on the Chat Customizations editor requires navigating a multi-layer architecture spanning core workbench code, sessions-window overrides, an extension API chain, and component fixtures, where changes in one layer silently break others. ## Core Features & Use Cases - Architecture Map: Documents the harness descriptor pattern (IHarnessDescriptor, ISectionOverride, ICustomizationItemProvider) and the key folders for core, sessions, and tree-view code. - Extension API Sync Checklist: Lists all five layers (proposed .d.ts, IPC DTO, ExtHost, MainThread, internal interface) that must be updated together when adding fields to ICustomizationItem. - Testing & Debugging Playbook: Provides fixture IDs for screenshotting every editor tab, mock service requirements, CI regression gate guidance, and Playwright-based live debugging techniques for layout issues. - Use Case: When adding a new field to customization items, follow the five-layer sync table to update the proposed API, protocol DTO, both mapping layers, and the internal interface so nothing is missed. ## Quick Start Ask the AI to help modify the Chat Customizations editor, such as adding a new tab fixture or syncing a new field across the customization provider API layers.
