What problem does it solve? Working on the Chat Customizations editor requires coordinating harness descriptors, section overrides, extension API layers, and component fixtures across core and sessions codebases, and this Skill consolidates the ownership contracts, interface chains, and testing patterns needed to make changes safely. ## Core Features & Use Cases - Interface Contract Guidance: Documents IHarnessDescriptor, ISectionOverride, and ICustomizationItemProvider so widgets stay harness-agnostic and descriptor-driven. - Extension API Sync Chain: Maps the five layers (proposed .d.ts, IPC DTO, ExtHost, MainThread, internal interface) that must be updated together when adding fields to ICustomizationItem. - Component Fixture Testing: Explains how to screenshot specific editor tabs, populate mock data per customization type, exercise built-in grouping, and gate layout regressions in CI with blocksCi fixtures. - Live Product Debugging: Provides Playwright CLI workflows for inspecting list widget layout, diagnosing reflow timing issues, and reproducing bugs that fixtures cannot catch. - Use Case: When adding a new customization tab, follow the fixture variant pattern, mock the required services, and add blocksCi gating so layout regressions fail CI automatically. ## Quick Start Ask the AI to add a new section to the Chat Customizations management editor and create a screenshot fixture with CI regression gating for it.
