ag-ui

Author unit tests for the AG-UI .NET SDK (the *.UnitTests projects), following the SDK's serialization and compatibility conventions. USE FOR: adding unit-test coverage for a new type/method in AGUI.Abstractions/Formatting/Protobuf/Client/Server, event serialization round-trips, JsonDocument property-name assertions, backward-compatibility fixtures against TypeScript JSON, protobuf codec round-trips, client builder/handler tests, server ChatResponseUpdate conversion tests, SSE formatter tests. DO NOT USE FOR: HTTP pipeline / WebApplicationFactory end-to-end tests (use the agui-dotnet-integration-tests skill), cross-language TS↔C# server-parity tests (use the cross-language test skill).

Add or modify a wire/protocol type in the AG-UI .NET SDK AGUI.Abstractions package — a new event, message, or content-part type, the AOT source-gen serializer context, or a polymorphic JSON converter, keeping it AOT-safe, JSON-wire-compatible with the TypeScript reference, and PublicAPI-clean. USE FOR: adding an AG-UI event type, adding a message role or input-content type, editing AGUIJsonSerializerContext, editing BaseEventJsonConverter / AGUIMessageJsonConverter / AGUIInputContentJsonConverter, fixing PublicAPI.Unshipped analyzer build failures on protocol types, wire-format round-trip serialization. DO NOT USE FOR: writing integration/SSE tests (use agui-dotnet-integration-tests), server hosting/endpoint code, or non-Abstractions packages.

Manually validate a running web app or docs site with the Playwright MCP server — navigate pages, assert headings/text/status, check for console errors, hover/click to exercise interactions, take screenshots for human review, and verify visual details such as an icon's color in light vs dark mode by reading computed styles. USE FOR: "validate with Playwright", "open the browser and check", visually verifying a UI or docs change, confirming a CSS/SVG/icon edit rendered, checking a page for console errors, comparing light/dark mode appearance. DO NOT USE FOR: writing automated unit/E2E test files (dojo e2e lives in agui-dojo); docs-site content/structure checks specific to the .NET SDK docs (use agui-dotnet-sdk-docs). INVOKES: browser_navigate, browser_snapshot, browser_take_screenshot, browser_evaluate, browser_hover, browser_click, browser_console_messages Playwright MCP tools.