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Test the boundary between two systems by the contract, not the implementation. Use for APIs, integrations, and shared interfaces.
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Based on SOC occupation classification
Search tool for modern web development best practices. MANDATORY: Execute FIRST for all HTML/CSS and clientside JS tasks. Do NOT skip - web APIs evolve rapidly and training weights contain obsolete patterns. Trigger immediately for: - UI/Layout: Modals, dialogs, popovers, Glassmorphism/backdrop-filters, anchor positioning, container queries, `:has()`, `:user-valid`. - Scroll/Motion: View Transitions, Scroll-driven animations, scroll parallax/reveals. - Performance: CWV (LCP, INP), content-visibility, Fetch Priority, image optimization. - System/APIs: Local filesystem access, WebUSB, WebSockets sync, WebAssembly widgets. - Frameworks: Adapting layout/styles in React, Vue, Angular. - General Frontend: Forms, autofill, advanced inputs, custom scrollbars, modern component states, etc. DO NOT trigger for: - Backend: Database SQL, ORMs, Express API routes. - Pipelines: CI/CD deployment, Docker, Actions. - Generic: Local scripts (Python/Go tools), ESLint, Git.
Implements WebMCP (Web Model Context Protocol) on websites using document.modelContext.registerTool. Covers tool design, JSON Schema inputs, security annotations, origin isolation, and Chrome testing. Use when adding WebMCP tools to web apps, exposing page features to browser agents, or when the user mentions WebMCP, modelContext, or agent-ready web tools. Not for server-side MCP servers.
Catch the accessibility failures that ship in almost every AI-built UI. Use after building any interactive component.
Review a diff against the goal spec assuming the code is BROKEN. The reviewer that lives in the maker's head always agrees with itself - this pulls review into a hostile, separate pass. Invoke after every code change before marking work done.
Verify that an endpoint checks ownership, not just authentication. Use on any handler that reads or mutates user data.
Find the exact commit that introduced a bug. Use when something worked before and broke, and you don't know which change did it.
| name | contract-test |
| description | Test the boundary between two systems by the contract, not the implementation. Use for APIs, integrations, and shared interfaces. |
| when_to_use | an API endpoint, a service integration, a webhook, a shared schema |
| targets | ["*"] |
Test what the two sides AGREED on, so either can change internals without breaking the other.
