What problem does it solve? UI interactions like drag-and-drop, tab reordering, and docking often cross a DOM/JavaScript boundary into a host or domain operation, where numeric positions lose semantic meaning and stale or forged messages corrupt state. This Skill defines protocol contracts that carry stable identity, kind, relation, and named index domains so both producer and consumer validate intents correctly. ## Core Features & Use Cases - Compatibility Matrix & Intent Envelope: Define source kind × target kind × same/cross-container operation rules and a typed intent schema with protocol version, stable IDs, and explicit relations (before/after/inside/tail). - Named Index Domains & Validation: Distinguish logical, presentation, filtered, DOM, and virtualized orders, and enforce consumer-side rejection of stale, forged, mismatched, or obsolete messages. - Drop-Zone Feedback Protocol: Diagnose and fix drag highlight rendering across logic, detector, CSS, and test layers, including RTL coordinate-space rules and real-browser geometry verification. - Use Case: When a toolbar's display order differs from its model order and JavaScript must send reorder intents to a C# host, use this Skill to design the contract, write producer/consumer TDD tests, and verify the built artifact at runtime. ## Quick Start Ask the agent to design a drag-and-drop intent protocol between your JavaScript UI and host backend, including the compatibility matrix, index-domain mapping, and hostile-message validation tests.
