Ue Mass Entity

This gives Claude the vocabulary and structural knowledge to work with Unreal Engine's Mass Entity framework, an archetype-based ECS for simulating thousands of entities with cache-friendly data layouts. It covers the core distinctions between fragments, tags, shared fragments, and chunk fragments, shows how to configure processors with queries and execution ordering, and explains critical details like when to use BatchCreateEntities versus single entity spawning, how FMassEntityHandle validity checks actually work, and the difference between mutable and const shared fragments. Worth having if you're building crowds, traffic systems, or any large-scale simulation where traditional actor-based approaches would tank performance. The framework is opinionated and has sharp edges around execution context and archetype mutations.