# Docs
### Scope
Design and API documentation for `collection_tools`. Organized as typed doc entity instances: features describe what the crate does, invariants define behavioral contracts, and API docs reference the public interface.
See [entities.md](entities.md) for the complete registry of all doc instances.
### Responsibility Table
| [entities.md](entities.md) | Master registry of all doc entity types and instances |
| [doc_graph.yml](doc_graph.yml) | Cross-reference graph linking all doc instances |
| [feature/](feature/readme.md) | Feature documentation — what the crate does and when to use it |
| [invariant/](invariant/readme.md) | Invariant documentation — behavioral contracts that must always hold |
| [api/](api/readme.md) | API reference — public macro signatures, expansion contracts, and re-exports |