HSDD Contract: First-Class Versioned Interfaces

A contract is the only thing one HSDD node may know about another. It is a standalone, versioned file, not prose buried in a spec.

Core principle: A contract has two parts with two jobs. The YAML frontmatter is machine-readable metadata projected into the registry. The body is the human-facing interface injected into a consuming phase's context. A consumer reads exactly one of those, never the producing node's internals.

When to Use