Module schema_registry 

Content-addressed schema/reducer artifacts.

Implements the schema-artifact part of docs/THEORY.md Section 5.1, where event tuples reference a content-addressed schema field that pins the replay semantics:

schema = content-addressed schema and reducer reference

And §5.5:

Schema and reducer artifacts are fixed by content hash.

What this module ships

• SchemaArtifact: a typed, content-addressed artifact whose id is the SHA-256 of its canonical content.
• SchemaRegistry: a registry mapping artifact id to artifact, used to verify that an event references a known schema before replay.
• Verification primitives that future event-replay code can call to check schema availability and detect schema drift.

What this module does NOT do

It does not yet replace the existing StateEvent::schema: String version-tag field. That replacement is a wider substrate change (target v0.85+) that ripples into canonicalization, event-id derivation, and existing event-set hashes. This module ships the artifact + registry primitive on which that replacement will sit.

Structs

SchemaArtifact

A content-addressed schema or reducer artifact.

SchemaRegistry

A registry of known schema artifacts.