0005: Schemas Are Versioned And Backward-Compatible

Status: Accepted for STAGE 0.3

Context

STAGE 0.1 manifests exist in an adopted project and external trials. The 0.3 method needs richer profiles, operations, ownership, and evidence without invalidating those records or silently rewriting human decisions.

Decision

• Preserve immutable versioned schemas for supported artifact versions.
• Select validation rules from the artifact's declared version.
• Keep an explicit compatibility policy and migration command.
• Make migration opt-in, reviewable, and non-destructive by default.
• Represent ambiguous legacy ownership as unresolved rather than guessing.

Consequences

• Existing 0.1 manifests remain valid.
• New projects use the current schema.
• Removing old schema support requires a future documented compatibility decision, not incidental validator cleanup.