schema(json): unify IR/evidence schema drafts across the spec family

[flyingrobots]

Work Type

integrity

Hill Supported

Schema consumers and validators can reason about the IR/evidence schema family without draft-mismatch caveats or unsafe cross-draft assumptions.

Sponsor Actor

• Maintainer evolving the schema family
• Tooling or CI consumer validating Wesley JSON artifacts

Playback

A maintainer can point to one explicit schema-draft strategy for the IR/evidence family, and validation tooling exercises that strategy instead of relying on caveats buried in spec docs.

Problem

The IR family still mixes draft 2020-12 and draft-07 JSON Schema documents. The split is documented, but it still creates tooling friction and weakens the contract unless the compatibility boundary is explicit and tested.

Proposed Change

• choose one supported schema-draft strategy or an explicit compatibility boundary
• align the schema family and validation tooling to that strategy
• protect the chosen boundary with validation and fixture coverage

Invariants

• schema validation remains deterministic
• cross-schema references are either safe or explicitly disallowed/documented
• docs and tooling agree on the supported draft story

Non-Goals

• redesigning the entire schema family in one slice
• changing artifact semantics unrelated to schema-draft compatibility
• silently relying on tool-specific behavior without documentation

Acceptance / Tests

• supported schema-draft strategy is explicit
• cross-references between schema groups are safe or explicitly documented
• validation/tooling coverage protects the chosen draft boundary