Schema compatibility is claim-boundary compatibility.

Version policy

A schema compatibility policy names the artifact, version, field mappings, deprecated fields, required assumptions, coverage / exactness boundaries, and non-conclusions.

schema-compatibility-policy-v0 :=
  artifactId
  + schemaVersion
  + fieldMappings
  + deprecatedFields
  + requiredAssumptions
  + coverageExactnessBoundaries
  + nonConclusions

Compatibility outcomes

notComparable is a valid boundary outcome, not a generic failure. If schema, unit, projection, or coverage does not align, the tool should avoid inventing a delta.

• compatible The artifact can be read under the mapped schema while preserving boundaries.
• requiresMigration A migration path is needed before comparison or reporting is meaningful.
• notComparable The artifacts are not comparable under the available projection or coverage.
• blockedFormalClaimPromotion The migration would strengthen a weak boundary into a formal claim without required preconditions.

Catalog

The catalog includes Sig0, AIR, Feature Extension Report, obstruction witnesses, drift ledgers, reported axes, B10 operational feedback artifacts, and Architecture Dynamics reports such as PR force, signature trajectory, and dynamics metrics.

• Core artifacts archsig-sig0-v0, aat-air-v0, feature-extension-report-v0, and obstruction-witness-v0.
• Operational artifacts Daily ledger, calibration review, team threshold, ownership monitor, repair adoption, incident correlation, and hypothesis refresh.
• Dynamics artifacts pr-force-report-v0, signature-trajectory-report-v0, and architecture-dynamics-metrics-report-v0.

Migration rules

A migration is not safe if it removes an older non-conclusion, silently discharges a new required assumption, or loses coverage and exactness metadata.