Protocol messages must stay checkable and versioned
Validation checks fit; versioning names the contract
Validation posture
Valid messages are complete, attributable, and safe
CheckQuestionPass conditionBoundary
Completeness
Are required fields present
Action, evidence, lifecycle, and version refs exist
Structure
Attribution
Can the actor be recognized
Agent and capability refs are present
Identity
Boundary
Are payloads kept out
Private payloads remain behind refs
Safety
Version discipline
Protocol change must stay visible
Draft v0.1 is current
Current launch model, not stable release
Changes must be explicit
Schema changes must be published
Compatibility is knowable
Message forms and refs must stay legible