Creative status fields are server-owned and cannot be mutated directly from the client. When a creative reaches Approved, Mediasphere performs two cryptographic-grade governance actions automatically:

• Version Locking: The exact CreativeVersion that passed review is stamped as approved_version_id and is_final_deliverable=true, blocking silent file overwrites.
• Immutable Approval Snapshot (CreativeApprovalSnapshot): A frozen record captures every reviewer decision, linked ProductClaim status, active UsageRight summary, legal clearance confirmation, and approval-gate verdict at that exact second.

Governed amendments & Approval Certificates

If an approved creative must be updated (for example, a regulatory rate change or copy update), initiate a Governed Amendment. You must provide an amendment_reason; once the new version is approved, Mediasphere creates a new CreativeApprovalSnapshot chained to the prior snapshot via prior_snapshot_id. You can also download a PDF Approval Certificate for any approved creative.