Clarify campaign review interventions

docs/CAMPAIGN_HANDBOOK.md

@@ -141,6 +141,14 @@ just the authoring form:
    content, recipients, attachment inputs, owner context, or non-secret
    transport identity changes, revalidate and rebuild.
 
+The Review & Send surface separates three kinds of attention. Critical
+blockers must be corrected before delivery, individual review items require a
+recorded message decision, and non-critical group items may be acknowledged
+together after individual review is complete. Each warning or blocker names
+the required action, the responsible role, and the workspace to open. The
+review summary keeps reviewed and remaining counts visible; a completed review
+acknowledges the group items and remains bound to the current build token.
+
 This evidence is the Campaign input to separation-of-duties policy. Generic
 approve/reject chains, delegation, substitutions, escalation, and signatures
 belong to the optional Approvals capability. Campaign must not claim an