Validation answers whether a message is well formed and locally consistent. Governance at execution answers whether this specific effect is authorized to become real under current org lifecycle, delegation, and structural contracts at the commit boundary.
Before attributing external doctrine phrases to independent authors, verify against primary sources and MESSAGING_COPY_BLOCKS.md (see EGRESS_RECEIPT_MERKLE_ANNEX_V0 §0.0 discipline in-repo).
Inadmissible despite “correct”
A payload can validate against a schema yet still be inadmissible at T₁—for example when authority or lifecycle changed between plan and commit. The cost is reversal, audit narrative, and trust—not token count.