docs: require trigger class in governance changelog

Author: LalaSkye

docs/governance/CHANGELOG.md

@@ -6,8 +6,19 @@ Scope: governance-surface changes in `commit-gate-core`
 
 ---
 
+## Entry rule
+
+Each changelog entry that records a governance-surface change must name the trigger class that fired.
+
+This keeps the appellate record readable under pressure.
+
+---
+
 ## 2026-05-06 — Receipt-scope trigger class added
 
+Trigger class:
+Receipt-scope semantics change.
+
 Commits:
 - `68ac94c3` — `CHANGE_CONTROL.md`
 - `5a2a8ca4` — `docs/governance/README.md`