diff --git a/frontend/src/lib/shared/discussion/mentionConstants.ts b/frontend/src/lib/shared/discussion/mentionConstants.ts
index 3b946345..04721782 100644
--- a/frontend/src/lib/shared/discussion/mentionConstants.ts
+++ b/frontend/src/lib/shared/discussion/mentionConstants.ts
@@ -3,4 +3,8 @@
  *  cap and the debounce window consistent across both files. */
 export const MAX_QUERY_LENGTH = 100;
 export const SEARCH_DEBOUNCE_MS = 150;
+/** Defensive client-side cap on the result list. Single consumer today
+ *  (PersonMentionEditor), kept here for symmetry with the other limit
+ *  knobs so the @mention configuration lives in one place. Felix #1 on
+ *  PR #629 round 4. */
 export const SEARCH_RESULT_LIMIT = 5;