diff --git a/db.go b/db.go
index 3f75e3b..65fe7bd 100644
--- a/db.go
+++ b/db.go
@@ -53,11 +53,19 @@ type Comment struct {
 
 // Query is the read-side query derived from a search session's state.
 //
-// ADDING A FIELD? Scoped invalidation (inval.go) re-implements this struct's
-// filter semantics: update queryMatches AND the invalBattery test battery, or
-// writes will under-invalidate the new facet's cache keys — a silent
-// stale-list bug. (The drift-proof alternative, probing membership with
-// buildWhere itself, is sketched in slop-essays/scoped-invalidation.md.)
+// ADDING A FIELD? Three places re-express this struct's filter semantics and
+// silently break if the new facet misses one:
+//
+//   - ftsQuery AND statusLabelClauses (db.go): selectivity routing
+//     (walkBeatsFTS) can serve a filter from EITHER, so a facet added to one
+//     but not the other returns WRONG ROWS on the other path. Add the facet to
+//     both (or guard it out in walkBeatsFTS) and extend
+//     TestDenseLabelRoutingEquivalent's shapes.
+//   - queryMatches (inval.go): scoped invalidation; a missing facet means
+//     under-invalidation — silently stale cached lists. Extend invalBattery.
+//
+// (The drift-proof alternative, probing membership with buildWhere itself, is
+// sketched in slop-essays/scoped-invalidation.md.)
 type Query struct {
 	Text   string
 	Status string // "open" | "closed" | "all"