diff --git a/backend/internal/store/syncruns.go b/backend/internal/store/syncruns.go
index 65b6954..eab7c76 100644
--- a/backend/internal/store/syncruns.go
+++ b/backend/internal/store/syncruns.go
@@ -18,7 +18,10 @@ const (
 	SyncStatusError   = "error"
 )
 
-// SyncRun records one backfill or incremental sync attempt.
+// SyncRun records one sync attempt. Every run recorded today is
+// SyncKindFull (the "Sync now" action, covering backfill + incremental sync
+// + detail/workout fill in a single pass) -- "backfill"/"incremental" only
+// ever appear in historical rows predating that consolidation.
 type SyncRun struct {
 	ID                int64
 	Kind              string