diff --git a/modules/cabana/relation.go b/modules/cabana/relation.go
index 5615e26..7ebc1c6 100644
--- a/modules/cabana/relation.go
+++ b/modules/cabana/relation.go
@@ -544,10 +544,17 @@ func normalizeRelationQuery(schema *RelationSchema, candidates bool, in Relation
 		panel = schema.Manage
 	}
 	sortKey := in.Sort
-	if sortKey == "" && len(panel.List.Columns) > 0 {
-		sortKey = panel.List.Columns[0].Key
-	}
-	if sortKey != "" {
+	if sortKey == "" {
+		// No explicit sort: use the first sortable column, or none (the
+		// primary key then orders the page). Only a sort the client names is
+		// validated, so a panel whose first column is not sortable still loads.
+		for _, col := range panel.List.Columns {
+			if col.Sortable {
+				sortKey = col.Key
+				break
+			}
+		}
+	} else {
 		valid := false
 		for _, col := range panel.List.Columns {
 			if col.Key == sortKey && col.Sortable {
diff --git a/modules/cabana/relation_test.go b/modules/cabana/relation_test.go
index 8a292ec..36c07a5 100644
--- a/modules/cabana/relation_test.go
+++ b/modules/cabana/relation_test.go
@@ -94,6 +94,27 @@ func TestRelationStablePages(t *testing.T) {
 	}
 }
 
+// TestRelationDefaultSort pins WR-06: with no sort in the request the panel
+// orders by its first sortable column, or by the primary key when none is
+// sortable, instead of rejecting the request.
+func TestRelationDefaultSort(t *testing.T) {
+	schema := &RelationSchema{
+		View:   RelationPanel{List: RelationList{Columns: []RelationColumn{{Key: "label"}, {Key: "email", Sortable: true}}}},
+		Manage: RelationPanel{List: RelationList{Columns: []RelationColumn{{Key: "label"}}}},
+	}
+	_, _, key, _, err := normalizeRelationQuery(schema, false, RelationQuery{})
+	if err != nil || key != "email" {
+		t.Fatalf("view default sort = %q err=%v, want the first sortable column", key, err)
+	}
+	_, _, key, _, err = normalizeRelationQuery(schema, true, RelationQuery{})
+	if err != nil || key != "" {
+		t.Fatalf("manage default sort = %q err=%v, want none (primary key order)", key, err)
+	}
+	if _, _, _, _, err := normalizeRelationQuery(schema, false, RelationQuery{Sort: "label"}); err == nil {
+		t.Fatal("an explicit sort on a non-sortable column was accepted")
+	}
+}
+
 func TestRelationCandidateExclusions(t *testing.T) {
 	contract := relationTestController{}.AdminRelationContracts()[0]
 	ids, err := contract.ExcludedRelatedIDs(&relationTestOwner{OwnerID: 41})