fix: align group private chat permission semantics

server/db/mysql/group_schema_test.go

@@ -171,3 +171,24 @@ func TestSharedDBGroupFileLinkIncludesTenantID(t *testing.T) {
 		t.Fatal("TenantGroupFileCreate must not rely on im_filemsglinks.tenant_id default")
 	}
 }
+
+func TestTenantUsersShareOpenPrivateGroupChecksBothMembersAndSetting(t *testing.T) {
+	source, err := os.ReadFile("tenant_groups.go")
+	if err != nil {
+		t.Fatal(err)
+	}
+	body := sourceBetween(t, string(source), "func (a *adapter) TenantUsersShareOpenPrivateGroup", "\nfunc (a *adapter) TenantGroupMemberUpdate")
+	for _, required := range []string{
+		"INNER JOIN im_group_members AS gm2",
+		"gm2.topic=gm1.topic",
+		"INNER JOIN im_group_settings AS gs",
+		"gs.member_private_chat=1",
+		"gm1.member_status=?",
+		"gm2.member_status=?",
+		"gs.group_status=?",
+	} {
+		if !strings.Contains(body, required) {
+			t.Fatalf("TenantUsersShareOpenPrivateGroup must check active shared group and setting; missing %q", required)
+		}
+	}
+}