mavend: an unconfigured capability names the gap (V-479)

Netscan and the crawler both declined their own turn when the wiring was
nil, and the question fell through to the search leg. "какие устройства в
сети?" came back as a paragraph about routers in general, and a question
about his own LAN went to an upstream engine — the personal boundary
exists to stop exactly that. A URL he named came back answered as though
he had not named it.

Both now claim the turn once their own recogniser has matched, and say
which capability is missing: net_off and page_off in the query family.

TestQueryWebPassesWhenNotConfigured encoded the old decision, that
announcing a configuration status is only for a capability that exists and
failed. It is rewritten, not deleted: the gap is the answer now.

cmd/mavend/netscan_test.go

@@ -10,6 +10,8 @@ import (
 
 	"github.com/kami/maven/internal/config"
 	"github.com/kami/maven/internal/ipc"
+	"github.com/kami/maven/internal/phraser"
+	"github.com/kami/maven/internal/router"
 )
 
 func TestWireNetScanOffUnlessEnabled(t *testing.T) {
@@ -169,3 +171,22 @@ func TestScanSummarySpeaksACountAndWritesTheAddresses(t *testing.T) {
 		t.Errorf("a repeat question rescanned and rewrote the record (%d notes)", api.n)
 	}
 }
+
+// An unconfigured scanner names the gap instead of declining the turn.
+//
+// Falling through sent "какие устройства в сети?" to the search leg, which
+// answered with a paragraph about routers in general — and put a question about
+// his own LAN on an upstream engine, which the personal boundary exists to
+// prevent (Vikunja #479).
+func TestQueryNetworkNamesTheGapWhenNotConfigured(t *testing.T) {
+	h := &reactiveHandler{}
+	reply, ok := h.queryNetwork(context.Background(), &queryTurn{
+		dec: router.Decision{Utterance: "какие устройства в сети?"},
+	})
+	if !ok {
+		t.Fatal("an unconfigured scanner let the question fall through to search")
+	}
+	if !phraser.IsQ(phraser.QueryNetOff, nil, reply) {
+		t.Errorf("got %q, want the gap named", reply)
+	}
+}