Fold three tests into existing ones, drive the marker test by channels, keep the last view through set(nil) and drop it once the node is held

Claude-Session: https://claude.ai/code/session_01NcbgfFSnn24M3GcqttoU7i

internal/selfcompose/compose_while_passing_test.go

@@ -21,7 +21,7 @@ import (
 // Issue 1965 (shanks 2026-11-05 22:27: the verb compose gave no answer in 30 s while a pass waited on the bus): an ask
 // that comes while a pass runs is answered at once, says one more pass is queued and what the running one waits on, and
 // the queued pass is made when the running one ends.
-func TestComposeAnsweredWhileAPassRuns(t *testing.T) {
+func composeAnsweredWhileAPassRuns(t *testing.T) {
 	b := newFakeBus()
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()

internal/selfcompose/composedstate_test.go

@@ -69,6 +69,7 @@ func (f *fakeComposed) written() []string {
 // the same build landing again writes nothing. And a module's keys are kept while among the five it wrote last or named
 // by a want, and deleted otherwise.
 func TestTheNodePublishesItsCompositions(t *testing.T) {
+	t.Run("the verb compose is answered while a pass runs", composeAnsweredWhileAPassRuns)
 	b := newFakeBus()
 	fp := meshcatalogclient.SourcePrefix2 + strings.Repeat("a", 64)
 	ofp := meshcatalogclient.SourcePrefix2 + strings.Repeat("c", 64)