distribution's program listens on 5100 and the registry container on 5001, so no mapping names the store's port

The composer finds a listen's machine port in a container mapping that names
it on either side (MachineSide). The program's listen 5000 matched the
registry container's inner 5000 in 127.0.0.1:5001:5000, so the store's address
became the container's loopback side and the program's own port was never
opened: the move to 83cd1a3d on 2026-11-08 23:25 UTC cut the artifact store off
(issue 1966 note 109). The program now binds 5100, where every machine fetches
(the artifact-store alias and the seats' reach agree), and the container serves
5001 inside and out. A row holds that no container names 5100.

Undo: revert this commit.

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

modules/distribution/internal/holder/health.go

@@ -17,7 +17,7 @@ func Health(front Catalog, finding func(kind, subject, words string, raised bool
 	for _, seat := range Seats {
 		got, err := front.Versions(ProbeName)
 		if err != nil {
-			words := fmt.Sprintf("the store's read side does not answer %s's versions through distribution's program (port 5000): %v; is the program distribution running?", seat, err)
+			words := fmt.Sprintf("the store's read side does not answer %s's versions through distribution's program (port 5100): %v; is the program distribution running?", seat, err)
 			if finding != nil {
 				finding(FindingReadSide, seat, words, true)
 			}

modules/distribution/internal/holder/holder_test.go

@@ -869,7 +869,7 @@ func TestTheHolderOfTheTwoImageSeats(t *testing.T) {
 			switch r["id"] {
 			case "store":
 				store = i
-				if ports, _ := r["ports"].([]any); len(ports) != 1 || ports[0] != "127.0.0.1:5001:5000" {
+				if ports, _ := r["ports"].([]any); len(ports) != 1 || ports[0] != "127.0.0.1:5001:5001" {
 					t.Errorf("the store's ports = %v, want the loopback only", r["ports"])
 				}
 				// The check of another kind beside the program's tool (ADR 0227 rule 8, ADR 0240 rule 2; the operator,
@@ -887,6 +887,15 @@ func TestTheHolderOfTheTwoImageSeats(t *testing.T) {
 		if store < 0 || program < 0 || store > program {
 			t.Errorf("store at %d, program at %d: want the store listed first", store, program)
 		}
+		// The store's address is the listen registry where the machine put it (ADR 0632 §1), and the program binds it
+		// itself: no container's mapping may name its port on either side, or the composer reads that mapping's loopback
+		// side as the address (the move of 2026-11-08 23:25 UTC cut the store off so; issue 1966 note 109).
+		if len(m.Listens) != 1 || m.Listens[0].Port != 5100 {
+			t.Fatalf("listens = %+v, want registry on 5100, where every machine fetches", m.Listens)
+		}
+		if at, mayAssign := m.MachineSide(5100); at != 5100 || mayAssign {
+			t.Errorf("the machine side of 5100 = %d (may assign %v), want 5100 bound by the program, named by no container", at, mayAssign)
+		}
 		// Running review F2: incoming asks the bus 8 GiB, the most the objects template allows, equal to IncomingCap
 		// (said only where no binding is read); transfers keeps for good, the holder dropping an idle one by its key
 		// in idle, a state of keys with their own time to live.