From fbd00c89436c53a36fd67cb8bb7dbaddf0ee7579 Mon Sep 17 00:00:00 2001
From: jochen <jschoubben@gmail.com>
Date: Thu, 29 Oct 2026 22:10:44 +0100
Subject: [PATCH] Refuse a manifest that lists its claimed seat's event among
 its own emits, so a holder never says a seat event where no consumer hears it
 (issue 1952, second of a kind)

---
 go/catalogue/delivery_seat.go | 25 +++++++++++++++++++++++++
 go/catalogue/manifest.go      |  1 +
 go/catalogue/seats_test.go    | 12 ++++++++++++
 3 files changed, 38 insertions(+)

diff --git a/go/catalogue/delivery_seat.go b/go/catalogue/delivery_seat.go
index f1d2d24..5cab2ce 100644
--- a/go/catalogue/delivery_seat.go
+++ b/go/catalogue/delivery_seat.go
@@ -1,5 +1,7 @@
 package catalogue
 
+import "fmt"
+
 // The delivery's owner (novox/hq ADR 0239, to-be 47): one holder for the mesh, the module mesh-delivery,
 // which owns a delivery — one commit in one repository, from its pull request's head to every machine —
 // and a delivery group, and asks the controller for every act. A seat of the mesh's own, so the role has
@@ -105,6 +107,29 @@ func SeatSays(emits []string, event string) bool {
 	return false
 }
 
+// seatEventProblems refuses a module that lists among its own `emits` an event a seat it claims says (the lead,
+// 2026-10-29, issue 1952, the second of a kind: the self-check's `checked` and mesh-hand-acts' `act-recorded`). A
+// consumer of `<seat>.<event>` hears the seat's subject (SeatSays), so the holder says it there, with stdio.SeatPublish
+// on `mesh.seat.<seat>.event.<event>`; said through stdio.Emit as the module's own, it lands where nobody listens. Caught
+// here, when the manifest is read at the build, not when nothing is heard on the machines.
+func seatEventProblems(m Manifest) []string {
+	var problems []string
+	for _, c := range m.Claims {
+		seat, known := SeatNamed(c.Name)
+		if !known || len(seat.Emits) == 0 {
+			continue
+		}
+		for _, e := range m.Emits {
+			if SeatSays(seat.Emits, e) {
+				problems = append(problems, fmt.Sprintf("%s lists %q among its own emits, and the seat %s it claims says it: "+
+					"say it on the seat with stdio.SeatPublish(\"mesh.seat.%s.event.%s\", ...) and leave it out of emits, or "+
+					"no consumer of %s.%s hears it", m.Module, e, seat.Name, seat.Name, e, seat.Name, e))
+			}
+		}
+	}
+	return problems
+}
+
 // topicMatches is whether an event's name matches a declared pattern, `*` one dot-separated segment and
 // `>` or `**` the rest.
 func topicMatches(pattern, event string) bool {
diff --git a/go/catalogue/manifest.go b/go/catalogue/manifest.go
index ca3eba9..1423d11 100644
--- a/go/catalogue/manifest.go
+++ b/go/catalogue/manifest.go
@@ -2093,6 +2093,7 @@ func parseManifest(raw []byte, predefined PredefinedList) (Manifest, error) {
 	problems = append(problems, declaredSeatProblems(m)...)
 	problems = append(problems, RunsAsProblems(m)...)
 	problems = append(problems, ProcessBusProblems(m)...)
+	problems = append(problems, seatEventProblems(m)...)
 	problems = append(problems, ReadsHolderProblems(m)...)
 	problems = append(problems, FilesHolderProblems(m)...)
 	if m.Computed != "" && len(m.Resources) > 0 {
diff --git a/go/catalogue/seats_test.go b/go/catalogue/seats_test.go
index 168056e..0226c15 100644
--- a/go/catalogue/seats_test.go
+++ b/go/catalogue/seats_test.go
@@ -184,6 +184,18 @@ func TestAClaimOnASeatAnotherModuleDeclaresIsAccepted(t *testing.T) {
 	if problems := CatalogueProblems(Shelf{claimant.Module: claimant, "someone": declarer}); len(problems) != 0 {
 		t.Fatalf("a claim on a declared seat was refused: %v", problems)
 	}
+	// The second of a kind (issue 1952; the lead, 2026-10-29): a holder that lists its seat's event among its own emits
+	// would say it where no consumer hears it, so the manifest is refused, naming the seat's subject; the seat's
+	// holder saying nothing of its own is accepted.
+	holder := func(emits string) []byte {
+		return []byte(`{"module":"mesh-self-check","version":"1","emits":` + emits + `,"claims":[{"name":"mesh-self-check","scope":"mesh","serves":["doctor","probes"]}]}`)
+	}
+	if _, err := ParseManifest(holder(`["checked"]`)); err == nil || !strings.Contains(err.Error(), "mesh.seat.mesh-self-check.event.checked") {
+		t.Errorf("a seat's event listed as the module's own: %v", err)
+	}
+	if _, err := ParseManifest(holder(`[]`)); err != nil {
+		t.Errorf("a holder saying its seat's event on the seat was refused: %v", err)
+	}
 }
 
 // A module may define its own seat and claim it — the mesh enforces exclusivity without knowing