G A-10: Conn.EmitSeat says a seat's event as its holder on mesh.seat.<seat>.event.<event>

Builds: design 47 G A-10, §276, §498
Claude-Session: https://claude.ai/code/session_01JG73KEq4zoDfM9WtYpcQgZ

go/process/emit.go

@@ -19,6 +19,18 @@ import (
 // (EmitOptions.MessageID) is sent as x-event-id, and as the bus's own dedup id (Nats-Msg-Id), so a second
 // publish inside the stream's duplicate window is dropped; empty is a random one, as stdio.Emit on main.
 func (c *Conn) Emit(eventType string, body any, opts ...stdio.EmitOptions) error {
+	return c.emitOn("mesh.mod."+c.account.Module+".event."+eventType, body, opts)
+}
+
+// EmitSeat says a seat's event as its holder (design 47 G A-10, §276, §498): one call, publishing on
+// mesh.seat.<seat>.event.<event>, with the same envelope, headers and message id as Emit. The grants part grants every
+// holder the publish of its held seats' event subjects.
+func (c *Conn) EmitSeat(seat, event string, body any, opts ...stdio.EmitOptions) error {
+	return c.emitOn("mesh.seat."+seat+".event."+event, body, opts)
+}
+
+// emitOn publishes body on subject with the SDK's envelope.
+func (c *Conn) emitOn(subject string, body any, opts []stdio.EmitOptions) error {
 	data, err := json.Marshal(body)
 	if err != nil {
 		return err
@@ -32,7 +44,7 @@ func (c *Conn) Emit(eventType string, body any, opts ...stdio.EmitOptions) error
 	if id == "" {
 		id = eventID()
 	}
-	msg := nats.NewMsg("mesh.mod." + c.account.Module + ".event." + eventType)
+	msg := nats.NewMsg(subject)
 	msg.Header.Set("x-event-id", id)
 	msg.Header.Set("x-source", c.account.Module)
 	msg.Header.Set("x-node", c.account.Node)

go/process/emit_integration_test.go

@@ -19,7 +19,7 @@ func TestEmitTwiceWithTheSameIDIsKeptToOneWithTheSDKsHeaders(t *testing.T) {
 	account.Node = "novox"
 	_, adminJetStream := adminJS(t, url)
 	stream, err := adminJetStream.CreateStream(ctxFor(t), jetstream.StreamConfig{
-		Name: "MAIL_EVENTS", Subjects: []string{"mesh.mod.mesh-mail.event.>"}, Duplicates: time.Minute,
+		Name: "MAIL_EVENTS", Subjects: []string{"mesh.mod.mesh-mail.event.>", "mesh.seat.mail-sender.event.>"}, Duplicates: time.Minute,
 	})
 	if err != nil {
 		t.Fatalf("the admin could not make the events stream: %v", err)
@@ -37,12 +37,20 @@ func TestEmitTwiceWithTheSameIDIsKeptToOneWithTheSDKsHeaders(t *testing.T) {
 		}
 	}
 
+	// A seat's event goes on mesh.seat.<seat>.event.<event> with the same headers (design 47 G A-10).
+	if err := conn.EmitSeat("mail-sender", "sent", map[string]any{"send": "s1"}, stdio.EmitOptions{MessageID: "seat-s1"}); err != nil {
+		t.Fatalf("EmitSeat: %v", err)
+	}
+	if m, err := stream.GetLastMsgForSubject(ctxFor(t), "mesh.seat.mail-sender.event.sent"); err != nil || m.Header.Get("x-event-id") != "seat-s1" || m.Header.Get("x-source") != "mesh-mail" {
+		t.Fatalf("the seat's event: %v, %v", m, err)
+	}
+
 	info, err := stream.Info(ctxFor(t))
 	if err != nil {
 		t.Fatal(err)
 	}
-	if info.State.Msgs != 1 {
-		t.Fatalf("the stream holds %d messages, want exactly 1 (the second publish is a duplicate)", info.State.Msgs)
+	if info.State.Msgs != 2 {
+		t.Fatalf("the stream holds %d messages, want 2: one of the doubled publish, one of the seat's event", info.State.Msgs)
 	}
 
 	msg, err := stream.GetMsg(ctxFor(t), 1)

go/process/fixture_integration_test.go

@@ -39,6 +39,7 @@ var sendGrants = []string{
 	"mesh.mod.mesh-mail.event.mail.send.failed",
 	"mesh.mod.mesh-mail.event.mail.send.sent",
 	"mesh.mod.mesh-mail.event.states",
+	"mesh.seat.mail-sender.event.sent", // a held seat's event, said through Conn.EmitSeat (design 47 G A-10)
 	"mesh.seat.operator-channel.call.tell.*.novox~mesh-mail~send",
 	"mesh.seat.operator-channel.call.tell.novox~mesh-mail~send",
 	"mesh.seat.operator-channel.tool.tell",