Grant the builder the build seats' streams' information and messages by name, so its take-over at start can tell an ask its key names is on its stream (issue 1910)

internal/broker/buildbacklog.go

@@ -9,8 +9,23 @@ import "git.novox.be/novox/mesh-sdk/go/delivery"
 const (
 	// ViewModule is the module of the delivery view (mesh-delivery-view).
 	ViewModule = "mesh-delivery-view"
+	// BuilderModule is the module of the builder (mesh-delivery-builder).
+	BuilderModule = "mesh-delivery-builder"
 )
 
+// BuildAskReads are the API subjects the builder requests when it takes over, at its start, a key naming an ask (issue
+// 1910): each build seat's stream's information and its messages by sequence, to tell whether the ask is on its stream.
+// Reads only: no consumer, no pull, no acknowledgement; the builder puts its asks by its seat use, as before.
+func BuildAskReads() []string {
+	var out []string
+	for _, lang := range delivery.AskLanguages {
+		if stream, err := delivery.AskStream(lang); err == nil {
+			out = append(out, "$JS.API.STREAM.INFO."+stream, "$JS.API.STREAM.MSG.GET."+stream)
+		}
+	}
+	return out
+}
+
 // BuildBacklogReads are the API subjects the view requests: the information of each build seat's stream and of each of its
 // shared workers (delivery.AskStream, delivery.AskWorker), and the message of the stream by sequence. Reads only: no
 // message is pulled, none acknowledged, none published.

internal/broker/buildbacklog_test.go

@@ -67,3 +67,22 @@ func TestTheViewReadsTheBuildSeatsWorkersByNameAndPublishesNoAsk(t *testing.T) {
 		t.Errorf("another module reads the build seats: %v", other)
 	}
 }
+
+// 1910: the builder may read each build seat's stream's information and its messages by sequence, by name, and may not
+// pull, acknowledge or make a consumer there, nor list every stream.
+func TestTheBuilderReadsTheBuildSeatsStreamsByName(t *testing.T) {
+	pub, _ := composedFor(t, BuilderModule)
+	for _, s := range []string{"$JS.API.STREAM.INFO.SEAT_NODE_BUILD_GO", "$JS.API.STREAM.MSG.GET.SEAT_NODE_BUILD_GO",
+		"$JS.API.STREAM.INFO.SEAT_NODE_BUILD_NODE", "$JS.API.STREAM.MSG.GET.SEAT_NODE_BUILD_IMAGE"} {
+		if !hasSubject(pub, s) {
+			t.Errorf("the builder cannot request %s", s)
+		}
+	}
+	perms, _ := PermissionsFor(Principal{Kind: KindModule, Node: "one", Module: BuilderModule})
+	for _, s := range []string{"$JS.API.STREAM.NAMES", "$JS.API.STREAM.INFO.SEAT_OPERATOR_CHANNEL",
+		"$JS.API.CONSUMER.MSG.NEXT.SEAT_NODE_BUILD_GO.SEAT_NODE_BUILD_GO_CHECK_worker", "$JS.API.CONSUMER.CREATE.SEAT_NODE_BUILD_GO"} {
+		if MayPublish(perms, s) {
+			t.Errorf("the builder may publish %s", s)
+		}
+	}
+}

internal/broker/nats.go

@@ -860,6 +860,11 @@ func PermissionsFor(p Principal) (Permissions, error) {
 		if p.Module == ViewModule {
 			pub = append(pub, BuildBacklogReads()...)
 		}
+		// The builder alone reads the build seats' streams by sequence, to put again at its start an ask a key names that no
+		// stream holds (issue 1910).
+		if p.Module == BuilderModule {
+			pub = append(pub, BuildAskReads()...)
+		}
 		// 1. Its own namespace: it publishes its events there and serves its tools there. Nothing
 		//    else may publish into it, so an event's source is a fact the server enforces rather
 		//    than a claim in the body (design 29 §2).