issue 1840/S3: keep each node's declared packages on the bus, so the pacman verbs can say what a node declares

internal/recordmirror/mirror.go

@@ -57,10 +57,13 @@ var (
 	// mesh-config publishes as its own (design 57 K3).
 	Predefined = Mirror{Name: broker.MirrorPredefined, Bucket: broker.PredefinedBucket,
 		Event: link.KeyPredefinedChanged}
+	// DeclaredPackages is each node's packages its modules declare, keyed by the node (ADR 0507 §5). It raises no event:
+	// the seat's emits, which the SDK states, do not name one, and a reader reads the bucket when it is asked.
+	DeclaredPackages = Mirror{Name: broker.MirrorDeclaredPackages, Bucket: broker.DeclaredPackagesBucket}
 )
 
 // Mirrors is every mirror this package writes, in the order they are written.
-func Mirrors() []Mirror { return []Mirror{DeclaredConfig, Predefined} }
+func Mirrors() []Mirror { return []Mirror{DeclaredConfig, Predefined, DeclaredPackages} }
 
 // The changes an event says.
 const (
@@ -251,7 +254,7 @@ func (w *Writer) put(ctx context.Context, key string, value []byte, before kept,
 
 // say raises one write's event, tried once more when refused and then counted as lost.
 func (w *Writer) say(ctx context.Context, key, change string, fields []string, revision uint64) {
-	if w.Announce == nil {
+	if w.Announce == nil || w.Mirror.Event == "" {
 		return
 	}
 	e := Event{Mirror: w.Mirror.Name, Key: key, Change: change, Fields: fields, Revision: revision, At: w.now().UTC()}

internal/recordmirror/mirror_integration_test.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/nats-io/nats.go/jetstream"
 	"github.com/novox/mesh-controller/internal/broker"
+	"github.com/novox/mesh-controller/internal/inventory"
 	"github.com/novox/mesh-controller/internal/testbus"
 )
 
@@ -246,3 +247,49 @@ func TestNatsARemovalWithoutTheLeaseRemovesNothing(t *testing.T) {
 		t.Errorf("the key was removed without the lease: %v", err)
 	}
 }
+
+// 1840/AC5 (ADR 0507 §5, ADR 0289 §1): the declared-packages mirror, keyed by the node, writes a node's value once; a second
+// pass over the same declaration writes nothing (the bucket takes no message); a package newly declared changes the one key;
+// a node gone removes its key. It raises no event: the seat's emits name none for it.
+func TestNatsTheDeclaredPackagesMirrorWritesOnlyOnAChange(t *testing.T) {
+	js, api := aMirrorBus(t)
+	events := listen(t, js.Conn(), "mesh.seat."+broker.ControllerSeat+".event.>")
+	w := aWriter(t, js, api, DeclaredPackages)
+	ctx := t.Context()
+	value := func(node string, resources ...map[string]any) []byte {
+		t.Helper()
+		owner := map[string]string{}
+		for _, r := range resources {
+			owner[r["id"].(string)] = "web"
+		}
+		v, err := inventory.DeclaredPackagesValue(node, resources, owner)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return v
+	}
+	curl := map[string]any{"id": "web.curl", "type": "package", "package": "curl"}
+	nano := map[string]any{"id": "web.nano", "type": "package", "package": "nano", "absent": true}
+
+	if r, err := w.Sync(ctx, map[string][]byte{"one": value("one", curl), "two": value("two")}); err != nil ||
+		r != (Result{Written: 2}) {
+		t.Fatalf("the first pass wrote %+v (%v)", r, err)
+	}
+	before := writes(t, api, DeclaredPackages.Bucket)
+	if r, err := w.Sync(ctx, map[string][]byte{"one": value("one", curl), "two": value("two")}); err != nil || r != (Result{}) {
+		t.Errorf("a pass over the same declarations wrote %+v (%v)", r, err)
+	}
+	if got := writes(t, api, DeclaredPackages.Bucket) - before; got != 0 {
+		t.Errorf("a pass over the same declarations put %d messages in the bucket", got)
+	}
+	if r, err := w.Sync(ctx, map[string][]byte{"one": value("one", curl, nano), "two": value("two")}); err != nil ||
+		r != (Result{Written: 1}) {
+		t.Errorf("a package newly declared wrote %+v (%v)", r, err)
+	}
+	if r, err := w.Sync(ctx, map[string][]byte{"one": value("one", curl, nano)}); err != nil || r != (Result{Removed: 1}) {
+		t.Errorf("a node gone wrote %+v (%v)", r, err)
+	}
+	if said := settle(events, 1); len(said) != 0 {
+		t.Errorf("the declared-packages mirror raised %+v", said)
+	}
+}