Keep the builder's history as its own log that readers declare and follow, the memberships as the grants part's state, and refuse a module's own stream, so every module's data is in the bus's predefined forms and readable by its tools (issue 1955, ADR 0571 clauses 1, 4, 5, 7)

go/process/state_integration_test.go

@@ -274,6 +274,44 @@ func TestStateWatchOnAGrantedBucket(t *testing.T) {
 		t.Fatalf("narrowed watch got %+v for a key it did not name", c)
 	case <-time.After(500 * time.Millisecond):
 	}
+
+	// ADR 0571 clause 1: another module's log, read on the process's own credential with exactly the read grants: the
+	// newest per key, every entry from a time, and a watch from the newest that then hears an appended entry.
+	if _, err := adminJetStream.CreateStream(ctx, jetstream.StreamConfig{Name: "LOG_mesh-delivery-builder_build-log",
+		Subjects: []string{"mesh.log.mesh-delivery-builder.build-log.>"}, AllowDirect: true}); err != nil {
+		t.Fatal(err)
+	}
+	for _, k := range []string{"letta", "gitea", "letta"} {
+		if _, err := adminJetStream.Publish(ctx, "mesh.log.mesh-delivery-builder.build-log."+k, []byte(`{"module":"`+k+`"}`)); err != nil {
+			t.Fatal(err)
+		}
+		time.Sleep(5 * time.Millisecond)
+	}
+	builds := conn.ReadLog("mesh-delivery-builder", "build-log")
+	newest, err := builds.Newest("")
+	if err != nil || len(newest) != 2 || newest[0].Key != "gitea" || newest[1].Sequence != 3 {
+		t.Fatalf("the newest per key are %+v: %v", newest, err)
+	}
+	since, err := builds.Since(newest[0].At, "letta")
+	if err != nil || len(since) != 1 || since[0].Sequence != 3 {
+		t.Fatalf("letta since gitea's build is %+v: %v", since, err)
+	}
+	heard := make(chan stdio.LogEntry, 4)
+	if err := builds.Watch("letta", stdio.LogFromNewest, func(e stdio.LogEntry) error { heard <- e; return nil }); err != nil || len(heard) != 1 {
+		t.Fatalf("a watch from the newest handed %d at its start: %v", len(heard), err)
+	}
+	<-heard
+	if _, err := adminJetStream.Publish(ctx, "mesh.log.mesh-delivery-builder.build-log.letta", []byte(`{}`)); err != nil {
+		t.Fatal(err)
+	}
+	select {
+	case e := <-heard:
+		if e.Sequence != 4 || e.Key != "letta" {
+			t.Fatalf("the watch heard %+v", e)
+		}
+	case <-time.After(10 * time.Second):
+		t.Fatal("the watch did not hear the appended entry")
+	}
 }
 
 // 1840/AC8: given an account not granted a bucket, when it watches it, then the refusal names the bucket.