Announce the controller's states, keep every module's word, and grant a read only where its owner announced the state readable; the copied list of the controller's mirrors goes (issue 1790, D1-D4, ADR 0495, ADR 0513 §3)

internal/broker/writers.go

@@ -87,6 +87,22 @@ func ownModule(p Principal, pattern string) bool {
 	return false
 }
 
+// ownAnnouncer is a module, a process of it or the node tools carrying it saying what that module keeps, or the
+// controller saying what it keeps itself (novox/hq ADR 0495 clause 2): each under its own name alone.
+func ownAnnouncer(p Principal, pattern string) bool {
+	tokens := strings.Split(pattern, ".")
+	if len(tokens) < 3 {
+		return false
+	}
+	switch p.Kind {
+	case KindController:
+		return tokens[2] == ControllerSeat
+	case KindProcess:
+		return p.Module == tokens[2]
+	}
+	return ownModule(p, pattern)
+}
+
 // ownProvisioner is a machine's provisioner client saying a report about its own machine: the third token of
 // `prov.applied.<node>.…` is its machine (novox/hq ADR 0349 §4, design 57 P3).
 func ownProvisioner(p Principal, pattern string) bool {
@@ -181,6 +197,14 @@ var WritersTable = []WriterRow{
 		KeptIn:   "key-value " + PlansBuildingBucket + ", aged out when not refreshed",
 		Others:   "the build seat's holders read it and take no new check while a key is there (ADR 0483)",
 		Subjects: kvOf(PlansBuildingBucket), Writes: isController},
+	// What a module keeps and who may read it (novox/hq ADR 0495 clauses 2 and 3, issue 1790): said by the module, kept by
+	// the controller.
+	{State: "a module's states announced", Writer: "the module itself, from its code, under its own name",
+		KeptIn: "the bus (EVENTS)", Others: "the controller keeps the last of each and grants readers from it",
+		Subjects: []string{"mesh.mod.*.event.states"}, Writes: ownAnnouncer},
+	{State: "the states announced", Writer: "controller, from each module's announcement",
+		KeptIn: "key-value " + StatesAnnouncedBucket, Others: "the composition of the bus's users reads it",
+		Subjects: kvOf(StatesAnnouncedBucket), Writes: isController},
 	{State: "a merge announced", Writer: "one announcer per forge (the hook, or the poll when the hook is absent — never both)",
 		KeptIn: "the bus", Others: "—", Subjects: []string{"mesh.mod.*.event.pull.merged"}, Writes: ownModule},
 	// A pull request's head, before it merges (novox/hq to-be 45 §9): the same one announcer.