issue 1840/S1c: name declared-packages among the controller's readable states, so a manifest may read it

go/catalogue/state.go

@@ -134,8 +134,8 @@ func StateProblems(m Manifest) []string {
 // second way and granted to the module's own principal as well. Named here so a read of one is a read of
 // kept state. The bus's list is broker.ControllerMirrors; a test keeps the two agreeing.
 // plans-building is the plans in their build phase, read by the checker to hold checks while a delivery builds (ADR 0483
-// clause 2, issue 1687).
-var ControllerMirrors = []string{"assignments", "declared-config", "predefined", "builds", "rollouts", "checks-running", "plans-building"}
+// clause 2, issue 1687). declared-packages is the packages a node's declaration names (ADR 0507, issue 1840/S1c).
+var ControllerMirrors = []string{"assignments", "declared-config", "predefined", "builds", "rollouts", "checks-running", "plans-building", "declared-packages"}
 
 // StateReadsNothingDeclares is every read across a catalogue whose owner is present and declares no
 // such state. An absent owner says nothing — a module may be installed long before the one whose

go/catalogue/state_test.go

@@ -92,6 +92,15 @@ func TestAReadOfThePlansBuildingIsAReadOfKeptState(t *testing.T) {
 	}
 }
 
+// A module may read `mesh-controller.declared-packages` (issue 1840/S1c, ADR 0507): the packages a node's declaration names.
+func TestAReadOfTheDeclaredPackagesIsAReadOfKeptState(t *testing.T) {
+	controller := Manifest{Module: ControllerSeatName}
+	reader := Manifest{Module: "some-reader", Reads: []string{"mesh-controller.declared-packages"}}
+	if p := StateReadsNothingDeclares([]Manifest{controller, reader}); len(p) != 0 {
+		t.Fatalf("a read of the controller's declared-packages was refused: %v", p)
+	}
+}
+
 // **Across the whole catalogue**: every state name is local, and every read whose owner is present
 // names state that owner keeps.
 func TestEveryManifestsStateIsLocalAndEveryReadIsKept(t *testing.T) {