Name plans-building among the controller's readable states and pin the SDK that does (issue 1687, ADR 0483 clause 2)

internal/broker/controller_buckets.go

@@ -153,7 +153,7 @@ func ChainBuckets() []string { return []string{BuildsBucket, RolloutsBucket, Ass
 // ControllerMirrors are the local names of the controller's buckets a module may read: the record mirrors and the
 // chain's buckets.
 func ControllerMirrors() []string {
-	return []string{MirrorAssignments, MirrorDeclaredConfig, MirrorPredefined, ChainBuilds, ChainRollouts, ChecksRunning}
+	return []string{MirrorAssignments, MirrorDeclaredConfig, MirrorPredefined, ChainBuilds, ChainRollouts, ChecksRunning, PlansBuilding}
 }
 
 // MirrorsWrittenByAnother are the controller's mirrors whose writer is not the controller, each with its reason: the rule

internal/broker/plans_building_mirror_test.go

@@ -0,0 +1,30 @@
+package broker
+
+import (
+	"slices"
+	"testing"
+)
+
+// Issue 1687 (ADR 0483 clause 2): a module whose manifest reads mesh-controller.plans-building may name it in `reads`, and
+// reads the bucket and writes none; the controller writes it, so it is no mirror written by another.
+func TestAModuleReadingPlansBuildingReadsAndWritesNone(t *testing.T) {
+	if !slices.Contains(ControllerMirrors(), "plans-building") || BucketName(ControllerSeat, PlansBuilding) != PlansBuildingBucket {
+		t.Fatalf("a module cannot name %s in `reads`: %v", PlansBuildingBucket, ControllerMirrors())
+	}
+	if _, other := MirrorsWrittenByAnother[PlansBuilding]; other {
+		t.Error("the controller writes the plans building itself")
+	}
+	perms, err := PermissionsFor(Principal{Kind: KindModule, Node: "one", Module: "mesh-delivery-checker", PasswordHash: "x",
+		Reads: []string{"mesh-controller.plans-building"}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	stream := "KV_" + PlansBuildingBucket
+	has(t, perms.Publish, "$JS.API.STREAM.INFO."+stream)
+	has(t, perms.Publish, "$JS.API.DIRECT.GET."+stream+".>")
+	for _, p := range perms.Publish {
+		if SubjectsOverlap(p, "$KV."+PlansBuildingBucket+".plan-1") {
+			t.Errorf("the reading module may write %s through %q", PlansBuildingBucket, p)
+		}
+	}
+}

internal/broker/writers.go

@@ -177,7 +177,7 @@ var WritersTable = []WriterRow{
 		KeptIn: "key-value " + CheckRunningBucket + ", aged out when not renewed", Others: "the build seat's holders read it to drop a duplicate request",
 		Subjects: kvOf(CheckRunningBucket), Writes: holdsTheBuildSeat,
 		Shared: "every machine holding the build seat puts the key of the check it runs and deletes it when the check ends"},
-	{State: "a delivery plan in its build phase", Writer: "controller (lease holder), at the first build's ask and at each refresh",
+	{State: "the plans-building mirror", Writer: "controller (lease holder), at the first build's ask and at each refresh",
 		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},

internal/broker/writers_test.go

@@ -30,7 +30,7 @@ var designRows = []string{
 	"a pull request's check asked",
 	"a pull request's check running",
 	// The plans in their build phase, a bucket the build seat's holders read (ADR 0483 clause 2, issue 1687).
-	"a delivery plan in its build phase",
+	"the plans-building mirror",
 	"a merge announced",
 	"a pull request's head announced",
 	"a pull request's merge check",