Move restic's last good night per item into the sdk's health layouts, so restic's night process writes it and the self-check reads one layout (issue 1955, ADR 0571 clause 3)

go/buscompose/buscompose_test.go

@@ -614,7 +614,7 @@ func healthChecks(t *testing.T) {
 	users, err := Users(Records{Nodes: []string{"a"}, Assigned: map[string][]Declared{"a": {
 		{Module: "mesh-conditions", State: []Bucket{bucket("mesh-conditions", "conditions"), bucket("mesh-conditions", "takeover")},
 			Reads: []string{"mesh-self-check.findings", "mesh-healers.attempts", ControllerConditions}},
-		{Module: "mesh-self-check", State: []Bucket{bucket("mesh-self-check", "findings")}},
+		{Module: "mesh-self-check", State: []Bucket{bucket("mesh-self-check", "findings")}, Reads: []string{"restic.good"}},
 		{Module: "mesh-healers", State: []Bucket{bucket("mesh-healers", "findings"), bucket("mesh-healers", "attempts"), bucket("mesh-healers", "would")}},
 		{Module: WatchmanModule, State: []Bucket{bucket(WatchmanModule, "findings")}, Reads: []string{delivery.NodeHealthRead}},
 		{Module: "mesh-hand-acts", State: []Bucket{bucket("mesh-hand-acts", "warrants")}, Logs: []Log{{Module: "mesh-hand-acts", Name: "acts"}}},
@@ -630,7 +630,7 @@ func healthChecks(t *testing.T) {
 		{Module: delivery.AssignerModule, State: []Bucket{bucket(delivery.AssignerModule, delivery.SeatHoldersState)}},
 		// ADR 0571 clause 3: disk-load keeps the readings; the backup holder reads them.
 		{Module: "disk-load", State: []Bucket{bucket("disk-load", "readings")}},
-		{Module: "restic", Reads: []string{"disk-load.readings"}},
+		{Module: "restic", Reads: []string{"disk-load.readings"}, Processes: []ProcessPrincipal{{Process: "night", State: []string{"good"}}}},
 		// ADR 0571 clauses 1, 9: the indexer reads the builder's log through its own consumer; the catalogue module asks
 		// the builder's tool.
 		{Module: delivery.BuilderModule, Logs: []Log{{Module: delivery.BuilderModule, Name: delivery.BuilderLog, MaxAgeDays: 30}}},
@@ -652,6 +652,9 @@ func healthChecks(t *testing.T) {
 			"$JS.API.DIRECT.GET.KV_mesh-provisioner_plans.$KV.mesh-provisioner_plans.a.keycloak"},
 		"a.mesh-hand-acts": {"$KV.mesh-hand-acts_warrants.mesh-config.ask-1", "mesh.log.mesh-hand-acts.acts.act-1"},
 		"a.disk-load":      {"$KV.disk-load_readings.a.pg.data"},
+		// ADR 0571 clause 3: restic's night writes each item's last good night; the self-check reads it.
+		"a.restic.night":    {"$KV.restic_good.a.pg.data"},
+		"a.mesh-self-check": {"$JS.API.DIRECT.GET.KV_restic_good.$KV.restic_good.a.pg.data"},
 		"a.restic": {"$JS.API.DIRECT.GET.KV_disk-load_readings.$KV.disk-load_readings.a.pg.data",
 			// ADR 0571 clause 7: its own membership from the grants part's state.
 			"$JS.API.DIRECT.GET.KV_mesh-grants_memberships.$KV.mesh-grants_memberships.a.restic"},
@@ -670,12 +673,16 @@ func healthChecks(t *testing.T) {
 	mayNot := map[string][]string{
 		// The keeper writes no findings and no attempts; no observer writes the keeper's buckets (clause 2).
 		"a.mesh-conditions": {"$KV.mesh-self-check_findings.x", "$KV.mesh-healers_attempts.x", "$KV.mesh-controller_conditions.x"},
-		"a.mesh-self-check": {"$KV.mesh-conditions_conditions.x", "$KV.mesh-conditions_takeover.switch"},
+		"a.mesh-self-check": {"$KV.mesh-conditions_conditions.x", "$KV.mesh-conditions_takeover.switch", "$KV.restic_good.a.pg.data"},
 		// Only mesh-provisioner writes provisions and plans, and it writes none of the grants part's states (ADR 0570
 		// clauses 1, 8).
 		"a.mesh-provisioner": {"$KV.mesh-grants_accounts.a.m", "$KV.mesh-grants_user-list.sealed"},
 		"a.mesh-vault": {"$KV.mesh-provisioner_provisions.a.keycloak.postgres-database", "$KV.mesh-provisioner_plans.a.keycloak",
 			"mesh.seat.artifact-store.event.artifacts-gone"},
+		// Each writes its own state alone, and these users are composed.
+		"a.restic.night":          {"$KV.disk-load_readings.a.pg.data"},
+		"a.disk-load":             {"$KV.restic_good.a.pg.data"},
+		"a.mesh-delivery-builder": {"$KV.disk-load_readings.a.pg.data"},
 		// Only the assigner writes seat-holders.
 		"a.artifact-store-tools": {"$KV.mesh-delivery-assigner_seat-holders.mesh-broker"},
 		// Only disk-load writes its readings.