A3: the view tools' usage reader is built by one function main and its test use

Builds: design 47 G A-128

modules/mesh-delivery-view/cmd/mesh-delivery-view-tools/main.go

@@ -461,6 +461,17 @@ func seatStateRead(holder func(seat string) (string, bool), read func(name strin
 		Get: func(key string) (json.RawMessage, error) { return at().Get(key) }}
 }
 
+// usageReaderOf is the usage tools' reader: the haves, the config's resolved values and the checker's tries read as they are, a
+// build seat's steps and pauses in the state of the seat's holder (ofHolder), and the backlog the view program's socket answers;
+// main and its test wire it the one way.
+func usageReaderOf(haves view.StateRead, seats *buildrun.BuildSeats, holder func(seat string) (string, bool), state func(name string) view.StateRead, backlog func() ([]view.BacklogRow, error)) view.UsageReader {
+	return view.UsageReader{Haves: haves, Resolved: state("mesh-config.resolved"), Tries: state("mesh-delivery-checker.tries"),
+		Seats:    seats,
+		StepsOf:  ofHolder(holder, state, view.StepsState),
+		PausesOf: ofHolder(holder, state, buildstep.PausesState),
+		Backlog:  backlog}
+}
+
 func main() {
 	logf := func(f string, a ...any) { fmt.Fprintf(os.Stderr, "[mesh-delivery-view-tools] "+f+"\n", a...) }
 	// The catalog half per watched branch, followed by the bundle itself through meshcatalogclient's branch follower on
@@ -500,11 +511,7 @@ func main() {
 		}
 		return nil
 	}, holderOf(stdio.Ask))
-	u := view.UsageReader{Haves: r.HavesState, Resolved: read(stdio.State("mesh-config.resolved")), Tries: read(stdio.State("mesh-delivery-checker.tries")),
-		Seats:    seats,
-		StepsOf:  ofHolder(holderOf(stdio.Ask), func(name string) view.StateRead { return read(stdio.State(name)) }, view.StepsState),
-		PausesOf: ofHolder(holderOf(stdio.Ask), func(name string) view.StateRead { return read(stdio.State(name)) }, buildstep.PausesState),
-		Backlog:  backlogOf(socket())}
+	u := usageReaderOf(r.HavesState, seats, holderOf(stdio.Ask), func(name string) view.StateRead { return read(stdio.State(name)) }, backlogOf(socket()))
 	// view_first_views and view_first_view_again: where the view's process stands with its first views of the indexer's and
 	// the assigner's states (ADR 0615 §6), and a re-read by hand.
 	tools := append(Tools(r, u), gate.Tools()...)

modules/mesh-delivery-view/cmd/mesh-delivery-view-tools/main_test.go

@@ -18,6 +18,7 @@ import (
 	"git.novox.be/novox/mesh-contracts/go/seats/nodeengine"
 	"git.novox.be/novox/mesh-contracts/health-and-repair/go/clients/meshwatchdogsclient"
 	"git.novox.be/novox/mesh-contracts/identity-and-access/go/clients/meshvaultclient"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-builder/buildrun"
 	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-builder/builds"
 	stdio "git.novox.be/novox/mesh-sdk/go"
 	"git.novox.be/novox/mesh-sdk/go/busretry"
@@ -675,6 +676,19 @@ func TestBuildSeatStatesAreReadInTheHoldersState(t *testing.T) {
 	if _, err := signers.Get(view.SignersKeyKey); err != nil || !slices.Equal(named, []string{"acme-mesh-vault.signers"}) {
 		t.Errorf("the signers read %v, %v; want acme-mesh-vault.signers", named, err)
 	}
+	// The usage reader main wires reads the same way: the steps and pauses at the holder, the checker's tries and the config's
+	// resolved values by their names, the haves and the backlog as given.
+	named = nil
+	seats := &buildrun.BuildSeats{}
+	u := usageReaderOf(view.StateRead{}, seats, holder, read, func() ([]view.BacklogRow, error) { return []view.BacklogRow{{}}, nil })
+	u.StepsOf("node-build-go")
+	u.PausesOf("node-build-go")
+	if want := []string{"mesh-config.resolved", "mesh-delivery-checker.tries", "acme-node-build-go.steps", "acme-node-build-go.pauses"}; !slices.Equal(named, want) || u.Seats != seats {
+		t.Errorf("the usage reader reads %v, seats %p; want %v, %p", named, u.Seats, want, seats)
+	}
+	if rows, err := u.Backlog(); err != nil || len(rows) != 1 {
+		t.Errorf("the usage reader's backlog = %v, %v", rows, err)
+	}
 	// So are the provisioner's provisions (A-318).
 	named = nil
 	provisions := seatStateRead(holder, read, view.ProvisionsSeat, view.ProvisionsState)