diff --git a/cmd/mesh-controller/compose_equal_integration_test.go b/cmd/mesh-controller/compose_equal_integration_test.go
index 57b62ecd..cd965f0a 100644
--- a/cmd/mesh-controller/compose_equal_integration_test.go
+++ b/cmd/mesh-controller/compose_equal_integration_test.go
@@ -4,11 +4,14 @@ package main
 
 import (
 	"context"
+	"flag"
 	"fmt"
 	"os"
 	"sort"
 	"strings"
+	"sync"
 	"testing"
+	"time"
 
 	"git.novox.be/novox/mesh-sdk/go/compose"
 	snapshot "git.novox.be/novox/mesh-sdk/go/facts"
@@ -20,6 +23,8 @@ import (
 // scrubbed as the snapshot is), else the snapshot of a small mesh of its own; raises it into throwaway stores as the merge
 // gate does; and composes every machine both ways.
 //
+// It runs only when named (a try with this test's name as the tests pattern); a whole-suite run skips it.
+//
 //	(a) Foreseeing on the fresh store: the same error or none, the same validator problems, LeftOut and its reasons, Withheld,
 //	    Unbound, Unplaced, HandedOnly and the own secrets named foreseen; and the ports mesh-sdk names foreseen are the ones the
 //	    controller allocates when it sends.
@@ -31,11 +36,19 @@ import (
 // field that differs; a machine both paths refuse alike is said, not failed. The test is deleted with the controller's
 // composition (issue 1389).
 func TestEveryMachineComposesAlikeBothWays(t *testing.T) {
+	// It is slow (it composes every machine of the live mesh several times each way) and is deleted with the controller's
+	// composition (issue 1389), so it runs only when asked for by name: a try or a `go test -run` that names it. A merge check
+	// runs every test and does not.
+	if run := flag.Lookup("test.run"); run == nil || !strings.Contains(run.Value.String(), "TestEveryMachineComposesAlikeBothWays") {
+		t.Skip("runs only when named: a try with the tests pattern TestEveryMachineComposesAlikeBothWays")
+	}
 	ctx := t.Context()
 	admin := os.Getenv("MESH_TEST_POSTGRES")
 	if admin == "" {
 		t.Skip("no throwaway PostgreSQL (MESH_TEST_POSTGRES) to raise the mesh in")
 	}
+	started := time.Now()
+	phase := func(what string) { t.Logf("[%s] %s", time.Since(started).Round(time.Second), what) }
 	f, source := equalityFacts(t)
 	t.Logf("the facts of %s (%s): %d machine(s)", f.Taken.Format("2006-01-02 15:04:05"), source, len(f.Machines))
 	shelf, err := shelfOfFacts(f)
@@ -43,108 +56,149 @@ func TestEveryMachineComposesAlikeBothWays(t *testing.T) {
 		t.Fatal(err)
 	}
 	sources := sourcesOfFacts(f)
-	var failures []string
 
-	// (a) on the fresh store. mesh-sdk's composition first: it writes nothing, where the controller's makes every pair
-	// credential on the way.
-	fresh, dropFresh, err := throwawayStores(ctx, admin)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if _, err := raiseFromFacts(ctx, fresh, f, shelf, sources); err != nil {
-		dropFresh()
-		t.Fatal(err)
-	}
-	sdkForeseen := map[string]composedBoth{}
-	foreseenPorts := map[string][]string{}
-	for _, m := range f.Machines {
-		in, err := readComposeInput(ctx, fresh)
+	// Three stores, raised from the same snapshot, are three independent pieces of work and run together: (a) both ways on a
+	// fresh store, (b) and (c) the controller's sends and readings, (b) mesh-sdk's sends.
+	var (
+		wg                       sync.WaitGroup
+		oldForeseen, sdkForeseen = map[string]composedBoth{}, map[string]composedBoth{}
+		foreseenPorts            = map[string][]string{}
+		readOld, readSDK         = map[string]composedBoth{}, map[string]composedBoth{}
+		oldMade, sdkMade         made
+		oldRefused               = map[string]bool{}
+		sendRefused              = map[string]string{}
+		errA, errOld, errSDK     error
+	)
+	wg.Add(3)
+	go func() { // (a) Foreseeing on the fresh store.
+		defer wg.Done()
+		fresh, drop, err := throwawayStores(ctx, admin)
 		if err != nil {
-			dropFresh()
-			t.Fatalf("%s: the adapter cannot read the mesh: %v", m.Name, err)
+			errA = err
+			return
 		}
-		d, problems, cerr := compose.ComposeIn(in.Input, m.Name, compose.Foreseeing)
-		if cerr == nil {
-			foreseenPorts[m.Name] = append([]string(nil), d.ForeseenPorts...)
-			sort.Strings(foreseenPorts[m.Name])
+		defer drop()
+		if _, err := raiseFromFacts(ctx, fresh, f, shelf, sources); err != nil {
+			errA = err
+			return
+		}
+		// mesh-sdk's composition first: it writes nothing, where the controller's makes every pair credential on the way. The
+		// Input is read once for all of its machines.
+		cached := withInputCache(ctx)
+		for _, m := range f.Machines {
+			in, err := inputFor(cached, fresh)
+			if err != nil {
+				errA = fmt.Errorf("%s: the adapter cannot read the mesh: %w", m.Name, err)
+				return
+			}
+			d, problems, cerr := compose.ComposeIn(in.Input, m.Name, compose.Foreseeing)
+			if cerr == nil {
+				foreseenPorts[m.Name] = append([]string(nil), d.ForeseenPorts...)
+				sort.Strings(foreseenPorts[m.Name])
+			}
+			sdkForeseen[m.Name] = capturedFrom(sendableOf(d), problems, cerr)
+		}
+		phase("(a) mesh-sdk's Foreseeing of every machine")
+		gens, gensErr := generators(ctx, fresh)
+		for _, m := range f.Machines {
+			if gensErr != nil {
+				oldForeseen[m.Name] = composedBoth{Err: gensErr.Error()}
+				continue
+			}
+			d, problems, err := composedAndValidated(ctx, fresh, m.Name, gens, Foreseeing)
+			oldForeseen[m.Name] = capturedFrom(d, problems, err)
+		}
+		phase("(a) the controller's Foreseeing of every machine")
+	}()
+	go func() { // (b) and (c): the controller's send of every machine, then both ways of reading.
+		defer wg.Done()
+		oldStore, drop, err := throwawayStores(ctx, admin)
+		if err != nil {
+			errOld = err
+			return
+		}
+		defer drop()
+		if _, err := raiseFromFacts(ctx, oldStore, f, shelf, sources); err != nil {
+			errOld = err
+			return
+		}
+		oldGens, oldGensErr := generators(ctx, oldStore)
+		for _, m := range f.Machines {
+			if oldGensErr != nil {
+				break
+			}
+			if _, _, err := composedAndValidated(ctx, oldStore, m.Name, oldGens, Allocating); err != nil {
+				oldRefused[m.Name] = true
+			}
+		}
+		phase("(b) the controller's send of every machine")
+		if oldMade, err = madeIn(ctx, oldStore); err != nil {
+			errOld = err
+			return
+		}
+		cached := withInputCache(ctx)
+		for _, m := range f.Machines {
+			if oldGensErr != nil {
+				readOld[m.Name] = composedBoth{Err: oldGensErr.Error()}
+			} else {
+				d, problems, err := composedAndValidated(ctx, oldStore, m.Name, oldGens, Reading)
+				readOld[m.Name] = capturedFrom(d, problems, err)
+			}
+			d, problems, err := composeQuestion(cached, oldStore, m.Name, compose.Reading, true)
+			readSDK[m.Name] = capturedFrom(d, problems, err)
+		}
+		phase("(c) both ways of reading every machine after the controller's send")
+	}()
+	go func() { // (b) mesh-sdk's send of every machine.
+		defer wg.Done()
+		sdkStore, drop, err := throwawayStores(ctx, admin)
+		if err != nil {
+			errSDK = err
+			return
+		}
+		defer drop()
+		if _, err := raiseFromFacts(ctx, sdkStore, f, shelf, sources); err != nil {
+			errSDK = err
+			return
+		}
+		for _, m := range f.Machines {
+			if _, err := composeSend(ctx, sdkStore, m.Name); err != nil {
+				sendRefused[m.Name] = err.Error()
+			}
+		}
+		phase("(b) mesh-sdk's send of every machine")
+		sdkMade, errSDK = madeIn(ctx, sdkStore)
+	}()
+	wg.Wait()
+	for _, err := range []error{errA, errOld, errSDK} {
+		if err != nil {
+			t.Fatal(err)
 		}
-		sdkForeseen[m.Name] = capturedFrom(sendableOf(d), problems, cerr)
 	}
-	oldForeseen := map[string]composedBoth{}
-	gens, gensErr := generators(ctx, fresh)
-	for _, m := range f.Machines {
-		if gensErr != nil {
-			oldForeseen[m.Name] = composedBoth{Err: gensErr.Error()}
-			continue
-		}
-		d, problems, err := composedAndValidated(ctx, fresh, m.Name, gens, Foreseeing)
-		oldForeseen[m.Name] = capturedFrom(d, problems, err)
-	}
-	dropFresh()
+
+	var failures []string
 	for _, m := range f.Machines {
 		failures = append(failures, bothWaysDiffer(m.Name, "(a) Foreseeing", oldForeseen[m.Name], sdkForeseen[m.Name], false)...)
-	}
-
-	// (b) and (c): the controller's send of every machine, then both ways of reading, on one store.
-	oldStore, dropOld, err := throwawayStores(ctx, admin)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if _, err := raiseFromFacts(ctx, oldStore, f, shelf, sources); err != nil {
-		dropOld()
-		t.Fatal(err)
-	}
-	oldGens, oldGensErr := generators(ctx, oldStore)
-	for _, m := range f.Machines {
-		if oldGensErr != nil {
-			break
-		}
-		_, _, _ = composedAndValidated(ctx, oldStore, m.Name, oldGens, Allocating)
-	}
-	oldMade, err := madeIn(ctx, oldStore)
-	if err != nil {
-		dropOld()
-		t.Fatal(err)
-	}
-	readOld, readSDK := map[string]composedBoth{}, map[string]composedBoth{}
-	for _, m := range f.Machines {
-		if oldGensErr != nil {
-			readOld[m.Name] = composedBoth{Err: oldGensErr.Error()}
-		} else {
-			d, problems, err := composedAndValidated(ctx, oldStore, m.Name, oldGens, Reading)
-			readOld[m.Name] = capturedFrom(d, problems, err)
-		}
-		d, problems, err := composeQuestion(ctx, oldStore, m.Name, compose.Reading, true)
-		readSDK[m.Name] = capturedFrom(d, problems, err)
-	}
-	dropOld()
-	for _, m := range f.Machines {
 		failures = append(failures, bothWaysDiffer(m.Name, "(c) Reading after the send", readOld[m.Name], readSDK[m.Name], true)...)
 	}
-
-	sdkStore, dropSDK, err := throwawayStores(ctx, admin)
-	if err != nil {
-		t.Fatal(err)
+	// A machine refused on either side sends nothing, so what the controller made on the way to refusing it is no send's.
+	refused := map[string]bool{}
+	for m := range sendRefused {
+		refused[m] = true
 	}
-	if _, err := raiseFromFacts(ctx, sdkStore, f, shelf, sources); err != nil {
-		dropSDK()
-		t.Fatal(err)
+	for m := range oldRefused {
+		refused[m] = true
 	}
-	sendRefused := map[string]string{}
-	for _, m := range f.Machines {
-		if _, err := composeSend(ctx, sdkStore, m.Name); err != nil {
-			sendRefused[m.Name] = err.Error()
-		}
+	for m := range refused {
+		t.Logf("%s: refused on one side or both, so its ports and secrets are left out of the comparison of the send", m)
 	}
-	sdkMade, err := madeIn(ctx, sdkStore)
-	dropSDK()
-	if err != nil {
-		t.Fatal(err)
-	}
-	failures = append(failures, madeDiffer("(b) the send", oldMade, sdkMade)...)
+	failures = append(failures, madeDiffer("(b) the send", oldMade, sdkMade, refused)...)
 
 	// (a)'s ports: those mesh-sdk names foreseen, for each machine, are the ones the controller's send allocated to it.
 	for _, m := range f.Machines {
+		if refused[m.Name] {
+			continue
+		}
 		var allocated []string
 		for _, p := range oldMade.Ports {
 			if node, rest, ok := strings.Cut(p, " "); ok && node == m.Name {
@@ -162,7 +216,7 @@ func TestEveryMachineComposesAlikeBothWays(t *testing.T) {
 			}
 			if !found {
 				failures = append(failures, fmt.Sprintf("%s, (a) Foreseeing: mesh-sdk names the port %s foreseen and the "+
-					"controller's send allocates none for it (it allocates %v)", m.Name, want, allocated))
+					"controller's send allocates none for it", m.Name, want))
 			}
 		}
 	}