diff --git a/cmd/mesh-controller/compose_once_integration_test.go b/cmd/mesh-controller/compose_once_integration_test.go
new file mode 100644
index 00000000..16dd7c4c
--- /dev/null
+++ b/cmd/mesh-controller/compose_once_integration_test.go
@@ -0,0 +1,44 @@
+//go:build integration
+
+package main
+
+import (
+	"testing"
+
+	"git.novox.be/novox/mesh-sdk/go/compose"
+)
+
+// 1382/AC5: composing every node of one operation builds the Input once; without an operation's cache, once for each.
+func TestComposingEveryNodeOfAnOperationBuildsTheInputOnce(t *testing.T) {
+	open, _ := aMeshWithSecrets(t)
+	built := 0
+	was := composeInputBuilt
+	composeInputBuilt = func() { built++ }
+	t.Cleanup(func() { composeInputBuilt = was })
+	ctx := withInputCache(t.Context())
+	nodes, err := open.inventory.Nodes(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, n := range nodes {
+		if _, _, err := resolveNode(ctx, open, n.Name); err != nil && !unresolvable(err) {
+			t.Fatal(err)
+		}
+		if _, _, err := composeQuestion(ctx, open, n.Name, compose.Reading, false); err != nil && !unresolvable(err) {
+			t.Fatal(err)
+		}
+	}
+	if _, err := generatorsOf(ctx, open); err != nil {
+		t.Fatal(err)
+	}
+	if built != 1 {
+		t.Fatalf("an operation over %d node(s) built the Input %d time(s)", len(nodes), built)
+	}
+	built = 0
+	if _, _, err := resolveNode(t.Context(), open, nodes[0].Name); err != nil && !unresolvable(err) {
+		t.Fatal(err)
+	}
+	if built != 1 {
+		t.Fatalf("a composition with no cache built the Input %d time(s)", built)
+	}
+}
diff --git a/cmd/mesh-controller/compose_perform.go b/cmd/mesh-controller/compose_perform.go
new file mode 100644
index 00000000..32d2f822
--- /dev/null
+++ b/cmd/mesh-controller/compose_perform.go
@@ -0,0 +1,218 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"sort"
+	"strconv"
+	"strings"
+
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/compose"
+	"github.com/novox/mesh-controller/internal/inventory"
+)
+
+// perform makes what a composition named foreseen (novox/hq ADR 0453 clause 3, design 47 R4b, issue 1385).
+//
+// **The composition makes nothing; a send does.** mesh-sdk's composition over an Input names what the next send would make
+// (the ports it would assign, the credentials it would seal, the core boxes it would ask the vault for, the seats it would
+// pass on, the certificate it would issue) and stands in for each. A send composes, performs, reads the stores again and
+// composes again (send in compose_sdk.go), and refuses to send a declaration that still names anything foreseen. A question
+// (status, facts, probes, the merge gate's reading) never reaches this file.
+//
+// What is made is exactly what the controller's own composition made on the way to a declaration it was going to send:
+//   - every pair credential no row holds, for every machine that resolves, since planning one node resolved them all;
+//   - the seats the mesh passes on, with the hand act (not on a throwaway mesh, whose hand act has nowhere to go);
+//   - the machine ports the node's modules were given none for;
+//   - the node's own secrets, by the controller's own rules (a bus credential nobody issued was refused by the composition);
+//   - the core credentials, asked of the vault every send, so a rotated one reaches the machine;
+//   - the certificate of a machine that was never certified.
+//
+// perform returns whether it made or recorded anything: the reason the caller reads the stores again.
+func perform(ctx context.Context, open *stores, in *meshInput, node string, d compose.Declared) (bool, error) {
+	inv := open.inventory
+	did := false
+
+	// The seats passed on: recorded in the store with the controller's own hand act (ADR 0449 §4, issue 1317).
+	if len(d.Passes.Passes) > 0 {
+		var w io.Writer = os.Stderr
+		if lw, ok := ctx.Value(leftOutKey{}).(io.Writer); ok {
+			w = lw
+		}
+		for _, line := range d.Passes.Said {
+			fmt.Fprintln(w, line)
+		}
+		sp := seatPassingOn(inv, w)
+		for _, p := range d.Passes.Passes {
+			moved, err := inv.PassSeat(ctx, p.Seat.Name, p.Seat.Scope, p.From, p.To)
+			if err != nil {
+				// Said, and the record stays as it was: a composition is never refused for it.
+				fmt.Fprintf(w, "%s could not be passed from %s on %s to %s on %s: %v\n", p.Seat.Name,
+					p.From.Module, p.From.Node, p.To.Module, p.To.Node, err)
+				continue
+			}
+			if !moved {
+				continue // another composition passed it first, and wrote the act
+			}
+			did = true
+			if inv.Throwaway() {
+				continue
+			}
+			if err := sp.act(ctx, p); err != nil {
+				fmt.Fprintf(w, "%s passed from %s on %s to %s on %s, and the hand act could NOT be recorded: %v\n",
+					p.Seat.Name, p.From.Module, p.From.Node, p.To.Module, p.To.Node, err)
+			}
+		}
+	}
+
+	// Every pair credential the stores hold none for: made once and kept, and sealed to both ends before it was ever written
+	// down. The error is the one planFor met: the machine that needs it, and why none could be made.
+	for _, p := range in.wouldMake {
+		if err := makePair(ctx, inv, p); err != nil {
+			return did, fmt.Errorf("%s on %s needs %s from %s and no credential could be made for it: %w",
+				p.ConsumerModule, p.Consumer, p.Name, p.Provider, err)
+		}
+		did = true
+	}
+
+	// The ports this node's modules were given none for.
+	if len(d.ForeseenPorts) > 0 {
+		shelf, err := inv.Catalogue(ctx)
+		if err != nil {
+			return did, err
+		}
+		for _, one := range d.ForeseenPorts {
+			module, port, ok := strings.Cut(one, ":")
+			wanted, perr := strconv.Atoi(port)
+			if !ok || perr != nil {
+				return did, fmt.Errorf("the composition named a port the controller cannot read: %q", one)
+			}
+			fixed := false
+			for _, l := range nodeShelf(in, shelf, node)[module].Listens {
+				if l.Port == wanted {
+					fixed = l.Fixed
+				}
+			}
+			if _, err := inv.PortFor(ctx, node, module, wanted, fixed); err != nil {
+				return did, fmt.Errorf("%s needs %d reachable on %s and it could not be assigned: %w", module, wanted, node, err)
+			}
+			did = true
+		}
+	}
+
+	// The node's own secrets: a module's superuser password, an administrator, an account. The composition refused what the
+	// send refuses (a bus credential nobody issued, a given value under an old key).
+	for _, one := range d.StoodIn {
+		module, name, ok := strings.Cut(one, "/")
+		if !ok || strings.Contains(one, " ") {
+			continue // a grant's sealed copy, the certificate or the bus's list: made below or by nobody
+		}
+		if _, err := inv.SecretForModule(ctx, node, module, name); err != nil {
+			return did, err
+		}
+		did = true
+	}
+
+	// The core's own credentials, asked of the vault on every send so a rotated one reaches the machine (core_box.go).
+	n, ok := nodeOf(in.Input, node)
+	if ok && n.Stated && n.Contract >= compose.VaultBoxContract {
+		resolved, err := compose.Resolve(in.Input, node)
+		if err != nil {
+			return did, err
+		}
+		hands := n.Stated && n.Contract >= compose.HandedContract
+		handing := catalogue.Rendering{Hands: hands, Provisioner: provisionerAccount(resolved.Plan)}
+		boxes, err := coreBoxesFor(ctx, inv, node, resolved.Plan.Modules, func(m catalogue.Manifest) bool {
+			return handing.Handing(m)
+		}, Allocating)
+		if err != nil {
+			return did, err
+		}
+		if len(boxes.keep) > 0 {
+			did = true
+		}
+		// A core credential the vault did not answer for and no box was kept for is composed by the controller's own seal
+		// (core_box.go, ADR 0396); the composition over an Input has no such fallback, so the send is refused, said.
+		if len(boxes.byController) > 0 {
+			return did, fmt.Errorf("the vault did not answer for the core credentials of %s (%s) and no box of theirs is kept: "+
+				"nothing is sent until it does", node, strings.Join(boxes.byController, ", "))
+		}
+	}
+
+	// The certificate of a machine that was never certified: issued and kept, with the authority when there is none yet.
+	for _, one := range d.StoodIn {
+		if strings.HasPrefix(one, "the certificate and the authority of ") {
+			if _, _, err := certificateFor(ctx, open, node); err != nil {
+				return did, err
+			}
+			did = true
+			break
+		}
+	}
+	return did, nil
+}
+
+// makePair makes one pair credential by the controller's own read of it: the credential for the pair, or the provider's one
+// credential sealed to this consumer too. A credential only a person gives is never made (it is not a would-make).
+func makePair(ctx context.Context, inv *inventory.Inventory, p inventory.PairCredential) error {
+	var err error
+	switch p.Kind {
+	case inventory.PairShared:
+		_, err = inv.SharedSecretFor(ctx, p.Name, p.Consumer, p.ConsumerModule, p.Provider, p.ProviderModule, p.Local, p.Own)
+	case inventory.PairPlain:
+		_, err = inv.SecretFor(ctx, p.Name, p.Consumer, p.ConsumerModule, p.Provider, p.Local)
+	default:
+		return errors.New("a credential only a person gives is not made")
+	}
+	if inventory.IsNotGiven(err) {
+		return nil
+	}
+	return err
+}
+
+// stillForeseen says what a composed declaration still stands in for: the lists the composition names, and the stand-in itself
+// anywhere in the body (a pair credential's stand-in is not in any list). A declaration that has any is never sent.
+func stillForeseen(d compose.Declared) []string {
+	var left []string
+	left = append(left, d.Foreseen...)
+	left = append(left, d.StoodIn...)
+	for _, p := range d.ForeseenPorts {
+		left = append(left, "the port "+p)
+	}
+	for _, c := range d.CoreBoxesWanted {
+		left = append(left, "the vault's box for "+c.Module+"/"+c.Name)
+	}
+	for _, p := range d.Passes.Passes {
+		left = append(left, "the pass of "+p.Seat.Name+" to "+p.To.Module+" on "+p.To.Node)
+	}
+	if body, err := d.Body(); err == nil {
+		for _, marker := range []string{catalogue.ForeseenSealed, "asked of the vault by the next send", compose.ForeseenCertificate,
+			compose.ForeseenBusUsers} {
+			if strings.Contains(string(body), marker) {
+				left = append(left, "a stand-in: "+marker)
+			}
+		}
+	}
+	sort.Strings(left)
+	return slicesCompact(left)
+}
+
+func slicesCompact(in []string) []string {
+	var out []string
+	for _, s := range in {
+		if len(out) == 0 || out[len(out)-1] != s {
+			out = append(out, s)
+		}
+	}
+	return out
+}
+
+// nodeShelf is the shelf as one node composes its own set: the current one with each module it keeps at the build it runs put
+// in place of the current.
+func nodeShelf(in *meshInput, shelf map[string]catalogue.Manifest, node string) map[string]catalogue.Manifest {
+	n, _ := nodeOf(in.Input, node)
+	return shelfWith(shelf, n.Kept)
+}
diff --git a/cmd/mesh-controller/compose_perform_integration_test.go b/cmd/mesh-controller/compose_perform_integration_test.go
new file mode 100644
index 00000000..f42c93dc
--- /dev/null
+++ b/cmd/mesh-controller/compose_perform_integration_test.go
@@ -0,0 +1,183 @@
+//go:build integration
+
+package main
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+	"testing"
+
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/compose"
+	"github.com/novox/mesh-controller/internal/link"
+)
+
+func aWebModule() catalogue.Manifest {
+	return catalogue.Manifest{Module: "web", Version: "1",
+		Listens:    []catalogue.Listening{{Port: 8080, From: catalogue.FromEverywhere}},
+		OwnSecrets: catalogue.OwnSecrets{"admin": {Path: "/etc/web/admin"}},
+		Resources: []map[string]any{
+			{"id": "server", "type": "container", "name": "web", "ports": []any{"8080"},
+				"image": "registry.example/web@sha256:" + strings.Repeat("a", 64)},
+		}}
+}
+
+// 1385/AC1: a port the composition names foreseen is allocated with the inventory's PortFor for that module and port, a second
+// composition names it no more, and the number is the one the controller's own Allocating composition gives in the same store.
+func TestPerformAllocatesAForeseenPortAndTheNumberIsTheControllers(t *testing.T) {
+	open := aMesh(t)
+	ctx := t.Context()
+	register(t, open, aWebModule())
+	if _, err := assign(ctx, open, "laptop", "web"); err != nil {
+		t.Fatal(err)
+	}
+	in, err := readComposeInput(ctx, open)
+	if err != nil {
+		t.Fatal(err)
+	}
+	d, _, err := compose.ComposeIn(in.Input, "laptop", compose.Foreseeing)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(d.ForeseenPorts) != 1 || d.ForeseenPorts[0] != "web:8080" {
+		t.Fatalf("the composition names the ports %v foreseen, want web:8080", d.ForeseenPorts)
+	}
+	did, err := perform(ctx, open, in, "laptop", d)
+	if err != nil || !did {
+		t.Fatalf("perform did %v: %v", did, err)
+	}
+	held, err := open.inventory.PortsFor(ctx, "laptop")
+	if err != nil || len(held) != 1 || held[0].Module != "web" || held[0].Wanted != 8080 {
+		t.Fatalf("the port perform allocated reads %+v: %v", held, err)
+	}
+	in, err = readComposeInput(ctx, open)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if again, _, err := compose.ComposeIn(in.Input, "laptop", compose.Foreseeing); err != nil || len(again.ForeseenPorts) != 0 {
+		t.Fatalf("a second composition names %v foreseen: %v", again.ForeseenPorts, err)
+	}
+	// The number is the one the controller allocates in the same store.
+	plan, settings, err := planFor(ctx, open, "laptop")
+	if err != nil {
+		t.Fatal(err)
+	}
+	old, err := declarationFor(ctx, open, "laptop", plan, settings)
+	if err != nil {
+		t.Fatal(err)
+	}
+	after, _, err := compose.ComposeIn(in.Input, "laptop", compose.Foreseeing)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got, want := portsOf(after.Resources), portsOf(old.Resources); got != want {
+		t.Fatalf("the declaration publishes %s; the controller's allocation publishes %s", got, want)
+	}
+}
+
+func portsOf(resources []map[string]any) string {
+	var out []string
+	for _, r := range resources {
+		if r["type"] == "container" {
+			out = append(out, fmt.Sprint(r["name"], r["ports"]))
+		}
+	}
+	return strings.Join(out, ";")
+}
+
+// 1385/AC2: an own secret named foreseen is made with SecretForModule, and a pair credential the Input names would-make is
+// made as planFor chose; both exist after the send's composition and a second composition names neither.
+func TestPerformMakesTheOwnSecretsAndThePairCredentialsTheCompositionNamed(t *testing.T) {
+	open, _ := aMeshWithSecrets(t)
+	ctx := t.Context()
+	inv := open.inventory
+	register(t, open, aWebModule())
+	register(t, open, aConsumerOfTheBucket("reports"))
+	for _, m := range []string{"web", "reports"} {
+		if _, err := assign(ctx, open, "laptop", m); err != nil {
+			t.Fatal(err)
+		}
+	}
+	before, err := madeIn(ctx, open)
+	if err != nil {
+		t.Fatal(err)
+	}
+	declared, err := composeSend(ctx, open, "laptop")
+	if err != nil {
+		t.Fatalf("the send is refused: %v", err)
+	}
+	if len(declared.foreseen) != 0 {
+		t.Fatalf("the declaration still names %v foreseen", declared.foreseen)
+	}
+	after, err := madeIn(ctx, open)
+	if err != nil {
+		t.Fatal(err)
+	}
+	madeNow := func(have, was []string) []string {
+		seen := map[string]bool{}
+		for _, s := range was {
+			seen[s] = true
+		}
+		var out []string
+		for _, s := range have {
+			if !seen[s] {
+				out = append(out, s)
+			}
+		}
+		return out
+	}
+	if got := madeNow(after.OwnSecrets, before.OwnSecrets); len(got) != 1 || !strings.Contains(got[0], "web/admin") {
+		t.Errorf("the own secrets made are %v, want laptop web/admin", got)
+	}
+	if got := madeNow(after.Pairs, before.Pairs); len(got) != 1 || !strings.Contains(got[0], "reports") {
+		t.Errorf("the pair credentials made are %v, want the one of reports", got)
+	}
+	// And the credential is the one a second composition reads as held.
+	in, err := readComposeInput(ctx, open)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(in.wouldMake) != 0 {
+		t.Errorf("after the send the next send would still make %v", in.wouldMake)
+	}
+	if _, err := inv.SecretsFrom(ctx, "anchor"); err != nil {
+		t.Fatal(err)
+	}
+}
+
+// 1385/AC3: with the vault unreachable and no box of the credential kept, the send fails naming the module, and composes
+// nothing to send.
+func TestAVaultThatIsSilentRefusesTheSendWhereNoBoxIsKept(t *testing.T) {
+	open, vault := aCoreMesh(t, link.VaultBoxContract)
+	vault.silent = errors.New("no responders")
+	declared, err := composeSend(t.Context(), open, "laptop")
+	if err == nil || !strings.Contains(err.Error(), "mesh-provisioner-client") {
+		t.Fatalf("the send was not refused, naming the module: %v", err)
+	}
+	if len(declared.Resources) != 0 {
+		t.Fatal("a declaration came with the refusal")
+	}
+}
+
+// 1385/AC6: perform is idempotent: a second send's composition over the stores it left makes and records nothing.
+func TestAFinishedSendMakesNothingTheSecondTime(t *testing.T) {
+	open, _ := aMeshWithSecrets(t)
+	ctx := t.Context()
+	register(t, open, aWebModule())
+	if _, err := assign(ctx, open, "laptop", "web"); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := composeSend(ctx, open, "laptop"); err != nil {
+		t.Fatal(err)
+	}
+	before := tableState(t, open.inventory)
+	if _, err := composeSend(ctx, open, "laptop"); err != nil {
+		t.Fatal(err)
+	}
+	for k, v := range tableState(t, open.inventory) {
+		if before[k] != v {
+			t.Errorf("a second send of the same machine moved %s", k)
+		}
+	}
+}
diff --git a/cmd/mesh-controller/compose_sdk.go b/cmd/mesh-controller/compose_sdk.go
new file mode 100644
index 00000000..e8a933db
--- /dev/null
+++ b/cmd/mesh-controller/compose_sdk.go
@@ -0,0 +1,260 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"os"
+	"sort"
+	"strings"
+	"sync"
+
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/compose"
+)
+
+// The controller's composition on mesh-sdk's (novox/hq ADR 0453 clause 3, design 47 R4b, issues 1386 to 1388): every
+// caller that planned or composed a node reads the Input once for its operation (compose_input.go), asks the SDK to
+// compose over it, and, when it sends, performs what the composition names foreseen (compose_perform.go) and composes again.
+
+// inputCacheKey carries an operation's Input in its context, so the planning of every node of one verb reads the stores once.
+type inputCacheKey struct{}
+
+type inputCache struct {
+	mu sync.Mutex
+	by map[string]*meshInput
+}
+
+// withInputCache is ctx for an operation: the Input read for it is kept until a send changes what it read. A context that
+// carries none reads the stores for each composition, which is correct and slow.
+func withInputCache(ctx context.Context) context.Context {
+	if _, ok := ctx.Value(inputCacheKey{}).(*inputCache); ok {
+		return ctx
+	}
+	return context.WithValue(ctx, inputCacheKey{}, &inputCache{by: map[string]*meshInput{}})
+}
+
+// keptSignature is what the Input read depends on in ctx: which recorded modules each machine keeps at the build it runs
+// (recorded_kept.go), so an Input read for a person's push is never taken for one read for a gated send.
+func keptSignature(ctx context.Context) string {
+	skip, on := keptExcept(ctx)
+	var names []string
+	for m := range skip {
+		names = append(names, m)
+	}
+	sort.Strings(names)
+	every, _ := ctx.Value(keepEveryBuildKey{}).(string)
+	settings, _ := ctx.Value(keepForSettingsKey{}).(string)
+	return fmt.Sprintf("kept=%v;except=%v;every=%s;settings=%s", on, names, every, settings)
+}
+
+// inputFor is the Input for ctx's operation.
+func inputFor(ctx context.Context, open *stores) (*meshInput, error) {
+	cache, ok := ctx.Value(inputCacheKey{}).(*inputCache)
+	if !ok {
+		return readComposeInput(ctx, open)
+	}
+	sig := keptSignature(ctx)
+	cache.mu.Lock()
+	defer cache.mu.Unlock()
+	if in := cache.by[sig]; in != nil {
+		return in, nil
+	}
+	in, err := readComposeInput(ctx, open)
+	if err != nil {
+		return nil, err
+	}
+	cache.by[sig] = in
+	return in, nil
+}
+
+// forgetInput drops what the operation read, because a send made or recorded something it read.
+func forgetInput(ctx context.Context) {
+	if cache, ok := ctx.Value(inputCacheKey{}).(*inputCache); ok {
+		cache.mu.Lock()
+		cache.by = map[string]*meshInput{}
+		cache.mu.Unlock()
+	}
+}
+
+// resolveNode works out everything a node should run, from what was assigned to it (planFor on the SDK): over the Input,
+// writing nothing. A failure to compose the node's own modules is marked notResolvable, as planFor marked it; every other
+// failure is returned as it is.
+func resolveNode(ctx context.Context, open *stores, node string) (catalogue.Resolution, catalogue.SettingsBy, error) {
+	in, err := inputFor(ctx, open)
+	if err != nil {
+		return catalogue.Resolution{}, nil, err
+	}
+	resolved, err := compose.Resolve(in.Input, node)
+	if err != nil {
+		if compose.IsUnresolvable(err) {
+			return catalogue.Resolution{}, nil, notResolvable{err}
+		}
+		return catalogue.Resolution{}, nil, err
+	}
+	logUnheld(node, resolved.Plan.Unheld)
+	return resolved.Plan, resolved.Settings, nil
+}
+
+// generatorsOf is what every node's declaration is composed with, over the whole mesh (generators on the SDK).
+func generatorsOf(ctx context.Context, open *stores) (map[string]catalogue.Generator, error) {
+	in, err := inputFor(ctx, open)
+	if err != nil {
+		return nil, err
+	}
+	return compose.Generators(in.Input)
+}
+
+// composeQuestion composes a node's declaration as a question asks it: nothing is made, and what a send would make is a
+// stand-in (Foreseeing) or left out (Reading). It also answers what the node-engine's validator refuses of it. The lines the
+// composition found are said where the controller says its own (standard error, or the writer an act gave).
+//
+// withOrder says the declaration carries the order it was last sent under (composedAndValidated's, which a comparison with the
+// last send needs); without it the order is none, as declarationWith left it for the sender to stamp.
+func composeQuestion(ctx context.Context, open *stores, node string, mode compose.Mode, withOrder bool) (sendable, []string, error) {
+	in, err := inputFor(ctx, open)
+	if err != nil {
+		return sendable{}, nil, err
+	}
+	d, problems, err := compose.ComposeIn(in.Input, node, mode)
+	if err != nil {
+		return sendable{}, nil, markUnresolvable(err)
+	}
+	sayFound(ctx, d)
+	out := sendableOf(d)
+	if !withOrder {
+		out.Sequence, out.Epoch, out.Generation = 0, 0, 0
+	}
+	return out, problems, nil
+}
+
+// markUnresolvable is an error of a node whose own set does not compose, as planFor marked it.
+func markUnresolvable(err error) error {
+	if compose.IsUnresolvable(err) {
+		return notResolvable{err}
+	}
+	return err
+}
+
+// composeSend composes a node's declaration to send it, as the Allocating composition did: composed over what is read,
+// then what it named foreseen is made (perform), the stores are read again and it is composed again. A declaration that
+// still names anything foreseen is refused, said, and never sent.
+func composeSend(ctx context.Context, open *stores, node string) (sendable, error) {
+	for attempt := 0; ; attempt++ {
+		in, err := inputFor(ctx, open)
+		if err != nil {
+			return sendable{}, err
+		}
+		d, _, err := compose.ComposeIn(in.Input, node, compose.Foreseeing)
+		if err != nil {
+			return sendable{}, markUnresolvable(err)
+		}
+		left := stillForeseen(d)
+		resolved, rerr := compose.Resolve(in.Input, node)
+		if rerr != nil {
+			return sendable{}, markUnresolvable(rerr)
+		}
+		if len(resolved.Foreseen) > 0 {
+			left = append(left, resolved.Foreseen...)
+		}
+		if len(left) == 0 && len(in.wouldMake) == 0 {
+			sayFound(ctx, d)
+			out := sendableOf(d)
+			// The sender stamps the order it allots (order.stamp); a composition for a send carries none of its own.
+			out.Sequence, out.Epoch, out.Generation = 0, 0, 0
+			here, _ := nodeOf(in.Input, node)
+			out.Builds = buildsOf(in.Input, here, resolved.Plan, d.LeftOutWhy)
+			out.Bindings = boundToData(resolved.Plan, d.LeftOutWhy)
+			if len(d.Filled) > 0 {
+				if out.plans, err = handedPlans(in, node, resolved); err != nil {
+					return sendable{}, err
+				}
+			}
+			return out, nil
+		}
+		if attempt > 0 {
+			return sendable{}, fmt.Errorf("%s was composed twice and still names what only a send makes (%s): nothing is sent "+
+				"that stands in for a value", node, strings.Join(left, "; "))
+		}
+		if _, err := perform(ctx, open, in, node, d); err != nil {
+			return sendable{}, err
+		}
+		// What was made is in the stores now: the next read is a fresh one.
+		forgetInput(ctx)
+	}
+}
+
+// sayFound says the lines a composition found while composing, once each: a machine left out of the rest of the mesh, a seat
+// that two claimants could take, the bus's users left out for want of a credential.
+func sayFound(ctx context.Context, d compose.Declared) {
+	if len(d.Said) == 0 {
+		return
+	}
+	var w io.Writer = os.Stderr
+	if lw, ok := ctx.Value(leftOutKey{}).(io.Writer); ok {
+		w = lw
+	}
+	for _, line := range d.Said {
+		fmt.Fprintln(w, line)
+	}
+}
+
+// sendableOf is a composed declaration as the controller's sends know it.
+func sendableOf(d compose.Declared) sendable {
+	out := sendable{Resources: d.Resources, Sequence: d.Sequence, Epoch: d.Epoch, Generation: d.Generation,
+		ReadsModules: d.ReadsModules, moduleOf: d.ModuleOf, buildIDs: d.BuildIDs, modules: d.Modules,
+		localNetwork: d.LocalNetwork, Received: d.Received, Mesh: d.Mesh, BusUsers: d.BusUsers,
+		LeftOut: d.LeftOut, leftOutWhy: d.LeftOutWhy, withheld: d.Withheld, unbound: d.Unbound, foreseen: d.Foreseen,
+		unplaced: d.Unplaced, handedOnly: d.HandedOnly, Filled: d.Filled, Provisioner: d.Provisioner,
+		requiredBy: d.RequiredBy}
+	if d.Adoption != nil {
+		out.Adoption = &adoptionEnvelope{Taken: d.Adoption.Taken, Untaken: d.Adoption.Untaken}
+	}
+	return out
+}
+
+// buildsOf is the build of each module a declaration for the node carries, as a send records it (novox/hq issue 259): the
+// module's current build for each module in it, the build it was last sent for one left out of it, and a module kept at the
+// build the machine runs carried at that one (ADR 0245). Never nil.
+func buildsOf(in compose.Input, node compose.Node, plan catalogue.Resolution, leftOut map[string]string) map[string]string {
+	before := node.SentBuilds
+	if !node.SentKnown {
+		before = nil
+	}
+	out := map[string]string{}
+	for _, m := range plan.Modules {
+		if _, left := leftOut[m.Module]; left {
+			if was, kept := before[m.Module]; kept {
+				out[m.Module] = was
+			}
+			continue
+		}
+		out[m.Module] = in.CurrentBuilds[m.Module]
+	}
+	for m, was := range node.KeptBuilds {
+		if _, carried := out[m]; carried {
+			out[m] = was
+		}
+	}
+	return out
+}
+
+// handedPlans is the plan of each module handed to the provisioner, which the assignments mirror keeps with the send (design
+// 57 P6): the composition's declaration does not carry it, so it is composed from the same rendering again.
+func handedPlans(in *meshInput, node string, resolved compose.Resolved) (map[string]catalogue.Plan, error) {
+	rendered, err := compose.Render(in.Input, node, compose.Foreseeing)
+	if err != nil {
+		return nil, err
+	}
+	gens, err := compose.Generators(in.Input)
+	if err != nil {
+		return nil, err
+	}
+	with := rendered.Rendering
+	with.Generators = gens
+	composed, err := resolved.Plan.Compose(with)
+	if err != nil {
+		return nil, err
+	}
+	return composed.Plans, nil
+}
diff --git a/cmd/mesh-controller/compose_sdk_test.go b/cmd/mesh-controller/compose_sdk_test.go
new file mode 100644
index 00000000..dddfd8a7
--- /dev/null
+++ b/cmd/mesh-controller/compose_sdk_test.go
@@ -0,0 +1,123 @@
+package main
+
+import (
+	"context"
+	"reflect"
+	"strings"
+	"testing"
+
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/compose"
+	"github.com/novox/mesh-controller/internal/inventory"
+)
+
+// A declaration as the SDK composes it is the one the controller sends, byte for byte, whatever it carries: the body is the
+// envelope's only marshaller on either side (design 47 R4b, issue 1386).
+func TestASendableIsTheComposedDeclarationByteForByte(t *testing.T) {
+	d := compose.Declared{
+		Resources: []map[string]any{{"id": "files.config", "type": "file"}, {"id": "mesh.hosts", "type": "file"}},
+		Sequence:  7, Epoch: 3, Generation: 9, ReadsModules: true,
+		ModuleOf: map[string]string{"files.config": "files"}, BuildIDs: map[string]string{"files": "b-1"},
+		Adoption: &compose.Adoption{Taken: []string{"files"}, Untaken: map[string][]string{"nats": {"nats.server"}}},
+		Filled:   []string{"/etc/files/filled.json"}, Provisioner: "mesh-provisioner",
+		LeftOut: []string{"cache"}, LeftOutWhy: map[string]string{"cache": "a setting cannot compose"},
+	}
+	want, err := d.Body()
+	if err != nil {
+		t.Fatal(err)
+	}
+	got, err := sendableOf(d).Body()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(got) != string(want) {
+		t.Fatalf("the controller would send\n%s\nand the composition made\n%s", got, want)
+	}
+	if empty, err := sendableOf(compose.Declared{}).Body(); err != nil || !strings.Contains(string(empty), `"owns_nothing":true`) {
+		t.Fatalf("an empty declaration is not deliberate: %s %v", empty, err)
+	}
+}
+
+// 1386: what a send records as carried is what the controller's own carriedOn recorded.
+func TestWhatASendRecordsAsCarriedIsWhatTheControllerRecorded(t *testing.T) {
+	plan := catalogue.Resolution{Modules: []catalogue.Manifest{{Module: "postgres"}, {Module: "files"}, {Module: "cache"}}}
+	current := map[string]inventory.CurrentBuild{"postgres": {Commit: "p2"}, "files": {Commit: "f2"}, "cache": {Commit: "c2"}}
+	leftOut := map[string]string{"cache": "a setting cannot compose"}
+	for name, c := range map[string]struct {
+		sent  map[string]string
+		known bool
+		kept  map[string]string
+	}{
+		"nothing sent":         {},
+		"sent and kept":        {sent: map[string]string{"postgres": "p1", "cache": "c1", "files": "f1"}, known: true, kept: map[string]string{"postgres": "p1"}},
+		"sent but not known":   {sent: map[string]string{"cache": "c1"}},
+		"kept a module not in": {known: true, kept: map[string]string{"mail": "m1"}},
+	} {
+		var names []string
+		for _, m := range plan.Modules {
+			names = append(names, m.Module)
+		}
+		before := c.sent
+		if !c.known {
+			before = nil
+		}
+		want := carriedBuilds(names, leftOut, current, before)
+		for m, was := range c.kept {
+			if _, carried := want[m]; carried {
+				want[m] = was
+			}
+		}
+		in := compose.Input{CurrentBuilds: map[string]string{"postgres": "p2", "files": "f2", "cache": "c2"}}
+		node := compose.Node{SentBuilds: c.sent, SentKnown: c.known, KeptBuilds: c.kept}
+		if got := buildsOf(in, node, plan, leftOut); !reflect.DeepEqual(got, want) {
+			t.Errorf("%s: a send records %v, the controller recorded %v", name, got, want)
+		}
+	}
+}
+
+// 1385: a declaration that stands in for a value anywhere is still foreseen, in a list the composition names or in the body
+// alone (a pair credential's stand-in is in no list); one that stands in for nothing is not. It failed first, before the body
+// was scanned.
+func TestADeclarationThatStandsInForAValueIsStillForeseen(t *testing.T) {
+	clean := compose.Declared{Resources: []map[string]any{{"id": "files.config", "type": "file", "content": "ok"}}}
+	if left := stillForeseen(clean); len(left) != 0 {
+		t.Fatalf("a declaration that stands in for nothing is foreseen: %v", left)
+	}
+	for name, d := range map[string]compose.Declared{
+		"an own secret":     {StoodIn: []string{"files/admin"}},
+		"a port":            {ForeseenPorts: []string{"files:80"}},
+		"a core box":        {CoreBoxesWanted: []compose.CoreBoxWanted{{Node: "anchor", Module: "mesh-vault", Name: "root"}}},
+		"a pass of a seat":  {Passes: compose.Passes{Passes: []catalogue.SeatPass{{Seat: catalogue.Seat{Name: "mesh-store"}}}}},
+		"a pair credential": {Resources: []map[string]any{{"id": "files.needs-db", "sealed": catalogue.ForeseenSealed}}},
+		"the certificate":   {Resources: []map[string]any{{"id": "proxy.cert", "content": compose.ForeseenCertificate}}},
+		"the bus's list":    {Resources: []map[string]any{{"id": "nats.users", "content": compose.ForeseenBusUsers}}},
+		"the vault's box":   {Resources: []map[string]any{{"id": "x", "box": catalogue.ForeseenVaultBox}}},
+	} {
+		if left := stillForeseen(d); len(left) == 0 {
+			t.Errorf("%s: a declaration that stands in for it is not foreseen", name)
+		}
+	}
+}
+
+// 1386: an Input read for a person's push is never the one read for a send that keeps recorded builds, and the cache is
+// emptied by what a send made.
+func TestAnInputIsCachedPerWhatItKeepsAndForgottenAfterASend(t *testing.T) {
+	ctx := withInputCache(context.Background())
+	plain := keptSignature(ctx)
+	kept := keptSignature(keepingRecorded(ctx))
+	bus := keptSignature(keepingRecorded(ctx, "nats"))
+	every := keptSignature(keepingEveryBuild(ctx, "anchor"))
+	for name, sig := range map[string]string{"a push": plain, "a kept send": kept, "the bus step": bus, "the grants step": every} {
+		for other, o := range map[string]string{"a push": plain, "a kept send": kept, "the bus step": bus, "the grants step": every} {
+			if name != other && sig == o {
+				t.Errorf("%s and %s read the same Input", name, other)
+			}
+		}
+	}
+	cache := ctx.Value(inputCacheKey{}).(*inputCache)
+	cache.by[plain] = &meshInput{}
+	forgetInput(ctx)
+	if len(cache.by) != 0 {
+		t.Fatal("what a send made left the Input it read in the cache")
+	}
+}