Let the kept compositions' pass end at the stop (issue 1945, ADR 0545, review 3)

followKept went on composing every kept key, and the config consumer every
touched node, after the controller was told to stop. Both now check the stop
before each key and each node; the writes of an unfinished batch are refused
at once, so the next controller takes them.
Research 072: milestone 2, the composer reacting to the change of an input.

cmd/mesh-controller/acts.go

@@ -399,6 +399,8 @@ func blockedElsewhere(ctx context.Context, open *stores, except string) string {
 // purpose, never by re-assigning); and when the bus cannot be reached from here, the line names the
 // verb and the push that would refuse the module until it is run — never a silent placeholder (novox/hq issue 203).
 func issueOnAssign(ctx context.Context, open *stores, node, module string) string {
+	// Mint only what no row names: the assignments' watch hears the same write and may issue at once (ADR 0543).
+	ctx = onlyIfAbsent(ctx)
 	inv := open.inventory
 	shelf, err := inv.Catalogue(ctx)
 	if err != nil {

cmd/mesh-controller/asker_wire.go

@@ -12,6 +12,7 @@ import (
 	"sort"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/nats-io/nats.go"
@@ -27,7 +28,7 @@ import (
 )
 
 // askerFrom is the serving controller's asker; nil in any other process.
-var askerFrom *asker
+var askerFrom atomic.Pointer[asker]
 
 // askWithin is how long a verb a warrant chose is given to answer.
 const askWithin = time.Minute
@@ -573,8 +574,8 @@ func startAsking(ctx context.Context, open *stores, server *link.Server, conn *n
 		fmt.Printf("the operator's answers cannot be heard, so nothing is asked: %v\n", err)
 		return
 	}
-	askerFrom = a
-	go a.keep(ctx)
+	askerFrom.Store(a)
+	goServing(ctx, func() { a.keep(ctx) })
 }
 
 // servingAsker is the serving controller's asker, wired to the mesh: what it reads, publishes, performs and

cmd/mesh-controller/assignment_accounts.go

@@ -0,0 +1,387 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"strings"
+	"sync"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+
+	"github.com/novox/mesh-controller/internal/broker"
+	"github.com/novox/mesh-controller/internal/chain"
+	"github.com/novox/mesh-controller/internal/inventory"
+)
+
+// An assignment that stands issues its node's bus accounts and the module's grant (novox/hq ADR 0543, issue 1945; a
+// step of research 072's grants: the memberships and credentials heard from placement, not from a send or a build).
+//
+// ADR 0539 clause 7 issues a module's credential and grant when its build is done. A module already built and assigned
+// to one more node never has a build done again, so nothing issued that node's account: on 2026-10-25 at 17:19
+// mesh-build-node and mesh-build-go were assigned to ace, composed for it, and the bus's user list never named
+// ace.mesh-build-node nor ace.mesh-build-go; one runtime found no credential, the other was refused by the bus, both
+// restarting every 5 s. The assign act composes the assigned node alone (composedAfterAct): never the node holding the
+// bus, never the grant.
+//
+// So the write of an assignments key is the event. When a key `<node>.<module>` of the assignments bucket comes to stand
+// (a new key, or one that was ended or pending), the lease holder issues the module's accounts on that node that are not
+// minted (idempotent: a minted account is never issued again, a rotation is on purpose), composes the node holding the
+// bus so its user list carries them, and writes the grants. A rewrite of an assignment that already stood (the
+// provisioner's plan kept in its value) does nothing. A starting controller looks at every standing assignment once,
+// from one reading of the catalogue: it issues what is missing, then composes the bus's node and writes the grants
+// once. The assign act issues too; both mint only an account no row names, in one statement, so exactly one of them
+// mints and seals it (mintBusUser, the review of issue 1945).
+
+// assignmentAccountSteps are what an assignment that comes to stand does, each a step a test may stand in for.
+type assignmentAccountSteps struct {
+	// holds says this controller holds the lease: only its holder issues.
+	holds func(ctx context.Context) bool
+	// catalogue reads the catalogue once, for every assignment a look issues for.
+	catalogue func(ctx context.Context) (map[string]catalogue.Manifest, error)
+	// issue issues the module's accounts on the node that are not minted, from the catalogue read; issued says it
+	// minted one, line what it did.
+	issue func(ctx context.Context, shelf map[string]catalogue.Manifest, node, module string) (issued bool, line string, err error)
+	// busHolder is the node holding the bus, "" for none.
+	busHolder func(ctx context.Context) (string, error)
+	// compose writes the nodes' compositions; grants writes the grants issued.
+	compose func(ctx context.Context, nodes []string) error
+	grants  func(ctx context.Context) error
+}
+
+// settle issues what the standing assignment of module on node lacks. fresh says the assignment just came to stand: the
+// bus's node is composed and the grants written even when every account was minted before (a module assigned again
+// keeps its account, and the bus's user list left it out while it was unassigned). It answers what it did, "" for
+// nothing.
+func (s assignmentAccountSteps) settle(ctx context.Context, node, module string) (string, error) {
+	if module == controllerModule {
+		// The controller's own module is issued at the terminal alone: its `broker` secret is the credential it is
+		// using (rollout.go), and it is assigned and unassigned there only (refusedMovingTheController).
+		return "", nil
+	}
+	if !s.holds(ctx) {
+		return "", errNotHolding
+	}
+	shelf, err := s.catalogue(ctx)
+	if err != nil {
+		return "", fmt.Errorf("the catalogue cannot be read: %w", err)
+	}
+	_, line, err := s.issue(ctx, shelf, node, module)
+	if err != nil {
+		return "", fmt.Errorf("its bus accounts on %s are not issued: %w", node, err)
+	}
+	said, err := s.cover(ctx)
+	prefix := module + " on " + node + ": "
+	if line != "" {
+		prefix += line + "; "
+	}
+	return prefix + said, err
+}
+
+// look is the start's look: the accounts every standing assignment lacks, issued one after another from one reading of
+// the catalogue, then the bus's node composed and the grants written once, when it looked at any assignment, whatever
+// it issued (an assignment that came to stand while no controller heard it may have its accounts and still lack its
+// place in the bus's user list or its grant). It answers what it did.
+func (s assignmentAccountSteps) look(ctx context.Context, standing []chain.Assignment) (string, error) {
+	var looked []chain.Assignment
+	for _, a := range standing {
+		if a.Module != controllerModule {
+			looked = append(looked, a)
+		}
+	}
+	if len(looked) == 0 {
+		return "", nil
+	}
+	if !s.holds(ctx) {
+		return "", errNotHolding
+	}
+	shelf, err := s.catalogue(ctx)
+	if err != nil {
+		return "", fmt.Errorf("the catalogue cannot be read: %w", err)
+	}
+	var lines []string
+	for _, a := range looked {
+		if ctx.Err() != nil {
+			return "", ctx.Err()
+		}
+		if _, line, err := s.issue(ctx, shelf, a.Node, a.Module); err != nil {
+			return "", fmt.Errorf("%s's bus accounts on %s are not issued: %w", a.Module, a.Node, err)
+		} else if line != "" {
+			lines = append(lines, a.Module+" on "+a.Node+": "+line)
+		}
+	}
+	said, err := s.cover(ctx)
+	lines = append(lines, fmt.Sprintf("%d standing assignment(s) looked at; %s", len(looked), said))
+	return strings.Join(lines, "\n"), err
+}
+
+// errNotHolding is a controller that does not hold the lease: it issues nothing, and tries again until it holds it.
+var errNotHolding = errors.New("this controller does not hold the lease")
+
+// cover composes the node holding the bus and writes the grants, and says so.
+func (s assignmentAccountSteps) cover(ctx context.Context) (string, error) {
+	holder, err := s.busHolder(ctx)
+	if err != nil {
+		return "", fmt.Errorf("the node holding the bus cannot be read: %w", err)
+	}
+	if holder != "" {
+		if err := s.compose(ctx, []string{holder}); err != nil {
+			return "", fmt.Errorf("the bus's user list on %s is not composed: %w", holder, err)
+		}
+	}
+	if err := s.grants(ctx); err != nil {
+		return "", err
+	}
+	if holder != "" {
+		return "the bus's user list composed on " + holder + ", the grants written", nil
+	}
+	return "the grants written", nil
+}
+
+// assignmentStands says a value of the assignments bucket holds an assignment that stands: made (a module only pulled in
+// by another names no time assigned), not ended and in no state (chain.Assignment.Stands).
+func assignmentStands(a chain.Assignment) bool {
+	return !a.Assigned.IsZero() && a.Stands() && a.Node != "" && a.Module != ""
+}
+
+// assignmentTurns keeps which keys of the assignments bucket stood when last heard, to tell an assignment that comes to
+// stand from a rewrite of one that stood.
+type assignmentTurns struct {
+	mu    sync.Mutex
+	stood map[string]bool
+}
+
+// heard records a value of key (nil for a delete or a purge) and answers whether it holds an assignment that just came
+// to stand.
+func (t *assignmentTurns) heard(key string, value []byte) (chain.Assignment, bool) {
+	var a chain.Assignment
+	stands := false
+	if value != nil && json.Unmarshal(value, &a) == nil {
+		stands = assignmentStands(a)
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if t.stood == nil {
+		t.stood = map[string]bool{}
+	}
+	was := t.stood[key]
+	t.stood[key] = stands
+	return a, stands && !was
+}
+
+// ownAccountOf is the username of the account a module speaks on the bus with on node, its own and no process's: the
+// module's when it reads a `broker` own secret, else its provisioner client's when it runs one; false when it has none
+// (a module whose accounts are its processes' alone, or one that does not speak on the bus).
+func ownAccountOf(m catalogue.Manifest, node string) (string, bool) {
+	if _, reads := m.OwnSecrets["broker"]; reads {
+		return broker.Principal{Kind: broker.KindModule, Node: node, Module: m.Module}.Username(), true
+	}
+	if runsTheProvisionerClient(m) {
+		return broker.Principal{Kind: broker.KindProvisioner, Node: node, Module: m.Module}.Username(), true
+	}
+	return "", false
+}
+
+// issueAssignmentAccounts issues module's accounts on node that are not minted: its own (issueOnTheNewBus) and its
+// processes' (issueMissingProcessAccounts). A module the catalogue does not hold, or one with nowhere to deliver an
+// account (mayIssue), has nothing to issue; an account minted before is kept.
+func issueAssignmentAccounts(ctx context.Context, inv *inventory.Inventory, shelf map[string]catalogue.Manifest,
+	node, module string) (bool, string, error) {
+	// Mint only what no row names: the assign act hears its own write and may issue at once (the review of issue 1945).
+	ctx = onlyIfAbsent(ctx)
+	m, known := shelf[module]
+	if !known || mayIssue(m) != nil {
+		return false, "", nil
+	}
+	if user, own := ownAccountOf(m, node); own {
+		_, minted, err := inv.BusUserHash(ctx, user)
+		if err != nil {
+			return false, "", fmt.Errorf("whether %s is minted cannot be read: %w", user, err)
+		}
+		if !minted {
+			busAddress, err := broker.BusAddress()
+			if err != nil {
+				return false, "", err
+			}
+			// Its processes' accounts too: issueOnTheNewBus issues every one of them with the module's own.
+			if err := issueOnTheNewBus(ctx, inv, m, node, busAddress); err != nil {
+				return false, "", err
+			}
+			return true, "its bus credential issued as " + user, nil
+		}
+	}
+	line, err := issueMissingProcessAccounts(ctx, inv, m, node)
+	if err != nil {
+		return false, "", err
+	}
+	return line != "", line, nil
+}
+
+// liveAssignmentAccountSteps are the steps on the controller's own stores and the bus: the composer's passes, as the
+// done keys' take-ins use them, so a node asked for by both is composed once a pass.
+func liveAssignmentAccountSteps(open *stores) assignmentAccountSteps {
+	inv := open.inventory
+	return assignmentAccountSteps{
+		holds: func(ctx context.Context) bool {
+			// The lease's gate, as every act's: a serving controller the bus does not grant the lease yet acts unleased.
+			_, err := theLease.epoch(ctx)
+			return err == nil
+		},
+		catalogue: func(ctx context.Context) (map[string]catalogue.Manifest, error) { return inv.Catalogue(ctx) },
+		issue: func(ctx context.Context, shelf map[string]catalogue.Manifest, node, module string) (bool, string, error) {
+			return issueAssignmentAccounts(ctx, inv, shelf, node, module)
+		},
+		busHolder: func(ctx context.Context) (string, error) {
+			holders, err := seatHolders(ctx, inv)
+			if err != nil {
+				return "", err
+			}
+			return holders[catalogue.BrokerSeat].Node, nil
+		},
+		compose: func(ctx context.Context, nodes []string) error {
+			return composerFor(open).compose(ctx, nodes, false)
+		},
+		grants: func(ctx context.Context) error {
+			return composerFor(open).compose(ctx, nil, true)
+		},
+	}
+}
+
+// assignmentAccountsRetry is how long a settle that failed waits before it tries again.
+var assignmentAccountsRetry = 30 * time.Second
+
+// untilSettled runs settle until it works or ctx ends: a failure, or a controller not holding the lease, is said and
+// tried again every assignmentAccountsRetry, never dropped, since no later write of the key may come.
+func untilSettled(ctx context.Context, what string, settle func(context.Context) (string, error)) {
+	for {
+		said, err := settle(ctx)
+		if err == nil {
+			if said != "" {
+				for _, line := range strings.Split(said, "\n") {
+					fmt.Printf("assignments: %s\n", line)
+				}
+			}
+			return
+		}
+		if ctx.Err() != nil {
+			return
+		}
+		fmt.Printf("assignments: %s: %v; tried again in %s\n", what, err, assignmentAccountsRetry)
+		select {
+		case <-ctx.Done():
+			return
+		case <-time.After(assignmentAccountsRetry):
+		}
+	}
+}
+
+// watchAssignmentAccounts settles every assignment of the assignments bucket that comes to stand, for as long as ctx: the
+// bucket's current values first (the start's look, settled as not fresh), then each write. A watch that ends, or a
+// bucket not there yet, is watched again a minute later.
+func watchAssignmentAccounts(ctx context.Context, open *stores) {
+	steps := liveAssignmentAccountSteps(open)
+	goServing(ctx, func() {
+		runAssignmentWatches(ctx, open.inventory.WatchAssignments, func(a chain.Assignment) {
+			inBackground(ctx, func() {
+				untilSettled(ctx, a.Module+" on "+a.Node, func(ctx context.Context) (string, error) {
+					return steps.settle(ctx, a.Node, a.Module)
+				})
+			})
+		}, func(look []chain.Assignment) {
+			// The start's look, once in the process: one reading of the catalogue, one assignment after another,
+			// then one composition of the bus's node and the grants (issues 1945 and 1277).
+			inBackground(ctx, func() {
+				untilSettled(ctx, "the start's look", func(ctx context.Context) (string, error) {
+					return steps.look(ctx, look)
+				})
+			})
+		}, func() bool {
+			select {
+			case <-ctx.Done():
+				return false
+			case <-time.After(time.Minute):
+				return true
+			}
+		})
+	})
+}
+
+// runAssignmentWatches watches the assignments again each time a watch ends, until ctx ends or pause says stop: each
+// assignment that comes to stand is handed to fresh, and the standing ones of the first watch that reads them all (its
+// Caught mark) to look, once. A watch that ends, or fails to open, before the start's look ran is no start's look: the
+// next one is, with what it hears from nothing (a fresh assignmentTurns), so no key it handed is dropped and no burst of
+// fresh settles replaces the look (the review of issue 1945).
+func runAssignmentWatches(ctx context.Context, watch func(context.Context) (<-chan chain.Entry, error),
+	fresh func(chain.Assignment), look func([]chain.Assignment), pause func() bool) {
+	turns := &assignmentTurns{}
+	first := true
+	for {
+		var atStart []chain.Assignment
+		if err := watchAssignmentsOnce(ctx, watch, turns, first, func(a chain.Assignment, isFresh bool) {
+			if !isFresh {
+				atStart = append(atStart, a)
+				return
+			}
+			fresh(a)
+		}, func() {
+			first = false
+			look(atStart)
+			atStart = nil
+		}); err != nil && ctx.Err() == nil {
+			fmt.Printf("assignments: the assignments are not heard, so a new assignment's bus accounts wait: %v\n", err)
+		}
+		if first {
+			turns = &assignmentTurns{} // the start's look has not run: the next watch hears every standing key anew
+		}
+		if ctx.Err() != nil || !pause() {
+			return
+		}
+	}
+}
+
+// watchAssignmentsOnce watches the assignments until the watch or ctx ends, handing each assignment that comes to stand
+// to settle. On the process's first watch, the current values are the start's look (not fresh) and read is called once
+// they are all handed (the chain's Caught mark); every other value, and every value of a watch opened again after one
+// ended, is fresh: an assignment that came to stand while no watch heard it is settled whole, never as the start's look
+// (the review of issue 1945).
+func watchAssignmentsOnce(ctx context.Context, watch func(context.Context) (<-chan chain.Entry, error),
+	turns *assignmentTurns, first bool, settle func(a chain.Assignment, fresh bool), read func()) error {
+	ctx, stop := context.WithCancel(ctx)
+	defer stop()
+	entries, err := watch(ctx)
+	if err != nil {
+		return err
+	}
+	current := true
+	for {
+		select {
+		case <-ctx.Done():
+			return nil
+		case e, ok := <-entries:
+			if !ok {
+				if ctx.Err() != nil {
+					return nil
+				}
+				return fmt.Errorf("the watch ended")
+			}
+			if e.Caught {
+				if current {
+					current = false // the current values are read: what follows is written from now on
+					if first {
+						read()
+					}
+				}
+				continue
+			}
+			var value []byte
+			if !e.Deleted {
+				value = e.Value
+			}
+			if a, turned := turns.heard(e.Key, value); turned {
+				settle(a, !current || !first)
+			}
+		}
+	}
+}

cmd/mesh-controller/assignment_accounts_test.go

@@ -0,0 +1,344 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"strings"
+	"testing"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"github.com/novox/mesh-controller/internal/broker"
+	"github.com/novox/mesh-controller/internal/chain"
+)
+
+// An assignment that comes to stand issues its node's bus accounts and the module's grant (ADR 0543, issue 1945): on
+// 2026-10-25 at 17:19 mesh-build-node and mesh-build-go, built long before, were assigned to ace, and nothing issued
+// ace's accounts nor put them in the bus's user list.
+
+func anAssignmentValue(t *testing.T, a chain.Assignment) []byte {
+	t.Helper()
+	raw, err := json.Marshal(a)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return raw
+}
+
+// Only a write that makes the key stand turns it: a rewrite of a standing assignment (the provisioner's plan kept in its
+// value), an ended one, a pending one or a module only pulled in by another does not. The process's first watch hands
+// the assignments standing when it starts to the start's look (not fresh), says once that they are all read, and hands
+// each assignment written afterwards as fresh; a watch opened again after one ended hands every standing assignment it
+// has not seen stand as fresh and never calls the start's look (the review of issue 1945).
+func TestAnAssignmentThatComesToStand(t *testing.T) {
+	at := time.Date(2026, 10, 25, 16, 19, 42, 0, time.UTC)
+	stands := chain.Assignment{Node: "ace", Module: "mesh-build-node", Assigned: at}
+	ended := stands
+	ended.Ended = at.Add(time.Hour)
+	pending := stands
+	pending.State = chain.StatePending
+	pulled := chain.Assignment{Node: "ace", Module: "mesh-build-node", RequiredBy: "mesh-build-go"}
+	replanned := stands
+	replanned.Provisioning = json.RawMessage(`{"plan":1}`)
+
+	type write struct {
+		value   *chain.Assignment // nil for a delete
+		turning bool
+	}
+	for _, c := range []struct {
+		name   string
+		writes []write
+	}{
+		{"a new assignment turns", []write{{&stands, true}}},
+		{"a rewrite of one that stands does not", []write{{&stands, true}, {&replanned, false}, {&stands, false}}},
+		{"an ended one does not", []write{{&ended, false}}},
+		{"assigned again after it ended turns again", []write{{&stands, true}, {&ended, false}, {&stands, true}}},
+		{"a pending one does not, and turns once made", []write{{&pending, false}, {&stands, true}}},
+		{"a module only pulled in does not", []write{{&pulled, false}}},
+		{"one deleted and written again turns again", []write{{&stands, true}, {nil, false}, {&stands, true}}},
+	} {
+		t.Run(c.name, func(t *testing.T) {
+			turns := &assignmentTurns{}
+			for i, w := range c.writes {
+				var value []byte
+				if w.value != nil {
+					value = anAssignmentValue(t, *w.value)
+				}
+				a, turned := turns.heard("ace.mesh-build-node", value)
+				if turned != w.turning {
+					t.Fatalf("write %d: turned %v, want %v", i, turned, w.turning)
+				}
+				if turned && (a.Node != "ace" || a.Module != "mesh-build-node") {
+					t.Fatalf("write %d: the assignment turned is %s on %s", i, a.Module, a.Node)
+				}
+			}
+		})
+	}
+
+	type handed struct {
+		key   string
+		fresh bool
+	}
+	for _, first := range []bool{true, false} {
+		t.Run(fmt.Sprintf("the watch, first %v", first), func(t *testing.T) {
+			bucket := chain.NewMemory()
+			put := func(a chain.Assignment) {
+				t.Helper()
+				value := anAssignmentValue(t, a)
+				if e, held, _ := bucket.Get(t.Context(), a.Key()); held {
+					if _, err := bucket.Update(t.Context(), a.Key(), value, e.Revision); err != nil {
+						t.Fatal(err)
+					}
+					return
+				}
+				if _, err := bucket.Create(t.Context(), a.Key(), value); err != nil {
+					t.Fatal(err)
+				}
+			}
+			put(chain.Assignment{Node: "g14", Module: "mesh-build-go", Assigned: at})
+			got := make(chan handed, 8)
+			read := make(chan struct{}, 8)
+			ctx, stop := context.WithCancel(t.Context())
+			done := make(chan error, 1)
+			go func() {
+				done <- watchAssignmentsOnce(ctx, bucket.Watch, &assignmentTurns{}, first,
+					func(a chain.Assignment, fresh bool) { got <- handed{a.Key(), fresh} },
+					func() { read <- struct{}{} })
+			}()
+			next := func() handed {
+				t.Helper()
+				select {
+				case h := <-got:
+					return h
+				case <-time.After(5 * time.Second):
+					t.Fatal("nothing handed")
+					return handed{}
+				}
+			}
+			// Standing when the watch opened: the start's look on the first watch, fresh on any other.
+			if h := next(); h != (handed{"g14.mesh-build-go", !first}) {
+				t.Fatalf("the standing assignment was handed %+v", h)
+			}
+			put(chain.Assignment{Node: "g14", Module: "mesh-build-go", Assigned: at, Provisioning: json.RawMessage(`{"plan":2}`)})
+			put(chain.Assignment{Node: "ace", Module: "mesh-build-node", Assigned: at})
+			if h := next(); h != (handed{"ace.mesh-build-node", true}) {
+				t.Fatalf("handed %+v, want ace.mesh-build-node as fresh (and nothing for the rewrite before it)", h)
+			}
+			stop()
+			if err := <-done; err != nil {
+				t.Fatal(err)
+			}
+			if want := map[bool]int{true: 1, false: 0}[first]; len(read) != want {
+				t.Fatalf("the start's look was called %d time(s), want %d", len(read), want)
+			}
+		})
+	}
+	// A first watch that fails to open, or ends before its Caught mark, is no start's look: the next watch is, and hands
+	// every standing assignment to it once, none as fresh (the review of issue 1945: a burst of fresh settles, or keys
+	// handed and dropped).
+	for _, firstWatch := range []string{"fails to open", "ends before its Caught mark"} {
+		t.Run("a first watch that "+firstWatch, func(t *testing.T) {
+			bucket := chain.NewMemory()
+			standing := chain.Assignment{Node: "g14", Module: "mesh-build-go", Assigned: at}
+			if _, err := bucket.Create(t.Context(), standing.Key(), anAssignmentValue(t, standing)); err != nil {
+				t.Fatal(err)
+			}
+			watches := 0
+			watch := func(ctx context.Context) (<-chan chain.Entry, error) {
+				watches++
+				if watches > 1 {
+					return bucket.Watch(ctx)
+				}
+				if firstWatch == "fails to open" {
+					return nil, errors.New("the chain is not open yet")
+				}
+				cut := make(chan chain.Entry, 1)
+				cut <- chain.Entry{Key: standing.Key(), Value: anAssignmentValue(t, standing)}
+				close(cut)
+				return cut, nil
+			}
+			var looks [][]chain.Assignment
+			var fresh []chain.Assignment
+			ctx, stop := context.WithCancel(t.Context())
+			defer stop()
+			runAssignmentWatches(ctx, watch, func(a chain.Assignment) { fresh = append(fresh, a) },
+				func(look []chain.Assignment) { looks = append(looks, look); stop() },
+				func() bool { return ctx.Err() == nil })
+			if len(looks) != 1 || len(looks[0]) != 1 || looks[0][0].Key() != standing.Key() || len(fresh) != 0 {
+				t.Fatalf("after %d watch(es): looks %v, fresh %v; want one look at %s and nothing fresh",
+					watches, looks, fresh, standing.Key())
+			}
+		})
+	}
+}
+
+// settle issues what is missing and then puts it on the bus: the node holding the bus composed (its user list) and the
+// grants written, even when every account was minted before (a module assigned again keeps its account). The start's
+// look reads the catalogue once, issues for each standing assignment, and composes the bus's node and writes the grants
+// once when it looked at any. Neither acts for a controller that does not hold the lease, nor for the controller's own
+// module.
+func TestSettlingAndTheStartsLook(t *testing.T) {
+	ace := func(m string) chain.Assignment { return chain.Assignment{Node: "ace", Module: m} }
+	cases := []struct {
+		name               string
+		look               []chain.Assignment // nil: settle mesh-build-node on ace
+		module             string
+		notHolding         bool
+		issued             bool
+		issueErr, composeE error
+		holder             string
+		wantIssues         int
+		wantComposed       []string
+		wantGrants         bool
+		wantErr            string
+	}{
+		{name: "an account not minted", module: "mesh-build-node", issued: true, holder: "novox", wantIssues: 1,
+			wantComposed: []string{"novox"}, wantGrants: true},
+		{name: "an account minted before: the bus and the grants still", module: "mesh-build-go", holder: "novox",
+			wantIssues: 1, wantComposed: []string{"novox"}, wantGrants: true},
+		{name: "no lease: nothing, and tried again", module: "mesh-build-node", notHolding: true, issued: true,
+			holder: "novox", wantErr: errNotHolding.Error()},
+		{name: "the controller's own module is the terminal's", module: controllerModule, issued: true, holder: "novox"},
+		{name: "no bus holder: the grants still", module: "mesh-build-node", issued: true, wantIssues: 1, wantGrants: true},
+		{name: "an issue that fails is the error, nothing composed", module: "mesh-build-node",
+			issueErr: errors.New("the bus cannot be reached"), holder: "novox", wantIssues: 1, wantErr: "the bus cannot be reached"},
+		{name: "a composition that fails is the error, no grant", module: "mesh-build-node", issued: true, holder: "novox",
+			composeE: errors.New("store refused"), wantIssues: 1, wantComposed: []string{"novox"}, wantErr: "store refused"},
+		{name: "the start's look: each issued, the bus and the grants once",
+			look: []chain.Assignment{ace("mesh-build-node"), ace(controllerModule), ace("mesh-build-go")}, issued: true,
+			holder: "novox", wantIssues: 2, wantComposed: []string{"novox"}, wantGrants: true},
+		{name: "the start's look with every account minted still covers once",
+			look: []chain.Assignment{ace("mesh-build-node"), ace("mesh-build-go")}, holder: "novox", wantIssues: 2,
+			wantComposed: []string{"novox"}, wantGrants: true},
+		{name: "the start's look at nothing does nothing", look: []chain.Assignment{ace(controllerModule)}, holder: "novox"},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			var composed []string
+			issues, catalogues, grants := 0, 0, 0
+			steps := assignmentAccountSteps{
+				holds: func(context.Context) bool { return !c.notHolding },
+				catalogue: func(context.Context) (map[string]catalogue.Manifest, error) {
+					catalogues++
+					return map[string]catalogue.Manifest{}, nil
+				},
+				issue: func(context.Context, map[string]catalogue.Manifest, string, string) (bool, string, error) {
+					issues++
+					if c.issued {
+						return true, "its bus credential issued", c.issueErr
+					}
+					return false, "", c.issueErr
+				},
+				busHolder: func(context.Context) (string, error) { return c.holder, nil },
+				compose: func(_ context.Context, nodes []string) error {
+					composed = append(composed, nodes...)
+					return c.composeE
+				},
+				grants: func(context.Context) error { grants++; return nil },
+			}
+			var said string
+			var err error
+			if c.look != nil {
+				said, err = steps.look(t.Context(), c.look)
+			} else {
+				said, err = steps.settle(t.Context(), "ace", c.module)
+			}
+			if c.wantErr != "" {
+				if err == nil || !strings.Contains(err.Error(), c.wantErr) {
+					t.Fatalf("error %v, want one saying %q", err, c.wantErr)
+				}
+			} else if err != nil {
+				t.Fatal(err)
+			}
+			if issues != c.wantIssues || catalogues > 1 {
+				t.Fatalf("%d issue(s) from %d reading(s) of the catalogue, want %d from at most one", issues, catalogues, c.wantIssues)
+			}
+			if strings.Join(composed, ",") != strings.Join(c.wantComposed, ",") {
+				t.Fatalf("composed %v, want %v", composed, c.wantComposed)
+			}
+			if want := map[bool]int{true: 1}[c.wantGrants]; grants != want {
+				t.Fatalf("grants written %d time(s), want %d", grants, want)
+			}
+			if c.wantGrants && c.wantErr == "" && !strings.Contains(said, "the grants written") {
+				t.Fatalf("said %q, want it to name the grants", said)
+			}
+		})
+	}
+}
+
+// The accounts a module speaks with on a node: the module's own when it reads `broker`, its provisioner client's when
+// it runs one alone, none when its accounts are its processes' or it does not speak on the bus. A process's account is
+// held in the provisioner client's form, named for the process and carrying no claims, and may be issued only when
+// the process declares its own secret broker-<process id> (ADR 0436 §2; issue 1181).
+func TestTheAccountsAModuleSpeaksWithOnANode(t *testing.T) {
+	client := aProvisioner()
+	delete(client.OwnSecrets, "broker")
+	for _, c := range []struct {
+		name string
+		m    catalogue.Manifest
+		user string
+		own  bool
+	}{
+		{"a module reading broker", catalogue.Manifest{Module: "mesh-build-node",
+			OwnSecrets: catalogue.OwnSecrets{"broker": {Path: "/var/lib/mesh-build-node/broker"}}},
+			broker.Principal{Kind: broker.KindModule, Node: "ace", Module: "mesh-build-node"}.Username(), true},
+		{"a module reading broker and running the client", aProvisioner(),
+			broker.Principal{Kind: broker.KindModule, Node: "ace", Module: "mesh-provisioner"}.Username(), true},
+		{"the provisioner client alone", client,
+			broker.Principal{Kind: broker.KindProvisioner, Node: "ace", Module: "mesh-provisioner"}.Username(), true},
+		{"no broker, no client", catalogue.Manifest{Module: "hello-web"}, "", false},
+	} {
+		t.Run(c.name, func(t *testing.T) {
+			user, own := ownAccountOf(c.m, "ace")
+			if user != c.user || own != c.own {
+				t.Fatalf("got %q %v, want %q %v", user, own, c.user, c.own)
+			}
+		})
+	}
+
+	t.Run("a process's account", func(t *testing.T) {
+		user := broker.Principal{Kind: broker.KindProcess, Node: "novox", Module: "mesh-mail", Process: "send"}.Username()
+		if user != "novox.mesh-mail.send" {
+			t.Fatalf("the process's username: %q", user)
+		}
+		held, err := heldProcessAccount(broker.Broker{Fingerprint: "abc"}, "novox.example:4222", "novox", "mesh-mail",
+			user, "a-password")
+		if err != nil {
+			t.Fatal(err)
+		}
+		var got map[string]any
+		if err := json.Unmarshal(held, &got); err != nil {
+			t.Fatal(err)
+		}
+		want := map[string]any{"url": "nats://novox.example:4222", "fingerprint": "abc", "node": "novox",
+			"module": "mesh-mail", "user": "novox.mesh-mail.send", "password": "a-password"}
+		for k, v := range want {
+			if got[k] != v {
+				t.Errorf("%s: %v, want %v", k, got[k], v)
+			}
+		}
+		if len(got) != len(want) {
+			t.Errorf("the held account carries %v; want exactly %v (never claims — a process holds no seat)", got, want)
+		}
+	})
+
+	t.Run("a process may be issued only with its own broker secret", func(t *testing.T) {
+		// mesh-mail's real shape: no `broker` of its own, its process declaring bus (review round 1 of issue 1181).
+		if err := mayIssue(mailSenderWithProcess()); err != nil {
+			t.Fatalf("a module with no broker of its own, whose process declares bus, was refused: %v", err)
+		}
+		m := mailSenderWithProcess()
+		delete(m.OwnSecrets, "broker-send")
+		err := mayIssue(m)
+		if err == nil {
+			t.Fatal("a process with no broker-<id> own secret was issued an account")
+		}
+		for _, want := range []string{"mesh-mail", "send", "broker-send", "own-secrets"} {
+			if !strings.Contains(err.Error(), want) {
+				t.Errorf("the refusal does not say %q: %v", want, err)
+			}
+		}
+	})
+}

cmd/mesh-controller/build.go

@@ -273,4 +273,7 @@ type answers struct {
 	// applied, is not well: an assignment somebody made is not made yet, or will not be.
 	pending       []inventory.PendingAssignment
 	pendingUnread string
+	// takeIn is the take-in's backlog of done keys on the bus (novox/hq ADR 0544 §6), nil where it cannot be read
+	// (a process with no bus, or a consumer not made yet).
+	takeIn *takeInBacklog
 }

cmd/mesh-controller/chain.go

@@ -49,7 +49,7 @@ func attachTheChain(ctx context.Context, inv *inventory.Inventory, server *link.
 	// keys laid out before skips them, so this takes seconds; one that fails is tried again beside the serving, loudly.
 	if err := inv.LayBuildsOut(ctx, func(format string, args ...any) { fmt.Printf("chain: "+format+"\n", args...) }); err != nil {
 		fmt.Printf("chain: the builds are not laid out under their modules yet, and none is read until they are: %v\n", err)
-		go layBuildsOutSoon(ctx, inv)
+		goServing(ctx, func() { layBuildsOutSoon(ctx, inv) })
 	}
 	// The requests the move of delivery 1 found never handed over are not asked again: the controller asks no build
 	// (novox/hq ADR 0501; issue 1851, A10), and the builder builds every fingerprint the indexer writes.
@@ -80,7 +80,11 @@ func layBuildsOutSoon(ctx context.Context, inv *inventory.Inventory) {
 			Source: "chain", Summary: "the builds are not laid out under their modules, so none is read: "}
 		if err != nil {
 			fmt.Printf("chain: the builds are not laid out under their modules, and none is read until they are: %v\n", err)
-			if keeper := conditionsFrom; keeper != nil && !failed {
+			if ctx.Err() != nil {
+				return // stopped: the next controller lays them out
+			}
+			// A cancelled layout is tried again and raises nothing: a cancellation is no fault of the chain (issue 1945).
+			if keeper := conditionsFrom; keeper != nil && !failed && !errors.Is(err, context.Canceled) {
 				o.Summary += err.Error()
 				if _, oerr := keeper.Observe(ctx, o); oerr == nil {
 					failed = true

cmd/mesh-controller/composed_integration_test.go

@@ -102,8 +102,10 @@ func TestTheDeclarationsStreamGoesOnceEveryNodeRunsTheNewEngine(t *testing.T) {
 	// The new node-engine registered at its fingerprint, from its done key.
 	n6 := fpOf('6')
 	keys, trunk := aKeyFor("mesh-host", "6", n6, "novox/mesh-host", "", "f00d0123456789ab")
-	if _, err := liveDoneKeySteps(m.open, trunkKeys{keyBuckets: keys, trunk: trunk}).take(ctx, "mesh-host"); err != nil {
-		t.Fatal(err)
+	settled, _ := liveTakeInSteps(m.open, trunkKeys{keyBuckets: keys, trunk: trunk}, m.js).batch(ctx,
+		[]delivered{{module: "mesh-host", again: true}}, map[string]string{})
+	if len(settled) != 1 || settled[0].err != nil || settled[0].verdict != acknowledged {
+		t.Fatalf("the take-in of mesh-host: %+v", settled)
 	}
 	if _, err := m.js.CreateOrUpdateKeyValue(ctx, jetstream.KeyValueConfig{Bucket: sdkdelivery.HaveBucket, History: sdkdelivery.HaveHistory}); err != nil {
 		t.Fatal(err)

cmd/mesh-controller/composed_keys.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"maps"
+	"slices"
 	"sort"
 	"strings"
 	"sync"
@@ -12,205 +14,285 @@ import (
 	"git.novox.be/novox/mesh-sdk/go/catalogue"
 	sdkdelivery "git.novox.be/novox/mesh-sdk/go/delivery"
 	"github.com/nats-io/nats.go/jetstream"
+	"github.com/novox/mesh-controller/internal/broker"
 	"github.com/novox/mesh-controller/internal/builderkeys"
 	"github.com/novox/mesh-controller/internal/conditions"
 	"github.com/novox/mesh-controller/internal/inventory"
 )
 
 // A new fingerprint of a registered module, from its done key to its compositions (novox/hq ADR 0539 clauses 5 and 7,
-// ADR 0501 §2). With no delivery plan left to take a module's done key in, a write of the builder's or the indexer's
-// keys does it: the controller takes in the done key of the fingerprint the indexer's trunk value names (registers the
-// module at it, as a plan's take-in did), composes every node the module is assigned to (which makes what a module's
-// new manifest needs, a credential among it, as a send made it), composes the node holding the bus (its user list now
-// carries the module's permissions at the new fingerprint: a new revision of the bus module's composition alone,
-// written into its want at once by the assigner), and writes `grants.<module>.<fp>`. The assigner's sixth and seventh
-// rules then let a want name the fingerprint. **No timer**: woken by the keys, and a starting controller looks at every
-// module once (doneKeysAtStart).
+// ADR 0501 §2, ADR 0544). With no delivery plan left to take a module's done key in, a write of the builder's or the
+// indexer's keys does it: the controller takes in the done key of the fingerprint the indexer's trunk value names
+// (registers the module at it, as a plan's take-in did), composes every node the module is assigned to (which makes what
+// a module's new manifest needs, a credential among it), composes the node holding the bus (its user list now carries
+// the module's permissions at the new fingerprint), and writes `grants.<module>.<fp>`. The assigner's sixth and seventh
+// rules then let a want name the fingerprint.
+//
+// **A durable pull consumer, not a watch** (ADR 0544; research 072, milestones 2 and 4). The writes are read from two
+// durable consumers (take_in_consumer.go): the bus keeps what is not taken in yet, so a restart takes in only what the
+// controller before it left unacknowledged, and the start's look is the consumers' own catch-up. A batch of keys asks the
+// composer twice whatever its size, and a key with nothing new composes nothing.
 
-// doneKeySteps are what taking a module's done key in does, each a step a test may stand in for.
-type doneKeySteps struct {
-	// held says the catalogue holds the module (a new one is the new-module take-in's, new_modules.go).
-	held func(ctx context.Context, module string) (bool, error)
+// takeInSteps are what taking a batch of done keys in does, each a step a test may stand in for.
+type takeInSteps struct {
+	// catalogue is every module the catalogue holds, with the nodes it is assigned to: read once a batch. A module it
+	// does not hold is the new-module take-in's (new_modules.go).
+	catalogue func(ctx context.Context) (map[string][]string, error)
 	// trunk is the indexer's trunk value of the module.
 	trunk func(ctx context.Context, module string) (sdkdelivery.Module, error)
-	// registeredAt says the module is registered at the commit.
-	registeredAt func(ctx context.Context, module, commit string) (bool, error)
-	// takeIn registers the module from the builder's done key of the trunk's fingerprint (takeInKey); errKeyWaits when
-	// the key is not done yet.
+	// registered says whether the module is registered at the trunk's commit, and whether at its fingerprint: a commit
+	// that moves while the fingerprint stays (a catalogue merge that leaves the module's sources alone) is no new build.
+	registered func(ctx context.Context, module string, trunk sdkdelivery.Module) (atCommit, atFP bool, err error)
+	// recordCommit records the module's registration at the trunk's commit, its fingerprint unchanged: nothing composed.
+	recordCommit func(ctx context.Context, module, commit string) error
+	// takeIn registers the module from the builder's done key of the trunk's fingerprint (takeInKey).
 	takeIn func(ctx context.Context, module string, trunk sdkdelivery.Module) error
-	// nodesOf are the nodes the module is assigned to; busHolder the node holding the bus, "" for none.
-	nodesOf   func(ctx context.Context, module string) ([]string, error)
+	// taken says the module's compositions at fp exist for every node and its grant is written: nothing to compose.
+	taken func(ctx context.Context, module, fp string, nodes []string) (bool, error)
+	// busHolder is the node holding the bus, "" for none.
 	busHolder func(ctx context.Context) (string, error)
-	// compose writes the nodes' compositions; grants writes the grants issued.
-	compose func(ctx context.Context, nodes []string) error
-	grants  func(ctx context.Context) error
+	// compose composes the nodes, and writes the grants after when grants: each node's error, and the grants'.
+	compose func(ctx context.Context, nodes []string, grants bool) (map[string]error, error, error)
 }
 
-// take takes module's done key in and composes what it changed. It answers what it did in a line, "" when there was
-// nothing to do.
-func (s doneKeySteps) take(ctx context.Context, module string) (string, error) {
-	held, err := s.held(ctx, module)
-	if err != nil || !held {
-		return "", err
-	}
-	trunk, err := s.trunk(ctx, module)
-	if errors.Is(err, builderkeys.ErrNoValue) {
-		return "", nil
-	}
-	if err != nil {
-		return "", err
-	}
-	if !strings.HasPrefix(trunk.FP2, sdkdelivery.SourcePrefix2) {
-		return "", nil
-	}
-	at, err := s.registeredAt(ctx, module, trunk.Commit)
-	if err != nil {
-		return "", err
-	}
-	said := ""
-	if !at {
-		if err := s.takeIn(ctx, module, trunk); err != nil {
-			return "", err
-		}
-		said = fmt.Sprintf("%s registered from the builder's done key %s (%s)", module, short(trunk.FP2), short(trunk.Commit))
-	}
-	nodes, err := s.nodesOf(ctx, module)
-	if err != nil {
-		return said, err
-	}
-	if len(nodes) == 0 {
-		return said, nil
-	}
-	// The module's nodes first: composing them makes what the new manifest needs, its credentials among it.
-	if err := s.compose(ctx, nodes); err != nil {
-		return said, err
-	}
-	// Then the bus's user list, which carries the module's permissions at its new fingerprint.
-	holder, err := s.busHolder(ctx)
-	if err != nil {
-		return said, err
-	}
-	if holder != "" && !inList(nodes, holder) {
-		if err := s.compose(ctx, []string{holder}); err != nil {
-			return said, err
-		}
-	}
-	// Then the grant, which with the composition lets a want name the fingerprint (rules 6 and 7).
-	if err := s.grants(ctx); err != nil {
-		return said, err
-	}
-	if said == "" {
-		said = fmt.Sprintf("%s at %s", module, short(trunk.FP2))
-	}
-	return said + "; composed for " + strings.Join(nodes, ", ") + ", its grant written", nil
+// delivered is one key a consumer delivered: its module, and whether it was delivered before (a take-in that may have
+// stopped half-way, so it is taken in whole).
+type delivered struct {
+	module string
+	again  bool
+	// deliveries is how often the bus delivered it, this time included: what a refusal's delay grows with.
+	deliveries uint64
 }
 
-func inList(list []string, s string) bool {
-	for _, v := range list {
-		if v == s {
-			return true
-		}
-	}
-	return false
-}
+// verdict is what becomes of a module's delivered keys.
+type verdict int
 
-// doneKeyTakeOnce is one take-in; a variable so a test may stand in for it. doneKeysSay says a line of the take-ins.
-var (
-	doneKeyTakeOnce = takeDoneKeyOnce
-	doneKeysSay     = func(s string) { fmt.Println(s) }
+const (
+	// acknowledged: taken in, nothing new, a wait a later write ends, or a build key that failed.
+	acknowledged verdict = iota
+	// refused: delivered again by the bus after doneKeyRetry (a wait on a read, or a failure).
+	refused
 )
 
-// doneKeysBeforeLetGo is called just before a follower lets go of its module; a variable so a test can wake the module
-// at that moment. Nil does nothing.
-var doneKeysBeforeLetGo func(module string)
-
-// doneKeysLookAgain marks a module woken while a take-in of it ran: that take-in goes round once more.
-var doneKeysLookAgain sync.Map
-
-// doneKeysMu keeps one take-in of a module's done key at a time in this process, per module.
-var doneKeysMu sync.Map
-
-// takeDoneKey is a woken module's take-in on the live stores and buckets, said. A take-in that fails (its compositions
-// or its grant not written) is tried again every doneKeyRetry while it fails, loudly: printed each time, and an urgent
-// condition raised by the first until it has worked, as the chain's own moves are (layBuildsOutSoon). A key not done
-// yet is no failure: it is said once for each reason it waits for and looked at again every doneKeyRetry.
-func takeDoneKey(ctx context.Context, open *stores, module string) {
-	mu, _ := doneKeysMu.LoadOrStore(module, &sync.Mutex{})
-	for {
-		if !mu.(*sync.Mutex).TryLock() {
-			// A take-in of the module already follows it: it is told to look again once it is done, so a newer key
-			// written meanwhile is never lost (the review of issue 1945).
-			doneKeysLookAgain.Store(module, true)
-			return
-		}
-		followDoneKey(ctx, open, module)
-		if doneKeysBeforeLetGo != nil {
-			doneKeysBeforeLetGo(module)
-		}
-		mu.(*sync.Mutex).Unlock()
-		// A wake between this follower's last look and its letting go failed its TryLock and only marked the module:
-		// looked at again now that it is let go, and taken once more (the review of issue 1945).
-		if _, again := doneKeysLookAgain.LoadAndDelete(module); !again || ctx.Err() != nil {
-			return
-		}
-	}
+// settledKey is what a batch did with one module.
+type settledKey struct {
+	module  string
+	verdict verdict
+	// taken: registered, composed and granted now (not nothing new); its condition is cleared.
+	taken bool
+	// nothingNew: registered and composed before, so nothing was done.
+	nothingNew bool
+	// waits is why it waits, "" when it does not.
+	waits string
+	// err is a failure: raised as the module's condition.
+	err error
+	// said is the line said of it, "" for none.
+	said string
 }
 
-// followDoneKey takes a module's done key in, under the module's lock, until it is taken in or ctx ends: a failure or a
-// wait is tried again every doneKeyRetry.
-func followDoneKey(ctx context.Context, open *stores, module string) {
-	failed := false
-	saidWait := ""
-	for {
-		doneKeysLookAgain.Delete(module) // what this look reads covers every wake before it
-		err := takeOnceInSlot(ctx, open, module)
-		o := doneKeyObservation(module)
-		if err == nil {
-			if keeper := conditionsFrom; keeper != nil && failed {
-				_, _ = keeper.Clear(ctx, o.Key(), "composed and granted")
-				failed = false
-			}
-			if _, again := doneKeysLookAgain.LoadAndDelete(module); again {
-				continue // a wake came while this one ran: once more, for the key written meanwhile
-			}
-			return
+// batch takes the delivered keys in, each module once: it answers one settledKey per module in the order first
+// delivered, and the number of composer passes it asked. memo is, per module, the trunk (fingerprint and commit) this
+// process took in last; a module at the same trunk delivered for the first time has nothing new.
+func (s takeInSteps) batch(ctx context.Context, keys []delivered, memo map[string]string) ([]settledKey, int) {
+	var order []string
+	again := map[string]bool{}
+	for _, k := range keys {
+		if _, seen := again[k.module]; !seen {
+			order = append(order, k.module)
 		}
-		if errors.Is(err, errKeyWaits) {
-			// A take-in that waits is said once for each reason, and tried again every doneKeyRetry: the key write that
-			// would wake it may never come (issue 1945, live on 2026-10-25: mesh-host's take-in waited unsaid).
-			if why := err.Error(); why != saidWait {
-				doneKeysSay(fmt.Sprintf("done keys: %s waits: %s; looked at again every %s", module,
-					strings.TrimPrefix(why, errKeyWaits.Error()+": "), doneKeyRetry))
-				saidWait = why
-			}
-		} else {
-			doneKeysSay(fmt.Sprintf("done keys: %s: %v; tried again in %s", module, err, doneKeyRetry))
+		again[k.module] = again[k.module] || k.again
+	}
+	out := make([]settledKey, 0, len(order))
+	all := func(v verdict, err error) ([]settledKey, int) {
+		for _, m := range order {
+			out = append(out, settledKey{module: m, verdict: v, err: err})
 		}
-		if errors.Is(err, errKeyWaits) {
-			select {
-			case <-ctx.Done():
-				return
-			case <-time.After(doneKeyRetry):
-			}
+		return out, 0
+	}
+	held, err := s.catalogue(ctx)
+	if err != nil {
+		return all(refused, fmt.Errorf("the catalogue cannot be read: %w", err))
+	}
+	type toCompose struct {
+		at    int
+		nodes []string
+		mark  string
+		said  string
+	}
+	var need []toCompose
+	for _, m := range order {
+		r := settledKey{module: m}
+		nodes, isHeld := held[m]
+		if !isHeld {
+			out = append(out, r)
 			continue
 		}
-		if keeper := conditionsFrom; keeper != nil && !failed {
-			o.Summary += err.Error()
-			if _, oerr := keeper.Observe(ctx, o); oerr == nil {
-				failed = true
+		trunk, err := s.trunk(ctx, m)
+		if errors.Is(err, builderkeys.ErrNoValue) {
+			out = append(out, r)
+			continue
+		}
+		if err == nil && !strings.HasPrefix(trunk.FP2, sdkdelivery.SourcePrefix2) {
+			// The indexer's next write names one: said once, as every wait for a write (ADR 0544 §4).
+			why := trunk.None2
+			if why == "" {
+				why = "the indexer wrote no fingerprint of the new form"
+			}
+			r.waits = fmt.Sprintf("%v: %s at %.8s has no fingerprint to take a build by: %s", errWaitsForAWrite, m,
+				trunk.Commit, why)
+			out = append(out, r)
+			continue
+		}
+		if err != nil {
+			r.verdict, r.err = refused, err
+			out = append(out, r)
+			continue
+		}
+		mark := trunk.FP2 + "@" + trunk.Commit
+		if !again[m] && memo[m] == mark {
+			r.nothingNew = true
+			out = append(out, r)
+			continue
+		}
+		at, atFP, err := s.registered(ctx, m, trunk)
+		if err == nil && !at && atFP {
+			// Only the commit moved (issue 1945: every catalogue merge took about 200 modules in again, 25 minutes): the
+			// new commit is recorded, and the module is judged as one registered, composed only if something is missing.
+			if err = s.recordCommit(ctx, m, trunk.Commit); err == nil {
+				at = true
 			}
 		}
-		select {
-		case <-ctx.Done():
-			return
-		case <-time.After(doneKeyRetry):
+		if err != nil {
+			r.verdict, r.err = refused, err
+			out = append(out, r)
+			continue
+		}
+		said := ""
+		if !at {
+			if err := s.takeIn(ctx, m, trunk); err != nil {
+				switch {
+				case errors.Is(err, errWaitsForAWrite):
+					r.waits = err.Error()
+				case errors.Is(err, errKeyWaits):
+					r.verdict, r.waits = refused, err.Error()
+				case errors.Is(err, errKeyFailed):
+					r.err = err // acknowledged: only a new build ends it, and its key is delivered then
+				default:
+					r.verdict, r.err = refused, err
+				}
+				out = append(out, r)
+				continue
+			}
+			said = fmt.Sprintf("%s registered from the builder's done key %s (%s)", m, short(trunk.FP2), short(trunk.Commit))
+		} else if !again[m] {
+			// Registered at its trunk already: composed and granted by a take-in before this one, or at this
+			// controller's start, unless that take-in stopped half-way, which leaves a composition or the grant missing.
+			if done, err := s.taken(ctx, m, trunk.FP2, nodes); err == nil && done {
+				memo[m] = mark
+				r.nothingNew = true
+				out = append(out, r)
+				continue
+			}
+		}
+		if len(nodes) == 0 {
+			memo[m] = mark
+			r.taken, r.said = true, said
+			out = append(out, r)
+			continue
+		}
+		if said == "" {
+			said = fmt.Sprintf("%s at %s", m, short(trunk.FP2))
+		}
+		need = append(need, toCompose{at: len(out), nodes: nodes, mark: mark, said: said})
+		out = append(out, r)
+	}
+	if len(need) == 0 {
+		return out, 0
+	}
+	refuseNeed := func(err error) ([]settledKey, int) {
+		for _, n := range need {
+			out[n.at].verdict, out[n.at].err = refused, err
+		}
+		return out, 0
+	}
+	holder, err := s.busHolder(ctx)
+	if err != nil {
+		return refuseNeed(fmt.Errorf("the node holding the bus cannot be read: %w", err))
+	}
+	// The modules' nodes first, in one pass: composing them makes what their new manifests need, credentials among it.
+	var union []string
+	for _, n := range need {
+		for _, node := range n.nodes {
+			if node != holder && !slices.Contains(union, node) {
+				union = append(union, node)
+			}
 		}
 	}
+	sort.Strings(union)
+	passes := 0
+	failed := map[string]error{}
+	if len(union) > 0 {
+		f, _, err := s.compose(ctx, union, false)
+		passes++
+		if err != nil {
+			return refuseNeed(err)
+		}
+		maps.Copy(failed, f)
+	}
+	// Then the bus's user list, which carries the modules' permissions at their new fingerprints, and the grants, which
+	// with the compositions let a want name each fingerprint (rules 6 and 7).
+	var bus []string
+	if holder != "" {
+		bus = []string{holder}
+	}
+	f, grantsErr, err := s.compose(ctx, bus, true)
+	passes++
+	if err != nil {
+		return refuseNeed(err)
+	}
+	maps.Copy(failed, f)
+	for _, n := range need {
+		var errs []error
+		for _, node := range append(slices.Clone(n.nodes), bus...) {
+			if e := failed[node]; e != nil && !slices.ContainsFunc(errs, func(x error) bool { return x == e }) {
+				errs = append(errs, e)
+			}
+		}
+		if grantsErr != nil {
+			errs = append(errs, grantsErr)
+		}
+		r := &out[n.at]
+		if len(errs) > 0 {
+			r.verdict, r.err = refused, errors.Join(errs...)
+			continue
+		}
+		memo[r.module] = n.mark
+		r.taken = true
+		r.said = n.said + "; composed for " + strings.Join(n.nodes, ", ") + ", its grant written"
+	}
+	return out, passes
 }
 
-// doneKeyRetry is how long a failed take-in of a done key waits before it tries again.
+// doneKeysSay says a line of the take-ins; a variable so a test may hear it.
+var doneKeysSay = func(s string) { fmt.Println(s) }
+
+// doneKeyRetry is how long the bus waits before it delivers again a key whose take-in was refused the first time; each
+// refusal after doubles it, up to doneKeyRetryMost, so a key refused for long (a manifest word this controller does not
+// read yet, a node whose composition keeps failing) costs a take-in every few minutes, not every half minute.
 var doneKeyRetry = 30 * time.Second
 
+// doneKeyRetryMost is the longest a refused key waits before it is delivered again.
+const doneKeyRetryMost = 10 * time.Minute
+
+// refusalDelay is how long the bus waits before it delivers again a key refused on its deliveries-th delivery.
+func refusalDelay(deliveries uint64) time.Duration {
+	d := doneKeyRetry
+	for i := uint64(1); i < deliveries && d < doneKeyRetryMost; i++ {
+		d *= 2
+	}
+	return min(d, doneKeyRetryMost)
+}
+
 // kindNotComposed is the condition of a module's new fingerprint whose compositions or grant are not written: until
 // they are, no want can name it.
 const kindNotComposed = "fingerprint-not-composed"
@@ -221,40 +303,37 @@ func doneKeyObservation(module string) conditions.Observation {
 		Summary: module + "'s new fingerprint is not composed or granted, so no want can name it: "}
 }
 
-// takeDoneKeyOnce is one take-in of a module's done key.
-func takeDoneKeyOnce(ctx context.Context, open *stores, module string) error {
-	keys, closeKeys, err := openBuilderKeys()
-	if err != nil {
-		return fmt.Errorf("the builder's keys cannot be read: %w", err)
-	}
-	defer closeKeys()
-	said, err := liveDoneKeySteps(open, keys).take(ctx, module)
-	if err == nil && said != "" {
-		fmt.Printf("done keys: %s\n", said)
-	}
-	return err
-}
-
-// liveDoneKeySteps are the steps on the controller's own stores and the bus.
-func liveDoneKeySteps(open *stores, keys registerKeys) doneKeySteps {
+// liveTakeInSteps are the steps on the controller's own stores and the bus.
+func liveTakeInSteps(open *stores, keys registerKeys, js jetstream.JetStream) takeInSteps {
 	inv := open.inventory
-	return doneKeySteps{
-		held: func(ctx context.Context, module string) (bool, error) {
-			_, err := inv.SourceOf(ctx, module)
-			if errors.Is(err, inventory.ErrNoSuchModule) {
-				return false, nil
+	return takeInSteps{
+		catalogue: func(ctx context.Context) (map[string][]string, error) {
+			entries, err := inv.Catalogued(ctx)
+			if err != nil {
+				return nil, err
 			}
-			return err == nil, err
+			out := make(map[string][]string, len(entries))
+			for _, e := range entries {
+				out[e.Manifest.Module] = e.On
+			}
+			return out, nil
 		},
 		trunk: func(ctx context.Context, module string) (sdkdelivery.Module, error) {
 			return keys.ModuleAt(ctx, module, "")
 		},
-		registeredAt: func(ctx context.Context, module, commit string) (bool, error) {
+		registered: func(ctx context.Context, module string, trunk sdkdelivery.Module) (bool, bool, error) {
 			src, err := inv.SourceOf(ctx, module)
 			if err != nil {
-				return false, err
+				return false, false, err
 			}
-			return sameCommitID(src.BuiltFrom, commit), nil
+			if sameCommitID(src.BuiltFrom, trunk.Commit) {
+				return true, true, nil
+			}
+			fp, err := registeredFingerprint(ctx, inv, keys, module, src.BuiltFrom)
+			return false, err == nil && fp != "" && fp == trunk.FP2, nil
+		},
+		recordCommit: func(ctx context.Context, module, commit string) error {
+			return inv.RecordBuiltFrom(ctx, module, commit)
 		},
 		takeIn: func(ctx context.Context, module string, trunk sdkdelivery.Module) error {
 			_, _, err := takeInKey(ctx, inv, keys, keyTake{Module: module, Trunk: trunk, Ask: registrationAsk{Merge: trunk.Commit}})
@@ -263,17 +342,8 @@ func liveDoneKeySteps(open *stores, keys registerKeys) doneKeySteps {
 			}
 			return err
 		},
-		nodesOf: func(ctx context.Context, module string) ([]string, error) {
-			entries, err := inv.Catalogued(ctx)
-			if err != nil {
-				return nil, err
-			}
-			for _, e := range entries {
-				if e.Manifest.Module == module {
-					return e.On, nil
-				}
-			}
-			return nil, nil
+		taken: func(ctx context.Context, module, fp string, nodes []string) (bool, error) {
+			return composedAndGranted(ctx, js, module, fp, nodes)
 		},
 		busHolder: func(ctx context.Context) (string, error) {
 			holders, err := seatHolders(ctx, inv)
@@ -284,123 +354,64 @@ func liveDoneKeySteps(open *stores, keys registerKeys) doneKeySteps {
 		},
 		// The composer's, never the take-in's own: one pass at a time composes each node asked for once, and writes the
 		// grants once (issue 1945, composer.go).
-		compose: func(ctx context.Context, nodes []string) error {
-			return composerFor(open).compose(ctx, nodes, false)
-		},
-		grants: func(ctx context.Context) error {
-			return composerFor(open).compose(ctx, nil, true)
+		compose: func(ctx context.Context, nodes []string, grants bool) (map[string]error, error, error) {
+			return composerFor(open).composeEach(ctx, nodes, grants)
 		},
 	}
 }
 
-// watchDoneKeys wakes the take-in of a module's done key for each module the builder or the indexer writes, until ctx
-// ends: never on the watch's own goroutine.
-func watchDoneKeys(ctx context.Context, open *stores) {
-	keys, closeKeys, err := openBuilderKeys()
-	if err != nil {
-		fmt.Printf("done keys: the builder's keys are not watched: %v\n", err)
-		return
+// registeredFingerprint is the fingerprint a module is registered at, as currentFingerprints reads it: its commit's
+// newest build's, or the indexer's value at the commit when the commit has no build of its own; "" when neither says.
+func registeredFingerprint(ctx context.Context, inv *inventory.Inventory, keys registerKeys, module, commit string) (string, error) {
+	if commit == "" {
+		return "", nil
 	}
-	if err := builderkeys.Watch(ctx, keys.JS, func(module string) {
-		inBackground(func() { takeDoneKey(ctx, open, module) })
-	}); err != nil {
-		closeKeys()
-		fmt.Printf("done keys: the builder's keys are not watched: %v\n", err)
-		return
-	}
-	go func() {
-		<-ctx.Done()
-		closeKeys()
-	}()
-	// And every module once now, after the watch is open so no write falls between the two.
-	inBackground(func() {
-		doneKeysAtStart(ctx, catalogedModules(open), func(module string) { takeDoneKeyAtStart(ctx, open, module) })
-	})
-}
-
-// doneKeysAtStart takes in the done key of every catalogued module once, one after another: the start's look the watch of
-// new writes cannot give (it hears updates only). A done key written while no controller served, or whose take-in the
-// controller this one replaced was stopped in, is taken here; without it the module stays in the node's own composition
-// with no credential until its keys are written again (issue 1945, live on 2026-10-25 at 02:34). A take-in with nothing
-// to do does nothing; a catalogue that cannot be read is said.
-func doneKeysAtStart(ctx context.Context, modules func(context.Context) ([]string, error), take func(module string)) {
-	names, err := modules(ctx)
-	if err != nil {
-		fmt.Printf("done keys: the modules are not looked at once at the start: %v\n", err)
-		return
-	}
-	sort.Strings(names)
-	// Side by side, a few at a time: their compositions meet in the composer's passes, each node composed once per pass
-	// (issue 1945), so the start's look is not one module's composition after another.
-	sem := make(chan struct{}, startTakeIns)
-	var wg sync.WaitGroup
-	for _, m := range names {
-		if ctx.Err() != nil {
-			break
+	if id, err := inv.BuildOf(ctx, module, commit); err == nil && id != "" {
+		if b, found, err := inv.BuildByID(ctx, id); err == nil && found && b.SourceFingerprint != "" {
+			return b.SourceFingerprint, nil
 		}
-		sem <- struct{}{}
-		wg.Add(1)
-		go func() {
-			defer func() { <-sem; wg.Done() }()
-			take(m)
-		}()
 	}
-	wg.Wait()
+	at, err := keys.ModuleAt(ctx, module, commit)
+	if err != nil {
+		return "", err
+	}
+	return at.FP2, nil
 }
 
-// startTakeIns is how many take-ins the start's look runs at once, and how many run at once in all.
-const startTakeIns = 16
-
-// takeInSlots are the take-ins that may run at once in this process, the watch's and the start's look's together: a
-// burst of done keys (about 120 at 16:07:36 on 2026-10-25) once started a take-in each, all at once, and their reads
-// filled the store until it refused every connection (issues 1945 and 1277).
-var takeInSlots = make(chan struct{}, startTakeIns)
-
-// takeOnceInSlot is one take-in once a slot is free; a take-in that waits for its next try holds none.
-func takeOnceInSlot(ctx context.Context, open *stores, module string) error {
-	select {
-	case takeInSlots <- struct{}{}:
-	case <-ctx.Done():
-		return ctx.Err()
+// composedAndGranted says the bus holds module's grant at fp and its composition at fp for every node: a few reads of
+// keys, never a composition.
+func composedAndGranted(ctx context.Context, js jetstream.JetStream, module, fp string, nodes []string) (bool, error) {
+	grants, err := js.KeyValue(ctx, broker.GrantsBucket)
+	if err != nil {
+		return false, err
 	}
-	defer func() { <-takeInSlots }()
-	return doneKeyTakeOnce(ctx, open, module)
-}
-
-// takeDoneKeyAtStart is one take-in of the start's look, under the module's lock; one that fails is handed to takeDoneKey,
-// which tries again every doneKeyRetry, loudly, so a failing module never holds up the look at the others.
-func takeDoneKeyAtStart(ctx context.Context, open *stores, module string) {
-	mu, _ := doneKeysMu.LoadOrStore(module, &sync.Mutex{})
-	if !mu.(*sync.Mutex).TryLock() {
-		// A take-in already follows the module: told to look again, it takes what the start would have (issue 1945).
-		doneKeysLookAgain.Store(module, true)
-		return
+	key, err := sdkdelivery.ControllerGrantKey(module, fp)
+	if err != nil {
+		return false, err
 	}
-	doneKeysLookAgain.Delete(module) // what this look reads covers every wake before it
-	err := takeOnceInSlot(ctx, open, module)
-	mu.(*sync.Mutex).Unlock()
-	// Read after letting go, as every holder of a module's lock does: a wake during this look only marked the module
-	// (the review of issue 1945).
-	_, again := doneKeysLookAgain.LoadAndDelete(module)
-	if err != nil || again {
-		// A failure, a wait or a wake meanwhile is followed by takeDoneKey, which says it and looks again.
-		inBackground(func() { takeDoneKey(ctx, open, module) })
+	if _, err := grants.Get(ctx, key); err != nil {
+		if errors.Is(err, jetstream.ErrKeyNotFound) {
+			return false, nil
+		}
+		return false, err
 	}
-}
-
-// catalogedModules are the names of every module the catalogue holds.
-func catalogedModules(open *stores) func(context.Context) ([]string, error) {
-	return func(ctx context.Context) ([]string, error) {
-		entries, err := open.inventory.Catalogued(ctx)
+	digests, err := js.KeyValue(ctx, sdkdelivery.ControllerComposedBucket)
+	if err != nil {
+		return false, err
+	}
+	for _, node := range nodes {
+		key, err := sdkdelivery.ComposedKey(node, module, fp)
 		if err != nil {
-			return nil, err
+			return false, err
 		}
-		out := make([]string, 0, len(entries))
-		for _, e := range entries {
-			out = append(out, e.Manifest.Module)
+		if _, err := digests.Get(ctx, key); err != nil {
+			if errors.Is(err, jetstream.ErrKeyNotFound) {
+				return false, nil
+			}
+			return false, err
 		}
-		return out, nil
 	}
+	return true, nil
 }
 
 // doneKeysComposers are the composers of the done keys' take-ins in this process, one for each set of stores (a test

cmd/mesh-controller/composed_keys_cap_test.go

@@ -1,58 +0,0 @@
-package main
-
-import (
-	"context"
-	"fmt"
-	"sync"
-	"sync/atomic"
-	"testing"
-	"time"
-)
-
-// A burst of done keys runs at most startTakeIns take-ins at once, the watch's and the start's look together: at
-// 16:07:36 on 2026-10-25 the builder rewrote about 120 done keys at once, each woke its own take-in, and each opened
-// pools of its own until novox's store refused every connection (issues 1945 and 1277).
-func TestABurstOfDoneKeysRunsAtMostSixteenTakeInsAtOnce(t *testing.T) {
-	was := doneKeyTakeOnce
-	t.Cleanup(func() { doneKeyTakeOnce = was })
-	var running, most atomic.Int64
-	var taken atomic.Int64
-	doneKeyTakeOnce = func(context.Context, *stores, string) error {
-		now := running.Add(1)
-		for {
-			m := most.Load()
-			if now <= m || most.CompareAndSwap(m, now) {
-				break
-			}
-		}
-		time.Sleep(2 * time.Millisecond)
-		running.Add(-1)
-		taken.Add(1)
-		return nil
-	}
-	ctx := context.Background()
-	var wg sync.WaitGroup
-	// The watch's wakes: one take-in each, in the background, as watchDoneKeys starts them.
-	for i := range 120 {
-		wg.Add(1)
-		go func() { defer wg.Done(); takeDoneKey(ctx, nil, fmt.Sprintf("burst-%03d", i)) }()
-	}
-	// And the start's look at the same moment, over other modules.
-	wg.Add(1)
-	go func() {
-		defer wg.Done()
-		var start []string
-		for i := range 40 {
-			start = append(start, fmt.Sprintf("start-%03d", i))
-		}
-		doneKeysAtStart(ctx, func(context.Context) ([]string, error) { return start, nil },
-			func(m string) { takeDoneKeyAtStart(ctx, nil, m) })
-	}()
-	wg.Wait()
-	if got := taken.Load(); got != 160 {
-		t.Fatalf("took in %d modules, want 160", got)
-	}
-	if m := most.Load(); m > startTakeIns {
-		t.Fatalf("ran %d take-ins at once, want at most %d", m, startTakeIns)
-	}
-}

cmd/mesh-controller/composed_keys_start_test.go

@@ -1,34 +0,0 @@
-package main
-
-import (
-	"context"
-	"errors"
-	"reflect"
-	"sort"
-	"sync"
-	"testing"
-)
-
-// A starting controller takes in the done key of every catalogued module once, beside the watch of new writes: a done key
-// written while no controller served, or whose take-in the controller it replaced was stopped in, is otherwise never
-// taken, and its module stays in the node's own composition with no credential (issue 1945, live on 2026-10-25 at 02:34:
-// the controller replaced mid take-in left mesh-provisioner-client, gitea, postgres and many more unregistered at their
-// new fingerprints, and the new one, watching updates only, never looked).
-func TestAStartingControllerTakesEveryModulesDoneKeyOnce(t *testing.T) {
-	var took []string
-	var mu sync.Mutex
-	doneKeysAtStart(context.Background(), func(context.Context) ([]string, error) {
-		return []string{"mesh-provisioner-client", "gitea", "postgres"}, nil
-	}, func(module string) { mu.Lock(); took = append(took, module); mu.Unlock() })
-	sort.Strings(took)
-	if want := []string{"gitea", "mesh-provisioner-client", "postgres"}; !reflect.DeepEqual(took, want) {
-		t.Fatalf("took %v, want %v", took, want)
-	}
-	// A catalogue that cannot be read takes nothing and is said, never fatal.
-	took = nil
-	doneKeysAtStart(context.Background(), func(context.Context) ([]string, error) { return nil, errors.New("down") },
-		func(module string) { took = append(took, module) })
-	if len(took) != 0 {
-		t.Fatalf("took %v from a catalogue that could not be read", took)
-	}
-}

cmd/mesh-controller/composed_keys_test.go

@@ -4,84 +4,305 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"fmt"
+	"slices"
 	"strings"
 	"testing"
+	"time"
 
 	sdkdelivery "git.novox.be/novox/mesh-sdk/go/delivery"
+	"github.com/nats-io/nats.go/jetstream"
 	"github.com/novox/mesh-controller/internal/builderkeys"
 )
 
-// stepsFor are doneKeySteps over a module registered at registered, whose trunk value names fp at commit, assigned to
-// nodes, the bus held on holder; every act is written to acts in order.
-func stepsFor(acts *[]string, registered, commit, fp string, nodes []string, holder string) doneKeySteps {
-	return doneKeySteps{
-		held: func(_ context.Context, module string) (bool, error) { return module == "mesh-mail", nil },
-		trunk: func(context.Context, string) (sdkdelivery.Module, error) {
-			if fp == "" {
+// aTakeIn is a mesh for the take-in's steps: per module its registered commit, its trunk (commit, fingerprint), its
+// nodes, whether its compositions and grant exist, and what its take-in answers; every act is written to acts.
+type aTakeIn struct {
+	registered map[string]string
+	sameFP     map[string]bool   // registered at another commit, at the trunk's fingerprint
+	trunks     map[string]string // module -> commit; no entry: no trunk value
+	nodes      map[string][]string
+	taken      map[string]bool
+	takeInErr  map[string]error
+	composeErr map[string]error
+	grantsErr  error
+	holder     string
+	acts       []string
+}
+
+func (m *aTakeIn) steps() takeInSteps {
+	fp := func(module string) string { return sdkdelivery.SourcePrefix2 + strings.Repeat(module[:1], 64) }
+	return takeInSteps{
+		catalogue: func(context.Context) (map[string][]string, error) {
+			m.acts = append(m.acts, "catalogue")
+			out := map[string][]string{}
+			for k, v := range m.nodes {
+				out[k] = v
+			}
+			return out, nil
+		},
+		trunk: func(_ context.Context, module string) (sdkdelivery.Module, error) {
+			commit, ok := m.trunks[module]
+			if !ok {
 				return sdkdelivery.Module{}, builderkeys.ErrNoValue
 			}
-			return sdkdelivery.Module{Commit: commit, FP2: fp}, nil
+			return sdkdelivery.Module{Commit: commit, FP2: fp(module)}, nil
+		},
+		registered: func(_ context.Context, module string, trunk sdkdelivery.Module) (bool, bool, error) {
+			if m.registered[module] == trunk.Commit {
+				return true, true, nil
+			}
+			return false, m.sameFP[module], nil
+		},
+		recordCommit: func(_ context.Context, module, commit string) error {
+			m.acts = append(m.acts, "record "+module+" at "+commit)
+			return nil
 		},
-		registeredAt: func(_ context.Context, _ string, c string) (bool, error) { return c == registered, nil },
 		takeIn: func(_ context.Context, module string, trunk sdkdelivery.Module) error {
-			*acts = append(*acts, "take in "+module+" at "+trunk.Commit)
-			return nil
+			m.acts = append(m.acts, "take in "+module+" at "+trunk.Commit)
+			return m.takeInErr[module]
 		},
-		nodesOf:   func(context.Context, string) ([]string, error) { return nodes, nil },
-		busHolder: func(context.Context) (string, error) { return holder, nil },
-		compose: func(_ context.Context, ns []string) error {
-			*acts = append(*acts, "compose "+strings.Join(ns, ","))
-			return nil
+		taken:     func(_ context.Context, module, _ string, _ []string) (bool, error) { return m.taken[module], nil },
+		busHolder: func(context.Context) (string, error) { return m.holder, nil },
+		compose: func(_ context.Context, nodes []string, grants bool) (map[string]error, error, error) {
+			act := "compose " + strings.Join(nodes, ",")
+			if grants {
+				act += " and grants"
+			}
+			m.acts = append(m.acts, act)
+			failed := map[string]error{}
+			for _, n := range nodes {
+				if e := m.composeErr[n]; e != nil {
+					failed[n] = e
+				}
+			}
+			if grants {
+				return failed, m.grantsErr, nil
+			}
+			return failed, nil, nil
 		},
-		grants: func(context.Context) error { *acts = append(*acts, "grants"); return nil },
 	}
 }
 
-// 1945/AC3 (unit half): a done key of a new fingerprint of an assigned module is taken in, then the module's nodes are
-// composed, then the node holding the bus (its user list), then the grants: the grant and the composition exist
-// before the assigner's rules let a want name the fingerprint. A module registered at the trunk's commit already is
-// composed and granted without a second take-in; one assigned nowhere, unregistered, or with no trunk value is left
-// alone.
-func TestADoneKeyIsTakenInComposedAndGranted(t *testing.T) {
-	fp := sdkdelivery.SourcePrefix2 + strings.Repeat("c", 64)
-	var acts []string
-	said, err := stepsFor(&acts, "old", "new", fp, []string{"ace", "g14"}, "novox").take(context.Background(), "mesh-mail")
-	if err != nil {
-		t.Fatal(err)
+// A batch of done keys takes each module in once and asks the composer at most twice, whatever its size: once for the
+// nodes of every module with something new, then once for the node holding the bus with the grants (ADR 0544 §5). A
+// module registered at its trunk whose compositions and grant exist, or that this process took in at the same trunk,
+// composes nothing (§3): the old take-in composed it three times over, every key and every start (issue 1945, 17:36 on
+// 2026-10-25). A key delivered again is taken in whole. A wait for a write is acknowledged, a wait on a read and a
+// failure refused, a failed build key acknowledged with its condition (§4).
+func TestATakeInBatch(t *testing.T) {
+	waitsForAWrite := fmt.Errorf("%w: the key is building", errWaitsForAWrite)
+	waitsOnARead := fmt.Errorf("%w: the store is away", errKeyWaits)
+	keyFailed := fmt.Errorf("%w: the build failed", errKeyFailed)
+	type want struct {
+		verdict           verdict
+		taken, nothingNew bool
+		waits, err        bool
 	}
-	if got := strings.Join(acts, "; "); got != "take in mesh-mail at new; compose ace,g14; compose novox; grants" {
-		t.Errorf("the acts were %q", got)
+	cases := []struct {
+		name   string
+		mesh   aTakeIn
+		keys   []delivered
+		memo   map[string]string
+		acts   []string
+		passes int
+		want   map[string]want
+	}{
+		{name: "a new fingerprint: taken in, its nodes, then the bus's node and the grants",
+			mesh: aTakeIn{registered: map[string]string{"mail": "old"}, trunks: map[string]string{"mail": "new"},
+				nodes: map[string][]string{"mail": {"ace", "g14", "novox"}}, holder: "novox"},
+			keys: []delivered{{module: "mail"}},
+			acts: []string{"catalogue", "take in mail at new", "compose ace,g14", "compose novox and grants"}, passes: 2,
+			want: map[string]want{"mail": {taken: true}}},
+		{name: "registered, composed and granted: nothing composed (fails on the old take-in)",
+			mesh: aTakeIn{registered: map[string]string{"mail": "new", "nats": "n"}, trunks: map[string]string{"mail": "new", "nats": "n"},
+				nodes: map[string][]string{"mail": {"ace"}, "nats": {"novox"}}, taken: map[string]bool{"mail": true, "nats": true},
+				holder: "novox"},
+			keys: []delivered{{module: "mail"}, {module: "nats"}, {module: "mail"}},
+			acts: []string{"catalogue"},
+			want: map[string]want{"mail": {nothingNew: true}, "nats": {nothingNew: true}}},
+		{name: "a catalogue merge that moved the commit and not the fingerprint: recorded, nothing composed",
+			mesh: aTakeIn{registered: map[string]string{"mail": "a85d9037"}, sameFP: map[string]bool{"mail": true},
+				trunks: map[string]string{"mail": "2df05030"}, nodes: map[string][]string{"mail": {"ace"}},
+				taken: map[string]bool{"mail": true}, holder: "novox"},
+			keys: []delivered{{module: "mail"}},
+			acts: []string{"catalogue", "record mail at 2df05030"}, want: map[string]want{"mail": {nothingNew: true}}},
+		{name: "taken in by this process at the same trunk: nothing new, not even a look at its keys",
+			mesh: aTakeIn{registered: map[string]string{"mail": "new"}, trunks: map[string]string{"mail": "new"},
+				nodes: map[string][]string{"mail": {"ace"}}, holder: "novox"},
+			keys: []delivered{{module: "mail"}},
+			memo: map[string]string{"mail": sdkdelivery.SourcePrefix2 + strings.Repeat("m", 64) + "@new"},
+			acts: []string{"catalogue"}, want: map[string]want{"mail": {nothingNew: true}}},
+		{name: "delivered again: taken in whole, even when it looks done",
+			mesh: aTakeIn{registered: map[string]string{"mail": "new"}, trunks: map[string]string{"mail": "new"},
+				nodes: map[string][]string{"mail": {"ace"}}, taken: map[string]bool{"mail": true}, holder: "novox"},
+			keys: []delivered{{module: "mail", again: true}},
+			acts: []string{"catalogue", "compose ace", "compose novox and grants"}, passes: 2,
+			want: map[string]want{"mail": {taken: true}}},
+		{name: "a take-in that stopped half-way: composed",
+			mesh: aTakeIn{registered: map[string]string{"mail": "new"}, trunks: map[string]string{"mail": "new"},
+				nodes: map[string][]string{"mail": {"ace"}}, holder: "novox"},
+			keys: []delivered{{module: "mail"}},
+			acts: []string{"catalogue", "compose ace", "compose novox and grants"}, passes: 2,
+			want: map[string]want{"mail": {taken: true}}},
+		{name: "three modules, one pass for their nodes and one for the bus",
+			mesh: aTakeIn{registered: map[string]string{}, trunks: map[string]string{"mail": "1", "web": "2", "bus": "3"},
+				nodes: map[string][]string{"mail": {"ace", "novox"}, "web": {"g14", "ace"}, "bus": {"novox"}}, holder: "novox"},
+			keys: []delivered{{module: "mail"}, {module: "web"}, {module: "bus"}},
+			acts: []string{"catalogue", "take in mail at 1", "take in web at 2", "take in bus at 3", "compose ace,g14",
+				"compose novox and grants"}, passes: 2,
+			want: map[string]want{"mail": {taken: true}, "web": {taken: true}, "bus": {taken: true}}},
+		{name: "assigned nowhere, held by no catalogue, no trunk value: nothing composed",
+			mesh: aTakeIn{registered: map[string]string{}, trunks: map[string]string{"mail": "1", "odd": "2"},
+				nodes: map[string][]string{"mail": nil, "none": {"ace"}}, holder: "novox"},
+			keys: []delivered{{module: "mail"}, {module: "odd"}, {module: "none"}},
+			acts: []string{"catalogue", "take in mail at 1"},
+			want: map[string]want{"mail": {taken: true}, "odd": {}, "none": {}}},
+		{name: "a grant not written refuses the key, never swallowed",
+			mesh: aTakeIn{registered: map[string]string{}, trunks: map[string]string{"mail": "1"},
+				nodes: map[string][]string{"mail": {"ace"}}, holder: "novox", grantsErr: errors.New("the bucket mesh-controller_grants: not found")},
+			keys: []delivered{{module: "mail"}},
+			acts: []string{"catalogue", "take in mail at 1", "compose ace", "compose novox and grants"}, passes: 2,
+			want: map[string]want{"mail": {verdict: refused, err: true}}},
+		{name: "a node that fails refuses only its modules",
+			mesh: aTakeIn{registered: map[string]string{}, trunks: map[string]string{"mail": "1", "web": "2"},
+				nodes: map[string][]string{"mail": {"ace"}, "web": {"g14"}}, holder: "novox",
+				composeErr: map[string]error{"ace": errors.New("store refused")}},
+			keys:   []delivered{{module: "mail"}, {module: "web"}},
+			acts:   []string{"catalogue", "take in mail at 1", "take in web at 2", "compose ace,g14", "compose novox and grants"},
+			passes: 2, want: map[string]want{"mail": {verdict: refused, err: true}, "web": {taken: true}}},
+		{name: "waits and failures: a write's wait acknowledged, a read's refused, a failed key acknowledged",
+			mesh: aTakeIn{registered: map[string]string{}, trunks: map[string]string{"a": "1", "b": "2", "c": "3"},
+				nodes: map[string][]string{"a": {"ace"}, "b": {"ace"}, "c": {"ace"}}, holder: "novox",
+				takeInErr: map[string]error{"a": waitsForAWrite, "b": waitsOnARead, "c": keyFailed}},
+			keys: []delivered{{module: "a"}, {module: "b"}, {module: "c"}},
+			acts: []string{"catalogue", "take in a at 1", "take in b at 2", "take in c at 3"},
+			want: map[string]want{"a": {waits: true}, "b": {verdict: refused, waits: true}, "c": {err: true}}},
 	}
-	if !strings.Contains(said, "registered from the builder's done key") {
-		t.Errorf("said %q", said)
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			memo := c.memo
+			if memo == nil {
+				memo = map[string]string{}
+			}
+			settled, passes := c.mesh.steps().batch(t.Context(), c.keys, memo)
+			if !slices.Equal(c.mesh.acts, c.acts) {
+				t.Fatalf("the acts were\n  %q\nwant\n  %q", c.mesh.acts, c.acts)
+			}
+			if passes != c.passes {
+				t.Fatalf("%d composer pass(es), want %d", passes, c.passes)
+			}
+			if len(settled) != len(c.want) {
+				t.Fatalf("settled %d module(s), want %d: %+v", len(settled), len(c.want), settled)
+			}
+			for _, r := range settled {
+				w := c.want[r.module]
+				got := want{verdict: r.verdict, taken: r.taken, nothingNew: r.nothingNew, waits: r.waits != "", err: r.err != nil}
+				if got != w {
+					t.Errorf("%s: %+v, want %+v (%v)", r.module, got, w, r.err)
+				}
+				if r.taken && memo[r.module] == "" {
+					t.Errorf("%s was taken in and not remembered", r.module)
+				}
+			}
+		})
 	}
 
-	acts = nil
-	if _, err := stepsFor(&acts, "new", "new", fp, []string{"novox"}, "novox").take(context.Background(), "mesh-mail"); err != nil {
-		t.Fatal(err)
-	}
-	if got := strings.Join(acts, "; "); got != "compose novox; grants" {
-		t.Errorf("a module registered at its trunk already: %q", got)
-	}
+	// And each delivered key is acknowledged or refused by its module's verdict, the refused with the retry's delay.
+	t.Run("acknowledged and refused", func(t *testing.T) {
+		mesh := aTakeIn{registered: map[string]string{}, trunks: map[string]string{"a": "1", "b": "2"},
+			nodes: map[string][]string{"a": {"ace"}, "b": {"ace"}}, takeInErr: map[string]error{"b": waitsOnARead}}
+		var acked, naked []string
+		msg := func(module string) takeInMsg {
+			return takeInMsg{delivered: delivered{module: module, deliveries: 3}, ack: func() { acked = append(acked, module) },
+				nak: func(d time.Duration) {
+					if d != refusalDelay(3) {
+						t.Errorf("refused with a delay of %s", d)
+					}
+					naked = append(naked, module)
+				}}
+		}
+		state := &takeInState{memo: map[string]string{}, raised: map[string]bool{}, saidWait: map[string]string{}}
+		said := state.take(t.Context(), mesh.steps(), []takeInMsg{msg("a"), msg("b"), msg("a")})
+		if !slices.Equal(acked, []string{"a", "a"}) || !slices.Equal(naked, []string{"b"}) {
+			t.Fatalf("acknowledged %v and refused %v", acked, naked)
+		}
+		if !strings.Contains(said, "1 taken in") || !strings.Contains(said, "1 waiting") {
+			t.Fatalf("said %q", said)
+		}
+	})
 
-	for name, s := range map[string]doneKeySteps{
-		"assigned nowhere": stepsFor(&acts, "old", "new", fp, nil, "novox"),
-		"no trunk value":   stepsFor(&acts, "old", "new", "", []string{"ace"}, "novox"),
+	// A key refused for long holds no slot the others need: each consumer leaves far more keys unacknowledged than a
+	// batch takes, so 8 keys refused on each stop no ninth (the review of ADR 0544: with 8 a consumer, they stopped it
+	// for good), and a refusal waits longer each time, up to ten minutes.
+	t.Run("refused keys stop no other", func(t *testing.T) {
+		for _, bucket := range []string{sdkdelivery.ModulesBucket, sdkdelivery.BuilderBuildsBucket} {
+			if c := takeInConfig(bucket); c.MaxAckPending < 8+startTakeIns || c.AckPolicy != jetstream.AckExplicitPolicy {
+				t.Errorf("%s: %d unacknowledged at most (%v): 8 refused keys and a batch do not fit", bucket,
+					c.MaxAckPending, c.AckPolicy)
+			}
+		}
+		was := time.Duration(0)
+		for n := uint64(1); n <= 8; n++ {
+			d := refusalDelay(n)
+			if d < was || d > doneKeyRetryMost || (n == 1 && d != doneKeyRetry) {
+				t.Fatalf("the %d. refusal waits %s (the one before %s)", n, d, was)
+			}
+			was = d
+		}
+		if was != doneKeyRetryMost {
+			t.Fatalf("the 8. refusal waits %s, want %s", was, doneKeyRetryMost)
+		}
+	})
+}
+
+// The take-in stalls when it holds work (keys not delivered yet, or a batch handed and not settled) and settles none
+// for five minutes; refused keys waiting for their delay are no work, so a quiet mesh is no stall. The first look
+// always says what it found, so a stall raised before a restart is cleared once this controller moves (ADR 0544 §6
+// and its second review).
+func TestATakeInStallsWhenItHoldsWorkAndSettlesNone(t *testing.T) {
+	at := time.Date(2026, 10, 25, 17, 36, 0, 0, time.UTC)
+	type reading struct {
+		after            time.Duration
+		pending, taking  uint64
+		handed, settled  uint64
+		stalled, changed bool
+	}
+	for _, c := range []struct {
+		name     string
+		readings []reading
+	}{
+		{"keys not delivered and nothing settled", []reading{
+			{0, 190, 8, 50, 50, false, true}, // the first look always says what it found
+			{4 * time.Minute, 190, 8, 50, 50, false, false},
+			{5 * time.Minute, 190, 8, 50, 50, true, true},
+			{6 * time.Minute, 190, 8, 50, 50, true, false},
+			{7 * time.Minute, 180, 8, 60, 60, false, true},
+			{20 * time.Minute, 0, 0, 60, 60, false, false},
+		}},
+		{"refused keys waiting alone are no stall", []reading{
+			{0, 0, 3, 40, 40, false, true},
+			{30 * time.Minute, 0, 3, 40, 40, false, false},
+		}},
+		{"every key settled, one of them refused by the bus, nothing pending: no stall", []reading{
+			{0, 0, 1, 3, 3, false, true},
+			{6 * time.Minute, 0, 1, 3, 3, false, false},
+		}},
+		{"a batch handed and never settled is a stall", []reading{
+			{0, 0, 16, 56, 40, false, true},
+			{5 * time.Minute, 0, 16, 56, 40, true, true},
+		}},
 	} {
-		acts = nil
-		if _, err := s.take(context.Background(), "mesh-mail"); err != nil {
-			t.Fatal(err)
-		}
-		if name == "assigned nowhere" && strings.Join(acts, "; ") != "take in mesh-mail at new" {
-			t.Errorf("%s: %v", name, acts)
-		}
-		if name == "no trunk value" && len(acts) != 0 {
-			t.Errorf("%s: %v", name, acts)
-		}
-	}
-	acts = nil
-	if _, err := stepsFor(&acts, "old", "new", fp, []string{"ace"}, "novox").take(context.Background(), "unknown"); err != nil || len(acts) != 0 {
-		t.Errorf("a module the catalogue does not hold: %v %v", acts, err)
+		t.Run(c.name, func(t *testing.T) {
+			w := &stallWatch{}
+			for i, r := range c.readings {
+				stalled, changed := w.look(takeInBacklog{Pending: r.pending, Taking: r.taking}, r.handed, r.settled,
+					at.Add(r.after))
+				if stalled != r.stalled || changed != r.changed {
+					t.Fatalf("reading %d: stalled %v changed %v, want %v %v", i, stalled, changed, r.stalled, r.changed)
+				}
+			}
+		})
 	}
 }
 
@@ -115,15 +336,3 @@ func TestAChangedUserListIsANewRevisionOfTheBusModulesCompositionAlone(t *testin
 		}
 	}
 }
-
-// 1945 (the review's D1): a grant that is not written is the take-in's error, never swallowed: with no send left,
-// nothing else would write it, and no want could name the fingerprint.
-func TestAGrantNotWrittenIsTheTakeInsError(t *testing.T) {
-	fp := sdkdelivery.SourcePrefix2 + strings.Repeat("c", 64)
-	var acts []string
-	s := stepsFor(&acts, "old", "new", fp, []string{"ace"}, "novox")
-	s.grants = func(context.Context) error { return errors.New("the bucket mesh-controller_grants: not found") }
-	if _, err := s.take(context.Background(), "mesh-mail"); err == nil || !strings.Contains(err.Error(), "grants") {
-		t.Errorf("a grant not written: %v", err)
-	}
-}

cmd/mesh-controller/composed_keys_waits_test.go

@@ -1,184 +0,0 @@
-package main
-
-import (
-	"context"
-	"fmt"
-	"strings"
-	"sync"
-	"testing"
-	"time"
-)
-
-// A take-in that waits is said once for each reason it waits for, and tried again every doneKeyRetry until it is taken
-// in: never left for a key write that may not come (issue 1945, live on 2026-10-25: mesh-host's take-in at 26bd waited,
-// said nothing, and nothing woke it until another write).
-func TestAWaitingTakeInIsSaidOnceAndTriedAgain(t *testing.T) {
-	was, wasRetry, wasSay := doneKeyTakeOnce, doneKeyRetry, doneKeysSay
-	t.Cleanup(func() { doneKeyTakeOnce, doneKeyRetry, doneKeysSay = was, wasRetry, wasSay })
-	doneKeyRetry = 5 * time.Millisecond
-	var mu sync.Mutex
-	var said []string
-	doneKeysSay = func(s string) { mu.Lock(); said = append(said, s); mu.Unlock() }
-	calls := 0
-	doneKeyTakeOnce = func(context.Context, *stores, string) error {
-		calls++
-		switch {
-		case calls <= 2:
-			return fmt.Errorf("%w: the artifact store could not hold mesh-host's artifact", errKeyWaits)
-		case calls == 3:
-			return fmt.Errorf("%w: mesh-host's key cannot be read", errKeyWaits)
-		}
-		return nil
-	}
-	done := make(chan struct{})
-	go func() { takeDoneKey(context.Background(), nil, "mesh-host"); close(done) }()
-	select {
-	case <-done:
-	case <-time.After(5 * time.Second):
-		t.Fatal("a waiting take-in was not tried again until it was taken in")
-	}
-	if calls != 4 {
-		t.Fatalf("tried %d times, want 4", calls)
-	}
-	mu.Lock()
-	defer mu.Unlock()
-	waits := 0
-	for _, s := range said {
-		if strings.Contains(s, "mesh-host waits") {
-			waits++
-		}
-	}
-	if waits != 2 {
-		t.Fatalf("said %q: want each of the two reasons once", said)
-	}
-}
-
-// A wake while a take-in of the module already follows it adds no second one: the follower looks again itself.
-func TestAWakeWhileATakeInFollowsAddsNone(t *testing.T) {
-	was, wasRetry, wasSay := doneKeyTakeOnce, doneKeyRetry, doneKeysSay
-	t.Cleanup(func() { doneKeyTakeOnce, doneKeyRetry, doneKeysSay = was, wasRetry, wasSay })
-	doneKeyRetry = 20 * time.Millisecond
-	doneKeysSay = func(string) {}
-	var mu sync.Mutex
-	calls := 0
-	release := make(chan struct{})
-	doneKeyTakeOnce = func(context.Context, *stores, string) error {
-		mu.Lock()
-		calls++
-		mu.Unlock()
-		select {
-		case <-release:
-			return nil
-		default:
-			return fmt.Errorf("%w: the key says building", errKeyWaits)
-		}
-	}
-	follower := make(chan struct{})
-	go func() { takeDoneKey(context.Background(), nil, "board"); close(follower) }()
-	time.Sleep(5 * time.Millisecond)
-	returned := make(chan struct{})
-	go func() { takeDoneKey(context.Background(), nil, "board"); close(returned) }()
-	select {
-	case <-returned:
-	case <-time.After(time.Second):
-		t.Fatal("a second wake waited for the follower")
-	}
-	close(release)
-	<-follower
-}
-
-// A wake while a take-in of the module follows it is not lost: the follower goes round once more after it succeeds, so
-// a newer build's key written meanwhile is taken in (the review of issue 1945).
-func TestAWakeDuringATakeInIsTakenAfterIt(t *testing.T) {
-	was, wasRetry, wasSay := doneKeyTakeOnce, doneKeyRetry, doneKeysSay
-	t.Cleanup(func() { doneKeyTakeOnce, doneKeyRetry, doneKeysSay = was, wasRetry, wasSay })
-	doneKeyRetry = 20 * time.Millisecond
-	doneKeysSay = func(string) {}
-	var mu sync.Mutex
-	calls := 0
-	inFirst := make(chan struct{})
-	release := make(chan struct{})
-	doneKeyTakeOnce = func(context.Context, *stores, string) error {
-		mu.Lock()
-		calls++
-		n := calls
-		mu.Unlock()
-		if n == 1 {
-			close(inFirst)
-			<-release
-		}
-		return nil
-	}
-	follower := make(chan struct{})
-	go func() { takeDoneKey(context.Background(), nil, "mesh-host"); close(follower) }()
-	<-inFirst
-	takeDoneKey(context.Background(), nil, "mesh-host") // the newer key's wake, while the first runs
-	close(release)
-	<-follower
-	mu.Lock()
-	defer mu.Unlock()
-	if calls != 2 {
-		t.Fatalf("taken %d times: the wake during the take-in was lost", calls)
-	}
-}
-
-// A wake that comes after the follower's last look but before it lets go of the module is not lost: the follower looks
-// at the mark again once it has let go, and takes the module once more (the review of issue 1945).
-func TestAWakeJustBeforeTheFollowerLetsGoIsTaken(t *testing.T) {
-	was, wasRetry, wasSay, wasHook := doneKeyTakeOnce, doneKeyRetry, doneKeysSay, doneKeysBeforeLetGo
-	t.Cleanup(func() {
-		doneKeyTakeOnce, doneKeyRetry, doneKeysSay, doneKeysBeforeLetGo = was, wasRetry, wasSay, wasHook
-	})
-	doneKeyRetry = 10 * time.Millisecond
-	doneKeysSay = func(string) {}
-	var mu sync.Mutex
-	calls := 0
-	doneKeyTakeOnce = func(context.Context, *stores, string) error {
-		mu.Lock()
-		calls++
-		mu.Unlock()
-		return nil
-	}
-	woke := false
-	doneKeysBeforeLetGo = func(module string) {
-		if !woke {
-			woke = true
-			takeDoneKey(context.Background(), nil, module) // fails its TryLock and marks the module
-		}
-	}
-	takeDoneKey(context.Background(), nil, "mesh-host")
-	mu.Lock()
-	defer mu.Unlock()
-	if calls != 2 {
-		t.Fatalf("taken %d times: the wake just before the follower let go was lost", calls)
-	}
-}
-
-// A wake during the start's take-in of a module is not lost: the start pass reads the mark once it lets go of the module,
-// and hands the module to takeDoneKey, which takes it once more (the review of issue 1945: the third dropped wake of its
-// kind).
-func TestAWakeDuringTheStartsTakeInIsTaken(t *testing.T) {
-	was, wasRetry, wasSay := doneKeyTakeOnce, doneKeyRetry, doneKeysSay
-	t.Cleanup(func() { doneKeyTakeOnce, doneKeyRetry, doneKeysSay = was, wasRetry, wasSay })
-	doneKeyRetry = 10 * time.Millisecond
-	doneKeysSay = func(string) {}
-	var mu sync.Mutex
-	calls := 0
-	doneKeyTakeOnce = func(context.Context, *stores, string) error {
-		mu.Lock()
-		calls++
-		n := calls
-		mu.Unlock()
-		if n == 1 {
-			takeDoneKey(context.Background(), nil, "mesh-host") // the newer key's wake, during the start's take-in
-		}
-		return nil
-	}
-	takeDoneKeyAtStart(context.Background(), nil, "mesh-host")
-	background.Wait()
-	mu.Lock()
-	defer mu.Unlock()
-	if calls != 2 {
-		t.Fatalf("taken %d times: the wake during the start's take-in was lost", calls)
-	}
-}

cmd/mesh-controller/composed_rejudge.go

@@ -134,7 +134,7 @@ func watchHavesForJudgement(ctx context.Context, open *stores) {
 		fmt.Printf("compositions: the haves are not watched: %v\n", err)
 		return
 	}
-	go func() {
+	goServing(ctx, func() {
 		defer bus.Close()
 		defer w.Stop()
 		for {
@@ -152,7 +152,7 @@ func watchHavesForJudgement(ctx context.Context, open *stores) {
 				if err != nil || isNode {
 					continue
 				}
-				inBackground(func() {
+				inBackground(ctx, func() {
 					if err := rejudgeOn(ctx, open, []string{node}, module); err != nil {
 						fmt.Printf("compositions: %s on %s is not judged again: %v\n", module, node, err)
 					}
@@ -165,5 +165,5 @@ func watchHavesForJudgement(ctx context.Context, open *stores) {
 				})
 			}
 		}
-	}()
+	})
 }

cmd/mesh-controller/composed_served_integration_test.go

@@ -608,8 +608,11 @@ func keepWhatServeSets(t *testing.T) {
 	t.Setenv(servedVar, "")
 	unheld, status, given, check, follow, keeper, hand := logUnheldChanges, statusFrom, givenEvents, checkEvents,
 		link.Calls.Follow, conditionsFrom, handActConn
+	doctor, asker := doctorFrom, askerFrom.Load()
 	t.Cleanup(func() {
 		logUnheldChanges, statusFrom, givenEvents, checkEvents, link.Calls.Follow, conditionsFrom, handActConn =
 			unheld, status, given, check, follow, keeper, hand
+		doctorFrom = doctor
+		askerFrom.Store(asker)
 	})
 }

cmd/mesh-controller/composed_start.go

@@ -316,20 +316,26 @@ func composeReplacedController(ctx context.Context, open *stores) error {
 // replacedComposition is the controller's composition on r's node at r's fingerprint: in composed with r's manifest
 // in place of the controller's registered one.
 func replacedComposition(in compose.Input, r replacedController) (sdkdelivery.Composed, error) {
+	return keptComposition(in, r.node, controllerModule, r.fp, r.manifest)
+}
+
+// keptComposition is module's composition on node at fp: in composed with manifest, that fingerprint's own, in place of
+// the module's registered one, in the reading mode (nothing made). in is not changed.
+func keptComposition(in compose.Input, node, module, fp string, manifest catalogue.Manifest) (sdkdelivery.Composed, error) {
 	shelf := make(map[string]catalogue.Manifest, len(in.Catalogue))
 	for k, v := range in.Catalogue {
 		shelf[k] = v
 	}
-	shelf[controllerModule] = r.manifest
+	shelf[module] = manifest
 	in.Catalogue = shelf
-	all, _, err := compose.Compositions(in, r.node, map[string]string{controllerModule: r.fp}, compose.Reading)
+	all, _, err := compose.Compositions(in, node, map[string]string{module: fp}, compose.Reading)
 	if err != nil {
 		return sdkdelivery.Composed{}, err
 	}
-	key, _ := sdkdelivery.ComposedKey(r.node, controllerModule, r.fp)
+	key, _ := sdkdelivery.ComposedKey(node, module, fp)
 	c, ok := all[key]
 	if !ok {
-		return sdkdelivery.Composed{}, fmt.Errorf("%s composes no %s with the replaced build's manifest", r.node, controllerModule)
+		return sdkdelivery.Composed{}, fmt.Errorf("%s composes no %s with the manifest of %s", node, module, short(fp))
 	}
 	return c, nil
 }

cmd/mesh-controller/composed_start_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"slices"
 	"strings"
 	"testing"
 
@@ -46,51 +47,97 @@ func TestTheFirstStartDeletesThePlansBucketsAndSaysEachOnce(t *testing.T) {
 	}
 }
 
-// 1945/AC6 (unit half): the controller this one replaced is composed on its node from its own build's manifest at its
-// own fingerprint: the composition holds what that manifest declares, not what the controller registered now declares.
-func TestTheReplacedControllerIsComposedFromItsOwnManifest(t *testing.T) {
-	now := catalogue.Manifest{Module: controllerModule, Version: "6", Resources: []map[string]any{
-		{"id": "settings", "type": "file", "path": "/etc/mesh-controller/settings", "content": "six\n"}}}
-	before := catalogue.Manifest{Module: controllerModule, Version: "5", Resources: []map[string]any{
-		{"id": "settings", "type": "file", "path": "/etc/mesh-controller/settings", "content": "five\n"}}}
-	in := compose.Input{Catalogue: map[string]catalogue.Manifest{controllerModule: now},
-		Nodes: []compose.Node{{Name: "anchor", Assigned: []string{controllerModule}, Stated: true}}}
-	fp := sdkdelivery.SourcePrefix2 + strings.Repeat("5", 64)
-	c, err := replacedComposition(in, replacedController{node: "anchor", fp: fp, manifest: before})
-	if err != nil {
-		t.Fatal(err)
-	}
-	if c.Module != controllerModule || c.FP != fp || c.Node != "anchor" || len(c.Resources) != 1 {
-		t.Fatalf("composed %s at %s on %s with %d resources", c.Module, c.FP, c.Node, len(c.Resources))
-	}
-	var f struct{ Content string }
-	_ = json.Unmarshal(c.Resources[0], &f)
-	if f.Content != "five\n" {
-		t.Errorf("the replaced controller's composition holds %q, its own manifest says five", f.Content)
-	}
-	if in.Catalogue[controllerModule].Version != "6" {
-		t.Errorf("composing the replaced controller changed the Input's catalogue")
-	}
-}
+// An earlier fingerprint is composed from its own build's manifest with today's inputs: the controller this one
+// replaced (1945/AC6), and every kept composition of a module whose config changed (ADR 0545: on 2026-10-25 a want back
+// to an earlier mesh-build-go on g14 applied the capacity of 0 its kept composition was made with). The composition
+// holds what that manifest declares and today's config, the kept keys are those of the touched modules at a
+// fingerprint other than the registered one, the build of a fingerprint is its newest that worked, and a write of
+// mesh-config's resolved values names the node and module it touches.
+func TestAnEarlierFingerprintIsComposedFromItsOwnManifest(t *testing.T) {
+	fp := func(c string) string { return sdkdelivery.SourcePrefix2 + strings.Repeat(c, 64) }
+	t.Run("from its own manifest, with today's inputs", func(t *testing.T) {
+		manifest := func(version string) catalogue.Manifest {
+			return catalogue.Manifest{Module: controllerModule, Version: version,
+				Settings: map[string]catalogue.SettingDeclaration{
+					"capacity": {Kind: catalogue.KindPreference, Default: float64(0), Why: "how many builds at once"}},
+				Resources: []map[string]any{{"id": "settings", "type": "file", "path": "/etc/mesh-controller/settings",
+					"content": version + " ${setting:capacity}\n"}}}
+		}
+		now, before := manifest("six"), manifest("five")
+		in := compose.Input{Catalogue: map[string]catalogue.Manifest{controllerModule: now},
+			Nodes: []compose.Node{{Name: "anchor", Assigned: []string{controllerModule}, Stated: true,
+				Settings: map[string][]catalogue.Layer{controllerModule: {{From: "mesh", Values: map[string]any{"capacity": float64(4)}}}}}}}
+		for name, compose := range map[string]func() (sdkdelivery.Composed, error){
+			"the replaced controller": func() (sdkdelivery.Composed, error) {
+				return replacedComposition(in, replacedController{node: "anchor", fp: fp("5"), manifest: before})
+			},
+			"a kept composition": func() (sdkdelivery.Composed, error) {
+				return keptComposition(in, "anchor", controllerModule, fp("5"), before)
+			},
+		} {
+			c, err := compose()
+			if err != nil {
+				t.Fatalf("%s: %v", name, err)
+			}
+			if c.Module != controllerModule || c.FP != fp("5") || c.Node != "anchor" || len(c.Resources) != 1 {
+				t.Fatalf("%s: composed %s at %s on %s with %d resources", name, c.Module, c.FP, c.Node, len(c.Resources))
+			}
+			var f struct{ Content string }
+			_ = json.Unmarshal(c.Resources[0], &f)
+			if f.Content != "five 4\n" {
+				t.Errorf("%s holds %q, want its own manifest's five with today's capacity 4", name, f.Content)
+			}
+		}
+		if in.Catalogue[controllerModule].Version != "six" {
+			t.Errorf("composing an earlier fingerprint changed the Input's catalogue")
+		}
+	})
 
-// 1945/AC6 (unit half): the controller replaced is the newest earlier build of the controller that worked and names a
-// fingerprint of the new form, not the one registered now.
-func TestTheReplacedControllerIsItsNewestEarlierBuild(t *testing.T) {
-	now, before, older := sdkdelivery.SourcePrefix2+strings.Repeat("6", 64), sdkdelivery.SourcePrefix2+strings.Repeat("5", 64),
-		sdkdelivery.SourcePrefix2+strings.Repeat("4", 64)
-	m := []byte(`{"module":"mesh-controller","version":"5"}`)
-	builds := []inventory.Build{
-		{ID: "c6", SourceFingerprint: now, Manifest: m},
-		{ID: "c5-failed", SourceFingerprint: before, Failed: "no", Manifest: m},
-		{ID: "c5", SourceFingerprint: before, Manifest: m},
-		{ID: "c4", SourceFingerprint: older, Manifest: m},
-	}
-	if b, ok := replacedBuild(builds, now); !ok || b.ID != "c5" {
-		t.Errorf("the replaced build is %+v (%v), want c5", b, ok)
-	}
-	if _, ok := replacedBuild(builds[:1], now); ok {
-		t.Errorf("a controller with no earlier build replaced one")
-	}
+	t.Run("which build, which keys, which touch", func(t *testing.T) {
+		m := []byte(`{"module":"mesh-controller","version":"5"}`)
+		builds := []inventory.Build{
+			{ID: "c6", SourceFingerprint: fp("6"), Manifest: m},
+			{ID: "c5-failed", SourceFingerprint: fp("5"), Failed: "no", Manifest: m},
+			{ID: "c5", SourceFingerprint: fp("5"), Manifest: m},
+			{ID: "c4", SourceFingerprint: fp("4"), Manifest: m},
+		}
+		if b, ok := replacedBuild(builds, fp("6")); !ok || b.ID != "c5" {
+			t.Errorf("the replaced build is %+v (%v), want c5", b, ok)
+		}
+		if _, ok := replacedBuild(builds[:1], fp("6")); ok {
+			t.Errorf("a controller with no earlier build replaced one")
+		}
+		if b, ok := buildAt(builds, fp("5")); !ok || b.ID != "c5" {
+			t.Errorf("the build at 5 is %+v (%v), want c5, the one that worked", b, ok)
+		}
+		if _, ok := buildAt(builds, fp("3")); ok {
+			t.Errorf("a fingerprint with no build has one")
+		}
+		key := func(node, module, f string) string { k, _ := sdkdelivery.ComposedKey(node, module, f); return k }
+		keys := []string{key("g14", "mesh-build-go", fp("2")), key("g14", "mesh-build-go", fp("1")),
+			key("g14", "mesh-build-go", fp("3")), key("g14", "hello-web", fp("1")), key("ace", "mesh-build-go", fp("1"))}
+		registered := map[string]string{"mesh-build-go": fp("3"), "hello-web": fp("9")}
+		got := keptToFollow(keys, "g14", map[string]bool{"mesh-build-go": true}, registered)
+		if want := []keptKey{{"mesh-build-go", fp("1")}, {"mesh-build-go", fp("2")}}; !slices.Equal(got, want) {
+			t.Errorf("kept to follow %v, want %v", got, want)
+		}
+		if got := keptToFollow(keys, "g14", nil, registered); len(got) != 3 {
+			t.Errorf("every module's kept compositions: %v", got)
+		}
+		for k, want := range map[string][2]string{"g14.mesh-build-go.capacity": {"g14", "mesh-build-go"},
+			"g14.mesh-build-go.limits.cpu": {"g14", "mesh-build-go"}, "g14.mesh-build-go": {}, "": {}} {
+			node, module, ok := configTouched(k)
+			if [2]string{node, module} != want || ok != (want[0] != "") {
+				t.Errorf("%q touches %s %s (%v), want %v", k, node, module, ok, want)
+			}
+		}
+		// A value set before the consumer was made reaches the kept compositions: it reads each key once at creation.
+		if c := configFollowConfig(); c.DeliverPolicy != jetstream.DeliverLastPerSubjectPolicy ||
+			c.AckPolicy != jetstream.AckExplicitPolicy {
+			t.Errorf("the config consumer delivers %v, acknowledged %v; want each key's last value, acknowledged",
+				c.DeliverPolicy, c.AckPolicy)
+		}
+	})
 }
 
 // 1945/AC14 (unit half): the declarations' stream stays while one node's have names another node-engine than the one

cmd/mesh-controller/composer.go

@@ -29,7 +29,13 @@ type composer struct {
 type waiter struct {
 	nodes  []string
 	grants bool
-	done   chan error
+	done   chan passResult
+}
+
+// passResult is a waiter's answer: the error of each of its nodes that failed, and of the grants when it asked for them.
+type passResult struct {
+	failed map[string]error
+	grants error
 }
 
 func newComposer(compose func(context.Context, []string) map[string]error, grants func(context.Context) error) *composer {
@@ -39,7 +45,23 @@ func newComposer(compose func(context.Context, []string) map[string]error, grant
 // compose asks for the nodes to be composed, and the grants written after when grants is true, and waits for the pass
 // that does it, with the errors of its own nodes alone.
 func (c *composer) compose(ctx context.Context, nodes []string, grants bool) error {
-	done := make(chan error, 1)
+	failed, grantsErr, err := c.composeEach(ctx, nodes, grants)
+	if err != nil {
+		return err
+	}
+	var errs []error
+	for _, n := range nodes {
+		if e := failed[n]; e != nil {
+			errs = append(errs, e)
+		}
+	}
+	return errors.Join(append(errs, grantsErr)...)
+}
+
+// composeEach is compose answering each node's error apart, and the grants' (ADR 0544 §5: a batch of take-ins asks one
+// pass and settles each module by its own nodes); err is ctx's when it ends first.
+func (c *composer) composeEach(ctx context.Context, nodes []string, grants bool) (map[string]error, error, error) {
+	done := make(chan passResult, 1)
 	c.mu.Lock()
 	for _, n := range nodes {
 		c.pending[n] = true
@@ -52,10 +74,10 @@ func (c *composer) compose(ctx context.Context, nodes []string, grants bool) err
 	default:
 	}
 	select {
-	case err := <-done:
-		return err
+	case r := <-done:
+		return r.failed, r.grants, nil
 	case <-ctx.Done():
-		return ctx.Err()
+		return nil, nil, ctx.Err()
 	}
 }
 
@@ -90,16 +112,16 @@ func (c *composer) run(ctx context.Context) {
 			grantsErr = c.writeGrants(ctx)
 		}
 		for _, w := range waiters {
-			var errs []error
+			r := passResult{failed: map[string]error{}}
 			for _, n := range w.nodes {
 				if err := failed[n]; err != nil {
-					errs = append(errs, err)
+					r.failed[n] = err
 				}
 			}
-			if w.grants && grantsErr != nil {
-				errs = append(errs, grantsErr)
+			if w.grants {
+				r.grants = grantsErr
 			}
-			w.done <- errors.Join(errs...)
+			w.done <- r
 		}
 	}
 }

cmd/mesh-controller/conditions.go

@@ -49,7 +49,7 @@ func keeperOn(ctx context.Context, conn *nats.Conn, looks conditions.LookStore)
 		Say:    func(format string, args ...any) { fmt.Fprintf(os.Stderr, format+"\n", args...) },
 		// What status leads with changed: composed again soon (a nudge outside the serving controller
 		// does nothing).
-		Changed: func() { statusFrom.nudge(); askerFrom.nudge() },
+		Changed: func() { statusFrom.nudge(); askerFrom.Load().nudge() },
 		// Written under the lease, carrying its epoch (novox/hq to-be 45 §6).
 		Epoch: func() (uint64, error) { return theLease.epoch(context.WithoutCancel(ctx)) }}), nil
 }

cmd/mesh-controller/declaration_files.go

@@ -225,6 +225,9 @@ func filesNotPutObservation(node, summary string) conditions.Observation {
 // notePut records how putting a send's objects went: a failure counts, the second in a row raises the condition, a success
 // clears the count and the condition.
 func notePut(ctx context.Context, node string, put error) {
+	if errors.Is(put, context.Canceled) || ctx.Err() != nil {
+		return // a send cut by a cancellation or a stop says nothing of the bucket (issue 1945)
+	}
 	filesFailMu.Lock()
 	if put == nil {
 		delete(filesFailed, node)

cmd/mesh-controller/declaration_files_test.go

@@ -415,6 +415,7 @@ func TestAPutThatFailsSendAfterSendRaisesAConditionAndClearsWhenItWorks(t *testi
 	was := conditionsFrom
 	conditionsFrom = k
 	t.Cleanup(func() { conditionsFrom = was })
+	forgetPutFailures(t, "cond-node")
 	key := filesNotPutObservation("cond-node", "").Key()
 	open := func() bool {
 		_, found, err := conditions.ReadOne(t.Context(), store, key)
@@ -442,6 +443,36 @@ func TestAPutThatFailsSendAfterSendRaisesAConditionAndClearsWhenItWorks(t *testi
 	}
 }
 
+// A send cut by a cancellation counts as no failure to put its files, however often (issue 1945: a cancellation is no fault
+// of the bucket).
+func TestAPutCutByACancellationRaisesNothing(t *testing.T) {
+	store := conditions.NewInMemory()
+	k := conditions.NewKeeper(t.Context(), conditions.Options{Store: store, History: store, Teller: &conditions.Told{}})
+	t.Cleanup(func() { k.Close(context.Background()) })
+	was := conditionsFrom
+	conditionsFrom = k
+	t.Cleanup(func() { conditionsFrom = was })
+	forgetPutFailures(t, "cut-node")
+	cut := fmt.Errorf("the files could not be put: %w", context.Canceled)
+	for range filesNotPutAfter + 1 {
+		notePut(t.Context(), "cut-node", cut)
+	}
+	if _, found, err := conditions.ReadOne(t.Context(), store, filesNotPutObservation("cut-node", "").Key()); err != nil || found {
+		t.Fatalf("sends cut by a cancellation raised the condition (found %v, %v)", found, err)
+	}
+}
+
+// forgetPutFailures starts the node's count of failed puts at nothing and leaves it so, as a run of the test again finds it.
+func forgetPutFailures(t *testing.T, node string) {
+	forget := func() {
+		filesFailMu.Lock()
+		delete(filesFailed, node)
+		filesFailMu.Unlock()
+	}
+	forget()
+	t.Cleanup(forget)
+}
+
 // aBusThatSays is a bus that keeps the declarations published to it and, at each, asks whether the node's bucket is held.
 type aBusThatSays struct {
 	link.Bus

cmd/mesh-controller/declared_packages_integration_test.go

@@ -87,3 +87,29 @@ func TestTheDeclaredPackagesMirrorNamesWhatEachNodesModulesDeclare(t *testing.T)
 		}
 	}
 }
+
+// 1945/AC-mirror-5: the digest the declared-packages mirror skips an unchanged pass by is made from a real reading of the
+// stores, is the same over two readings of the same records, and moves when an assignment does.
+func TestTheInputDigestOfTheStoresIsStable(t *testing.T) {
+	open := aMesh(t)
+	ctx := t.Context()
+	register(t, open, catalogue.Manifest{Module: "viewer", Version: "1", Resources: []map[string]any{
+		{"id": "pkg-curl", "type": "package", "package": "curl"}}})
+	read := func() string {
+		in, err := readComposeInput(ctx, open)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return inputDigest(in)
+	}
+	first, second := read(), read()
+	if first == "" || first != second {
+		t.Fatalf("two readings of the same records gave the digests %q and %q", first, second)
+	}
+	if _, err := assign(ctx, open, "anchor", "viewer"); err != nil {
+		t.Fatalf("assign: %v", err)
+	}
+	if read() == first {
+		t.Errorf("an assignment left the digest of the stores' Input at %s", first)
+	}
+}

cmd/mesh-controller/given.go

@@ -169,7 +169,7 @@ func watchHavesForGiven(ctx context.Context, open *stores) {
 		log.Printf("given values: the haves are not watched: %v", err)
 		return
 	}
-	go func() {
+	goServing(ctx, func() {
 		defer bus.Close()
 		defer w.Stop()
 		for {
@@ -195,8 +195,8 @@ func watchHavesForGiven(ctx context.Context, open *stores) {
 				if at.IsZero() {
 					continue
 				}
-				inBackground(func() { replaceGiven(ctx, open, node, map[string]time.Time{module: at}) })
+				inBackground(ctx, func() { replaceGiven(ctx, open, node, map[string]time.Time{module: at}) })
 			}
 		}
-	}()
+	})
 }

cmd/mesh-controller/kept_compositions.go

@@ -0,0 +1,352 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"sort"
+	"strings"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	sdkdelivery "git.novox.be/novox/mesh-sdk/go/delivery"
+	"github.com/nats-io/nats.go/jetstream"
+
+	"github.com/novox/mesh-controller/internal/broker"
+	"github.com/novox/mesh-controller/internal/conditions"
+	"github.com/novox/mesh-controller/internal/inventory"
+)
+
+// **A kept composition follows its inputs** (novox/hq ADR 0545, issue 1945). The controller composes a module only at
+// the fingerprint it is registered at, and keeps the compositions of up to five fingerprints (ADR 0539 §4) so that
+// going back is one want. A kept one was never composed again, so it carried the config of the moment it was made: on
+// 2026-10-25 a want back to an earlier mesh-build-go on g14 applied its capacity of 0, the value from before it was
+// set. Now a write of mesh-config's resolved values for a module on a node, heard from that bucket, composes the node
+// and then every kept fingerprint of that module on that node again, each from its own build's manifest with today's
+// inputs, writing only those whose composition differs (writeComposed). The writes are read from a durable consumer,
+// acknowledged once handled, so a change made while no controller ran is delivered to the next one, and a start
+// composes again only what was written since the last write handled, never every kept composition.
+
+// configTouched is the node and module a key of mesh-config_resolved (`<node>.<module>.<key>`) names.
+func configTouched(key string) (node, module string, ok bool) {
+	parts := strings.SplitN(key, ".", 3)
+	if len(parts) != 3 || parts[0] == "" || parts[1] == "" {
+		return "", "", false
+	}
+	return parts[0], parts[1], true
+}
+
+// keptKey is one kept composition to compose again.
+type keptKey struct{ module, fp string }
+
+// keptToFollow is, of a node's composition keys, each of modules (every module when nil) at a fingerprint other than
+// the one it is registered at, sorted: the kept compositions. The node's own composition and other nodes' are not.
+func keptToFollow(keys []string, node string, modules map[string]bool, registered map[string]string) []keptKey {
+	var out []keptKey
+	for _, key := range keys {
+		n, module, fp, isNode, err := sdkdelivery.ParseComposedKey(key)
+		if err != nil || isNode || n != node || (modules != nil && !modules[module]) {
+			continue
+		}
+		if fp == registered[module] || !strings.HasPrefix(fp, sdkdelivery.SourcePrefix2) {
+			continue
+		}
+		out = append(out, keptKey{module, fp})
+	}
+	sort.Slice(out, func(i, j int) bool {
+		if out[i].module != out[j].module {
+			return out[i].module < out[j].module
+		}
+		return out[i].fp < out[j].fp
+	})
+	return out
+}
+
+// buildAt is, of a module's builds newest first, the newest that worked at fp and kept its manifest.
+func buildAt(builds []inventory.Build, fp string) (inventory.Build, bool) {
+	for _, b := range builds {
+		if b.Worked() && b.SourceFingerprint == fp && len(b.Manifest) > 0 {
+			return b, true
+		}
+	}
+	return inventory.Build{}, false
+}
+
+// followKept composes again, on node, every kept composition of modules (every module when nil) with today's inputs,
+// and writes those that differ. It answers the keys written; a fingerprint whose build's manifest is gone is said and
+// left as it is.
+func followKept(ctx context.Context, open *stores, node string, modules map[string]bool) ([]string, error) {
+	if _, err := theLease.epoch(ctx); err != nil {
+		return nil, err
+	}
+	bus, err := aBus()
+	if err != nil {
+		return nil, err
+	}
+	defer bus.Close()
+	js, err := jetstream.New(bus.Conn())
+	if err != nil {
+		return nil, err
+	}
+	inv := open.inventory
+	registered, err := currentFingerprints(ctx, inv)
+	if err != nil {
+		return nil, err
+	}
+	at, err := openComposedPlace(ctx, js, bus.Conn(), node)
+	if err != nil {
+		return nil, err
+	}
+	lister, err := at.bucket.ListKeys(ctx)
+	if err != nil {
+		if errors.Is(err, jetstream.ErrNoKeysFound) {
+			return nil, nil // empty-on-error: a node with no compositions keeps none to compose again
+		}
+		return nil, err
+	}
+	var keys []string
+	for k := range lister.Keys() {
+		keys = append(keys, k)
+	}
+	kept := keptToFollow(keys, node, modules, registered)
+	if len(kept) == 0 {
+		return nil, nil
+	}
+	sign, err := controllerSigner(ctx, open)
+	if err != nil {
+		return nil, err
+	}
+	upgrades, err := inv.Upgrades(ctx)
+	if err != nil {
+		return nil, err
+	}
+	at.sign = sign
+	at.policy = func(module string) (string, string, string) {
+		u, ok := upgrades[module]
+		if !ok {
+			return "", "", ""
+		}
+		return u.Policy(), u.From, u.Why
+	}
+	in, err := inputFor(ctx, open)
+	if err != nil {
+		return nil, err
+	}
+	var wrote []string
+	var errs []error
+	builds := map[string][]inventory.Build{}
+	for _, k := range kept {
+		if ctx.Err() != nil {
+			return wrote, errors.Join(append(errs, ctx.Err())...) // stopped: the rest is the next controller's
+		}
+		if _, read := builds[k.module]; !read {
+			if builds[k.module], err = inv.Builds(ctx, k.module, 20); err != nil {
+				errs = append(errs, fmt.Errorf("%s's builds: %w", k.module, err))
+				continue
+			}
+		}
+		b, found := buildAt(builds[k.module], k.fp)
+		if !found {
+			fmt.Printf("compositions: %s's kept %s on %s has no build whose manifest is kept, and is not composed again\n",
+				k.module, short(k.fp), node)
+			continue
+		}
+		var m catalogue.Manifest
+		if err := json.Unmarshal(b.Manifest, &m); err != nil {
+			errs = append(errs, fmt.Errorf("the manifest of %s's build %s: %w", k.module, b.ID, err))
+			continue
+		}
+		c, err := keptComposition(in.Input, node, k.module, k.fp, m)
+		if err != nil {
+			errs = append(errs, fmt.Errorf("%s at %s on %s: %w", k.module, short(k.fp), node, err))
+			continue
+		}
+		key, _ := sdkdelivery.ComposedKey(node, k.module, k.fp)
+		// One write on the node's keys at a time in this process, held only for the write: composing in memory holds
+		// nothing, so a sweep never keeps a take-in from the node (the review of ADR 0545).
+		unlock := lockComposing(node)
+		w, err := writeComposed(ctx, at, key, c)
+		unlock()
+		if err != nil {
+			errs = append(errs, err)
+			continue
+		}
+		if w {
+			wrote = append(wrote, key)
+		}
+	}
+	if len(wrote) > 0 {
+		fmt.Printf("compositions: %s: kept compositions composed again with today's inputs: %s\n", node, strings.Join(wrote, ", "))
+	}
+	return wrote, errors.Join(errs...)
+}
+
+// configFollowGather is how long the config consumer waits after a write for more before it composes: mesh-config writes
+// a module's keys one by one.
+var configFollowGather = time.Second
+
+// configFollowConsumer is the controller's durable consumer of mesh-config's resolved values (ADR 0545 §1, §3).
+const configFollowConsumer = broker.ConfigFollowConsumer
+
+// configFollowConfig is that consumer: each resolved key's last value once when it is made, then each write,
+// acknowledged after the write is handled, so what a stop cut is delivered to the next controller. The first start of
+// the release that makes it composes again the kept compositions of every module with config, through the same gather,
+// lock and acknowledgement: mesh-config never writes an unchanged value again, so a value set before this release (g14's
+// mesh-build-go capacity of 2, against kept compositions carrying 0) would otherwise never reach them. Its deliver
+// policy is set before its first delivery; an existing durable's cannot be changed.
+func configFollowConfig() jetstream.ConsumerConfig {
+	return jetstream.ConsumerConfig{Durable: configFollowConsumer, FilterSubject: "$KV." + broker.ConfigResolvedBucket + ".>",
+		DeliverPolicy: jetstream.DeliverLastPerSubjectPolicy, AckPolicy: jetstream.AckExplicitPolicy, AckWait: takeInAckWait,
+		MaxAckPending: takeInPending, Description: "the controller's following of config into kept compositions (novox/hq ADR 0545)"}
+}
+
+// kindConfigNotFollowed is the condition of a config consumer that cannot be read: a change of config composes nothing
+// until it is.
+const kindConfigNotFollowed = "config-not-followed"
+
+func configNotFollowedObservation(err error) conditions.Observation {
+	return conditions.Observation{Scope: conditions.ScopeCore, ID: "config-follow", Token: kindConfigNotFollowed,
+		Kind: kindConfigNotFollowed, Severity: conditions.Urgent, Resolver: conditions.ResolverOperator, Source: "config",
+		Summary: fmt.Sprintf("mesh-config's resolved values are not heard, so a change of config composes nothing: %v", err)}
+}
+
+// watchConfigFollow reads the writes of mesh-config's resolved values from the controller's durable consumer and, for
+// each node and module they touch, composes the node and the module's kept compositions there again, until ctx ends
+// (ADR 0545). A consumer that cannot be made or read raises config-not-followed and is tried again a minute later; it is
+// cleared once it is read.
+func watchConfigFollow(ctx context.Context, open *stores) {
+	goServing(ctx, func() {
+		for {
+			err := followConfigOnce(ctx, open)
+			if ctx.Err() != nil {
+				return
+			}
+			fmt.Printf("config: %v; tried again in a minute\n", err)
+			if keeper := conditionsFrom; keeper != nil {
+				_, _ = keeper.Observe(ctx, configNotFollowedObservation(err))
+			}
+			select {
+			case <-ctx.Done():
+				return
+			case <-time.After(time.Minute):
+			}
+		}
+	})
+}
+
+// followConfigOnce reads the consumer until it fails or ctx ends.
+func followConfigOnce(ctx context.Context, open *stores) error {
+	bus, err := aBus()
+	if err != nil {
+		return err
+	}
+	defer bus.Close()
+	js, err := jetstream.New(bus.Conn())
+	if err != nil {
+		return err
+	}
+	c, err := js.CreateOrUpdateConsumer(ctx, "KV_"+broker.ConfigResolvedBucket, configFollowConfig())
+	if err != nil {
+		return fmt.Errorf("the consumer of %s: %w", broker.ConfigResolvedBucket, err)
+	}
+	it, err := c.Messages(jetstream.PullMaxMessages(startTakeIns))
+	if err != nil {
+		return fmt.Errorf("the consumer of %s: %w", broker.ConfigResolvedBucket, err)
+	}
+	defer it.Stop()
+	if keeper := conditionsFrom; keeper != nil {
+		_, _ = keeper.Clear(ctx, configNotFollowedObservation(nil).Key(), "mesh-config's resolved values are heard")
+	}
+	type next struct {
+		m   jetstream.Msg
+		err error
+	}
+	got := make(chan next)
+	go func() {
+		for {
+			m, err := it.Next()
+			select {
+			case got <- next{m, err}:
+			case <-ctx.Done():
+				if m != nil {
+					_ = m.Nak()
+				}
+				return
+			}
+			if err != nil {
+				return
+			}
+		}
+	}()
+	var held []jetstream.Msg
+	touched := map[string]map[string]bool{}
+	var gather <-chan time.Time
+	for {
+		select {
+		case <-ctx.Done():
+			for _, m := range held {
+				_ = m.Nak() // delivered at once to the next controller
+			}
+			return nil
+		case n := <-got:
+			if n.err != nil {
+				for _, m := range held {
+					_ = m.Nak()
+				}
+				return fmt.Errorf("the consumer of %s stopped: %w", broker.ConfigResolvedBucket, n.err)
+			}
+			held = append(held, n.m)
+			key := strings.TrimPrefix(n.m.Subject(), "$KV."+broker.ConfigResolvedBucket+".")
+			if node, module, ok := configTouched(key); ok {
+				if touched[node] == nil {
+					touched[node] = map[string]bool{}
+				}
+				touched[node][module] = true
+			}
+			if gather == nil {
+				gather = time.After(configFollowGather)
+			}
+		case <-gather:
+			gather = nil
+			now, msgs := touched, held
+			touched, held = map[string]map[string]bool{}, nil
+			forgetResolved() // the next composition reads the values just written, not a read of the last 5 s
+			failed := false
+			for node, modules := range now {
+				if ctx.Err() != nil {
+					failed = true // stopped: the writes are refused below and delivered to the next controller
+					break
+				}
+				if err := composerFor(open).compose(ctx, []string{node}, false); err != nil {
+					fmt.Printf("config: %s is not composed after its config changed: %v\n", node, err)
+					failed = true
+				}
+				if _, err := followKept(ctx, open, node, modules); err != nil {
+					fmt.Printf("config: %s's kept compositions are not composed again: %v\n", node, err)
+					failed = true
+				}
+			}
+			for _, m := range msgs {
+				if failed && ctx.Err() != nil {
+					_ = m.Nak() // stopped: delivered at once to the next controller
+				} else if failed {
+					_ = m.NakWithDelay(doneKeyRetry) // tried again: the bus delivers the writes again
+				} else {
+					acking, cancel := context.WithTimeout(context.WithoutCancel(ctx), 10*time.Second)
+					if err := m.DoubleAck(acking); err != nil {
+						fmt.Printf("config: the bus did not take the acknowledgement of %s: %v\n", m.Subject(), err)
+					}
+					cancel()
+				}
+			}
+		}
+	}
+}
+
+// forgetResolved drops the last read of mesh-config's resolved values.
+func forgetResolved() {
+	theResolved.mu.Lock()
+	theResolved.entries = nil
+	theResolved.mu.Unlock()
+}

cmd/mesh-controller/key_takein.go

@@ -39,6 +39,11 @@ import (
 // errKeyWaits says a take-in from a key waits: for the builder, a reference, the store or the forge. Never a failure.
 var errKeyWaits = errors.New("waits")
 
+// errWaitsForAWrite is a take-in that waits for the builder or the indexer to write again (the key not done, its
+// artifacts not referenced, no fingerprint of the new form): that write wakes it, so nothing looks again before it
+// (ADR 0544 §4).
+var errWaitsForAWrite = fmt.Errorf("%w for the builder's or the indexer's next write", errKeyWaits)
+
 // errKeyFailed says the module's key failed: the builder's own words follow.
 var errKeyFailed = errors.New("the builder's key failed")
 
@@ -298,12 +303,15 @@ func buildOfKey(ctx context.Context, keys keyReads, t keyTake, kc keyContext) (
 	waits := func(format string, a ...any) (inventory.Build, catalogue.Manifest, error) {
 		return inventory.Build{}, catalogue.Manifest{}, fmt.Errorf("%w: "+format, append([]any{errKeyWaits}, a...)...)
 	}
+	waitsForAWrite := func(format string, a ...any) (inventory.Build, catalogue.Manifest, error) {
+		return inventory.Build{}, catalogue.Manifest{}, fmt.Errorf("%w: "+format, append([]any{errWaitsForAWrite}, a...)...)
+	}
 	if t.Trunk.FP2 == "" && t.Hand == nil {
 		why := t.Trunk.None2
 		if why == "" {
 			why = "the indexer wrote no fingerprint of the new form"
 		}
-		return waits("%s at %.8s has no fingerprint to take a build by: %s", t.Module, t.Trunk.Commit, why)
+		return waitsForAWrite("%s at %.8s has no fingerprint to take a build by: %s", t.Module, t.Trunk.Commit, why)
 	}
 	k, err := keys.Build(ctx, t.Module, t.Trunk.FP2)
 	if t.Hand != nil {
@@ -319,9 +327,9 @@ func buildOfKey(ctx context.Context, keys keyReads, t keyTake, kc keyContext) (
 	case k.Failed():
 		return inventory.Build{}, catalogue.Manifest{}, fmt.Errorf("%w: %s", errKeyFailed, k.Says())
 	case !k.Done():
-		return waits("%s", k.Says())
+		return waitsForAWrite("%s", k.Says())
 	case len(k.Unreferenced()) > 0:
-		return waits("%s", k.Says())
+		return waitsForAWrite("%s", k.Says())
 	}
 	src, err := keys.Manifest(ctx, k.Build.Manifest)
 	if err != nil {

cmd/mesh-controller/modules.go

@@ -965,6 +965,26 @@ func processPrincipalFor(m catalogue.Manifest, processID string) (broker.Process
 	return broker.ProcessPrincipal{}, false
 }
 
+// mintOnlyIfAbsent marks a context whose issue mints only accounts no row names yet (onlyIfAbsent).
+type mintOnlyIfAbsent struct{}
+
+// onlyIfAbsent is ctx for an issue that must never replace a minted account: the assign act's and the assignments'
+// watch's, which may run at once for one account (novox/hq ADR 0543, the review of issue 1945).
+func onlyIfAbsent(ctx context.Context) context.Context {
+	return context.WithValue(ctx, mintOnlyIfAbsent{}, true)
+}
+
+// mintBusUser mints u's password. By default it replaces whatever stands (a rotation: `module issue`); under
+// onlyIfAbsent it mints only when no row names u, and won false says another caller minted it first and seals it,
+// so this one seals nothing.
+func mintBusUser(ctx context.Context, inv *inventory.Inventory, u inventory.BusUser) (string, bool, error) {
+	if only, _ := ctx.Value(mintOnlyIfAbsent{}).(bool); only {
+		return inv.MintBusPasswordIfAbsent(ctx, u)
+	}
+	password, err := inv.MintBusPassword(ctx, u)
+	return password, err == nil, err
+}
+
 // issueOnTheNewBus gives an assigned module its credential on the bus being built.
 //
 // **Three things differ from a management call, and each is the point of the move.** The credential
@@ -990,14 +1010,16 @@ func issueOnTheNewBus(ctx context.Context, inv *inventory.Inventory, m catalogue
 	}
 	if _, reads := m.OwnSecrets["broker"]; reads {
 		user := broker.Principal{Kind: broker.KindModule, Node: node, Module: m.Module}.Username()
-		password, err := inv.MintBusPassword(ctx, inventory.BusUser{
+		password, won, err := mintBusUser(ctx, inv, inventory.BusUser{
 			Username: user, Kind: busKindOf(m.Module), Node: node, Module: m.Module,
 		})
 		if err != nil {
 			return err
 		}
-		if err := issueWith(ctx, inv, m, node, busAddress, known, reachable, user, password); err != nil {
-			return err
+		if won {
+			if err := issueWith(ctx, inv, m, node, busAddress, known, reachable, user, password); err != nil {
+				return err
+			}
 		}
 	}
 	// Every process with a bus declaration gets an account of its own (novox/hq ADR 0436 §1, §2), minted and
@@ -1021,11 +1043,11 @@ func issueOnTheNewBus(ctx context.Context, inv *inventory.Inventory, m catalogue
 func issueProcess(ctx context.Context, inv *inventory.Inventory, m catalogue.Manifest, pr broker.ProcessPrincipal,
 	node, busAddress string, known broker.Broker, reachable string) error {
 	user := broker.Principal{Kind: broker.KindProcess, Node: node, Module: m.Module, Process: pr.Process}.Username()
-	password, err := inv.MintBusPassword(ctx, inventory.BusUser{
+	password, won, err := mintBusUser(ctx, inv, inventory.BusUser{
 		Username: user, Kind: inventory.BusProcess, Node: node, Module: m.Module,
 	})
-	if err != nil {
-		return err
+	if err != nil || !won {
+		return err // lost: the caller that minted it seals it
 	}
 	name := processSecretName(pr.Process)
 	held, err := heldProcessAccount(known, reachable, node, m.Module, user, password)
@@ -1091,11 +1113,11 @@ func runsTheProvisionerClient(m catalogue.Manifest) bool {
 func issueProvisionerClient(ctx context.Context, inv *inventory.Inventory, m catalogue.Manifest, node string,
 	known broker.Broker, reachable string) error {
 	user := broker.Principal{Kind: broker.KindProvisioner, Node: node, Module: m.Module}.Username()
-	password, err := inv.MintBusPassword(ctx, inventory.BusUser{
+	password, won, err := mintBusUser(ctx, inv, inventory.BusUser{
 		Username: user, Kind: inventory.BusProvisioner, Node: node, Module: m.Module,
 	})
-	if err != nil {
-		return err
+	if err != nil || !won {
+		return err // lost: the caller that minted it seals it
 	}
 	held, err := json.Marshal(struct {
 		URL         string `json:"url"`

cmd/mesh-controller/new_modules.go

@@ -200,14 +200,20 @@ func newModuleObservations(now time.Time) []conditions.Observation {
 // watchNewModules wakes the take-in of new modules for each module the builder or the indexer writes, until ctx ends, and
 // looks at every module once now. A bucket not there yet is said: the look at start and a first merge's word still work.
 func watchNewModules(ctx context.Context, open *stores) {
-	inBackground(func() {
+	inBackground(ctx, func() {
 		takeNewModules(ctx, open)
 	})
 	// And, beside it, the start's pass of release 6 and the take-in of each registered module's new done key (novox/hq
 	// ADR 0539 clauses 5, 7, 10 and 13; composed_start.go, composed_keys.go): the plans' buckets deleted, every node
 	// composed, the replaced controller composed, and from now on each new fingerprint registered, composed and granted.
-	inBackground(func() { composeAtStart(ctx, open) })
+	inBackground(ctx, func() { composeAtStart(ctx, open) })
 	watchDoneKeys(ctx, open)
+	// And a change of config composes the node and the touched modules' kept compositions again, heard from
+	// mesh-config's resolved values (ADR 0545, kept_compositions.go).
+	watchConfigFollow(ctx, open)
+	// And each assignment that comes to stand issues its node's bus accounts and the module's grant (ADR 0543): a module
+	// built long before is assigned to one more node with no build done again (issue 1945, assignment_accounts.go).
+	watchAssignmentAccounts(ctx, open)
 	watchHavesForJudgement(ctx, open)
 	// And the keep set keeps the builds every want names (ADR 0539 clause 1), with no plan left to name them.
 	open.inventory.SetWanted(wantedOnTheBus)
@@ -223,16 +229,16 @@ func watchNewModules(ctx context.Context, open *stores) {
 		fmt.Printf("new modules: the builder's keys are not watched: %v\n", err)
 		return
 	}
-	go func() {
+	goServing(ctx, func() {
 		<-ctx.Done()
 		closeKeys()
-	}()
+	})
 }
 
 // wakeNewModule takes module in when the catalogue does not hold it: never on the watch's own goroutine, which must keep
 // draining.
 func wakeNewModule(ctx context.Context, open *stores, module string) {
-	inBackground(func() {
+	inBackground(ctx, func() {
 		entries, err := open.inventory.Catalogued(ctx)
 		if err != nil {
 			return
@@ -250,14 +256,17 @@ func wakeNewModule(ctx context.Context, open *stores, module string) {
 // ends only once the work its mesh started has.
 var background sync.WaitGroup
 
-// inBackground runs work beside the caller, counted in background. A variable so a test of what a walk does around a
-// take-in may run it in the caller's turn and need not wait for it.
-var inBackground = func(work func()) {
+// inBackground runs work beside the caller, counted in background and, under a serving controller, in its serving group,
+// so serve's stop waits for it and a serve that is stopping starts none (serving_group.go). A variable so a test of what a
+// walk does around a take-in may run it in the caller's turn and need not wait for it.
+var inBackground = func(ctx context.Context, work func()) {
 	background.Add(1)
-	go func() {
+	if !goServing(ctx, func() {
 		defer background.Done()
 		work()
-	}()
+	}) {
+		background.Done()
+	}
 }
 
 // newModulesOf are the modules the indexer holds in a repository: what a first merge's word wakes.

cmd/mesh-controller/plain_words.go

@@ -59,6 +59,38 @@ func dataWords(o conditions.Observation) (what, module string) {
 }
 
 var plainWordings = map[string]func(conditions.Observation) words{
+	// A module's new build whose compositions or grant the controller could not write (composed_keys.go).
+	kindNotComposed: worded(func(o conditions.Observation) words {
+		m := "a module"
+		if p := idPart(o, 0); o.Scope == conditions.ScopeBuild && p != "" {
+			m = p // the module: raised in the build's scope, its id the module's name
+		}
+		return words{Headline: "A new build of " + m + " cannot be delivered",
+			Explanation: fmt.Sprintf("A new build of %s was made, and the mesh could not prepare it for the machines, so "+
+				"none can be given it yet. It is tried again every half minute; the details say what fails.", m),
+			Resolved: "the new build of " + m + " can be delivered"}
+	}),
+	// The take-in of done keys whose backlog stood still (take_in_consumer.go, novox/hq ADR 0544 §6).
+	kindTakeInStalled: worded(func(o conditions.Observation) words {
+		return words{Headline: "New builds are not being prepared for the machines",
+			Explanation: "The mesh prepares each new build for the machines as it is made, and has prepared none for " +
+				"five minutes while builds wait. Until it moves, no new build reaches a machine; the details say how many wait.",
+			Resolved: "new builds are being prepared again"}
+	}),
+	// A bucket of done keys whose take-in consumer could not be made (take_in_consumer.go, novox/hq ADR 0544 §6).
+	kindTakeInNotConsumed: worded(func(o conditions.Observation) words {
+		return words{Headline: "Some new builds are not being prepared",
+			Explanation: "The mesh could not start reading one of the two places new builds are announced in, so the " +
+				"builds announced there wait until the controller starts again. The details say which and why.",
+			Resolved: "the mesh reads where new builds are announced again"}
+	}),
+	// Config not followed into the compositions (kept_compositions.go, novox/hq ADR 0545).
+	kindConfigNotFollowed: worded(func(o conditions.Observation) words {
+		return words{Headline: "Changes of settings are not reaching the machines",
+			Explanation: "The mesh could not read the settings as they change, so a changed setting is not prepared for " +
+				"the machines until it can. It tries again every minute; the details say why.",
+			Resolved: "changes of settings reach the machines again"}
+	}),
 	// Machines and their node-engine.
 	"silent": worded(func(o conditions.Observation) words {
 		m := machineOr(o, "a machine")

cmd/mesh-controller/process_accounts.go

@@ -72,6 +72,8 @@ func issueMissingProcessAccounts(ctx context.Context, inv *inventory.Inventory,
 	if len(m.ProcessBuses()) == 0 || mayIssue(m) != nil {
 		return "", nil
 	}
+	// Only the missing: never a second password over one another caller minted between this look and the mint.
+	ctx = onlyIfAbsent(ctx)
 	minted, err := inv.BusMinted(ctx)
 	if err != nil {
 		return "", err

cmd/mesh-controller/process_issue_test.go

@@ -1,12 +1,9 @@
 package main
 
 import (
-	"encoding/json"
-	"strings"
 	"testing"
 
 	"git.novox.be/novox/mesh-sdk/go/catalogue"
-	"github.com/novox/mesh-controller/internal/broker"
 )
 
 // mailSenderWithProcess is mesh-mail's real manifest shape (novox/hq ADR 0436 §7, §8, the lead's fixture):
@@ -25,61 +22,6 @@ func mailSenderWithProcess() catalogue.Manifest {
 	return m
 }
 
-// review round 1, finding 1 (1181): a module declaring no `broker` of its own at all — mesh-mail's real
-// shape, tools served by the tool runner — still passes mayIssue on its process's bus declaration alone.
-func TestAModuleWithNoBrokerAndOnlyAProcessMayBeIssued(t *testing.T) {
-	if err := mayIssue(mailSenderWithProcess()); err != nil {
-		t.Fatalf("a module with no broker of its own, whose process declares bus, was refused: %v", err)
-	}
-}
-
-// 1181/AC1: a process with a bus declaration and no own secret broker-<process id> cannot be issued — the
-// same refusal mayIssue already gives a module with no `broker` (novox/hq ADR 0436 §2).
-func TestAProcessWithNoBrokerSecretCannotBeIssued(t *testing.T) {
-	m := mailSenderWithProcess()
-	delete(m.OwnSecrets, "broker-send")
-	err := mayIssue(m)
-	if err == nil {
-		t.Fatal("a process with no broker-<id> own secret was issued an account")
-	}
-	for _, want := range []string{"mesh-mail", "send", "broker-send", "own-secrets"} {
-		if !strings.Contains(err.Error(), want) {
-			t.Errorf("the refusal does not say %q: %v", want, err)
-		}
-	}
-	if err := mayIssue(mailSenderWithProcess()); err != nil {
-		t.Errorf("a process declaring its own broker-<id> secret was refused: %v", err)
-	}
-}
-
-// 1181/AC1: the account held for a process is the provisioner client's form — {url, fingerprint, node,
-// module, user, password} — named for the process, never the module's own account.
-func TestAProcesssHeldAccountIsTheProvisionersForm(t *testing.T) {
-	user := broker.Principal{Kind: broker.KindProcess, Node: "novox", Module: "mesh-mail", Process: "send"}.Username()
-	if user != "novox.mesh-mail.send" {
-		t.Fatalf("the process's username: %q", user)
-	}
-	held, err := heldProcessAccount(broker.Broker{Fingerprint: "abc"}, "novox.example:4222", "novox", "mesh-mail",
-		user, "a-password")
-	if err != nil {
-		t.Fatal(err)
-	}
-	var got map[string]any
-	if err := json.Unmarshal(held, &got); err != nil {
-		t.Fatal(err)
-	}
-	want := map[string]any{"url": "nats://novox.example:4222", "fingerprint": "abc", "node": "novox",
-		"module": "mesh-mail", "user": "novox.mesh-mail.send", "password": "a-password"}
-	for k, v := range want {
-		if got[k] != v {
-			t.Errorf("%s: %v, want %v", k, got[k], v)
-		}
-	}
-	if len(got) != len(want) {
-		t.Errorf("the held account carries %v; want exactly %v (never claims — a process holds no seat)", got, want)
-	}
-}
-
 // 1181/AC1: composed, the process's own secret belongs to its own account at 0600 (novox/hq ADR 0436 §1, §2;
 // the owner mechanism is issue 1170's, proven generically there — this is mesh-mail's own shape).
 func TestAProcessesOwnSecretIsOwnedByItsOwnAccount(t *testing.T) {

cmd/mesh-controller/push.go

@@ -125,7 +125,15 @@ func serve(ctx context.Context) (err error) {
 	defer theLease.release()
 	ctx, stopActing := context.WithCancel(ctx)
 	defer stopActing()
-	go func() {
+	// Every goroutine started from here is counted, and ended and waited for before serve returns (serving_group.go):
+	// on the way out by error here, and at the end before anything else is undone.
+	ctx, running := withServingGroup(ctx)
+	stopRunning := func() {
+		stopActing()
+		running.stop()
+	}
+	defer stopRunning()
+	goServing(ctx, func() {
 		select {
 		case <-lost:
 			stopActing()
@@ -135,7 +143,7 @@ func serve(ctx context.Context) (err error) {
 		// asks the controller after this one rather than have a command started and killed with this
 		// process (novox/hq issue 289).
 		handingOver.Store(true)
-	}()
+	})
 	defer func() {
 		select {
 		case <-lost:
@@ -162,6 +170,17 @@ func serve(ctx context.Context) (err error) {
 	if err := attachTheChain(ctx, inv, server); err != nil {
 		return err
 	}
+	bus, isNATS := server.Bus().(link.OverNATS)
+	if !isNATS {
+		return errors.New("the mesh's verbs are served over the bus, and this control plane is not on it")
+	}
+	// The condition store, opened before anything that raises or reads a condition starts beside the serving, so none
+	// of them meets conditionsFrom being written (issue 1945); closed after they all ended.
+	keeper := openServingConditions(ctx, open, bus)
+	if keeper != nil {
+		defer closeConditions(keeper)
+		defer stopRunning() // on an error return, the goroutines end before the keeper closes
+	}
 
 	// The bus's own objects, asserted on every start. **Not created once at genesis**: a stream
 	// somebody deleted, a mesh raised from a restored backup, or a bus whose data directory was
@@ -176,7 +195,7 @@ func serve(ctx context.Context) (err error) {
 	// And the pending assignments settled on a tick of their own (novox/hq ADR 0261): made once their module
 	// is registered, ended with why when its build will not register it, raised and cleared as conditions.
 	// Never by a read.
-	go settlingPending(ctx, open)
+	goServing(ctx, func() { settlingPending(ctx, open) })
 	// The durations the core's bounds are set from are kept a month (novox/hq to-be 45 Phase 0).
 	// And what the catalogue decided a build meant. The builder's own result is already handled
 	// above; this is the other half — the control plane is the only one of the three that knows
@@ -224,19 +243,17 @@ func serve(ctx context.Context) (err error) {
 			"Those answer the reason when called; everything else is served as usual\n",
 			catalogue.ControllerSeatName, strings.Join(behind, ", "))
 	}
-	bus, isNATS := server.Bus().(link.OverNATS)
-	if !isNATS {
-		return errors.New("the mesh's verbs are served over the bus, and this control plane is not on it")
-	}
 	// The hand-act log is counted for `status` on this connection rather than a new one a minute; no longer serving, the
 	// connection is closed, and a verb run after in this process dials its own (a served test's leftover failed the
 	// next test's `conditions` with "connection closed", issue 1945).
 	handActConn = bus.Conn
 	defer func() { handActConn = nil }()
+	defer stopRunning() // on an error return, the goroutines end before handActConn is put back
 	// And everything else this controller does on the bus for a moment (novox/hq issue 327).
 	servingBus.Store(server.JetStream())
 	// No longer serving: nothing is lent, and dead-letters says it is not read here (novox/hq issue 330).
 	defer servingBus.Store(nil)
+	defer stopRunning() // on an error return, the goroutines end before the bus is taken back
 	// And says when it replaced a value given by hand (novox/hq ADR 0228).
 	givenEvents = bus
 	// And a pull request's merge check, asked when the forge announces its head and said when judged
@@ -247,18 +264,18 @@ func serve(ctx context.Context) (err error) {
 		return err
 	}
 	// Composed now and kept current, before the verb that answers from it is served.
-	go statusFrom.keep(ctx)
+	goServing(ctx, func() { statusFrom.keep(ctx) })
 	// The facts snapshot a merge check is fed (novox/hq to-be 45 §9): kept current while this
 	// controller holds the lease, read by the build seat from the artifact store.
-	go exportingFacts(ctx, open, bus.Conn.ConnectedServerVersion)
+	goServing(ctx, func() { exportingFacts(ctx, open, bus.Conn.ConnectedServerVersion) })
 	// The record mirrors (novox/hq ADR 0289, design 57 F3): the assignments and each registered module's
 	// declared config on the bus, written from the store only when a record changed, by the lease holder.
 	// The provisioner's plan of each handed module, as its machine was last sent it (design 57 P6), in the module's
 	// assignment.
 	inv.SetProvisioningPlans(inv.SentProvisioningPlans)
-	go mirroringRecords(ctx, open, inv, bus.Conn, bus)
+	goServing(ctx, func() { mirroringRecords(ctx, open, inv, bus.Conn, bus) })
 	// And the bucket of the files that travel by digest, judged against what each machine's latest declaration names (ADR 0486 §3).
-	go sweepingDeclarationFiles(ctx, inv, bus.Conn)
+	goServing(ctx, func() { sweepingDeclarationFiles(ctx, inv, bus.Conn) })
 	// And the modules the catalogue does not hold yet, registered from the builder's first done key of each, woken by
 	// the builder's and the indexer's writes (novox/hq ADR 0501 §6, issue 1851): nothing asks a first build.
 	watchNewModules(ctx, open)
@@ -290,7 +307,7 @@ func serve(ctx context.Context) (err error) {
 	// signals table, what the bus says about itself, and the self-check. A store that cannot be opened
 	// is said and the controller serves on: status then says the conditions cannot be read, and is
 	// not well — louder than not serving at all, and the push that repairs the bus still runs.
-	if stopWatching := watchTheMesh(ctx, open, server, bus); stopWatching != nil {
+	if stopWatching := watchTheMesh(ctx, open, server, bus, keeper); stopWatching != nil {
 		defer stopWatching()
 	}
 	stopServing, err := bus.ServeSeatTools(catalogue.ControllerSeatName, handlers, log.New(os.Stdout, "", log.LstdFlags))
@@ -305,7 +322,7 @@ func serve(ctx context.Context) (err error) {
 	}
 	defer stopCLI()
 	// Its read calls write no line each; how many each caller made is said once an hour (novox/hq issue 762).
-	go sayReadCalls(ctx)
+	goServing(ctx, func() { sayReadCalls(ctx) })
 	// And says so on the bus (novox/hq ADR 0197): what it serves, as the NATS services protocol asks.
 	stopAnnouncing, err := bus.Announce(seatAnnouncement(handlers), log.New(os.Stdout, "", log.LstdFlags))
 	if err != nil {
@@ -313,7 +330,10 @@ func serve(ctx context.Context) (err error) {
 	}
 	defer stopAnnouncing()
 
-	return server.Serve(ctx)
+	err = server.Serve(ctx)
+	// Ended and waited for before the verbs stop being served and the globals are put back, not after.
+	stopRunning()
+	return err
 }
 
 // OverlayCIDRVar is the range the mesh allocates node addresses from.

cmd/mesh-controller/readable.go

@@ -111,6 +111,9 @@ type meshStatus struct {
 	// why they could not be read.
 	Pending       []pendingStatus `json:"pending,omitempty"`
 	PendingUnread string          `json:"pendingUnread,omitempty"`
+	// TakeIn is the take-in's backlog of done keys: keys not delivered yet and keys being taken in (novox/hq ADR 0544
+	// §6). Absent where it cannot be read.
+	TakeIn *takeInBacklog `json:"take-in,omitempty"`
 }
 
 // pendingStatus is one pending assignment as status says it.
@@ -266,6 +269,7 @@ func statusAsJSON(asked answers) ([]byte, error) {
 	out.Failing = providerStandings(asked.conditions)
 	out.Overflowing = asked.overflowing
 	out.PendingUnread = asked.pendingUnread
+	out.TakeIn = asked.takeIn
 	for _, p := range asked.pending {
 		out.Pending = append(out.Pending, pendingStatus{Node: p.Node, Module: p.Module, State: p.State,
 			Build: p.Build, Repository: p.Repository, Path: p.Path, Since: p.Since, Settled: p.Settled, Note: p.Note})

cmd/mesh-controller/record_mirrors.go

@@ -2,12 +2,15 @@ package main
 
 import (
 	"context"
+	"crypto/sha256"
+	"encoding/hex"
 	"encoding/json"
 	"fmt"
 	"sort"
 	"time"
 
 	"git.novox.be/novox/mesh-sdk/go/compose"
+	sdkdelivery "git.novox.be/novox/mesh-sdk/go/delivery"
 	"github.com/nats-io/nats.go"
 	"github.com/nats-io/nats.go/jetstream"
 
@@ -24,7 +27,8 @@ import (
 // so no one call site sees every change; what every change has in common is that it is committed to the
 // store. So the serving controller reads the store every mirrorEvery and writes only what differs from what
 // the bucket holds (ADR 0289 §1): a quiet mesh writes nothing, and a change rolled back is never read. A
-// mirror is therefore at most mirrorEvery behind its store.
+// mirror is therefore at most mirrorEvery behind its store. The declared-packages mirror is the exception: it composes
+// every node, so it passes on a change of what it composes from, not on this tick (keepingDeclaredPackages, issue 1945).
 
 // mirrorEvery is how often the mirrors are compared with the store: two small reads of the store.
 const mirrorEvery = 10 * time.Second
@@ -45,21 +49,31 @@ func mirroringRecords(ctx context.Context, open *stores, inv *inventory.Inventor
 		return e
 	}
 	sources := map[string]func(context.Context) (map[string][]byte, error){
-		recordmirror.DeclaredConfig.Name:   inv.DeclaredConfigMirror,
-		recordmirror.Predefined.Name:       inv.PredefinedMirror,
-		recordmirror.DeclaredPackages.Name: declaredPackagesMirror(open),
+		recordmirror.DeclaredConfig.Name: inv.DeclaredConfigMirror,
+		recordmirror.Predefined.Name:     inv.PredefinedMirror,
 	}
+	packages := keepingDeclaredPackages(ctx, open, api, announce, epoch, holds)
+	held := false
 	writers := map[string]*recordmirror.Writer{}
 	failing := map[string]string{}
 	tick := time.NewTicker(mirrorEvery)
 	defer tick.Stop()
 	events := &assignmentEvents{}
 	for {
-		if holds() {
+		now := holds()
+		if now && !held {
+			// The lease taken: the declared-packages mirror is brought to the stores at once, not at its next change.
+			packages.poke()
+		}
+		held = now
+		if now {
 			// The assignments are keys of the bus, written by the verbs that change them (novox/hq ADR 0408): this tick
 			// keeps the provisioner's plan in their values and says what changed. They are no mirror of the store.
 			keepingAssignments(ctx, inv, announce, epoch, events, failing)
 			for _, m := range recordmirror.Mirrors() {
+				if sources[m.Name] == nil {
+					continue // the declared packages, kept on a change (keepingDeclaredPackages)
+				}
 				why := mirrorOnce(ctx, api, m, writers, sources[m.Name], announce, epoch, holds)
 				if why != failing[m.Name] {
 					if why != "" {
@@ -179,35 +193,263 @@ func keepingAssignments(ctx context.Context, inv *inventory.Inventory, announce
 	events.known = now
 }
 
-// declaredPackagesMirror is the source of the declared-packages mirror (ADR 0507 §5): each node's composition, asked as a
-// question that makes nothing, and the packages it declares with the modules that declare them. A node whose own set does
-// not compose has no key, and any other failure to read is the pass's error, so a key is never purged for a store that
-// could not be read.
+// declaredPackagesMirror is the source of the declared-packages mirror (ADR 0507 §5) over a fresh reading of the stores.
 func declaredPackagesMirror(open *stores) func(context.Context) (map[string][]byte, error) {
 	return func(ctx context.Context) (map[string][]byte, error) {
 		in, err := inputFor(ctx, open)
 		if err != nil {
 			return nil, err
 		}
-		// Which module owns each resource is carried only for a node-engine that reads it, so every node is asked as one that does.
-		asked := in.Input
-		asked.Nodes = append([]compose.Node(nil), in.Nodes...)
-		for i := range asked.Nodes {
-			asked.Nodes[i].ReadsModules = true
-		}
-		out := map[string][]byte{}
-		for _, n := range in.sortedNodes() {
-			d, _, err := compose.ComposeIn(asked, n.Name, compose.Foreseeing)
-			if compose.IsUnresolvable(err) {
-				continue
+		return declaredPackagesFrom(ctx, in)
+	}
+}
+
+// declaredPackagesFrom is the declared-packages mirror over an Input: each node's composition, asked as a question that makes
+// nothing, and the packages it declares with the modules that declare them. A node whose own set does not compose has no key,
+// and any other failure to read is the pass's error, so a key is never purged for a store that could not be read.
+func declaredPackagesFrom(_ context.Context, in *meshInput) (map[string][]byte, error) {
+	// Which module owns each resource is carried only for a node-engine that reads it, so every node is asked as one that does.
+	asked := in.Input
+	asked.Nodes = append([]compose.Node(nil), in.Nodes...)
+	for i := range asked.Nodes {
+		asked.Nodes[i].ReadsModules = true
+	}
+	out := map[string][]byte{}
+	for _, n := range in.sortedNodes() {
+		d, _, err := compose.ComposeIn(asked, n.Name, compose.Foreseeing)
+		if compose.IsUnresolvable(err) {
+			continue
+		}
+		if err != nil {
+			return nil, fmt.Errorf("the packages %s declares cannot be read: %w", n.Name, err)
+		}
+		if out[n.Name], err = inventory.DeclaredPackagesValue(n.Name, d.Resources, d.ModuleOf); err != nil {
+			return nil, err
+		}
+	}
+	return out, nil
+}
+
+// **The declared-packages mirror passes on a change, not on a tick** (issue 1945 note 22). Its source composes every node in
+// full, about 45 s on the control node; on the 10 s tick it never rested and held the controller at 130-175 % CPU. Every
+// change that can move a node's packages is a change of its composition, which the controller writes into the bucket of the
+// compositions' digests, and of the assignments, which the verbs write into theirs: a watch of those two buckets wakes the
+// keeper. A pass reads the stores' Input once and composes only when the Input's digest differs from the one it last
+// mirrored, so a wake that changed nothing it composes from costs one reading. One pass at a time; the wakes during a pass
+// are one pass after it, at least packagesGap after the last began. A rare safety pass (packagesSafetyEvery) covers a
+// change no watched key says, and with an unchanged digest composes nothing either.
+const (
+	packagesSafetyEvery = 10 * time.Minute
+	packagesGap         = 30 * time.Second
+)
+
+// packagesTiming is when the declared-packages mirror passes: the safety pass's period and the least time between the
+// starts of two passes.
+type packagesTiming struct{ safety, gap time.Duration }
+
+// packagesKeeper keeps the declared-packages mirror: read is the Input, compose the mirror's values from it, sync writes
+// those that differ from the bucket, holds says this controller holds the lease. Each a seam a test stands in for.
+type packagesKeeper struct {
+	read    func(ctx context.Context) (*meshInput, error)
+	compose func(ctx context.Context, in *meshInput) (map[string][]byte, error)
+	sync    func(ctx context.Context, want map[string][]byte) error
+	holds   func() bool
+	wake    chan struct{}
+	// last is the digest of the Input last mirrored whole; empty after a failure or while the lease is not held, so the
+	// next pass composes.
+	last string
+}
+
+func newPackagesKeeper(read func(context.Context) (*meshInput, error),
+	compose func(context.Context, *meshInput) (map[string][]byte, error),
+	sync func(context.Context, map[string][]byte) error, holds func() bool) *packagesKeeper {
+	return &packagesKeeper{read: read, compose: compose, sync: sync, holds: holds, wake: make(chan struct{}, 1)}
+}
+
+// poke says something the mirror composes from may have changed; never blocks, and pokes before a pass are one.
+func (k *packagesKeeper) poke() {
+	select {
+	case k.wake <- struct{}{}:
+	default:
+	}
+}
+
+// pass brings the mirror to the Input, composing only when the Input differs from the one last mirrored.
+func (k *packagesKeeper) pass(ctx context.Context) error {
+	if !k.holds() {
+		k.last = ""
+		return nil
+	}
+	in, err := k.read(ctx)
+	if err != nil {
+		k.last = ""
+		return fmt.Errorf("the store cannot be read: %w", err)
+	}
+	digest := inputDigest(in)
+	if digest != "" && digest == k.last {
+		return nil
+	}
+	want, err := k.compose(ctx, in)
+	if err != nil {
+		k.last = ""
+		return err
+	}
+	if err := k.sync(ctx, want); err != nil {
+		k.last = ""
+		return err
+	}
+	k.last = digest
+	return nil
+}
+
+// run passes once at its start, then on each wake and each safety period, until ctx ends. said hears why a pass failed,
+// and an empty line when one succeeds again.
+func (k *packagesKeeper) run(ctx context.Context, at packagesTiming, said func(why string)) {
+	safety := time.NewTicker(at.safety)
+	defer safety.Stop()
+	failing := ""
+	var began time.Time
+	for {
+		// The wakes so far are this pass's: drained before it reads, so a change after is a pass of its own.
+		select {
+		case <-k.wake:
+		default:
+		}
+		began = time.Now()
+		why := ""
+		if err := k.pass(ctx); err != nil {
+			why = err.Error()
+		}
+		if why != failing {
+			said(why)
+			failing = why
+		}
+		select {
+		case <-ctx.Done():
+			return
+		case <-k.wake:
+		case <-safety.C:
+		}
+		if rest := at.gap - time.Since(began); rest > 0 {
+			select {
+			case <-ctx.Done():
+				return
+			case <-time.After(rest):
 			}
+		}
+	}
+}
+
+// inputDigest is a digest of everything the composition reads (the Input, and why a node or the bus is refused): the same
+// for the same Input. Empty when it cannot be made, and then the pass composes.
+func inputDigest(in *meshInput) string {
+	refused := map[string]string{}
+	for node, err := range in.refused {
+		if err != nil {
+			refused[node] = err.Error()
+		}
+	}
+	bus := ""
+	if in.busRefused != nil {
+		bus = in.busRefused.Error()
+	}
+	body, err := json.Marshal(struct {
+		Input      compose.Input
+		Refused    map[string]string
+		BusRefused string
+	}{in.Input, refused, bus})
+	if err != nil {
+		return ""
+	}
+	sum := sha256.Sum256(body)
+	return hex.EncodeToString(sum[:])
+}
+
+// keepingDeclaredPackages keeps the declared-packages mirror for as long as ctx: woken by the watch of the compositions'
+// digests and of the assignments. It answers the keeper, whose poke a caller may also wake it with.
+func keepingDeclaredPackages(ctx context.Context, open *stores, api jetstream.JetStream, announce recordmirror.Announcer,
+	epoch func() uint64, holds func() bool) *packagesKeeper {
+	m := recordmirror.DeclaredPackages
+	var w *recordmirror.Writer
+	read := func(ctx context.Context) (*meshInput, error) {
+		reading, cancel := context.WithTimeout(ctx, 2*time.Minute)
+		defer cancel()
+		return readComposeInput(reading, open)
+	}
+	sync := func(ctx context.Context, want map[string][]byte) error {
+		writing, cancel := context.WithTimeout(ctx, 30*time.Second)
+		defer cancel()
+		if w == nil {
+			kv, err := api.KeyValue(writing, m.Bucket)
 			if err != nil {
-				return nil, fmt.Errorf("the packages %s declares cannot be read: %w", n.Name, err)
+				return fmt.Errorf("the bucket %s cannot be read: %v", m.Bucket, err)
+			}
+			w = &recordmirror.Writer{Mirror: m, KV: kv, Announce: announce, Epoch: epoch, Holds: holds}
+		}
+		lost := w.LostEvents
+		r, err := w.Sync(writing, want)
+		if r.Written+r.Removed > 0 {
+			fmt.Printf("the %s mirror moved: %d written, %d removed\n", m.Name, r.Written, r.Removed)
+		}
+		if w.LostEvents > lost {
+			fmt.Printf("the %s mirror lost %d event(s): the bucket holds the change, its notice was refused twice\n",
+				m.Name, w.LostEvents-lost)
+		}
+		return err
+	}
+	k := newPackagesKeeper(read, declaredPackagesFrom, sync, holds)
+	for _, bucket := range []string{sdkdelivery.ControllerComposedBucket, broker.AssignmentsBucket} {
+		goServing(ctx, func() { wakeOnBucket(ctx, api, bucket, k.poke) })
+	}
+	goServing(ctx, func() {
+		k.run(ctx, packagesTiming{safety: packagesSafetyEvery, gap: packagesGap}, func(why string) {
+			if why != "" {
+				fmt.Printf("the %s mirror cannot be kept: %s\n", m.Name, why)
+			} else {
+				fmt.Printf("the %s mirror is kept again\n", m.Name)
+			}
+		})
+	})
+	return k
+}
+
+// wakeOnBucket calls wake on every write or delete of a key in the bucket, for as long as ctx: only the keys' metadata is
+// watched. A bucket not there yet, or a watch that ends, is watched again a minute later; the safety pass covers the gap.
+func wakeOnBucket(ctx context.Context, api jetstream.JetStream, bucket string, wake func()) {
+	for {
+		if err := watchBucketOnce(ctx, api, bucket, wake); err != nil && ctx.Err() == nil {
+			fmt.Printf("the declared-packages mirror does not hear %s: %v\n", bucket, err)
+		}
+		select {
+		case <-ctx.Done():
+			return
+		case <-time.After(time.Minute):
+		}
+	}
+}
+
+// watchBucketOnce watches the bucket until its watch ends or ctx does.
+func watchBucketOnce(ctx context.Context, api jetstream.JetStream, bucket string, wake func()) error {
+	kv, err := api.KeyValue(ctx, bucket)
+	if err != nil {
+		return err
+	}
+	watch, err := kv.WatchAll(ctx, jetstream.UpdatesOnly(), jetstream.MetaOnly())
+	if err != nil {
+		return err
+	}
+	defer func() { _ = watch.Stop() }()
+	for {
+		select {
+		case <-ctx.Done():
+			return nil
+		case e, ok := <-watch.Updates():
+			if !ok {
+				return fmt.Errorf("the watch ended")
 			}
-			if out[n.Name], err = inventory.DeclaredPackagesValue(n.Name, d.Resources, d.ModuleOf); err != nil {
-				return nil, err
+			if e != nil {
+				wake()
 			}
 		}
-		return out, nil
 	}
 }

cmd/mesh-controller/record_mirrors_test.go

@@ -0,0 +1,191 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/compose"
+)
+
+// The declared-packages mirror composes only when what it composes from changed (issue 1945 note 22: it composed every node
+// in full every 10 s, a pass of about 45 s, so the controller on the control node never rested at 130-175 % CPU).
+
+// scaled is a cadence of the mirror with a second taken as a millisecond, so a test's minute is 60 ms.
+func scaled() packagesTiming {
+	return packagesTiming{safety: packagesSafetyEvery / 1000, gap: packagesGap / 1000}
+}
+
+const scaledMinute = 60 * time.Millisecond
+
+// fakeMesh is the keeper's input as a test changes it: each node's assigned modules, and the compositions counted by node.
+type fakeMesh struct {
+	mu       sync.Mutex
+	assigned map[string][]string
+	composed atomic.Int64 // node compositions
+	synced   atomic.Int64
+	lastSync map[string][]byte
+	// block, when set, holds the next composition until it is closed; entered is closed when that composition began.
+	block   chan struct{}
+	entered chan struct{}
+}
+
+func newFakeMesh(nodes int) *fakeMesh {
+	f := &fakeMesh{assigned: map[string][]string{}}
+	for i := 0; i < nodes; i++ {
+		f.assigned[fmt.Sprintf("node%d", i)] = []string{"base"}
+	}
+	return f
+}
+
+func (f *fakeMesh) assign(node, module string) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	f.assigned[node] = append(append([]string(nil), f.assigned[node]...), module)
+}
+
+func (f *fakeMesh) keeper() *packagesKeeper {
+	read := func(context.Context) (*meshInput, error) {
+		f.mu.Lock()
+		defer f.mu.Unlock()
+		in := compose.Input{Catalogue: map[string]catalogue.Manifest{"base": {Module: "base", Version: "1"}}}
+		for _, n := range nodesOfFake(f.assigned) {
+			in.Nodes = append(in.Nodes, compose.Node{Name: n, Assigned: append([]string(nil), f.assigned[n]...)})
+		}
+		return &meshInput{Input: in}, nil
+	}
+	composeAll := func(_ context.Context, in *meshInput) (map[string][]byte, error) {
+		f.mu.Lock()
+		block, entered := f.block, f.entered
+		f.block = nil
+		f.mu.Unlock()
+		if block != nil {
+			close(entered)
+			<-block
+		}
+		out := map[string][]byte{}
+		for _, n := range in.Nodes {
+			f.composed.Add(1)
+			out[n.Name] = []byte(fmt.Sprint(n.Assigned))
+		}
+		return out, nil
+	}
+	syncAll := func(_ context.Context, want map[string][]byte) error {
+		f.mu.Lock()
+		f.lastSync = want
+		f.mu.Unlock()
+		f.synced.Add(1)
+		return nil
+	}
+	return newPackagesKeeper(read, composeAll, syncAll, func() bool { return true })
+}
+
+func nodesOfFake(m map[string][]string) []string {
+	out := make([]string, 0, len(m))
+	for k := range m {
+		out = append(out, k)
+	}
+	for i := range out {
+		for j := i + 1; j < len(out); j++ {
+			if out[j] < out[i] {
+				out[i], out[j] = out[j], out[i]
+			}
+		}
+	}
+	return out
+}
+
+func runKeeper(t *testing.T, k *packagesKeeper) context.CancelFunc {
+	ctx, cancel := context.WithCancel(context.Background())
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		k.run(ctx, scaled(), func(string) {})
+	}()
+	t.Cleanup(func() {
+		cancel()
+		<-done
+	})
+	return cancel
+}
+
+func eventually(t *testing.T, what string, cond func() bool) {
+	t.Helper()
+	deadline := time.Now().Add(time.Second)
+	for !cond() {
+		if time.Now().After(deadline) {
+			t.Fatalf("not within a second: %s", what)
+		}
+		time.Sleep(time.Millisecond)
+	}
+}
+
+// 1945/AC-mirror-1: given a mesh whose input does not change, when a minute passes after the mirror's first pass, then it
+// composes no node (before: a pass every 10 s, each composing every node). The count per minute is said.
+func TestTheDeclaredPackagesMirrorComposesNothingWithoutAChange(t *testing.T) {
+	const nodes = 5
+	f := newFakeMesh(nodes)
+	runKeeper(t, f.keeper())
+	eventually(t, "the first pass", func() bool { return f.synced.Load() >= 1 })
+	start := f.composed.Load()
+	time.Sleep(scaledMinute)
+	perMinute := f.composed.Load() - start
+	t.Logf("node compositions in a minute of an unchanged mesh of %d nodes: %d", nodes, perMinute)
+	if perMinute != 0 {
+		t.Errorf("an unchanged mesh of %d nodes was composed %d times in a minute; want 0", nodes, perMinute)
+	}
+}
+
+// 1945/AC-mirror-2: given a pass that is running, when fifty changes arrive during it, then exactly one more pass follows,
+// never two at once and never one per change.
+func TestTheDeclaredPackagesMirrorPassesOncePerBurst(t *testing.T) {
+	f := newFakeMesh(1)
+	release := make(chan struct{})
+	f.block, f.entered = release, make(chan struct{})
+	k := f.keeper()
+	runKeeper(t, k)
+	<-f.entered
+	for i := 0; i < 50; i++ {
+		f.assign("node0", fmt.Sprintf("m%d", i))
+		k.poke()
+	}
+	close(release)
+	eventually(t, "the pass after the burst", func() bool { return f.synced.Load() >= 2 })
+	time.Sleep(2*scaled().gap + 20*time.Millisecond)
+	if got := f.synced.Load(); got != 2 {
+		t.Errorf("a burst of 50 changes during a pass gave %d passes in all; want 2 (the running one and one after)", got)
+	}
+}
+
+// 1945/AC-mirror-3: given the mirror at rest, when an input changes and its event arrives, then the change is mirrored.
+func TestTheDeclaredPackagesMirrorMirrorsAChange(t *testing.T) {
+	f := newFakeMesh(2)
+	k := f.keeper()
+	runKeeper(t, k)
+	eventually(t, "the first pass", func() bool { return f.synced.Load() >= 1 })
+	f.assign("node1", "viewer")
+	k.poke()
+	eventually(t, "the change mirrored", func() bool {
+		f.mu.Lock()
+		defer f.mu.Unlock()
+		return string(f.lastSync["node1"]) == "[base viewer]"
+	})
+}
+
+// 1945/AC-mirror-4: the digest of the input is the same for the same input and differs when an assignment differs.
+func TestTheInputDigestFollowsTheInput(t *testing.T) {
+	of := func(assigned ...string) *meshInput {
+		return &meshInput{Input: compose.Input{Nodes: []compose.Node{{Name: "anchor", Assigned: assigned}}}}
+	}
+	a, b, c := inputDigest(of("base")), inputDigest(of("base")), inputDigest(of("base", "viewer"))
+	if a == "" || a != b {
+		t.Errorf("the same input gave the digests %q and %q", a, b)
+	}
+	if a == c {
+		t.Errorf("an added assignment left the digest at %q", a)
+	}
+}

cmd/mesh-controller/serving_group.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"context"
+	"sync"
+)
+
+// **Every goroutine the serving controller starts ends before serve returns** (issue 1945). A loop or a watch started
+// beside the serving runs until serve's context ends, and serve's stop waits for it before it closes the stores, the
+// bus and the condition keeper those loops read: a loop that outlived its serve met the next serve's globals, its
+// closed stores and its bus, and in the test process that is the next test (a race on conditionsFrom, a package that
+// passed every test and still exited failing). Where it is checked: the tests that run serve whole, under -race.
+
+// servingGroup counts the goroutines one serve started. Once its stop began it starts nothing more: what would start is
+// work for a controller that is stopping.
+type servingGroup struct {
+	mu      sync.Mutex
+	stopped bool
+	wg      sync.WaitGroup
+}
+
+type servingGroupKey struct{}
+
+// withServingGroup is ctx carrying a new group, which goServing under it counts.
+func withServingGroup(ctx context.Context) (context.Context, *servingGroup) {
+	g := &servingGroup{}
+	return context.WithValue(ctx, servingGroupKey{}, g), g
+}
+
+// goServing runs work beside the caller, counted in the group ctx carries, so serve's stop waits for it. Under a group
+// whose stop began it runs nothing; under a context with no group (a part run alone, by a test or a verb) it is a plain
+// goroutine, as before. It says whether it started work.
+func goServing(ctx context.Context, work func()) bool {
+	g, _ := ctx.Value(servingGroupKey{}).(*servingGroup)
+	if g == nil {
+		go work()
+		return true
+	}
+	g.mu.Lock()
+	if g.stopped {
+		g.mu.Unlock()
+		return false
+	}
+	g.wg.Add(1)
+	g.mu.Unlock()
+	go func() {
+		defer g.wg.Done()
+		work()
+	}()
+	return true
+}
+
+// stop starts nothing more and waits for what was started; the caller ends their context first. A second stop waits
+// for nothing.
+func (g *servingGroup) stop() {
+	g.mu.Lock()
+	g.stopped = true
+	g.mu.Unlock()
+	g.wg.Wait()
+}

cmd/mesh-controller/states_announced.go

@@ -67,16 +67,16 @@ func keepAnnouncements(ctx context.Context, js *broker.JetStream, open *stores)
 			return
 		}
 		if changed {
-			inBackground(func() { composeAnnouncedReads(context.WithoutCancel(ctx), open) })
+			inBackground(ctx, func() { composeAnnouncedReads(context.WithoutCancel(ctx), open) })
 		}
 	})
 	if err != nil {
 		return fmt.Errorf("following the states announced: %w", err)
 	}
-	go func() {
+	goServing(ctx, func() {
 		<-ctx.Done()
 		consuming.Stop()
-	}()
+	})
 	return nil
 }
 

cmd/mesh-controller/status.go

@@ -151,6 +151,10 @@ func printStatus(asked answers) error {
 	}
 
 	printPending(asked.pending, asked.pendingUnread)
+	if b := asked.takeIn; b != nil && b.Total() > 0 {
+		fmt.Printf("the take-in of done keys has %d key(s) not taken in yet: %d waiting to be delivered, %d being taken in\n\n",
+			b.Total(), b.Pending, b.Taking)
+	}
 
 	if len(behind) > 0 {
 		var names []string
@@ -471,6 +475,13 @@ func theThreeQuestions(ctx context.Context, open *stores) (answers, error) {
 		out.pendingUnread = err.Error()
 		err = nil
 	}
+	// And the take-in's backlog of done keys, read from its consumers on the bus (novox/hq ADR 0544 §6): where there is
+	// a bus; a stall is a condition of its own, so this is said and judges nothing.
+	if _, onBus := broker.BusAddress(); onBus == nil {
+		if b, berr := readTakeInBacklog(ctx); berr == nil {
+			out.takeIn = &b
+		}
+	}
 	// And how many repairs were done by hand this week (novox/hq to-be 45 §7) — where there is a bus
 	// to read the log from; a process with none has no log to count.
 	if _, onBus := broker.BusAddress(); onBus == nil {

cmd/mesh-controller/status_summary.go

@@ -210,7 +210,7 @@ func (l nudgingListener) Heard(ctx context.Context, report link.Report) (bool, e
 	// And, once the move of the secrets into the vault has started, what is left of this machine's (design 57's V3,
 	// issue 676): a machine asleep when it started is moved when it is next heard from. Off the report's path.
 	if err == nil && l.open != nil && report.Superseded == "" && report.Rekey == nil && report.Node != "" {
-		go moveWhenHeard(context.WithoutCancel(ctx), l.open, moveHeardOn(), report.Node)
+		goServing(ctx, func() { moveWhenHeard(context.WithoutCancel(ctx), l.open, moveHeardOn(), report.Node) })
 	}
 	return news, err
 }

cmd/mesh-controller/take_in_consumer.go

@@ -0,0 +1,452 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	sdkdelivery "git.novox.be/novox/mesh-sdk/go/delivery"
+	"github.com/nats-io/nats.go/jetstream"
+	"github.com/novox/mesh-controller/internal/broker"
+	"github.com/novox/mesh-controller/internal/conditions"
+)
+
+// The take-in's two durable pull consumers (novox/hq ADR 0544; research 072, milestones 2 and 4). On the indexer's
+// modules bucket the consumer delivers each module's last trunk value when it is made, then each write: the start's look
+// of a controller whose consumer is new, and nothing at a restart but what the controller before it left
+// unacknowledged. On the builder's builds bucket it delivers each write from when it is made. A key is acknowledged once
+// its module is taken in, has nothing new, or waits for a write that will be delivered; any other wait or failure is
+// refused with a delay that grows with each refusal, and the bus delivers it again.
+//
+// **The bound on the store is the one take-in loop**, a batch of at most startTakeIns keys at a time (issues 1945 and
+// 1277: a burst of take-ins once filled the store until it refused every connection). The consumers' own limit on
+// unacknowledged keys is far above it, because a refused key stays unacknowledged until its delay ends: with a limit of
+// a batch, a handful of keys refused for long (a manifest word this controller does not read yet) would stop a consumer
+// for good, the build that reads the word among what it holds back (the review of ADR 0544).
+
+// startTakeIns is the most a batch takes: the take-ins that may wait on the store at once.
+const startTakeIns = 16
+
+// takeInPending is how many keys each consumer may leave unacknowledged: delivered and being taken in, or refused and
+// waiting for their delay. Far above a batch, so refused keys never stop the others.
+const takeInPending = 1000
+
+// takeInBuffered is how many delivered keys each consumer's reader holds ahead of the loop.
+const takeInBuffered = startTakeIns / 2
+
+// takeInAckWait is how long a delivered key may stay unacknowledged before the bus delivers it again: longer than a batch
+// takes, its two composer passes among it.
+const takeInAckWait = 10 * time.Minute
+
+// takeInGather is how long a batch waits for more keys after its first, so a burst is one batch.
+var takeInGather = 200 * time.Millisecond
+
+// takeInStall is how long a backlog may stand without a key delivered before it is a condition (ADR 0544 §6).
+var takeInStall = 5 * time.Minute
+
+// takeInMsg is one delivered key, as the take-in uses it.
+type takeInMsg struct {
+	delivered
+	ack func()
+	nak func(delay time.Duration)
+}
+
+// takeInKeyOf is the module a delivered key names, false for a delete or a purge, which takes nothing in.
+func takeInKeyOf(bucket string, m jetstream.Msg) (delivered, bool) {
+	if op := m.Headers().Get("KV-Operation"); op == "DEL" || op == "PURGE" {
+		return delivered{}, false
+	}
+	key := strings.TrimPrefix(m.Subject(), "$KV."+bucket+".")
+	module, _, _ := strings.Cut(key, ".")
+	if module == "" {
+		return delivered{}, false
+	}
+	var deliveries uint64 = 1
+	if meta, err := m.Metadata(); err == nil {
+		deliveries = meta.NumDelivered
+	}
+	return delivered{module: module, again: deliveries > 1, deliveries: deliveries}, true
+}
+
+// takeInConsumer is one bucket's consumer of the take-in.
+type takeInConsumer struct {
+	bucket   string
+	consumer jetstream.Consumer
+}
+
+// takeInConfig is the take-in's consumer on bucket's stream.
+func takeInConfig(bucket string) jetstream.ConsumerConfig {
+	deliver := jetstream.DeliverNewPolicy
+	if bucket == sdkdelivery.ModulesBucket {
+		deliver = jetstream.DeliverLastPerSubjectPolicy // the start's look: every module's trunk value once
+	}
+	return jetstream.ConsumerConfig{
+		Durable: broker.TakeInConsumer, FilterSubject: "$KV." + bucket + ".>", DeliverPolicy: deliver,
+		AckPolicy: jetstream.AckExplicitPolicy, AckWait: takeInAckWait, MaxAckPending: takeInPending,
+		Description: "the controller's take-in of done keys (novox/hq ADR 0544)",
+	}
+}
+
+// takeInConsumers makes or finds the take-in's consumer on each bucket's stream; one that cannot be made is said, and
+// the other is still read.
+func takeInConsumers(ctx context.Context, js jetstream.JetStream) []takeInConsumer {
+	var out []takeInConsumer
+	for _, bucket := range broker.TakeInBuckets {
+		c, err := js.CreateOrUpdateConsumer(ctx, "KV_"+bucket, takeInConfig(bucket))
+		o := takeInNotConsumedObservation(bucket, err)
+		if err != nil {
+			// Loud: a consumer whose deliver policy differs cannot be updated, and nothing of its bucket is taken in.
+			doneKeysSay("done keys: " + o.Summary)
+			if keeper := conditionsFrom; keeper != nil {
+				_, _ = keeper.Observe(ctx, o)
+			}
+			continue
+		}
+		// Made: a condition a controller before this one raised for it is cleared (a restart that works clears it).
+		if keeper := conditionsFrom; keeper != nil {
+			_, _ = keeper.Clear(ctx, o.Key(), "the take-in's consumer on "+bucket+" is made")
+		}
+		out = append(out, takeInConsumer{bucket: bucket, consumer: c})
+	}
+	return out
+}
+
+// watchDoneKeys takes in the done keys the two consumers deliver, batch after batch, until ctx ends, and watches their
+// backlog. A consumer that cannot be made is said: its bucket is then not taken in until the next start.
+func watchDoneKeys(ctx context.Context, open *stores) {
+	keys, closeKeys, err := openBuilderKeys()
+	if err != nil {
+		fmt.Printf("done keys: the builder's keys are not taken in: %v\n", err)
+		return
+	}
+	consumers := takeInConsumers(ctx, keys.JS)
+	if len(consumers) == 0 {
+		closeKeys()
+		return
+	}
+	in := make(chan takeInMsg)
+	// moving counts the keys handed to the loop and the keys it settled (acknowledged or refused, each as the bus took
+	// it): what tells a take-in that moves from one that holds work and does nothing (the stall watch, ADR 0544 §6).
+	moving := &takeInMoving{}
+	read := make([]jetstream.Consumer, 0, len(consumers))
+	// The connection closes only once the readers and the loop have ended, so the refusals they send at the stop reach
+	// the bus (the third review of ADR 0544).
+	var users sync.WaitGroup
+	for _, c := range consumers {
+		bucket := c.bucket
+		read = append(read, c.consumer)
+		it, err := c.consumer.Messages(jetstream.PullMaxMessages(takeInBuffered))
+		if err != nil {
+			fmt.Printf("done keys: the take-in's consumer on %s is not read: %v\n", bucket, err)
+			continue
+		}
+		goServing(ctx, func() {
+			<-ctx.Done()
+			it.Drain() // the keys it holds are handed out and refused at once below, not lost to their ack wait
+		})
+		users.Add(1)
+		goServing(ctx, func() {
+			defer users.Done()
+			for {
+				m, err := it.Next()
+				if err != nil {
+					if ctx.Err() == nil && !errors.Is(err, jetstream.ErrMsgIteratorClosed) {
+						fmt.Printf("done keys: the take-in's consumer on %s stopped: %v\n", bucket, err)
+					}
+					return
+				}
+				d, ok := takeInKeyOf(bucket, m)
+				if !ok {
+					_ = m.Ack()
+					continue
+				}
+				// Settled is the loop's attempt, whatever the bus answers: an acknowledgement it refuses (at a first start,
+				// until the bus node is composed) is delivered again and settled again, and never counts as work held
+				// (the third review of ADR 0544). Acknowledged synchronously and past the stop, so a refusal is said.
+				msg := takeInMsg{delivered: d, ack: func() {
+					acking, cancel := context.WithTimeout(context.WithoutCancel(ctx), 10*time.Second)
+					defer cancel()
+					if err := m.DoubleAck(acking); err != nil {
+						doneKeysSay(fmt.Sprintf("done keys: the bus did not take the acknowledgement of %s: %v", d.module, err))
+					}
+					moving.settled.Add(1)
+				},
+					nak: func(delay time.Duration) {
+						_ = m.NakWithDelay(delay)
+						moving.settled.Add(1)
+					}}
+				if ctx.Err() != nil {
+					_ = m.Nak()
+					continue // drained: each key it held, refused at once
+				}
+				select {
+				case in <- msg:
+					moving.handed.Add(1)
+				case <-ctx.Done():
+					_ = m.Nak() // delivered again at once to the controller after this one, not after the ack wait
+					continue
+				}
+			}
+		})
+	}
+	backlog := func(ctx context.Context) (takeInBacklog, error) { return backlogOf(ctx, read) }
+	steps := liveTakeInSteps(open, keys, keys.JS)
+	users.Add(1)
+	goServing(ctx, func() {
+		defer users.Done()
+		takeInLoop(ctx, in, steps, backlog)
+	})
+	goServing(ctx, func() { watchTakeInStall(ctx, backlog, moving) })
+	goServing(ctx, func() {
+		<-ctx.Done()
+		users.Wait()
+		closeKeys()
+	})
+}
+
+// takeInLoop gathers delivered keys into batches and takes each batch in, until ctx ends.
+func takeInLoop(ctx context.Context, in <-chan takeInMsg, steps takeInSteps,
+	backlog func(context.Context) (takeInBacklog, error)) {
+	t := &takeInState{memo: map[string]string{}, raised: map[string]bool{}, saidWait: map[string]string{}}
+	for {
+		var batch []takeInMsg
+		select {
+		case <-ctx.Done():
+			return
+		case m := <-in:
+			batch = append(batch, m)
+		}
+		gather := time.NewTimer(takeInGather)
+	more:
+		for len(batch) < startTakeIns {
+			select {
+			case m := <-in:
+				batch = append(batch, m)
+			case <-gather.C:
+				break more
+			case <-ctx.Done():
+				gather.Stop()
+				for _, m := range batch {
+					m.nak(0)
+				}
+				return
+			}
+		}
+		gather.Stop()
+		said := t.take(ctx, steps, batch)
+		if b, err := backlog(ctx); err == nil {
+			said += fmt.Sprintf("; backlog %d", b.Total())
+		}
+		doneKeysSay("done keys: " + said)
+	}
+}
+
+// takeInState is what the take-in keeps between batches in this process: the trunk each module was last taken in at,
+// the modules whose condition it raised, and the wait last said of each.
+type takeInState struct {
+	memo     map[string]string
+	raised   map[string]bool
+	saidWait map[string]string
+}
+
+// take takes one batch in and acknowledges or refuses each key, raising and clearing the modules' conditions. It answers
+// the batch in a line.
+func (t *takeInState) take(ctx context.Context, steps takeInSteps, batch []takeInMsg) string {
+	keys := make([]delivered, len(batch))
+	for i, m := range batch {
+		keys[i] = m.delivered
+	}
+	settled, passes := steps.batch(ctx, keys, t.memo)
+	verdicts := make(map[string]verdict, len(settled))
+	var taken, nothing, waiting, failed int
+	for _, r := range settled {
+		verdicts[r.module] = r.verdict
+		o := doneKeyObservation(r.module)
+		switch {
+		case r.err != nil:
+			failed++
+			doneKeysSay(fmt.Sprintf("done keys: %s: %v", r.module, r.err))
+			if keeper := conditionsFrom; keeper != nil && !t.raised[r.module] && ctx.Err() == nil &&
+				!errors.Is(r.err, context.Canceled) {
+				o.Summary += r.err.Error()
+				if _, err := keeper.Observe(ctx, o); err == nil {
+					t.raised[r.module] = true
+				}
+			}
+		case r.waits != "":
+			waiting++
+			if t.saidWait[r.module] != r.waits {
+				doneKeysSay(fmt.Sprintf("done keys: %s %s", r.module, r.waits))
+				t.saidWait[r.module] = r.waits
+			}
+		case r.taken:
+			taken++
+			delete(t.saidWait, r.module)
+			if r.said != "" {
+				doneKeysSay("done keys: " + r.said)
+			}
+			// Cleared on every take-in, whoever raised it: a controller before a restart, whose key was delivered again.
+			if keeper := conditionsFrom; keeper != nil {
+				if _, err := keeper.Clear(ctx, o.Key(), "composed and granted"); err == nil {
+					delete(t.raised, r.module)
+				}
+			}
+		case r.nothingNew:
+			nothing++
+		}
+	}
+	for _, m := range batch {
+		if verdicts[m.module] == refused {
+			if ctx.Err() != nil {
+				m.nak(0) // cut by the stop: the next controller takes it at once
+			} else {
+				m.nak(refusalDelay(m.deliveries))
+			}
+		} else {
+			m.ack()
+		}
+	}
+	return fmt.Sprintf("%d key(s) of %d module(s): %d taken in, %d with nothing new, %d waiting, %d failed; %d composer pass(es)",
+		len(batch), len(settled), taken, nothing, waiting, failed, passes)
+}
+
+// takeInBacklog is the take-in's backlog on the bus: keys not delivered yet, and keys delivered and not acknowledged
+// (being taken in, or refused and waiting for their delay).
+type takeInBacklog struct {
+	Pending uint64 `json:"pending"`
+	Taking  uint64 `json:"taking"`
+}
+
+// Total is every key the take-in has not acknowledged.
+func (b takeInBacklog) Total() uint64 { return b.Pending + b.Taking }
+
+// backlogOf reads the consumers' own counts from the bus.
+func backlogOf(ctx context.Context, consumers []jetstream.Consumer) (takeInBacklog, error) {
+	var b takeInBacklog
+	for _, c := range consumers {
+		info, err := c.Info(ctx)
+		if err != nil {
+			return takeInBacklog{}, err
+		}
+		b.Pending += info.NumPending
+		b.Taking += uint64(info.NumAckPending)
+	}
+	return b, nil
+}
+
+// readTakeInBacklog is the take-in's backlog for a reader in any process (`status`): the consumers asked by name.
+func readTakeInBacklog(ctx context.Context) (takeInBacklog, error) {
+	keys, closeKeys, err := openBuilderKeys()
+	if err != nil {
+		return takeInBacklog{}, err
+	}
+	defer closeKeys()
+	var consumers []jetstream.Consumer
+	for _, bucket := range broker.TakeInBuckets {
+		c, err := keys.JS.Consumer(ctx, "KV_"+bucket, broker.TakeInConsumer)
+		if err != nil {
+			return takeInBacklog{}, fmt.Errorf("the take-in's consumer on %s: %w", bucket, err)
+		}
+		consumers = append(consumers, c)
+	}
+	return backlogOf(ctx, consumers)
+}
+
+// kindTakeInStalled is the condition of a take-in that holds work and settles none (ADR 0544 §6); kindTakeInNotConsumed
+// that of a bucket whose consumer could not be made.
+const (
+	kindTakeInStalled     = "take-in-stalled"
+	kindTakeInNotConsumed = "take-in-not-consumed"
+)
+
+func takeInStalledObservation(b takeInBacklog, since time.Time) conditions.Observation {
+	return conditions.Observation{Scope: conditions.ScopeCore, ID: "take-in", Token: kindTakeInStalled,
+		Kind: kindTakeInStalled, Severity: conditions.Urgent, Resolver: conditions.ResolverOperator, Source: "done keys",
+		Summary: fmt.Sprintf("the take-in of done keys has %d key(s) waiting and has settled none since %s",
+			b.Total(), since.UTC().Format(time.RFC3339))}
+}
+
+// takeInNotConsumedObservation is the condition of bucket's consumer not made, with its own id, so it is raised and
+// cleared apart from a stall and from the other bucket's.
+func takeInNotConsumedObservation(bucket string, err error) conditions.Observation {
+	summary := "the take-in's consumer on " + bucket + " is made"
+	if err != nil {
+		summary = fmt.Sprintf("the take-in's consumer on %s is not made, so its keys are not taken in until the next "+
+			"start: %v", bucket, err)
+	}
+	return conditions.Observation{Scope: conditions.ScopeCore, ID: "take-in-" + bucket, Token: kindTakeInNotConsumed,
+		Kind: kindTakeInNotConsumed, Severity: conditions.Urgent, Resolver: conditions.ResolverOperator,
+		Source: "done keys", Summary: summary}
+}
+
+// takeInMoving counts the keys handed to the take-in loop and the keys it settled.
+type takeInMoving struct {
+	handed, settled atomic.Uint64
+}
+
+// stallWatch judges each look: stalled once there was work to do (keys not delivered yet, or keys handed to the loop
+// and not settled) and nothing settled for takeInStall. A refused key waiting for its delay is no work of the loop's:
+// with nothing else, a quiet mesh is not a stall; a loop that hangs on its batch is (the review of ADR 0544). Its first
+// look always says it changed, so a condition a controller before this one raised is cleared once this one moves.
+type stallWatch struct {
+	mu      sync.Mutex
+	settled uint64
+	movedAt time.Time
+	stalled bool
+	known   bool
+}
+
+// look takes a reading at now: the backlog, and how many keys were handed and settled; it answers whether the take-in
+// stalls and whether that changed (always on the first look).
+func (w *stallWatch) look(b takeInBacklog, handed, settled uint64, now time.Time) (stalled, changed bool) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	work := b.Pending > 0 || handed > settled
+	if !work || settled != w.settled || w.movedAt.IsZero() {
+		w.movedAt = now
+	}
+	w.settled = settled
+	nowStalled := work && now.Sub(w.movedAt) >= takeInStall
+	changed = !w.known || nowStalled != w.stalled
+	w.stalled, w.known = nowStalled, true
+	return nowStalled, changed
+}
+
+// watchTakeInStall reads the backlog every minute and raises take-in-stalled while the take-in holds work and settles
+// none, clearing it when it moves, and at its first look when it does not stall: a watchdog's timer, as research 072 §2
+// keeps them until the health part leaves the controller.
+func watchTakeInStall(ctx context.Context, backlog func(context.Context) (takeInBacklog, error), moving *takeInMoving) {
+	w := &stallWatch{}
+	tick := time.NewTicker(time.Minute)
+	defer tick.Stop()
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-tick.C:
+		}
+		b, err := backlog(ctx)
+		if err != nil {
+			continue
+		}
+		stalled, changed := w.look(b, moving.handed.Load(), moving.settled.Load(), time.Now())
+		keeper := conditionsFrom
+		if !changed || keeper == nil {
+			continue
+		}
+		w.mu.Lock()
+		since := w.movedAt
+		w.mu.Unlock()
+		o := takeInStalledObservation(b, since)
+		if stalled {
+			doneKeysSay("done keys: " + o.Summary)
+			_, _ = keeper.Observe(ctx, o)
+		} else {
+			_, _ = keeper.Clear(ctx, o.Key(), "the take-in moves")
+		}
+	}
+}

cmd/mesh-controller/watchdogs.go

@@ -545,10 +545,9 @@ func later(a, b time.Time) time.Time {
 	return b
 }
 
-// watchTheMesh opens the condition store and starts the watchdogs, the bus's advisories and the
-// self-check, for the serving controller; the returned function stops them. Nil when the store could
-// not be opened, which is said.
-func watchTheMesh(ctx context.Context, open *stores, server *link.Server, bus link.OverNATS) func() {
+// openServingConditions opens the condition store for the serving controller and makes it conditionsFrom. Nil when the store
+// could not be opened, which is said: status then says the conditions cannot be read.
+func openServingConditions(ctx context.Context, open *stores, bus link.OverNATS) *conditions.Keeper {
 	keeper, err := keeperOn(ctx, bus.Conn, storeLooks{open.inventory})
 	if err != nil {
 		fmt.Printf("the condition store could NOT be opened, so nothing that goes wrong is kept or said, and "+
@@ -556,6 +555,22 @@ func watchTheMesh(ctx context.Context, open *stores, server *link.Server, bus li
 		return nil
 	}
 	conditionsFrom = keeper
+	return keeper
+}
+
+// closeConditions flushes what the keeper holds and closes it, once nothing that raises a condition runs.
+func closeConditions(keeper *conditions.Keeper) {
+	flushing, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	keeper.Close(flushing)
+}
+
+// watchTheMesh starts the watchdogs, the bus's advisories and the self-check over the condition store's keeper, for the
+// serving controller; the returned function stops them and waits for them to end. Nil when there is no keeper.
+func watchTheMesh(ctx context.Context, open *stores, server *link.Server, bus link.OverNATS, keeper *conditions.Keeper) func() {
+	if keeper == nil {
+		return nil
+	}
 	logf := func(format string, args ...any) { fmt.Printf(format+"\n", args...) }
 	stopHearing, err := server.HearAdvisories(logf)
 	if err != nil {
@@ -568,26 +583,26 @@ func watchTheMesh(ctx context.Context, open *stores, server *link.Server, bus li
 	d := &doctor{open: open, js: server.JetStream(), keeper: keeper, teller: bus, watchdogs: w, host: host}
 	w.doctor = d
 	doctorFrom = d
+	// Its own group as well as serve's: its stop waits for what it started.
 	watching, stop := context.WithCancel(ctx)
-	go w.keep(watching)
-	go d.keep(watching)
+	watching, running := withServingGroup(watching)
+	goServing(watching, func() { w.keep(watching) })
+	goServing(watching, func() { d.keep(watching) })
 	// And the healers (novox/hq to-be 45 §7): what is open that a registered healer answers, repaired
 	// under the lease and the brake, every act said.
 	healers := newHealing(open, keeper, bus, server.JetStream())
-	go healers.keep(watching)
+	goServing(watching, func() { healers.keep(watching) })
 	// And the asker (novox/hq ADR 0259): what needs the operator and names its answers is asked of them,
 	// and the answer chosen is performed on its warrant.
 	startAsking(watching, open, server, bus.Conn, keeper)
-	go forgettingOldHeals(watching, open.inventory)
+	goServing(watching, func() { forgettingOldHeals(watching, open.inventory) })
 	fmt.Printf("watching the mesh: %d signal(s) every %s, %d probe(s) every %s; what is wrong is kept in %s "+
 		"and said as %s events\n", len(watchedRows()), watchEvery, len(runnableProbes()), doctorEvery,
 		broker.ConditionsBucket, conditions.Seat)
 	return func() {
 		stop()
+		running.stop()
 		stopHearing()
-		flushing, cancel := context.WithTimeout(context.Background(), 10*time.Second)
-		defer cancel()
-		keeper.Close(flushing)
 	}
 }
 

internal/broker/composed.go

@@ -182,3 +182,15 @@ func RaiseAfterDeclarations(r Raiser) error {
 	}
 	return AssertMeshConsumers(r)
 }
+
+// TakeInConsumer is the durable consumer the controller takes done keys in from, on the stream of each of TakeInBuckets
+// (novox/hq ADR 0544 §1).
+const TakeInConsumer = "mesh-controller-take-in"
+
+// TakeInBuckets are the buckets the take-in consumes: the indexer's modules (each module's trunk value) and the builder's
+// builds (each build's key).
+var TakeInBuckets = []string{delivery.ModulesBucket, delivery.BuilderBuildsBucket}
+
+// ConfigFollowConsumer is the durable consumer the controller follows mesh-config's resolved values with, on that
+// bucket's stream (novox/hq ADR 0545).
+const ConfigFollowConsumer = "mesh-controller-config-follow"

internal/broker/nats.go

@@ -432,6 +432,16 @@ var DegradableGrants = []DegradableGrant{
 		Reason: "carried only at genesis: the controller composes its own permissions into the bus module's composition, " +
 			"and writes a composition's digest only after the bus applied it (novox/hq ADR 0539 clauses 2 and 7)",
 	},
+	{
+		Subject: "$JS.ACK.KV_" + delivery.ModulesBucket + "." + TakeInConsumer + ".>",
+		Reason: "refused: an acknowledgement refused leaves the key delivered again after its wait, and the take-in's first " +
+			"batch with something new composes the bus's node, which grants it (novox/hq ADR 0544 §1)",
+	},
+	{
+		Subject: "$JS.ACK.KV_" + delivery.BuilderBuildsBucket + "." + TakeInConsumer + ".>",
+		Reason: "refused: an acknowledgement refused leaves the key delivered again after its wait, and the take-in's first " +
+			"batch with something new composes the bus's node, which grants it (novox/hq ADR 0544 §1)",
+	},
 	{
 		Subject: "$KV." + GrantsBucket + ".>",
 		Reason: "carried only at genesis: the controller composes its own permissions and pushes them to the bus at its " +
@@ -707,6 +717,11 @@ func PermissionsFor(p Principal) (Permissions, error) {
 		// ever, refused by the list it already has.
 		sub = append(sub, ControllerFollows...)
 		pub = append(pub, "$JS.ACK.EVENTS."+ControllerName+".>", "$JS.ACK.EVENTS."+MergesConsumerName+".>")
+		// And the take-in's two durable consumers on the indexer's and the builder's buckets (novox/hq ADR 0544 §1):
+		// acknowledged after each key is taken in, and no other consumer of those streams.
+		for _, bucket := range TakeInBuckets {
+			pub = append(pub, "$JS.ACK.KV_"+bucket+"."+TakeInConsumer+".>")
+		}
 
 		// **Where an enrolment's answer goes**, and `allow_responses` does not cover it. That
 		// permits one reply to the reply subject of a message the user received — and a message a
@@ -1258,6 +1273,11 @@ func PermissionsFor(p Principal) (Permissions, error) {
 				pub = append(pub, "mesh.seat."+v.Seat+"."+CallKind+"."+v.Verb+"."+CallerToken(p.Username()))
 			}
 		}
+		// And its consumer of mesh-config's resolved values, acknowledged once a change is composed (novox/hq ADR 0545):
+		// where mesh-config serves, as its verb, so genesis grants nothing of mesh-config.
+		if len(p.AsksTheConfig) > 0 {
+			pub = append(pub, "$JS.ACK.KV_"+ConfigResolvedBucket+"."+ConfigFollowConsumer+".>")
+		}
 	}
 
 	sort.Strings(pub)

internal/broker/testdata/composed.conf

@@ -29,7 +29,7 @@ accounts {
     ]
     users = [
       { user: "controller", password: "$2a$11$cccccccccccccccccccccc", permissions: {
-        publish: { allow: ["$JS.ACK.CONTROL.controller.>", "$JS.ACK.DEAD_LETTER_NOTICES.controller.>", "$JS.ACK.EVENTS.controller-merges.>", "$JS.ACK.EVENTS.controller.>", "$JS.API.>", "$KV.mesh-controller_asked.>", "$KV.mesh-controller_assignments.>", "$KV.mesh-controller_builds.>", "$KV.mesh-controller_calls.>", "$KV.mesh-controller_composed.>", "$KV.mesh-controller_condition-history.>", "$KV.mesh-controller_conditions.>", "$KV.mesh-controller_declared-config.>", "$KV.mesh-controller_declared-packages.>", "$KV.mesh-controller_delivery-merges.>", "$KV.mesh-controller_grants.>", "$KV.mesh-controller_hand-acts.>", "$KV.mesh-controller_lease.>", "$KV.mesh-controller_predefined.>", "$KV.mesh-controller_rollouts.>", "$KV.mesh-controller_states-announced.>", "$SRV.INFO", "_INBOX.enrol.>", "mesh.again.>", "mesh.assignment.>", "mesh.events.dead.>", "mesh.mod.*.tool.>", "mesh.mod.mesh-controller.event.states", "mesh.node.>", "mesh.seat.mesh-controller.event.applied", "mesh.seat.mesh-controller.event.artifacts-gone", "mesh.seat.mesh-controller.event.assignment-changed", "mesh.seat.mesh-controller.event.bucket-deleted", "mesh.seat.mesh-controller.event.built-before", "mesh.seat.mesh-controller.event.checked", "mesh.seat.mesh-controller.event.condition-changed", "mesh.seat.mesh-controller.event.condition-cleared", "mesh.seat.mesh-controller.event.condition-raised", "mesh.seat.mesh-controller.event.declared-config-changed", "mesh.seat.mesh-controller.event.doctor-heartbeat", "mesh.seat.mesh-controller.event.healer-acted", "mesh.seat.mesh-controller.event.predefined-changed", "mesh.seat.mesh-controller.event.refused", "mesh.seat.mesh-controller.event.rolled-back", "mesh.seat.mesh-controller.event.secret-replaced", "mesh.seat.mesh-controller.tool.plans", "mesh.seat.mesh-controller.tool.push", "mesh.seat.mesh-controller.tool.upgrade", "mesh.seat.mesh-delivery.tool.close", "mesh.seat.mesh-delivery.tool.groups", "mesh.seat.mesh-delivery.tool.release", "mesh.seat.mesh-delivery.tool.stalled", "mesh.seat.mesh-delivery.tool.stop", "mesh.seat.mesh-delivery.tool.times", "mesh.seat.node-backup.tool.backed-up.*", "mesh.seat.node-backup.tool.now.*", "mesh.seat.node-intrusion-prevention.tool.banned.*", "mesh.seat.node-launcher.tool.secret.*", "mesh.seat.node-service-manager.tool.restart.*", "mesh.seat.operator-channel.tool.tell"] }
+        publish: { allow: ["$JS.ACK.CONTROL.controller.>", "$JS.ACK.DEAD_LETTER_NOTICES.controller.>", "$JS.ACK.EVENTS.controller-merges.>", "$JS.ACK.EVENTS.controller.>", "$JS.ACK.KV_mesh-delivery-builder_builds.mesh-controller-take-in.>", "$JS.ACK.KV_mesh-delivery-indexer_modules.mesh-controller-take-in.>", "$JS.API.>", "$KV.mesh-controller_asked.>", "$KV.mesh-controller_assignments.>", "$KV.mesh-controller_builds.>", "$KV.mesh-controller_calls.>", "$KV.mesh-controller_composed.>", "$KV.mesh-controller_condition-history.>", "$KV.mesh-controller_conditions.>", "$KV.mesh-controller_declared-config.>", "$KV.mesh-controller_declared-packages.>", "$KV.mesh-controller_delivery-merges.>", "$KV.mesh-controller_grants.>", "$KV.mesh-controller_hand-acts.>", "$KV.mesh-controller_lease.>", "$KV.mesh-controller_predefined.>", "$KV.mesh-controller_rollouts.>", "$KV.mesh-controller_states-announced.>", "$SRV.INFO", "_INBOX.enrol.>", "mesh.again.>", "mesh.assignment.>", "mesh.events.dead.>", "mesh.mod.*.tool.>", "mesh.mod.mesh-controller.event.states", "mesh.node.>", "mesh.seat.mesh-controller.event.applied", "mesh.seat.mesh-controller.event.artifacts-gone", "mesh.seat.mesh-controller.event.assignment-changed", "mesh.seat.mesh-controller.event.bucket-deleted", "mesh.seat.mesh-controller.event.built-before", "mesh.seat.mesh-controller.event.checked", "mesh.seat.mesh-controller.event.condition-changed", "mesh.seat.mesh-controller.event.condition-cleared", "mesh.seat.mesh-controller.event.condition-raised", "mesh.seat.mesh-controller.event.declared-config-changed", "mesh.seat.mesh-controller.event.doctor-heartbeat", "mesh.seat.mesh-controller.event.healer-acted", "mesh.seat.mesh-controller.event.predefined-changed", "mesh.seat.mesh-controller.event.refused", "mesh.seat.mesh-controller.event.rolled-back", "mesh.seat.mesh-controller.event.secret-replaced", "mesh.seat.mesh-controller.tool.plans", "mesh.seat.mesh-controller.tool.push", "mesh.seat.mesh-controller.tool.upgrade", "mesh.seat.mesh-delivery.tool.close", "mesh.seat.mesh-delivery.tool.groups", "mesh.seat.mesh-delivery.tool.release", "mesh.seat.mesh-delivery.tool.stalled", "mesh.seat.mesh-delivery.tool.stop", "mesh.seat.mesh-delivery.tool.times", "mesh.seat.node-backup.tool.backed-up.*", "mesh.seat.node-backup.tool.now.*", "mesh.seat.node-intrusion-prevention.tool.banned.*", "mesh.seat.node-launcher.tool.secret.*", "mesh.seat.node-service-manager.tool.restart.*", "mesh.seat.operator-channel.tool.tell"] }
         subscribe: { allow: ["$JS.API.>", "$JS.EVENT.ADVISORY.CONSUMER.DELETED.>", "$JS.EVENT.ADVISORY.CONSUMER.MAX_DELIVERIES.>", "$SRV.INFO", "$SRV.INFO.mesh-controller", "$SRV.INFO.mesh-controller.>", "$SRV.PING", "$SRV.PING.mesh-controller", "$SRV.PING.mesh-controller.>", "$SRV.STATS", "$SRV.STATS.mesh-controller", "$SRV.STATS.mesh-controller.>", "_DELIVER.controller", "_DELIVER.controller.>", "_INBOX.controller.>", "mesh.control.>", "mesh.mod.*.event.provisioner.failing", "mesh.mod.*.event.provisioner.recovered", "mesh.mod.*.event.provisioner.retirement", "mesh.mod.gitea.event.pull.merged", "mesh.mod.gitea.event.pull.updated", "mesh.mod.mesh-catalog.event.catching-up", "mesh.mod.mesh-catalog.event.upgraded", "mesh.seat.mesh-build-machine.event.built", "mesh.seat.mesh-controller.tool.>", "mesh.seat.node-build-agent.event.built", "mesh.seat.operator-channel.event.decided.mesh-controller"] }
         allow_responses: { max: 1, ttl: "1m" }
       } }

internal/inventory/bususers.go

@@ -114,6 +114,37 @@ func (i *Inventory) writeBusUser(ctx context.Context, u BusUser, hash string) er
 	return nil
 }
 
+// MintBusPasswordIfAbsent mints u's password only when no row names u yet, in one statement: of two callers that both
+// found the account missing, exactly one wins, and the other is told it lost (won false, no password) and must seal
+// nothing, so the hash the bus holds is always the password the node is sealed (novox/hq ADR 0543, the review of
+// issue 1945: the assign act and the assignments' watch once each minted, the later hash beside the earlier seal).
+func (i *Inventory) MintBusPasswordIfAbsent(ctx context.Context, u BusUser) (string, bool, error) {
+	if u.Username == "" || u.Kind == "" {
+		return "", false, errors.New("a bus user needs a username and a kind")
+	}
+	raw := make([]byte, 32)
+	if _, err := rand.Read(raw); err != nil {
+		return "", false, fmt.Errorf("cannot generate a bus password: %w", err)
+	}
+	password := base64.RawURLEncoding.EncodeToString(raw)
+	hash, err := hashBusPassword(password)
+	if err != nil {
+		return "", false, fmt.Errorf("cannot hash a bus password: %w", err)
+	}
+	tag, err := i.store.Pool().Exec(ctx,
+		`insert into bus_user (username, kind, node, module, password_hash)
+		 values ($1, $2, $3, $4, $5)
+		 on conflict (username) do nothing`,
+		u.Username, u.Kind, u.Node, u.Module, string(hash))
+	if err != nil {
+		return "", false, fmt.Errorf("cannot record the bus user %s: %w", u.Username, err)
+	}
+	if tag.RowsAffected() == 0 {
+		return "", false, nil
+	}
+	return password, true, nil
+}
+
 func (i *Inventory) MintBusPassword(ctx context.Context, u BusUser) (string, error) {
 	if u.Username == "" || u.Kind == "" {
 		return "", errors.New("a bus user needs a username and a kind")

internal/inventory/bususers_integration_test.go

@@ -33,7 +33,7 @@ func TestABusPasswordIsReturnedOnceAndOnlyItsHashIsKept(t *testing.T) {
 	}
 }
 
-func TestMintingAgainRotatesRatherThanAddsAUser(t *testing.T) {
+func TestMintingAgainRotatesAndMintingIfAbsentHasOneWinner(t *testing.T) {
 	inv := ForTest(t)
 	ctx := context.Background()
 
@@ -62,6 +62,50 @@ func TestMintingAgainRotatesRatherThanAddsAUser(t *testing.T) {
 	if bcrypt.CompareHashAndPassword([]byte(hash), []byte(first)) == nil {
 		t.Fatal("the previous password still verifies, so a rotation revoked nothing")
 	}
+
+	// **Minting only if absent never rotates, and of several at once exactly one wins** (ADR 0543, the review of issue
+	// 1945): the assign act and the assignments' watch may both find an account missing; the winner's password is the
+	// one the store's hash verifies, so the one it seals is the one the bus accepts, and a loser seals nothing.
+	if _, won, err := inv.MintBusPasswordIfAbsent(ctx, aBusUser("shop")); err != nil || won {
+		t.Fatalf("a mint-if-absent over a minted account won %v (%v): it would replace a sealed password", won, err)
+	}
+	const racers = 8
+	type minted struct {
+		password string
+		won      bool
+		err      error
+	}
+	results := make(chan minted, racers)
+	for range racers {
+		go func() {
+			p, won, err := inv.MintBusPasswordIfAbsent(ctx, aBusUser("racer"))
+			results <- minted{p, won, err}
+		}()
+	}
+	var winner string
+	wins := 0
+	for range racers {
+		r := <-results
+		if r.err != nil {
+			t.Fatal(r.err)
+		}
+		if r.won {
+			wins++
+			winner = r.password
+		} else if r.password != "" {
+			t.Fatal("a caller that lost was handed a password to seal")
+		}
+	}
+	if wins != 1 {
+		t.Fatalf("%d of %d concurrent mints won, want exactly one", wins, racers)
+	}
+	stored, _, err := inv.BusUserHash(ctx, "one.racer")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := bcrypt.CompareHashAndPassword([]byte(stored), []byte(winner)); err != nil {
+		t.Fatal("the stored hash is not the winner's password: the node would be sealed a password the bus refuses")
+	}
 }
 
 func TestForgettingANodeTakesItsBusUsersWithIt(t *testing.T) {

internal/inventory/catalogue.go

@@ -210,6 +210,21 @@ func (i *Inventory) hasModule(ctx context.Context, name string) (bool, error) {
 // This is the whole of noticing. Nothing here builds anything — it writes down that the two
 // halves differ, which is what makes *is this current?* answerable without building, and what
 // makes a module that nobody rebuilt visible rather than silent.
+// RecordBuiltFrom records that a registered module stands at commit, its manifest and fingerprint unchanged: a catalogue
+// merge that left its sources alone (novox/hq ADR 0544 §3). The head moves with it, as a registration moves it; the
+// module's builds and manifest stay as they are.
+func (i *Inventory) RecordBuiltFrom(ctx context.Context, module, commit string) error {
+	tag, err := i.store.Pool().Exec(ctx,
+		`update module set built_from = $2, source_head = $2 where name = $1`, module, commit)
+	if err != nil {
+		return fmt.Errorf("cannot record %s at %s: %w", module, commit, err)
+	}
+	if tag.RowsAffected() == 0 {
+		return fmt.Errorf("%w: %s", ErrNoSuchModule, module)
+	}
+	return nil
+}
+
 func (i *Inventory) SourceMoved(ctx context.Context, module, head string) error {
 	tag, err := i.store.Pool().Exec(ctx,
 		`update module set source_head = $2, source_seen = now() where name = $1`, module, head)

internal/inventory/chain_assignments.go

@@ -361,3 +361,13 @@ func (i *Inventory) AssignmentValue(ctx context.Context, node, module string) (c
 	k, found, err := c.Assignments.Get(ctx, assignmentKey(node, module))
 	return k.Value, found, err
 }
+
+// WatchAssignments is the assignments bucket's raw entries, as the chain's watch gives them: every current value, a Caught
+// mark, then each write (novox/hq ADR 0543: an assignment that comes to stand issues its node's bus accounts).
+func (i *Inventory) WatchAssignments(ctx context.Context) (<-chan chain.Entry, error) {
+	c, err := i.theChain(ctx)
+	if err != nil {
+		return nil, err
+	}
+	return c.Assignments.Watch(ctx)
+}