Merge pull request 'Bus state by template: the judge's rules, manifest-accepted, the old-section count and the ledger account (issue 1966, B1)' (#146) from feat/bus-state into main

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

@@ -22,9 +22,22 @@ import (
 type asker func(key string, value []byte) (index.TakeInAsk, error)
 
 // Tools are the indexer's tools.
-func Tools(ask asker, now func() time.Time) []stdio.Tool {
+func Tools(ask asker, now func() time.Time, counts func() (index.OldSectionsCount, error)) []stdio.Tool {
 	str := func(args map[string]any, k string) string { s, _ := args[k].(string); return strings.TrimSpace(s) }
 	return []stdio.Tool{
+		{Name: index.OldSectionsTool,
+			Description: "How many accepted modules use each old section of a manifest (state, logs, streams, objects), the foundation " +
+				"(nats, mesh-grants, the indexer) left out: the count the judge refuses a use of a section at 0 by, as modules move " +
+				"their bus state into `requires` by template. Read from the indexer's oldsections state, kept as the indexer judges " +
+				"the manifests; an empty answer means the indexer has not judged since it started.",
+			Input: map[string]any{"type": "object", "properties": map[string]any{}},
+			Run: func(map[string]any) (any, error) {
+				c, err := counts()
+				if err != nil {
+					return nil, err
+				}
+				return c.Counts, nil
+			}},
 		{Name: index.TakeInTool,
 			Description: "Take a registered module in now: the indexer reads its manifest from the repository and commit the controller's " +
 				"build records register it from (at the head the gate's source names, when it names one), whatever it tried before, and " +
@@ -105,8 +118,22 @@ func askTakeIn(s stdio.KeptState, bound time.Duration) asker {
 	}
 }
 
+// heldCounts reads the count of the old sections the indexer keeps.
+func heldCounts(s stdio.KeptState) func() (index.OldSectionsCount, error) {
+	return func() (index.OldSectionsCount, error) {
+		e, err := s.Get(index.OldSectionsKey)
+		if err != nil {
+			return index.OldSectionsCount{}, fmt.Errorf("reading %s.%s: %w", index.OldSectionsBucket, index.OldSectionsKey, err)
+		}
+		if e == nil {
+			return index.OldSectionsCount{}, fmt.Errorf("the indexer has not counted the old sections yet: %s holds no %s", index.OldSectionsBucket, index.OldSectionsKey)
+		}
+		return index.DecodeOldSections(e.Value)
+	}
+}
+
 func main() {
-	if err := stdio.Serve("", Tools(askTakeIn(stdio.State(index.TakeInsState), 25*time.Second), time.Now)); err != nil {
+	if err := stdio.Serve("", Tools(askTakeIn(stdio.State(index.TakeInsState), 25*time.Second), time.Now, heldCounts(stdio.State(index.OldSectionsState)))); err != nil {
 		fmt.Fprintf(os.Stderr, "[mesh-delivery-indexer-tools] %v\n", err)
 		os.Exit(1)
 	}

modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer/main.go

@@ -296,8 +296,11 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 	// The published packages (ADR 0593 §2): a state this delivery brings, bound when it appears; until then every
 	// fingerprint takes the version line.
 	packages := process.AwaitBucket(ctx, js, conn, delivery.PackagesBucket, "no package is published, so every fingerprint takes the version line", logger.Printf)
-	ix := &index.Indexer{Store: kvStore{candidates}, Modules: kvStore{modules}, Manifests: kvStore{manifests}, Taken: awaitedStore{taken}, Builds: known,
-		Verdicts: awaitedStore{verdicts}, SayRefused: sayRefused(js, cred, logger.Printf),
+	// How many modules use each old section (issue 1966 D4): a state this delivery brings, bound when it appears; until then
+	// the judge refuses no use of an old section.
+	oldSections := process.AwaitBucket(ctx, js, conn, index.OldSectionsBucket, "the count of the old sections is not kept, so the judge refuses no use of one", logger.Printf)
+	ix := &index.Indexer{OldSections: awaitedStore{oldSections}, Store: kvStore{candidates}, Modules: kvStore{modules}, Manifests: kvStore{manifests}, Taken: awaitedStore{taken}, Builds: known,
+		Verdicts: awaitedStore{verdicts}, SayRefused: sayRefused(js, cred, logger.Printf), SayAccepted: sayAccepted(js, cred, logger.Printf),
 		Predefined: awaitedStore{predefined}, ConfigCandidates: awaitedStore{configCandidates}, Logf: logger.Printf,
 		Named: namedVia(calls.Call), Trunk: trunkVia(calls.Call), Contains: containsVia(calls.Call), Read: readVia(calls.Call),
 		ReadOpen: openVia(calls.Call), Packages: awaitedStore{packages}, Files: filesVia(calls.Call), GoSum: goSumVia(calls.Call), GoMod: goModVia(calls.Call)}

modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer/verdicts.go

@@ -36,3 +36,29 @@ func sayRefused(js jetstream.JetStream, cred process.Account, logf func(string,
 		}
 	}
 }
+
+// sayAccepted says the indexer's event manifest-accepted (issue 1966 D3, novox/hq ADR 0595 §4):
+// mesh.mod.<module>.event.manifest-accepted, carrying the module's bus-state entries whole, with the digest and judge as
+// the bus's dedup id (delivery.ManifestAccepted.EventID), so one acceptance is said once.
+func sayAccepted(js jetstream.JetStream, cred process.Account, logf func(string, ...any)) func(context.Context, delivery.ManifestAccepted) {
+	return func(ctx context.Context, a delivery.ManifestAccepted) {
+		data, err := json.Marshal(a)
+		if err != nil {
+			logf("judge: %s for %s is not said: %v", delivery.ManifestAcceptedEvent, a.Module, err)
+			return
+		}
+		msg := nats.NewMsg(cred.EventSubject(delivery.ManifestAcceptedEvent))
+		id := a.EventID()
+		msg.Header.Set("x-event-id", id)
+		msg.Header.Set("x-source", cred.Module)
+		msg.Header.Set("x-node", cred.Node)
+		msg.Header.Set("x-time", time.Now().UTC().Format(time.RFC3339Nano))
+		msg.Header.Set("content-type", "application/json")
+		msg.Data = data
+		pub, cancel := context.WithTimeout(context.WithoutCancel(ctx), 10*time.Second)
+		defer cancel()
+		if _, err := js.PublishMsg(pub, msg, jetstream.WithMsgID(id)); err != nil {
+			logf("judge: %s", fmt.Errorf("saying %s for %s: %w", delivery.ManifestAcceptedEvent, a.Module, err))
+		}
+	}
+}

modules/mesh-delivery-indexer/go.mod

@@ -3,7 +3,7 @@ module mesh-delivery-indexer
 go 1.26.0
 
 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261102191058-f02f142af128
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103142843-f8bd12e4b7b1
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0
 )

modules/mesh-delivery-indexer/go.sum

@@ -1,5 +1,7 @@
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261102191058-f02f142af128 h1:aI1DhZAuqVBXbybSqhLNOGX5rUOrn9T0cHNCDUQF7IQ=
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261102191058-f02f142af128/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103142843-f8bd12e4b7b1 h1:T66tg9T/1hHg6KN/bDScHPT41IHkxLAGGO8VJiAOlb8=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103142843-f8bd12e4b7b1/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op/go.mod h1:FQyySiasQQM8735Ddel3MRojmy4dA1IqCeyJ5jmPMbI=
 github.com/google/go-tpm v0.9.8 h1:slArAR9Ft+1ybZu0lBwpSmpwhRXaa85hWtMinMyRAWo=

modules/mesh-delivery-indexer/internal/index/candidates.go

@@ -54,10 +54,16 @@ type Indexer struct {
 	Taken Store
 	// Verdicts is the verdicts state (verdicts.go, novox/hq ADR 0578 §1); nil judges nothing.
 	Verdicts Store
+	// OldSections is the state of how many accepted modules use each old section (oldsections.go, issue 1966 D4); nil keeps no
+	// count and the judge refuses no use of an old section.
+	OldSections Store
 	// JudgeID names the judge a verdict says made it; empty is judge.Identity, the running program's.
 	JudgeID string
 	// SayRefused says the event manifest-refused for a refusal newly written; nil says nothing.
 	SayRefused func(ctx context.Context, r delivery.ManifestRefused)
+	// SayAccepted says the event manifest-accepted for an accepted verdict newly written whose manifest asks for bus state,
+	// carrying the entries whole (verdicts.go; issue 1966 D3); nil says nothing.
+	SayAccepted func(ctx context.Context, a delivery.ManifestAccepted)
 	// Packages is the packages state (delivery.PackagesBucket, packages.go; novox/hq ADR 0593 §2); nil publishes none,
 	// and every fingerprint takes the version line.
 	Packages Store

modules/mesh-delivery-indexer/internal/index/oldsections.go

@@ -0,0 +1,76 @@
+package index
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"maps"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	"mesh-delivery-indexer/judge"
+)
+
+// How many accepted modules use each old section (issue 1966 D4; novox/hq ADR 0595 §11): the indexer counts them, the
+// foundation left out, as it judges, keeps the count in its state oldsections under one key, and the tool
+// indexer_old_sections reads it. The judge refuses a manifest of another module that uses a section whose count is 0.
+const (
+	// OldSectionsTool is the tool that reads the count.
+	OldSectionsTool = "indexer_old_sections"
+	// OldSectionsState is the indexer's state of the count: the bucket mesh-delivery-indexer_oldsections.
+	OldSectionsState  = "oldsections"
+	OldSectionsBucket = delivery.IndexerModule + "_" + OldSectionsState
+	// OldSectionsKey is the one key it holds.
+	OldSectionsKey = "counts"
+)
+
+// OldSectionsCount is the value of the oldsections state: per old section, the accepted modules outside the foundation using it.
+type OldSectionsCount struct {
+	V      int            `json:"v"`
+	Counts map[string]int `json:"counts"`
+}
+
+// DecodeOldSections reads the oldsections value.
+func DecodeOldSections(value []byte) (OldSectionsCount, error) {
+	var c OldSectionsCount
+	if err := json.Unmarshal(value, &c); err != nil {
+		return c, fmt.Errorf("the count of the old sections cannot be read: %w", err)
+	}
+	if c.V != 1 {
+		return c, fmt.Errorf("a count of the old sections of version %d, not 1", c.V)
+	}
+	return c, nil
+}
+
+// heldOldSections is the count the last pass wrote (the accepted set it held): a module that keeps using a section was
+// accepted with it, so it is counted, and a fresh manifest changes nothing in it. Nil when none is held yet or it cannot be
+// read; a failed read is said, never taken as 0 (issue 1966 D4).
+func (ix *Indexer) heldOldSections(ctx context.Context) judge.OldSectionCounts {
+	value, _, found, err := ix.OldSections.Get(ctx, OldSectionsKey)
+	if err == nil && found {
+		var c OldSectionsCount
+		if c, err = DecodeOldSections(value); err == nil {
+			return c.Counts
+		}
+	}
+	if err != nil {
+		ix.logf("judge: the count of the old sections cannot be read (%v), so the zero rule is not applied in this pass", err)
+	}
+	return nil
+}
+
+// keepOldSections writes the counts under OldSectionsKey when they differ from the ones held.
+func (ix *Indexer) keepOldSections(ctx context.Context, counts judge.OldSectionCounts) error {
+	if ix.OldSections == nil {
+		return nil
+	}
+	return write(ctx, ix.OldSections, OldSectionsKey, func(value []byte, found bool) ([]byte, bool, error) {
+		if found {
+			if cur, err := DecodeOldSections(value); err == nil && maps.Equal(cur.Counts, counts) {
+				return nil, false, nil
+			}
+		}
+		next, err := json.Marshal(OldSectionsCount{V: 1, Counts: counts})
+		return next, false, err
+	})
+}

modules/mesh-delivery-indexer/internal/index/verdicts.go

@@ -74,7 +74,13 @@ func (ix *Indexer) JudgeAll(ctx context.Context, fresh map[string]bool) (Judged,
 		raws[name] = []byte(kept.JSON)
 		digests[name] = digest
 	}
-	refused, unnamed := judge.Shelf(raws, ix.predefinedList(ctx), 0)
+	predefined := ix.predefinedList(ctx)
+	// The old sections end when no module is left in them (issue 1966 D4): the count is the accepted set the last pass held.
+	var counts judge.OldSectionCounts
+	if ix.OldSections != nil {
+		counts = ix.heldOldSections(ctx)
+	}
+	refused, unnamed := judge.ShelfCounting(raws, predefined, 0, counts)
 	for _, p := range unnamed {
 		ix.logf("judge: a problem between the manifests that no one module's removal ends, so it refuses none: %s", p)
 	}
@@ -83,6 +89,7 @@ func (ix *Indexer) JudgeAll(ctx context.Context, fresh map[string]bool) (Judged,
 	if id == "" {
 		id = judge.Identity()
 	}
+	var accepted []catalogue.Manifest
 	for _, name := range slices.Sorted(maps.Keys(digests)) {
 		out.Judged++
 		v := delivery.ManifestVerdict{Module: name, State: delivery.VerdictAccepted, Judge: id, At: ix.now()}
@@ -94,6 +101,12 @@ func (ix *Indexer) JudgeAll(ctx context.Context, fresh map[string]bool) (Judged,
 				v.State, v.Problems = delivery.VerdictRefused, problems
 			}
 		}
+		if !v.Refused() {
+			if m, err := catalogue.Decode(raws[name]); err == nil {
+				m.Module = name
+				accepted = append(accepted, m)
+			}
+		}
 		wrote, err := ix.writeVerdict(ctx, digests[name], v)
 		if errors.Is(err, process.ErrNotYet) {
 			return out, fmt.Errorf("the state %s is not on the bus yet: %w", VerdictsBucket, err)
@@ -109,12 +122,20 @@ func (ix *Indexer) JudgeAll(ctx context.Context, fresh map[string]bool) (Judged,
 				if ix.SayRefused != nil {
 					ix.SayRefused(ctx, delivery.RefusedOf(digests[name], v))
 				}
+			} else if ix.SayAccepted != nil {
+				// A manifest asking for bus state, newly accepted, is said whole to the bus module (issue 1966 D3, ADR 0595 §4).
+				if m, problems := judge.Manifest(raws[name], predefined); len(problems) == 0 && len(m.BusState) > 0 {
+					ix.SayAccepted(ctx, delivery.AcceptedOf(digests[name], v, m))
+				}
 			}
 		}
 		if err := ix.carryVerdict(ctx, name, digests[name], v); err != nil {
 			ix.logf("judge: modules.%s does not carry its verdict: %v", name, err)
 		}
 	}
+	if err := ix.keepOldSections(ctx, judge.CountOldSections(accepted)); err != nil {
+		ix.logf("judge: the count of the old sections is not kept: %v", err)
+	}
 	return out, nil
 }
 

modules/mesh-delivery-indexer/internal/index/verdicts_test.go

@@ -2,6 +2,8 @@ package index
 
 import (
 	"context"
+	"errors"
+	"fmt"
 	"strings"
 	"testing"
 	"time"
@@ -118,9 +120,92 @@ func TestTheIndexerJudgesEveryManifestOnce(t *testing.T) {
 	if err := ix.writeOverlay(ctx, map[string]delivery.Module{"old": same}, nil, w); err != nil || !w.fresh[other] {
 		t.Fatalf("a changed digest is not fresh: %v %v", w.fresh, err)
 	}
+	// 1966/AC10: a newly accepted manifest asking for bus state is said once as manifest-accepted, carrying both entries
+	// whole; a verdict already held, and a manifest asking for none, say nothing.
+	var accepted []delivery.ManifestAccepted
+	ix.SayAccepted = func(_ context.Context, a delivery.ManifestAccepted) { accepted = append(accepted, a) }
+	moved := hold("moved", `{"module":"moved","version":"1","requires":[`+
+		`{"name":"cache","storage":"key-value","template":"state","options":{"history":8}},`+
+		`{"name":"audit","storage":"stream","template":"log","options":{"max-mib":64}}]}`)
+	for pass := 0; pass < 2; pass++ {
+		if _, err := ix.JudgeAll(ctx, map[string]bool{moved: true}); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if len(accepted) != 1 || accepted[0].Module != "moved" || accepted[0].Digest != moved || accepted[0].Judge != "judge-2" ||
+		len(accepted[0].BusState) != 2 || accepted[0].BusState[0].Name != "cache" || accepted[0].BusState[1].Template != "log" ||
+		string(accepted[0].BusState[0].Options["history"]) != "8" {
+		t.Fatalf("said accepted %+v", accepted)
+	}
+	// 1966/AC11: modules using state and none using logs but the foundation: logs counts 0, so a manifest of another
+	// module using logs is refused and the foundation's is accepted.
+	ix.OldSections = newMem()
+	hold("user", `{"module":"user","version":"1","state":["x"]}`)
+	hold("mesh-grants", `{"module":"mesh-grants","version":"1","logs":[{"name":"l"}]}`)
+	if _, err := ix.JudgeAll(ctx, nil); err != nil {
+		t.Fatal(err)
+	}
+	counts := func() map[string]int {
+		value, _, found, err := ix.OldSections.Get(ctx, OldSectionsKey)
+		if err != nil || !found {
+			t.Fatalf("no count of the old sections: %v", err)
+		}
+		c, err := DecodeOldSections(value)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return c.Counts
+	}
+	if c := counts(); c["state"] != 1 || c["logs"] != 0 || c["streams"] != 0 || c["objects"] != 0 {
+		t.Fatalf("the old sections count %v, want state 1 and the rest 0", c)
+	}
+	late := hold("late", `{"module":"late","version":"1","logs":[{"name":"l"}]}`)
+	grants := hold("mesh-grants", `{"module":"mesh-grants","version":"2","logs":[{"name":"l"},{"name":"m"}]}`)
+	if _, err := ix.JudgeAll(ctx, map[string]bool{late: true, grants: true}); err != nil {
+		t.Fatal(err)
+	}
+	if v := verdict(late); !v.Refused() || !strings.Contains(v.Problems[0], "late uses the old section logs, which no other module uses any more") {
+		t.Fatalf("late: %+v", v)
+	}
+	if v := verdict(grants); v.Refused() {
+		t.Fatalf("the foundation's manifest was refused: %+v", v)
+	}
+	// 1966/AC11: the sole user of an old section changes its manifest and keeps the section: accepted, since it was accepted
+	// with it (the count is the accepted set held from the last pass, not recounted from fresh digests).
+	hold("solo", `{"module":"solo","version":"1","objects":[{"name":"o","max-mib":1}]}`)
+	if _, err := ix.JudgeAll(ctx, nil); err != nil {
+		t.Fatal(err)
+	}
+	solo2 := hold("solo", `{"module":"solo","version":"2","objects":[{"name":"o","max-mib":2}]}`)
+	if _, err := ix.JudgeAll(ctx, map[string]bool{solo2: true}); err != nil {
+		t.Fatal(err)
+	}
+	if v := verdict(solo2); v.Refused() {
+		t.Fatalf("the sole user of objects, changing its manifest and keeping objects, was refused: %+v", v)
+	}
+	// A count that cannot be read is never taken as 0: the zero rule is not applied in that pass and the log says so.
+	var logged []string
+	ix.Logf = func(f string, a ...any) { logged = append(logged, fmt.Sprintf(f, a...)) }
+	held := ix.OldSections
+	ix.OldSections = unreadable{held}
+	retry := hold("late", `{"module":"late","version":"2","logs":[{"name":"l"}]}`)
+	if _, err := ix.JudgeAll(ctx, map[string]bool{retry: true}); err != nil {
+		t.Fatal(err)
+	}
+	if v := verdict(retry); v.Refused() || !strings.Contains(strings.Join(logged, "\n"), "the zero rule is not applied") {
+		t.Fatalf("a count that could not be read: %+v, logged %q", v, logged)
+	}
+	ix.OldSections = held
 	// Without the verdicts state the indexer judges nothing.
 	ix.Verdicts = nil
 	if j, err := ix.JudgeAll(ctx, nil); err != nil || j.Judged != 0 {
 		t.Fatalf("without the state: %+v %v", j, err)
 	}
 }
+
+// unreadable is a store whose reads fail.
+type unreadable struct{ Store }
+
+func (unreadable) Get(context.Context, string) ([]byte, uint64, bool, error) {
+	return nil, 0, false, errors.New("the bus did not answer")
+}

modules/mesh-delivery-indexer/judge/busstate.go

@@ -0,0 +1,420 @@
+package judge
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"slices"
+	"strings"
+
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+)
+
+// The rules for bus state asked for in `requires` (issue 1966 D1; novox/hq ADR 0595 §1 to §3, ADR 0596 §2, ADR 0597 §2,
+// design 25 § 12.1). mesh-sdk keeps only the entry's shape (ADR 0578 §7); every bound below is this judge's. An entry is
+// judged once, here, and a refusal names the module, the entry and the field.
+
+// optionKind is what an option's value is.
+type optionKind int
+
+const (
+	optionInt optionKind = iota
+	optionFlag
+	optionText
+	optionEvents
+)
+
+// optionRule is one option a template takes: its kind, its bound where it is a number, and whether it must be given.
+type optionRule struct {
+	kind        optionKind
+	least, most int
+	required    bool
+}
+
+// busTemplate is a template: the storage type it is on, the options it takes, and what it fixes in plain words.
+type busTemplate struct {
+	storage string
+	options map[string]optionRule
+	fixed   string
+}
+
+// busTemplates are the six templates of design 25 § 12.1 and the bounds of its table.
+var busTemplates = map[string]busTemplate{
+	catalogue.TemplateState: {
+		storage: catalogue.StorageKeyValue,
+		fixed:   "what happens when full, the size of a value and of the bucket, and the copies",
+		options: map[string]optionRule{
+			catalogue.OptionPastValues:     {kind: optionInt, least: 1, most: catalogue.StateMostHistory},
+			catalogue.OptionTimeToLive:     {kind: optionInt, least: 1, most: 315360000},
+			catalogue.OptionLifetimePerKey: {kind: optionFlag},
+			catalogue.OptionPerMachine:     {kind: optionFlag},
+		},
+	},
+	catalogue.TemplateEvents: {
+		storage: catalogue.StorageStream,
+		fixed:   "what happens when full (the oldest is dropped) and the module's own subjects",
+		options: map[string]optionRule{
+			"events":                {kind: optionEvents, required: true},
+			catalogue.OptionAgeDays: {kind: optionInt, least: catalogue.StreamLeastDays, most: catalogue.StreamMostDays},
+			catalogue.OptionCapMiB:  {kind: optionInt, least: catalogue.StreamLeastMiB, most: catalogue.StreamMostMiB},
+			catalogue.OptionGrant:   {kind: optionText},
+		},
+	},
+	catalogue.TemplateWorkQueue: {
+		storage: catalogue.StorageStream,
+		fixed:   "what happens when full (a new message is refused), one taker, and no grant",
+		options: map[string]optionRule{
+			"events":                   {kind: optionEvents, required: true},
+			catalogue.OptionDeliveries: {kind: optionInt, least: catalogue.StreamLeastDeliveries, most: catalogue.StreamMostDeliveries},
+			catalogue.OptionDuplicates: {kind: optionInt, least: 1, most: catalogue.StreamMostDays * 86400},
+			catalogue.OptionAgeDays:    {kind: optionInt, least: catalogue.StreamLeastDays, most: catalogue.StreamMostDays},
+			catalogue.OptionCapMiB:     {kind: optionInt, least: catalogue.StreamLeastMiB, most: catalogue.StreamMostMiB},
+		},
+	},
+	catalogue.TemplateLog: {
+		storage: catalogue.StorageStream,
+		fixed:   "what happens when full (a new entry is refused), that an entry is never rewritten, and its size",
+		options: map[string]optionRule{
+			catalogue.OptionCapMiB:  {kind: optionInt, least: catalogue.StreamLeastMiB, most: catalogue.StreamMostMiB},
+			catalogue.OptionAgeDays: {kind: optionInt, least: 1, most: 3650},
+		},
+	},
+	catalogue.TemplateObjects: {
+		storage: catalogue.StorageObjectStore,
+		fixed:   "what happens when full (a new object is refused) and that objects are kept for good",
+		options: map[string]optionRule{
+			catalogue.OptionCapMiB: {kind: optionInt, least: catalogue.ObjectsLeastMiB, most: catalogue.ObjectsMostMiB, required: true},
+			catalogue.OptionGrant:  {kind: optionText},
+		},
+	},
+	catalogue.TemplateLedger: {
+		storage: catalogue.StorageLedger,
+		fixed:   "what happens when full (a new entry is refused) and its state and index buckets",
+		options: map[string]optionRule{
+			catalogue.OptionCapMiB: {kind: optionInt, least: catalogue.StreamLeastMiB, most: catalogue.StreamMostMiB},
+		},
+	},
+}
+
+// bareStream is a stream of a module's own configuration, where no template fits: the three settings the judge
+// refuses one for missing (design 25 § 12.1), and those it may also give.
+var bareStream = map[string]optionRule{
+	catalogue.OptionCapMiB:  {kind: optionInt, least: catalogue.StreamLeastMiB, most: catalogue.StreamMostMiB, required: true},
+	catalogue.OptionAgeDays: {kind: optionInt, least: 1, most: 3650, required: true},
+	catalogue.OptionGrant:   {kind: optionText},
+	"events":                {kind: optionEvents},
+}
+
+// ledgerConfiguration is what a ledger's own configuration may give: how long its history is kept (design 25 § 12.1).
+var ledgerConfiguration = map[string]optionRule{
+	catalogue.OptionAgeDays: {kind: optionInt, least: 1, most: 3650},
+}
+
+// noAge is how a bare stream says it keeps its messages for good.
+const noAge = "none"
+
+// ledgerEffects are the four effects an operation may have (ADR 0597 §2).
+var ledgerEffects = []string{catalogue.EffectSetFields, catalogue.EffectSetEntry, catalogue.EffectAppend, catalogue.EffectRemove}
+
+// BusStateProblems is what is wrong with one manifest's bus state, judged on the manifest alone (issue 1966 D1).
+func BusStateProblems(m catalogue.Manifest) []string {
+	if len(m.BusState) == 0 {
+		return nil
+	}
+	var problems []string
+	if !stateName.MatchString(m.Module) {
+		problems = append(problems, fmt.Sprintf(
+			"%s keeps bus state, and a module's name is part of its names on the bus, which take one plain name — "+
+				"no dot (novox/hq ADR 0201, ADR 0595 §1)", m.Module))
+	}
+	storageOf := map[string]string{}
+	oldSection := map[string]string{} // a local name an old section keeps, to that section (issue 1966 D2)
+	for _, st := range m.State {
+		oldSection[st.Name] = "state"
+	}
+	for _, l := range m.Logs {
+		oldSection[l.Name] = "logs"
+	}
+	for _, st := range m.Streams {
+		oldSection[st.Name] = "streams"
+	}
+	for _, o := range m.Objects {
+		oldSection[o.Name] = "objects"
+	}
+	terminal := catalogue.TerminalKeys(m)
+	for _, e := range m.BusState {
+		at := fmt.Sprintf("%s's bus state %q", m.Module, e.Name)
+		switch {
+		case strings.Contains(e.Name, "_"):
+			problems = append(problems, fmt.Sprintf(
+				"%s: its name holds an underscore, which separates the module from the local name on the bus; use a "+
+					"hyphen (novox/hq design 25 § 12.1)", at))
+		case !stateName.MatchString(e.Name):
+			problems = append(problems, fmt.Sprintf(
+				"%s: its name is a local name — lower-case letters, digits and hyphens, no dot and no underscore; the "+
+					"mesh derives the name on the bus (novox/hq ADR 0201)", at))
+		}
+		if first, taken := storageOf[e.Name]; taken {
+			problems = append(problems, fmt.Sprintf(
+				"%s: the name is used twice (as %s and as %s); each name is one, whatever its storage type (novox/hq "+
+					"ADR 0595 §1)", at, first, e.Storage))
+		}
+		storageOf[e.Name] = e.Storage
+		if section, kept := oldSection[e.Name]; kept {
+			problems = append(problems, fmt.Sprintf(
+				"%s: the name is also kept in the old section %s; one local name is one form, so a module that moves an "+
+					"entry removes it from the old section (novox/hq ADR 0595 §11)", at, section))
+		}
+		problems = append(problems, busEntryProblems(at, e, terminal)...)
+	}
+	return problems
+}
+
+// busEntryProblems judges one entry's storage type, template, options and configuration.
+func busEntryProblems(at string, e catalogue.BusStateEntry, terminal []string) []string {
+	var problems []string
+	switch e.Storage {
+	case catalogue.StorageStream, catalogue.StorageKeyValue, catalogue.StorageObjectStore, catalogue.StorageLedger:
+	default:
+		return []string{fmt.Sprintf("%s: the storage type %q is unknown; it is %s", at, e.Storage,
+			strings.Join([]string{catalogue.StorageStream, catalogue.StorageKeyValue, catalogue.StorageObjectStore, catalogue.StorageLedger}, ", "))}
+	}
+	if e.Storage != catalogue.StorageLedger && len(e.Types) > 0 {
+		problems = append(problems, fmt.Sprintf("%s: types are a ledger's; storage type %s has none", at, e.Storage))
+	}
+	if e.Template == "" {
+		if e.Storage != catalogue.StorageStream {
+			return append(problems, fmt.Sprintf(
+				"%s: the storage type %s is asked for by its template; only a stream is asked for bare, with a "+
+					"configuration of its own (novox/hq design 25 § 12.1)", at, e.Storage))
+		}
+		if len(e.Options) > 0 {
+			problems = append(problems, fmt.Sprintf(
+				"%s: a bare stream gives its settings in its configuration, not in options", at))
+		}
+		return append(problems, settingsProblems(at, "configuration", e.Configuration, bareStream, "a bare stream", terminal, true)...)
+	}
+	tpl, known := busTemplates[e.Template]
+	switch {
+	case !known:
+		names := make([]string, 0, len(busTemplates))
+		for n := range busTemplates {
+			names = append(names, n)
+		}
+		slices.Sort(names)
+		return append(problems, fmt.Sprintf("%s: the template %q is unknown; it is %s", at, e.Template, strings.Join(names, ", ")))
+	case tpl.storage != e.Storage:
+		return append(problems, fmt.Sprintf(
+			"%s: the template %s is on the storage type %s, not %s", at, e.Template, tpl.storage, e.Storage))
+	}
+	problems = append(problems, settingsProblems(at, "options", e.Options, tpl.options, "the template "+e.Template+" (it fixes "+tpl.fixed+")", terminal, false)...)
+	if e.Template == catalogue.TemplateLedger {
+		problems = append(problems, settingsProblems(at, "configuration", e.Configuration, ledgerConfiguration, "a ledger's own configuration", terminal, false)...)
+		problems = append(problems, ledgerTypeProblems(at, e)...)
+	} else if len(e.Configuration) > 0 {
+		problems = append(problems, fmt.Sprintf(
+			"%s: the template %s is given a configuration; a configuration of its own is for a bare stream or a "+
+				"ledger whose history expires, and a template's settings are its options (novox/hq ADR 0595 §2)", at, e.Template))
+	}
+	if e.Template == catalogue.TemplateWorkQueue {
+		problems = append(problems, workQueueProblems(at, e)...)
+	}
+	return problems
+}
+
+// settingsProblems judges the given settings against the rules: an unknown one is refused (a fixed setting among them),
+// a number outside its bound, a kind mismatch, and a required one missing. A bare stream's when-full and age are read
+// here too.
+func settingsProblems(at, field string, given map[string]json.RawMessage, rules map[string]optionRule, of string, terminal []string, bare bool) []string {
+	var problems []string
+	for _, k := range sortedKeys(given) {
+		raw := given[k]
+		if bare && k == catalogue.ConfigWhenFull {
+			var v string
+			if json.Unmarshal(raw, &v) != nil || (v != catalogue.WhenFullRefuse && v != catalogue.WhenFullDropOldest) {
+				problems = append(problems, fmt.Sprintf(
+					"%s: %s %q is %s; a bare stream says %q or %q", at, field, k, string(raw), catalogue.WhenFullRefuse, catalogue.WhenFullDropOldest))
+			}
+			continue
+		}
+		rule, ok := rules[k]
+		if !ok {
+			if k == catalogue.ConfigWhenFull {
+				problems = append(problems, fmt.Sprintf(
+					"%s: %s %q is given to %s; what happens when full is fixed and is never an option (novox/hq ADR 0595 §3)", at, field, k, of))
+				continue
+			}
+			problems = append(problems, fmt.Sprintf(
+				"%s: %s %q is not a setting of %s (novox/hq ADR 0595 §3)", at, field, k, of))
+			continue
+		}
+		problems = append(problems, valueProblems(at, field, k, raw, rule, terminal, bare)...)
+	}
+	for _, k := range sortedKeys(rules) {
+		if _, given := given[k]; !given && rules[k].required {
+			problems = append(problems, fmt.Sprintf("%s: %s %q is missing; %s gives it", at, field, k, of))
+		}
+	}
+	if bare {
+		if _, given := given[catalogue.ConfigWhenFull]; !given {
+			problems = append(problems, fmt.Sprintf(
+				"%s: %s %q is missing; a bare stream says %q or %q", at, field, catalogue.ConfigWhenFull, catalogue.WhenFullRefuse, catalogue.WhenFullDropOldest))
+		}
+	}
+	return problems
+}
+
+// valueProblems judges one setting's value against its rule.
+func valueProblems(at, field, key string, raw json.RawMessage, rule optionRule, terminal []string, bare bool) []string {
+	switch rule.kind {
+	case optionInt:
+		if bare && key == catalogue.OptionAgeDays {
+			var word string
+			if json.Unmarshal(raw, &word) == nil && word == noAge {
+				return nil
+			}
+		}
+		n, ok := wholeNumber(raw)
+		if !ok {
+			return []string{fmt.Sprintf("%s: %s %q is %s, which is not a whole number", at, field, key, string(raw))}
+		}
+		if n < rule.least || n > rule.most {
+			extra := ""
+			if key == catalogue.OptionPastValues && n == 0 {
+				extra = "; 0 is refused here"
+			}
+			return []string{fmt.Sprintf("%s: %s %q is %d, outside its bound of %d to %d%s", at, field, key, n, rule.least, rule.most, extra)}
+		}
+	case optionFlag:
+		var b bool
+		if json.Unmarshal(raw, &b) != nil {
+			return []string{fmt.Sprintf("%s: %s %q is %s, which is not true or false", at, field, key, string(raw))}
+		}
+	case optionText:
+		var config string
+		if json.Unmarshal(raw, &config) != nil || !slices.Contains(terminal, config) {
+			return []string{fmt.Sprintf(
+				"%s: %s %q names %s, which is not a trusted config value of the module, set only at the controller's "+
+					"terminal or on the operator's Approve (novox/hq ADR 0348 §8)", at, field, key, string(raw))}
+		}
+	case optionEvents:
+		var events []string
+		if json.Unmarshal(raw, &events) != nil || len(events) == 0 {
+			return []string{fmt.Sprintf("%s: %s %q is %s; it is a list of at least one event", at, field, key, string(raw))}
+		}
+		var out []string
+		for _, ev := range events {
+			if err := eventPattern(ev, false); err != nil {
+				out = append(out, fmt.Sprintf("%s: %s %q carries %q: %v", at, field, key, ev, err))
+			}
+		}
+		return out
+	}
+	return nil
+}
+
+// wholeNumber reads a JSON number that is a whole number.
+func wholeNumber(raw json.RawMessage) (int, bool) {
+	dec := json.NewDecoder(bytes.NewReader(raw))
+	dec.UseNumber()
+	var n json.Number
+	if dec.Decode(&n) != nil {
+		return 0, false
+	}
+	i, err := n.Int64()
+	return int(i), err == nil
+}
+
+// workQueueProblems holds a work queue's duplicate window to its age (design 25 § 12.1: up to its age).
+func workQueueProblems(at string, e catalogue.BusStateEntry) []string {
+	raw, given := e.Options[catalogue.OptionDuplicates]
+	if !given {
+		return nil
+	}
+	window, ok := wholeNumber(raw)
+	if !ok {
+		return nil // valueProblems said so
+	}
+	days := catalogue.StreamDefaultDays
+	if age, ok := wholeNumber(e.Options[catalogue.OptionAgeDays]); ok && age > 0 {
+		days = age
+	}
+	if window > days*86400 {
+		return []string{fmt.Sprintf(
+			"%s: options %q is %d seconds, longer than the queue's age of %d days (novox/hq design 25 § 12.1)",
+			at, catalogue.OptionDuplicates, window, days)}
+	}
+	return nil
+}
+
+// ledgerTypeProblems judges a ledger's types: named locally and once, and every operation's effect one of the four.
+func ledgerTypeProblems(at string, e catalogue.BusStateEntry) []string {
+	var problems []string
+	if len(e.Types) == 0 {
+		problems = append(problems, fmt.Sprintf("%s: a ledger names at least one type (novox/hq ADR 0597 §1)", at))
+	}
+	seen := map[string]bool{}
+	for _, t := range e.Types {
+		where := fmt.Sprintf("%s: type %q", at, t.Name)
+		switch {
+		case !stateName.MatchString(t.Name):
+			problems = append(problems, fmt.Sprintf("%s: its name is lower-case letters, digits and hyphens", where))
+		case seen[t.Name]:
+			problems = append(problems, fmt.Sprintf("%s: the type is named twice", where))
+		}
+		seen[t.Name] = true
+		operations := map[string]bool{}
+		for _, op := range t.Operations {
+			if operations[op.Name] {
+				problems = append(problems, fmt.Sprintf("%s: the operation %q is named twice", where, op.Name))
+			}
+			operations[op.Name] = true
+			if !slices.Contains(ledgerEffects, op.Effect) {
+				problems = append(problems, fmt.Sprintf(
+					"%s: the operation %q has the effect %q, outside the four (%s) (novox/hq ADR 0597 §2)",
+					where, op.Name, op.Effect, strings.Join(ledgerEffects, ", ")))
+			}
+		}
+	}
+	return problems
+}
+
+// BusStateCatalogueProblems are the rules of bus state no single manifest can be judged against: two modules' names on
+// the bus alike, and a `reads` naming bus state in the new form, which has no readers (novox/hq ADR 0596 §2).
+func BusStateCatalogueProblems(shelf catalogue.Shelf) []string {
+	var problems []string
+	owner := map[string]string{} // a name on the bus, upper-cased, to the module asking for it
+	for _, module := range shelfOrder(shelf) {
+		for _, o := range shelf[module].Objects {
+			owner[strings.ToUpper(o.Bucket(module))] = module
+		}
+	}
+	for _, module := range shelfOrder(shelf) {
+		for _, e := range shelf[module].BusState {
+			name := catalogue.ObjectsBucket(module, e.Name)
+			if first, taken := owner[strings.ToUpper(name)]; taken && first != module {
+				problems = append(problems, fmt.Sprintf(
+					"%s's bus state %q has the name %s on the bus, which %s's already has or is alike; a name on the bus "+
+						"has one owner (novox/hq ADR 0201 §4)", module, e.Name, name, first))
+				continue
+			}
+			owner[strings.ToUpper(name)] = module
+		}
+	}
+	for _, module := range shelfOrder(shelf) {
+		for _, r := range shelf[module].Reads {
+			from, local, err := catalogue.ReadState(r)
+			if err != nil || from == module {
+				continue // StateProblems says why
+			}
+			for _, e := range shelf[from].BusState {
+				if e.Name == local {
+					problems = append(problems, fmt.Sprintf(
+						"%s reads %q, which %s has moved to bus state in `requires`; the new form has no readers: ask %s's "+
+							"tools, or hear its events (novox/hq ADR 0596 §2)", module, r, from, from))
+				}
+			}
+		}
+	}
+	return problems
+}

modules/mesh-delivery-indexer/judge/busstate_test.go

@@ -0,0 +1,95 @@
+package judge
+
+import (
+	"strings"
+	"testing"
+
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+)
+
+// A manifest's bus state, asked for in `requires` by template, is judged once and each refusal names the module, the entry
+// and the field (issue 1966 D1, D2; novox/hq design 25 § 12.1, ADR 0595, ADR 0596 §2, ADR 0597 §2).
+func TestBusStateIsJudgedOnce(t *testing.T) {
+	const ledger = `{"name":"records","storage":"ledger","template":"ledger","options":{"max-mib":512},"types":[` +
+		`{"name":"decision","schema":{"title":{"type":"text"}},"operations":[{"name":"propose","effect":"set-fields","fields":["title"]}]}]}`
+	manifest := func(entries string) string {
+		return `{"module":"a","version":"1","requires":[` + entries + `]}`
+	}
+	for _, c := range []struct {
+		name    string
+		raw     string
+		refused []string // words the first problem holds, in order: absent is accepted
+	}{
+		// 1966/AC8: a state, a log, objects and a ledger within bounds
+		{"within bounds", manifest(`{"name":"cache","storage":"key-value","template":"state","options":{"history":8,"key-ttl":true}},` +
+			`{"name":"audit","storage":"stream","template":"log","options":{"max-mib":64,"max-age-days":365}},` +
+			`{"name":"files","storage":"object-store","template":"objects","options":{"max-mib":2048}},` + ledger), nil},
+		// 1966/AC7: each refused case, naming the module, the entry and the field
+		{"unknown storage type", manifest(`{"name":"x","storage":"tape"}`), []string{"a's bus state \"x\"", "storage type \"tape\""}},
+		{"unknown template", manifest(`{"name":"x","storage":"stream","template":"pile"}`), []string{"\"x\"", "template \"pile\""}},
+		{"template on another storage type", manifest(`{"name":"x","storage":"stream","template":"state"}`), []string{"\"x\"", "template state is on the storage type key-value"}},
+		{"past values 0", manifest(`{"name":"x","storage":"key-value","template":"state","options":{"history":0}}`), []string{"\"x\"", "options \"history\" is 0", "0 is refused"}},
+		{"past values 65", manifest(`{"name":"x","storage":"key-value","template":"state","options":{"history":65}}`), []string{"\"x\"", "\"history\" is 65", "1 to 64"}},
+		{"a lifetime that is no number", manifest(`{"name":"x","storage":"key-value","template":"state","options":{"ttl-seconds":"soon"}}`), []string{"\"x\"", "\"ttl-seconds\""}},
+		{"events age over 30 days", manifest(`{"name":"x","storage":"stream","template":"events","options":{"events":["seen"],"max-age-days":31}}`), []string{"\"x\"", "\"max-age-days\" is 31", "1 to 30"}},
+		{"events cap over 8192", manifest(`{"name":"x","storage":"stream","template":"events","options":{"events":["seen"],"max-mib":8193}}`), []string{"\"x\"", "\"max-mib\" is 8193"}},
+		{"events naming none", manifest(`{"name":"x","storage":"stream","template":"events","options":{}}`), []string{"\"x\"", "\"events\" is missing"}},
+		{"a grant that is no trusted value", manifest(`{"name":"x","storage":"stream","template":"events","options":{"events":["seen"],"grant":"nobody"}}`), []string{"\"x\"", "\"grant\"", "trusted config value"}},
+		{"deliveries 11", manifest(`{"name":"x","storage":"stream","template":"work-queue","options":{"events":["job"],"max-deliveries":11}}`), []string{"\"x\"", "\"max-deliveries\" is 11", "1 to 10"}},
+		{"duplicates past the age", manifest(`{"name":"x","storage":"stream","template":"work-queue","options":{"events":["job"],"max-age-days":1,"duplicates":86401}}`), []string{"\"x\"", "\"duplicates\"", "longer than the queue's age of 1 days"}},
+		{"log age 3651", manifest(`{"name":"x","storage":"stream","template":"log","options":{"max-age-days":3651}}`), []string{"\"x\"", "\"max-age-days\" is 3651"}},
+		{"objects without a cap", manifest(`{"name":"x","storage":"object-store","template":"objects"}`), []string{"\"x\"", "\"max-mib\" is missing"}},
+		{"when full given as an option", manifest(`{"name":"x","storage":"stream","template":"log","options":{"when-full":"drop-oldest"}}`), []string{"\"x\"", "\"when-full\"", "fixed"}},
+		{"another fixed setting given", manifest(`{"name":"x","storage":"key-value","template":"state","options":{"max-value-kib":1024}}`), []string{"\"x\"", "\"max-value-kib\" is not a setting of the template state"}},
+		{"a configuration beside a template", manifest(`{"name":"x","storage":"key-value","template":"state","configuration":{"max-mib":1}}`), []string{"\"x\"", "configuration"}},
+		{"a name used twice across storage types", manifest(
+			`{"name":"x","storage":"key-value","template":"state"},{"name":"x","storage":"stream","template":"log"}`), []string{"\"x\"", "used twice (as key-value and as stream)"}},
+		{"a local name holding an underscore", manifest(`{"name":"my_x","storage":"key-value","template":"state"}`), []string{"\"my_x\"", "underscore"}},
+		{"a bare stream without when full", manifest(`{"name":"x","storage":"stream","configuration":{"max-mib":10,"max-age-days":"none"}}`), []string{"\"x\"", "\"when-full\" is missing"}},
+		{"a bare stream without a cap", manifest(`{"name":"x","storage":"stream","configuration":{"when-full":"refuse","max-age-days":3}}`), []string{"\"x\"", "\"max-mib\" is missing"}},
+		{"a bare stream without an age", manifest(`{"name":"x","storage":"stream","configuration":{"when-full":"refuse","max-mib":10}}`), []string{"\"x\"", "\"max-age-days\" is missing"}},
+		{"a bare stream, complete", manifest(`{"name":"x","storage":"stream","configuration":{"when-full":"drop-oldest","max-mib":10,"max-age-days":"none"}}`), nil},
+		{"a bare stream with a wrong when full", manifest(`{"name":"x","storage":"stream","configuration":{"when-full":"crash","max-mib":10,"max-age-days":9}}`), []string{"\"x\"", "\"when-full\"", "\"refuse\" or \"drop-oldest\""}},
+		{"a ledger effect outside the four", manifest(strings.Replace(ledger, `"set-fields"`, `"upsert"`, 1)), []string{"\"records\"", "effect \"upsert\"", "outside the four"}},
+		{"a ledger whose history expires", manifest(strings.Replace(ledger, `"options"`, `"configuration":{"max-age-days":30},"options"`, 1)), nil},
+	} {
+		_, problems := Manifest([]byte(c.raw), nil)
+		switch {
+		case c.refused == nil && len(problems) > 0:
+			t.Errorf("%s: refused: %v", c.name, problems)
+		case c.refused != nil && len(problems) == 0:
+			t.Errorf("%s: accepted", c.name)
+		case c.refused != nil:
+			text := strings.Join(problems, "\n")
+			at := 0
+			for _, word := range c.refused {
+				i := strings.Index(text[at:], word)
+				if i < 0 {
+					t.Errorf("%s: problems %q lack %q", c.name, text, word)
+					break
+				}
+				at += i
+			}
+		}
+	}
+	// Between the manifests: two modules' names on the bus alike, and a read of bus state that moved (ADR 0596 §2).
+	entry := func(name string) []catalogue.BusStateEntry {
+		return []catalogue.BusStateEntry{{Name: name, Storage: catalogue.StorageKeyValue, Template: catalogue.TemplateState}}
+	}
+	for _, c := range []struct {
+		name  string
+		shelf catalogue.Shelf
+		want  string
+	}{
+		{"names alike", catalogue.Shelf{"a_b": {Module: "a_b", BusState: entry("c")}, "a": {Module: "a", BusState: entry("b_c")}}, "has one owner"},
+		{"a read of moved state", catalogue.Shelf{"owner": {Module: "owner", BusState: entry("cache")},
+			"reader": {Module: "reader", Reads: []string{"owner.cache"}}}, "reader reads \"owner.cache\", which owner has moved"},
+		{"a read of state still kept", catalogue.Shelf{"owner": {Module: "owner", State: []catalogue.StateDeclaration{{Name: "cache"}}},
+			"reader": {Module: "reader", Reads: []string{"owner.cache"}}}, ""},
+	} {
+		got := strings.Join(BusStateCatalogueProblems(c.shelf), "\n")
+		if (c.want == "") != (got == "") || !strings.Contains(got, c.want) {
+			t.Errorf("%s: between the manifests: %q, want %q", c.name, got, c.want)
+		}
+	}
+}

modules/mesh-delivery-indexer/judge/judge.go

@@ -69,6 +69,12 @@ func problemsOf(err error) []string {
 // whose removal from the catalogue ends it (a rule two modules break together refuses both); one no removal ends is in
 // unnamed, for the caller to say. A module not in the answer is accepted.
 func Shelf(raws map[string][]byte, predefined catalogue.PredefinedList, longestMachine int) (refused map[string][]string, unnamed []string) {
+	return ShelfCounting(raws, predefined, longestMachine, nil)
+}
+
+// ShelfCounting is Shelf also refusing a manifest of a module outside the foundation that uses an old section whose count
+// is 0 (OldSectionProblems; issue 1966 D4); nil counts refuse none.
+func ShelfCounting(raws map[string][]byte, predefined catalogue.PredefinedList, longestMachine int, counts OldSectionCounts) (refused map[string][]string, unnamed []string) {
 	refused = map[string][]string{}
 	shelf := catalogue.Shelf{}
 	for name, raw := range raws {
@@ -81,6 +87,10 @@ func Shelf(raws map[string][]byte, predefined catalogue.PredefinedList, longestM
 			refused[name] = []string{fmt.Sprintf("the manifest is of module %q, not %q", m.Module, name)}
 			continue
 		}
+		if problems := OldSectionProblems(m, counts); len(problems) > 0 {
+			refused[name] = problems
+			continue
+		}
 		shelf[name] = m
 	}
 	between := Between(shelf, longestMachine)
@@ -179,6 +189,7 @@ const Unnamed = "(between manifests)"
 func Request(r composer.Request) (composer.Verdict, error) {
 	v := composer.Verdict{V: composer.Version, SDK: Identity()}
 	seen := map[string]bool{}
+	counts := trunkOldSections(r)
 	for _, c := range r.Cases {
 		if seen[c.Name] {
 			return composer.Verdict{}, fmt.Errorf("the case %q is named twice", c.Name)
@@ -191,7 +202,7 @@ func Request(r composer.Request) (composer.Verdict, error) {
 			}
 			raws[name] = m.Raw
 		}
-		refused, unnamed := Shelf(raws, r.Predefined, 0)
+		refused, unnamed := ShelfCounting(raws, r.Predefined, 0, counts)
 		cv := composer.CaseVerdict{Name: c.Name, Manifests: map[string]composer.ManifestRead{}}
 		for name := range raws {
 			if problems := refused[name]; len(problems) > 0 {
@@ -208,6 +219,39 @@ func Request(r composer.Request) (composer.Verdict, error) {
 	return v, nil
 }
 
+// TrunkCase is the case of a request holding the catalogue as the trunk holds it (the checker's JudgeTrunk).
+const TrunkCase = "trunk"
+
+// trunkOldSections counts the old sections the modules accepted at the trunk use, as the indexer counts them from its
+// verdicts (issue 1966 D4, ADR 0595 §11): a change is refused at the merge check exactly as at take-in (judged once, ADR
+// 0578). Nil where the request holds no trunk case, which refuses no use of a section.
+func trunkOldSections(r composer.Request) OldSectionCounts {
+	for _, c := range r.Cases {
+		if c.Name != TrunkCase {
+			continue
+		}
+		raws := map[string][]byte{}
+		for name, m := range c.Manifests {
+			if len(m.Raw) > 0 {
+				raws[name] = m.Raw
+			}
+		}
+		refused, _ := Shelf(raws, r.Predefined, 0)
+		var accepted []catalogue.Manifest
+		for name, raw := range raws {
+			if len(refused[name]) > 0 {
+				continue
+			}
+			if m, err := catalogue.Decode(raw); err == nil {
+				m.Module = name
+				accepted = append(accepted, m)
+			}
+		}
+		return CountOldSections(accepted)
+	}
+	return nil
+}
+
 var (
 	identityOnce sync.Once
 	identity     string

modules/mesh-delivery-indexer/judge/judge_test.go

@@ -86,6 +86,27 @@ func TestTheJudge(t *testing.T) {
 		v.Cases[0].Manifests["b"].Accepted || !strings.Contains(v.Cases[0].Manifests["b"].Refused, `requires "amqp"`) {
 		t.Fatalf("request: %+v %v", v, err)
 	}
+	// 1966/AC11: the checker's judge counts the old sections from the trunk case as the indexer does from its verdicts (the
+	// foundation left out): a change adding logs where no trunk module uses them is refused, the foundation's accepted, and
+	// state, which a trunk module uses, is accepted.
+	old := composer.Request{V: composer.Version, Cases: []composer.Case{
+		{Name: "change", Manifests: map[string]composer.Manifest{
+			"user":        {Raw: json.RawMessage(`{"module":"user","version":"1","state":["x"]}`)},
+			"late":        {Raw: json.RawMessage(`{"module":"late","version":"1","logs":[{"name":"l"}]}`)},
+			"newer":       {Raw: json.RawMessage(`{"module":"newer","version":"1","state":["y"]}`)},
+			"mesh-grants": {Raw: json.RawMessage(`{"module":"mesh-grants","version":"1","logs":[{"name":"l"}]}`)}}},
+		{Name: "trunk", Manifests: map[string]composer.Manifest{
+			"user":        {Raw: json.RawMessage(`{"module":"user","version":"1","state":["x"]}`)},
+			"mesh-grants": {Raw: json.RawMessage(`{"module":"mesh-grants","version":"1","logs":[{"name":"l"}]}`)}}}}}
+	ov, err := Request(old)
+	if err != nil {
+		t.Fatal(err)
+	}
+	got := ov.Cases[0].Manifests
+	if got["late"].Accepted || !strings.Contains(got["late"].Refused, "late uses the old section logs") ||
+		!got["newer"].Accepted || !got["user"].Accepted || !got["mesh-grants"].Accepted {
+		t.Errorf("the change's old sections: %+v", got)
+	}
 	r.Cases[0].Manifests["c"] = composer.Manifest{Digest: strings.Repeat("a", 64)}
 	if _, err := Request(r); err == nil {
 		t.Fatal("a manifest left as a digest was judged")

modules/mesh-delivery-indexer/judge/oldsections.go

@@ -0,0 +1,69 @@
+package judge
+
+import (
+	"fmt"
+	"slices"
+
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+)
+
+// The old sections end when no module is left in them (issue 1966 D4; novox/hq ADR 0595 §11): the indexer counts, per old
+// section, the accepted modules using it, the foundation left out, and the judge refuses a manifest of another module
+// that uses a section whose count is 0. The foundation (the bus module, the grants part and the indexer itself) is
+// created before the bus module can create anything, so it keeps the old sections for good and is always accepted.
+
+// OldSections are the sections of a manifest that keep bus state in the old forms.
+var OldSections = []string{"state", "logs", "streams", "objects"}
+
+// Foundation are the modules that keep using the old sections for good.
+var Foundation = []string{"nats", "mesh-grants", "mesh-delivery-indexer"}
+
+// OldSectionCounts is, per old section, how many accepted modules outside the foundation use it. Nil is no count: the
+// judge then refuses no use of a section.
+type OldSectionCounts map[string]int
+
+// SectionsUsed are the old sections a manifest uses, in OldSections' order.
+func SectionsUsed(m catalogue.Manifest) []string {
+	var used []string
+	for _, s := range OldSections {
+		if (s == "state" && len(m.State) > 0) || (s == "logs" && len(m.Logs) > 0) ||
+			(s == "streams" && len(m.Streams) > 0) || (s == "objects" && len(m.Objects) > 0) {
+			used = append(used, s)
+		}
+	}
+	return used
+}
+
+// CountOldSections counts, per old section, the manifests using it, the foundation's left out; every section is in the
+// answer, with 0 where none uses it.
+func CountOldSections(manifests []catalogue.Manifest) OldSectionCounts {
+	counts := OldSectionCounts{}
+	for _, s := range OldSections {
+		counts[s] = 0
+	}
+	for _, m := range manifests {
+		if slices.Contains(Foundation, m.Module) {
+			continue
+		}
+		for _, s := range SectionsUsed(m) {
+			counts[s]++
+		}
+	}
+	return counts
+}
+
+// OldSectionProblems are the old sections a manifest uses that no accepted module outside the foundation uses any more.
+func OldSectionProblems(m catalogue.Manifest, counts OldSectionCounts) []string {
+	if counts == nil || slices.Contains(Foundation, m.Module) {
+		return nil
+	}
+	var problems []string
+	for _, s := range SectionsUsed(m) {
+		if counts[s] == 0 {
+			problems = append(problems, fmt.Sprintf(
+				"%s uses the old section %s, which no other module uses any more (0 modules count); ask for it in "+
+					"`requires` by template (novox/hq ADR 0595 §11)", m.Module, s))
+		}
+	}
+	return problems
+}

modules/mesh-delivery-indexer/judge/rules.go

@@ -2626,6 +2626,8 @@ func parseManifest(raw []byte, predefined catalogue.PredefinedList) (catalogue.M
 	// And the object buckets it owns (novox/hq ADR 0592 §5, §9).
 	problems = append(problems, ObjectsProblems(m)...)
 	problems = append(problems, WorkQueueStreamProblems(m)...)
+	// And the bus state it asks for in `requires`, by template (busstate.go, novox/hq ADR 0595; issue 1966 D1).
+	problems = append(problems, BusStateProblems(m)...)
 	// And the defaults it gives its settings (setting_defaults.go, novox/hq ADR 0262), or, written in the
 	// config form, the whole declaration of each value (config.go, novox/hq ADR 0348).
 	if m.DeclaresConfig() {
@@ -4554,6 +4556,8 @@ func CatalogueProblems(shelf catalogue.Shelf) []string {
 	problems = append(problems, StreamNameProblems(shelf)...)
 	// An object bucket's name has one owner, and another module reads it only through its owner's grant (ADR 0592 §5, §9).
 	problems = append(problems, ObjectsCatalogueProblems(shelf)...)
+	// Bus state in `requires`: a name on the bus has one owner, and the new form has no readers (ADR 0595, ADR 0596 §2).
+	problems = append(problems, BusStateCatalogueProblems(shelf)...)
 	// A module that hears a restricted stream runs as an account of its own (novox/hq ADR 0376 §2).
 	problems = append(problems, RestrictedHearingProblems(shelf)...)
 	// A work-queue stream is never asked for by another module's consumes (novox/hq ADR 0436 §6).
@@ -5358,7 +5362,7 @@ func StateProblems(m catalogue.Manifest) []string {
 		seen[s.Name] = true
 		if s.History < 0 || s.History > catalogue.StateMostHistory {
 			problems = append(problems, fmt.Sprintf(
-				"%s keeps %d values of %q; a key keeps between 1 and %d", m.Module, s.History, s.Name, catalogue.StateMostHistory))
+				"%s keeps %d values of %q; a key keeps 0 or 1 to %d (0 is taken as 1)", m.Module, s.History, s.Name, catalogue.StateMostHistory))
 		}
 		if s.TTLSeconds < 0 {
 			problems = append(problems, fmt.Sprintf("%s gives %q a negative lifetime", m.Module, s.Name))

modules/mesh-delivery-indexer/judge/rules_test.go

@@ -54,12 +54,6 @@ func TestABinaryMustSayWhichSystemItIsFor(t *testing.T) {
 	}
 }
 
-func TestABinaryThatNamesASystemIsAccepted(t *testing.T) {
-	if got := buildProblemsOf(t, bundleFor("go", "arch")); got != "" {
-		t.Fatalf("a compiled bundle naming a system was refused:\n%s", got)
-	}
-}
-
 func TestABlockOutsideTheShapeIsRefused(t *testing.T) {
 	cases := map[string]string{
 		`{"seat":"node-bar","kind":"block","content":"[[block]]"}`:                                                                          "has no data",
@@ -913,6 +907,12 @@ func TestALogIsNamedLocallyAndCapped(t *testing.T) {
 		{`{"module":"a.b","version":"1","logs":["c"]}`, `no dot`},
 	} {
 		_, err := ParseManifest([]byte(c.manifest))
+		if c.says == "" {
+			if err != nil {
+				t.Errorf("%s was refused: %v", c.manifest, err)
+			}
+			continue
+		}
 		if err == nil {
 			t.Errorf("%s was accepted", c.manifest)
 			continue
@@ -2356,18 +2356,19 @@ func TestAPlaceholderOutsideTheHolderIsRefused(t *testing.T) {
 	}
 }
 
-// **And a language that runs anywhere must not name one.** A system that decides nothing reads as
-// though it did, which is the same fault as a restriction that restricts nothing (novox/hq ADR 0045).
-func TestAPortableBundleMayNotNameASystem(t *testing.T) {
-	got := buildProblemsOf(t, bundleFor("typescript", "arch"))
-	if !strings.Contains(got, "runs anywhere") {
-		t.Fatalf("a portable bundle was allowed to name a system:\n%s", got)
-	}
-}
-
-func TestAPortableBundleNamingNoSystemIsAccepted(t *testing.T) {
-	if got := buildProblemsOf(t, bundleFor("typescript", "")); got != "" {
-		t.Fatalf("an ordinary bundle was refused:\n%s", got)
+// **A language that runs anywhere must not name a system.** A system that decides nothing reads as
+// though it did, which is the same fault as a restriction that restricts nothing (novox/hq ADR 0045); a compiled
+// bundle names one, and a portable bundle naming none is an ordinary one.
+func TestABundleNamesASystemOnlyWhereItCompiles(t *testing.T) {
+	for _, c := range []struct{ language, system, refused string }{
+		{"go", "arch", ""},
+		{"typescript", "", ""},
+		{"typescript", "arch", "runs anywhere"},
+	} {
+		got := buildProblemsOf(t, bundleFor(c.language, c.system))
+		if (c.refused == "") != (got == "") || !strings.Contains(got, c.refused) {
+			t.Errorf("a %s bundle naming %q: %q, want %q", c.language, c.system, got, c.refused)
+		}
 	}
 }
 
@@ -2882,13 +2883,23 @@ func TestAStateNameIsLocalAndOneToken(t *testing.T) {
 		{`{"module":"a","version":"1","state":["mesh.servers"]}`, `keeps state "mesh.servers": a state is named locally`},
 		{`{"module":"a","version":"1","state":["my_servers"]}`, `keeps state "my_servers"`},
 		{`{"module":"a","version":"1","state":["s","s"]}`, `keeps state "s" twice`},
-		{`{"module":"a","version":"1","state":[{"name":"s","history":65}]}`, `a key keeps between 1 and 64`},
+		{`{"module":"a","version":"1","state":[{"name":"s","history":65}]}`, `a key keeps 0 or 1 to 64 (0 is taken as 1)`},
+		{`{"module":"a","version":"1","state":[{"name":"s","history":0}]}`, ``}, // 0 passes, as before (ADR 0579 §1)
+		// 1966/AC9: one name, one form
+		{`{"module":"a","version":"1","state":["x"],"requires":[{"name":"x","storage":"key-value","template":"state"}]}`,
+			`a's bus state "x": the name is also kept in the old section state`},
 		{`{"module":"a.b","version":"1","state":["s"]}`, `no dot`},
 		{`{"module":"a","version":"1","reads":["bindings"]}`, `a read is <module>.<name>`},
 		{`{"module":"a","version":"1","reads":["a.s"]}`, `which is its own state`},
 		{`{"module":"a","version":"1","state":[{"name":"s","shared":true}]}`, `{name, history, ttl-seconds, per-machine, key-ttl}`},
 	} {
 		_, err := ParseManifest([]byte(c.manifest))
+		if c.says == "" {
+			if err != nil {
+				t.Errorf("%s was refused: %v", c.manifest, err)
+			}
+			continue
+		}
 		if err == nil {
 			t.Errorf("%s was accepted", c.manifest)
 			continue

modules/mesh-delivery-indexer/manifest_test.go

@@ -84,12 +84,13 @@ func TestManifestDeclarations(t *testing.T) { // 1238/AC1, 1444 (reads the build
 		t.Errorf("module = %q", m.Module)
 	}
 	// 1126: placement is the seat mesh-placement's (ADR 0567): the indexer holds no placement state. ADR 0578 §1: it says
-	// a refused manifest as manifest-refused, its one event.
-	if !reflect.DeepEqual(m.Emits, []string{"manifest-refused"}) {
-		t.Errorf("emits = %v, want manifest-refused alone", m.Emits)
+	// a refused manifest as manifest-refused, and (issue 1966 D3, 1966/AC10) a newly accepted one asking for bus state as
+	// manifest-accepted.
+	if !reflect.DeepEqual(m.Emits, []string{"manifest-refused", "manifest-accepted"}) {
+		t.Errorf("emits = %v, want manifest-refused and manifest-accepted", m.Emits)
 	}
 	// 1126 note 76: heard keeps the last 64 FORGE messages the indexer handled, for indexer_heard.
-	if want := []state{{Name: "candidates", History: 10}, {Name: "heard", History: 64}, {Name: "manifests", History: 1}, {Name: "modules", History: 20}, {Name: "predefined", History: 5}, {Name: "config-candidates", History: 5}, {Name: "taken", History: 1}, {Name: "takeins", History: 1}, {Name: "verdicts", History: 5}, {Name: delivery.PackagesState, History: delivery.PackagesHistory}}; !reflect.DeepEqual(m.State, want) {
+	if want := []state{{Name: "candidates", History: 10}, {Name: "heard", History: 64}, {Name: "manifests", History: 1}, {Name: "modules", History: 20}, {Name: "predefined", History: 5}, {Name: "config-candidates", History: 5}, {Name: "taken", History: 1}, {Name: "takeins", History: 1}, {Name: "verdicts", History: 5}, {Name: "oldsections", History: 1}, {Name: delivery.PackagesState, History: delivery.PackagesHistory}}; !reflect.DeepEqual(m.State, want) {
 		t.Errorf("state = %+v, want %+v", m.State, want)
 	}
 	if want := []string{"mesh-build-go.toolchains", "mesh-build-node.toolchains", "mesh-delivery-assigner.placement", "mesh-delivery-builder.build-log", "mesh-delivery-checker.previews", "mesh-delivery-gate.source"}; !reflect.DeepEqual(sorted(m.Reads), want) {
@@ -112,8 +113,9 @@ func TestManifestDeclarations(t *testing.T) { // 1238/AC1, 1444 (reads the build
 	if want := []string{"gitea.gitea_commit_trees", "gitea.gitea_contains", "gitea.gitea_get_file", "gitea.gitea_open_pulls"}; !reflect.DeepEqual(m.Invokes, want) {
 		t.Errorf("invokes = %v, want %v", m.Invokes, want)
 	}
-	// 1945: indexer_take_in, served by its tools bundle through the takeins state; the process serves none.
-	if want := []string{"indexer_take_in"}; !reflect.DeepEqual(m.Tools, want) {
+	// 1945: indexer_take_in, served by its tools bundle through the takeins state; the process serves none. 1966/AC11:
+	// indexer_old_sections reads the count of the old sections (state oldsections).
+	if want := []string{"indexer_take_in", "indexer_old_sections"}; !reflect.DeepEqual(m.Tools, want) {
 		t.Errorf("tools = %v, want %v", m.Tools, want)
 	}
 	// No streams, no bus, no seat (ADR 0437 §4); it says no event.

modules/mesh-delivery-indexer/module.json

@@ -3,7 +3,8 @@
   "version": "1",
   "slug": "indexer",
   "tools": [
-    "indexer_take_in"
+    "indexer_take_in",
+    "indexer_old_sections"
   ],
   "consumes": [
     "mesh-build-go.toolchain.reported",
@@ -21,10 +22,12 @@
     { "name": "taken", "history": 1 },
     { "name": "takeins", "history": 1 },
     { "name": "verdicts", "history": 5 },
+    { "name": "oldsections", "history": 1 },
     { "name": "packages", "history": 5 }
   ],
   "emits": [
-    "manifest-refused"
+    "manifest-refused",
+    "manifest-accepted"
   ],
   "reads": [
     "mesh-build-go.toolchains",

modules/mesh-grants/go.mod

@@ -3,7 +3,7 @@ module mesh-grants
 go 1.26.0
 
 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261102191058-f02f142af128
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103142843-f8bd12e4b7b1
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0
 )

modules/mesh-grants/go.sum

@@ -1,5 +1,7 @@
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261102191058-f02f142af128 h1:aI1DhZAuqVBXbybSqhLNOGX5rUOrn9T0cHNCDUQF7IQ=
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261102191058-f02f142af128/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103142843-f8bd12e4b7b1 h1:T66tg9T/1hHg6KN/bDScHPT41IHkxLAGGO8VJiAOlb8=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103142843-f8bd12e4b7b1/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op/go.mod h1:FQyySiasQQM8735Ddel3MRojmy4dA1IqCeyJ5jmPMbI=
 github.com/google/go-tpm v0.9.8 h1:slArAR9Ft+1ybZu0lBwpSmpwhRXaa85hWtMinMyRAWo=

modules/mesh-grants/grants_test.go

@@ -2202,6 +2202,28 @@ func TestGrants(t *testing.T) {
 		if res := bare.Compose(); res.Accounts != nil || !strings.Contains(strings.Join(res.Errors, " "), "no bus address") {
 			t.Errorf("a part with no bus address wrote %+v: %v", res.Accounts, res.Errors)
 		}
+		// 1966/AC20 (issue 1966 D5, D5b; novox/hq ADR 0597 §9): a module asking for a ledger in `requires` is wanted a ledger
+		// account on each machine it is assigned to, minted by the vault like every kind and held in the tool runner's
+		// `ledgers`; the account is retired once the module leaves that machine.
+		l := fixture()
+		l.manifestOf("mod-x", strings.Replace(xManifest, `"state"`, `"requires":[{"name":"records","storage":"ledger","template":"ledger",`+
+			`"types":[{"name":"decision","schema":{},"operations":[{"name":"propose","effect":"set-fields"}]}]}],"state"`, 1))
+		l.assign("b", "mod-x")
+		l.loaded = shadowOf(t, l)
+		lp := partOn(l)
+		lp.Bus = grants.BusAddress{URL: "nats://a.mesh:4222"}
+		lp.Compose()
+		for _, user := range []string{"ledger.a.mod-x", "ledger.b.mod-x"} {
+			w, err := buscompose.ReadWantedAccount(user, l.own[grants.StateAccounts][user])
+			if err != nil || w.Kind != buscompose.KindLedger || w.OwnSecret() != "ledgers" || w.Module != "mod-x" {
+				t.Errorf("%s is wanted as %+v (%v)", user, w, err)
+			}
+		}
+		l.unassign("b", "mod-x")
+		if res := lp.Compose(); res.Accounts == nil || !slices.Equal(res.Accounts.Deleted, []string{"b.mod-x", "ledger.b.mod-x"}) ||
+			l.own[grants.StateAccounts]["ledger.a.mod-x"] == nil {
+			t.Errorf("after mod-x left b: %+v", res.Accounts)
+		}
 	})
 
 	// 774/AC5 (novox/hq ADR 0561 §1): the vault's account-issued wakes a pass, so the next list carries the new user's hash

modules/mesh-grants/internal/buscompose/accounts.go

@@ -50,7 +50,8 @@ type ClaimedSeat struct {
 // WantedAccount is one key of the grants part's state `accounts`: an account the mesh needs, without its password.
 type WantedAccount struct {
 	User string `json:"user"`
-	// Kind is KindModule (KindNodeTools for the runtime, named as a module is), KindProcess or KindProvisioner.
+	// Kind is KindModule (KindNodeTools for the runtime, named as a module is), KindProcess, KindProvisioner or
+	// KindLedger.
 	Kind   Kind   `json:"kind"`
 	Node   string `json:"node"`
 	Module string `json:"module"`
@@ -65,8 +66,12 @@ type WantedAccount struct {
 	At time.Time `json:"at"`
 }
 
+// LedgersSecret is the tool runner's own secret holding its machine's ledger accounts, a map of module to credential
+// (ADR 0597 §9).
+const LedgersSecret = "ledgers"
+
 // mintedKinds are the kinds of account the vault mints (ADR 0561 §1).
-var mintedKinds = []Kind{KindModule, KindNodeTools, KindProcess, KindProvisioner}
+var mintedKinds = []Kind{KindModule, KindNodeTools, KindProcess, KindProvisioner, KindLedger}
 
 // principal is the account as the composer names it.
 func (w WantedAccount) principal() Principal {
@@ -112,9 +117,12 @@ func (w WantedAccount) Same(o WantedAccount) bool {
 }
 
 // OwnSecret is the module's own secret the account is held in: `broker`, `broker-<process id>` or `provisioner-broker`
-// (the controller's names, ADR 0436 §2, ADR 0349 §11).
+// (the controller's names, ADR 0436 §2, ADR 0349 §11); a ledger account in the tool runner's `ledgers`, which keeps every
+// ledger account of its machine, by module (ADR 0597 §9).
 func (w WantedAccount) OwnSecret() string {
 	switch w.Kind {
+	case KindLedger:
+		return LedgersSecret
 	case KindProcess:
 		return "broker-" + w.Process
 	case KindProvisioner:

modules/mesh-grants/internal/buscompose/buscompose_test.go

@@ -49,6 +49,7 @@ func TestTheCopiedComposerComposesAsTheControllers(t *testing.T) {
 	t.Run("only declared streams are created", theGrantsPartCreatesOnlyDeclaredStreams)
 	t.Run("a declared stream is created as the controller asserted it", declaredStreamsAreCreatedAsTheControllerAssertsThem)
 	t.Run("every node's compositions are read by their named readers alone and written by their node", everyNodesCompositions)
+	t.Run("a module's ledger is written by its ledger account alone", aLedgerIsWrittenByItsLedgerAccountAlone)
 	// ADR 0567 §3, §9: a node reads every key of the seat's placement and its candidates (it composes with the whole
 	// proposal laid over), and none of its open proposals; it writes neither.
 	reads := strings.Join(NodeComposeReads("laptop"), " ")
@@ -942,3 +943,75 @@ func everyNodesCompositions(t *testing.T) {
 		t.Errorf("the view's membership issues %+v", m.State)
 	}
 }
+
+// 1966/AC20, AC21 (issue 1966 D5, ADR 0597 §9): a module asking for a ledger, assigned on two machines, gets one ledger account
+// on each, publishing only on that module's ledger histories and snapshots; the account is gone from a machine the module
+// leaves; and the module's own account, its process and the machine's tool runner hold no publish on its ledger.
+func aLedgerIsWrittenByItsLedgerAccountAlone(t *testing.T) {
+	assigned := func(nodes ...string) []Principal {
+		r := Records{Nodes: nodes, Assigned: map[string][]Declared{}}
+		for _, n := range nodes {
+			r.Assigned[n] = []Declared{
+				{Module: RuntimeModule},
+				{Module: "m", Ledgers: []string{"records", "audit"}, Processes: []ProcessPrincipal{{Process: "w"}}},
+				{Module: "plain"},
+			}
+		}
+		users, err := Users(r)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return users
+	}
+	ledgers := func(users []Principal) []string {
+		var out []string
+		for _, p := range users {
+			if p.Kind == KindLedger {
+				out = append(out, p.Username())
+			}
+		}
+		return out
+	}
+	both := assigned("a", "b")
+	if got := ledgers(both); !slices.Equal(got, []string{"ledger.a.m", "ledger.b.m"}) {
+		t.Fatalf("ledger accounts %v, want ledger.a.m and ledger.b.m", got)
+	}
+	if got := ledgers(assigned("a")); !slices.Equal(got, []string{"ledger.a.m"}) {
+		t.Fatalf("after m left b: ledger accounts %v, want ledger.a.m alone", got)
+	}
+	want := []string{"mesh.ledger.m.audit.history.>", "mesh.ledger.m.audit.snapshot.>",
+		"mesh.ledger.m.records.history.>", "mesh.ledger.m.records.snapshot.>"}
+	raw := []string{"mesh.ledger.m.records.history.decision/0290", "mesh.ledger.m.records.snapshot.decision/0290"}
+	for _, p := range both {
+		perms, err := PermissionsFor(p)
+		if err != nil {
+			t.Fatalf("%s: %v", p.Username(), err)
+		}
+		if p.Kind == KindLedger {
+			if !slices.Equal(perms.Publish, want) || len(perms.PublishDeny) != 0 {
+				t.Errorf("%s may publish %v, want %v alone", p.Username(), perms.Publish, want)
+			}
+			continue
+		}
+		for _, pattern := range perms.Publish {
+			for _, subject := range raw {
+				if SubjectsOverlap(pattern, subject) {
+					t.Errorf("%s may publish %s, which reaches the ledger subject %s", p.Username(), pattern, subject)
+				}
+			}
+		}
+		if p.Kind == KindModule || p.Kind == KindNodeTools || p.Kind == KindProcess {
+			if err := CheckWriters(p, want); err == nil {
+				t.Errorf("%s was granted a raw publish on a ledger's history", p.Username())
+			}
+		}
+	}
+	if err := CheckWriters(Principal{Kind: KindLedger, Node: "a", Module: "other", Ledgers: []string{"records"}}, want); err == nil {
+		t.Error("another module's ledger account was granted m's ledger histories")
+	}
+	for _, bad := range []Principal{{Kind: KindLedger, Node: "a", Module: "m"}, {Kind: KindLedger, Node: "a", Module: "m", Ledgers: []string{"a.b"}}} {
+		if _, err := PermissionsFor(bad); err == nil {
+			t.Errorf("%+v was composed", bad)
+		}
+	}
+}

modules/mesh-grants/internal/buscompose/ledger.go

@@ -0,0 +1,57 @@
+package buscompose
+
+import (
+	"fmt"
+	"slices"
+	"sort"
+	"strings"
+
+	sdk "git.novox.be/novox/mesh-sdk/go/buscompose"
+)
+
+// A module's ledger and the one account that writes it (issue 1966 D5; novox/hq ADR 0597 §9, design 25 § 12.4).
+//
+// **Only the tool runner's ledger credential publishes on a ledger's history** (ADR 0597 §9): one per module assignment,
+// named ledger.<machine>.<module> (KindLedger), scoped to the subjects of that module's ledger histories and snapshots, and
+// gone when the module is unassigned from the machine. The module's own account, its processes and the machine's tool
+// runner hold no publish there, so a raw publish on a history is refused by the bus. The subjects are named in one place, mesh-sdk's
+// buscompose (LedgerHistorySubject, LedgerSnapshotSubject), `mesh.ledger.<module>.<local name>.history|snapshot` and
+// one subject per instance below it (design 25 § 12.4).
+
+// LedgerPublishGrants are the publish patterns a module's ledger account is granted: the histories and the snapshots of the
+// ledgers named, every instance of each, and nothing else. Sorted.
+func LedgerPublishGrants(module string, locals []string) []string {
+	var out []string
+	for _, local := range locals {
+		out = append(out, sdk.LedgerHistorySubject(module, local)+".>", sdk.LedgerSnapshotSubject(module, local)+".>")
+	}
+	sort.Strings(out)
+	return out
+}
+
+// writesLedger is a module's ledger account publishing on that module's own ledgers' histories and snapshots, and no other
+// principal (ADR 0597 §9).
+func writesLedger(p Principal, pattern string) bool {
+	return p.Kind == KindLedger && slices.Contains(LedgerPublishGrants(p.Module, p.Ledgers), pattern)
+}
+
+// ledgerSubjects are the subjects no principal but a ledger account may publish on, for the writers table.
+var ledgerSubjects = []string{"mesh.ledger.*.*.history.>", "mesh.ledger.*.*.snapshot.>"}
+
+// ledgerPermissions are a ledger account's whole authority: publishing on its module's ledgers, and its own reply space for
+// the stream's acknowledgements. Refused when it names no ledger or a name that is no subject token.
+func ledgerPermissions(p Principal) (Permissions, error) {
+	pub := LedgerPublishGrants(p.Module, p.Ledgers)
+	if len(p.Ledgers) == 0 {
+		return Permissions{}, fmt.Errorf("%s asks for no ledger, so its account would publish nowhere", p.Username())
+	}
+	for _, l := range p.Ledgers {
+		if !safeSubject.MatchString(l) || strings.Contains(l, "_") {
+			return Permissions{}, fmt.Errorf("%s: %q cannot be part of a subject: a permission is a subject pattern, and this would widen it", p.Username(), l)
+		}
+	}
+	if err := CheckWriters(p, pub); err != nil {
+		return Permissions{}, err
+	}
+	return Permissions{Publish: pub, Subscribe: []string{p.inbox()}}, nil
+}

modules/mesh-grants/internal/buscompose/nats.go

@@ -52,6 +52,10 @@ const (
 	// exactly what its bus says — never root, never the operator account, and never able to answer a tool
 	// call or a seat's verb (§3). One per process and machine.
 	KindProcess Kind = "process"
+	// KindLedger is one module assignment's ledger credential (novox/hq ADR 0597 §9, design 25 § 12.4): held by that
+	// machine's tool runner, never by the module's own code, and the only account that publishes on that module's ledger
+	// histories and snapshots. One per module assignment, whose module asks for a ledger in `requires`.
+	KindLedger Kind = "ledger"
 )
 
 // RuntimeModule is the module that IS the node's tool runtime (novox/hq ADR 0175). Where it is
@@ -102,6 +106,9 @@ type Principal struct {
 	Kind   Kind
 	Node   string
 	Module string
+	// Ledgers are the local names of the ledgers its module asks for in `requires`, for a KindLedger principal alone
+	// (issue 1966 D5): its whole authority is publishing on those ledgers' histories and snapshots (LedgerPublishGrants).
+	Ledgers []string
 	// Process is the process resource's id, for a KindProcess principal alone (novox/hq ADR 0436 §2):
 	// Username and inbox are <node>.<module>.<process id>.
 	Process string
@@ -425,6 +432,10 @@ func (p Principal) Username() string {
 			return p.Login
 		}
 		return "node." + p.Node
+	case KindLedger:
+		// `ledger.<machine>.<module>`: never `<node>.<module>`, which is the module's own account or the tool runner's,
+		// so the module's code never holds it.
+		return "ledger." + p.Node + "." + p.Module
 	case KindProvisioner:
 		// Named for the machine, as a node is: one client per machine, whichever module runs it, and never
 		// `<node>.<module>`, which is the module's own account or the tool runner's.
@@ -567,6 +578,11 @@ func PermissionsFor(p Principal) (Permissions, error) {
 		return Permissions{Publish: pub, Subscribe: []string{p.inbox()}}, nil
 	}
 
+	// A ledger account publishes on its module's ledger histories and snapshots and nothing else (issue 1966 D5).
+	if p.Kind == KindLedger {
+		return ledgerPermissions(p)
+	}
+
 	if p.Kind == KindProcess && len(p.Removes) > 0 {
 		pub, err := BusRemovalGrants(p.Removes, p.FilesFor)
 		if err != nil {

modules/mesh-grants/internal/buscompose/users.go

@@ -103,6 +103,9 @@ type Declared struct {
 	// composed whether or not the module itself has an account (NoAccount), because a process account is
 	// delivered in its own secret, broker-<process id>, never the module's `broker`.
 	Processes []ProcessPrincipal
+	// Ledgers are the local names of the ledgers it asks for in `requires` (catalogue.StorageLedger); each assignment of a
+	// module with any gets a ledger principal of its own (issue 1966 D5, ADR 0597 §9).
+	Ledgers []string
 }
 
 // ProcessPrincipal is one process of a module that declares bus (novox/hq ADR 0436 §1, §2), as the broker
@@ -229,6 +232,11 @@ func Users(r Records) ([]Principal, error) {
 					out[len(out)-1].FilesFor = sortedCopy(r.Nodes)
 				}
 			}
+			// **A ledger account per assignment of a module that asks for a ledger** (issue 1966 D5, ADR 0597 §9): held by the
+			// machine's tool runner, so it is composed whether or not the module has an account of its own.
+			if len(d.Ledgers) > 0 {
+				out = append(out, Principal{Kind: KindLedger, Node: node, Module: d.Module, Ledgers: sortedCopy(d.Ledgers)})
+			}
 			if runtimeHere && d.Module == RuntimeModule {
 				continue
 			}

modules/mesh-grants/internal/buscompose/writers.go

@@ -236,6 +236,12 @@ var WritersTable = []WriterRow{
 			ProvisionerAppliedBucket,
 		Others:   "the watchman reads it; a failure is that machine's failed apply",
 		Subjects: []string{"prov.applied.*.>"}, Writes: ownProvisioner},
+	// A ledger's history and its snapshots (novox/hq ADR 0597 §9, issue 1966 D5): the tool runner's ledger credential of
+	// the owning module alone, so the module's own code, its processes and the runner's own account cannot write one raw.
+	{State: "a ledger's history and snapshots", Writer: "the tool runner's ledger credential of the owning module",
+		KeptIn:   "the bus, the ledger's history stream and its snapshot subject",
+		Others:   "the owner reads them through the tool runner's calls; nobody else reads them (ADR 0596 §2)",
+		Subjects: ledgerSubjects, Writes: writesLedger},
 }
 
 // CheckWriters refuses a grant that lets a principal publish on a subject the writers table gives

modules/mesh-grants/internal/grants/accounts.go

@@ -46,8 +46,9 @@ type BusAddress struct {
 	Fingerprint string
 }
 
-// WantedAccounts is every account the vault mints that the records compose, keyed by user, with the bus's address. A
-// node, the controller, an enrolment user or a person is never one (ADR 0561 §4, §5). Pure.
+// WantedAccounts is every account the vault mints that the records compose, keyed by user, with the bus's address: a
+// module's, a process's, a machine's provisioner client's and a module assignment's ledger account (issue 1966 D5b, ADR
+// 0597 §9). A node, the controller, an enrolment user or a person is never one (ADR 0561 §4, §5). Pure.
 func WantedAccounts(in Inputs, recs buscompose.Records, bus BusAddress) (map[string]buscompose.WantedAccount, error) {
 	principals, err := buscompose.Users(recs)
 	if err != nil {
@@ -62,7 +63,7 @@ func WantedAccounts(in Inputs, recs buscompose.Records, bus BusAddress) (map[str
 			if m, ok := manifestOn(in, p.Node, p.Module); ok {
 				w.Claims = ClaimsOf(m)
 			}
-		case buscompose.KindProcess, buscompose.KindProvisioner:
+		case buscompose.KindProcess, buscompose.KindProvisioner, buscompose.KindLedger:
 		default:
 			continue
 		}

modules/mesh-grants/internal/grants/records.go

@@ -139,6 +139,8 @@ func declaredFor(m catalogue.Manifest, seats map[string]catalogue.SeatDeclaratio
 		Served: catalogue.ServedSettings(m),
 		// Its own object buckets (ADR 0592 §5).
 		Objects: objectsOf(m),
+		// The ledgers it asks for in `requires` (issue 1966 D5): each assignment gets a ledger account.
+		Ledgers: ledgersOf(m),
 	}
 	d.Loads = loadsABundle(m)
 	if _, reads := m.OwnSecrets["broker"]; !reads {
@@ -282,6 +284,17 @@ func readsOfObjects(module, node string, reads, refused []string, manifests map[
 	return states, objects, refusedOut
 }
 
+// ledgersOf are the local names of the ledgers a manifest asks for in `requires`.
+func ledgersOf(m catalogue.Manifest) []string {
+	var out []string
+	for _, e := range m.BusState {
+		if e.Storage == catalogue.StorageLedger {
+			out = append(out, e.Name)
+		}
+	}
+	return out
+}
+
 func logsOf(m catalogue.Manifest) []buscompose.Log {
 	var out []buscompose.Log
 	for _, l := range m.Logs {