diff --git a/modules/mesh-delivery-checker/internal/check/graph_cycle.go b/modules/mesh-delivery-checker/internal/check/graph_cycle.go
index 0490f9a9..673ff548 100644
--- a/modules/mesh-delivery-checker/internal/check/graph_cycle.go
+++ b/modules/mesh-delivery-checker/internal/check/graph_cycle.go
@@ -10,6 +10,8 @@ import (
 	"git.novox.be/novox/mesh-sdk/go/catalogue"
 	"git.novox.be/novox/mesh-sdk/go/composer"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	"git.novox.be/novox/mesh-delivery/sdk/graph"
 )
 
 // The check refuses a change whose module graph has a cycle and names it (novox/hq ADR 0603 §2): modules that would each
@@ -49,15 +51,15 @@ func (st *state) refuseCycle(ctx context.Context) *delivery.Verdict {
 	if err != nil {
 		return fail(goModule, "the change's module graph cannot be worked out, so no cycle can be ruled out: "+err.Error())
 	}
-	cycle := delivery.ManifestGraph(change).Cycle()
+	cycle := graph.OfManifests(change).Cycle()
 	if cycle == nil {
 		st.c.note("the change's module graph has no cycle")
 		return nil
 	}
 	words := strings.Join(cycle, " -> ")
 	if before, err := read(req.Cases[1].Manifests); err == nil {
-		among := delivery.Graph{}
-		for name, n := range delivery.ManifestGraph(before) {
+		among := graph.Graph{}
+		for name, n := range graph.OfManifests(before) {
 			if slices.Contains(cycle, name) {
 				among[name] = n
 			}
diff --git a/modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer-tools/catalog.go b/modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer-tools/catalog.go
index 24411bac..62df17fb 100644
--- a/modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer-tools/catalog.go
+++ b/modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer-tools/catalog.go
@@ -7,6 +7,8 @@ import (
 	"git.novox.be/novox/mesh-sdk/go/catalogue"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 
+	"git.novox.be/novox/mesh-delivery/sdk/graph"
+
 	"mesh-delivery-indexer/internal/index"
 )
 
@@ -35,7 +37,7 @@ func CatalogTools(c index.CatalogRead) []stdio.Tool {
 }
 
 // catalogRead reads the indexer's modules, manifests and graph states for the seat's verbs.
-func catalogRead(modules, manifests, graph stdio.KeptState) index.CatalogRead {
+func catalogRead(modules, manifests, nodes stdio.KeptState) index.CatalogRead {
 	return index.CatalogRead{
 		Modules: func() (map[string]delivery.Module, error) {
 			keys, err := modules.Keys()
@@ -72,21 +74,21 @@ func catalogRead(modules, manifests, graph stdio.KeptState) index.CatalogRead {
 			kept, err := delivery.DecodeManifest(e.Value)
 			return kept.JSON, err
 		},
-		Graph: func() (delivery.Graph, error) {
-			keys, err := graph.Keys()
+		Graph: func() (graph.Graph, error) {
+			keys, err := nodes.Keys()
 			if err != nil {
 				return nil, err
 			}
-			g := delivery.Graph{}
+			g := graph.Graph{}
 			for _, k := range keys {
-				e, err := graph.Get(k)
+				e, err := nodes.Get(k)
 				if err != nil {
 					return nil, fmt.Errorf("graph.%s: %w", k, err)
 				}
 				if e == nil {
 					continue
 				}
-				if n, err := delivery.DecodeGraphNode(e.Value); err == nil {
+				if n, err := graph.Decode(e.Value); err == nil {
 					g[k] = n
 				}
 			}
@@ -97,5 +99,5 @@ func catalogRead(modules, manifests, graph stdio.KeptState) index.CatalogRead {
 
 // catalogTools are the seat's verbs over the indexer's own states, as main serves them once the indexer claims the seat.
 func catalogTools() []stdio.Tool {
-	return CatalogTools(catalogRead(stdio.State("modules"), stdio.State("manifests"), stdio.State(delivery.GraphState)))
+	return CatalogTools(catalogRead(stdio.State("modules"), stdio.State("manifests"), stdio.State(graph.State)))
 }
diff --git a/modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer/main.go b/modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer/main.go
index eb111122..0d896889 100644
--- a/modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer/main.go
+++ b/modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer/main.go
@@ -26,6 +26,8 @@ import (
 	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-builder/buildrun"
 	stdio "git.novox.be/novox/mesh-sdk/go"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	"git.novox.be/novox/mesh-delivery/sdk/graph"
 	"git.novox.be/novox/mesh-sdk/go/process"
 
 	"mesh-delivery-indexer/internal/index"
@@ -300,7 +302,7 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 	// 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)
 	// The module graph (ADR 0603 §2): a state this delivery brings, bound when it appears; until then no graph is written.
-	graph := process.AwaitBucket(ctx, js, conn, delivery.GraphBucket, "no module graph is written", logger.Printf)
+	graph := process.AwaitBucket(ctx, js, conn, graph.Bucket, "no module graph is written", 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,
diff --git a/modules/mesh-delivery-indexer/internal/index/candidates.go b/modules/mesh-delivery-indexer/internal/index/candidates.go
index e0cba4fe..b1620ac0 100644
--- a/modules/mesh-delivery-indexer/internal/index/candidates.go
+++ b/modules/mesh-delivery-indexer/internal/index/candidates.go
@@ -67,7 +67,7 @@ type Indexer struct {
 	// 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
-	// Graph is the module graph's state (delivery.GraphBucket, graph.go; novox/hq ADR 0603 §2); nil writes no graph.
+	// Graph is the module graph's state (graph.Bucket, graph.go; novox/hq ADR 0603 §2); nil writes no graph.
 	Graph Store
 	// Files asks the forge for every blob under each directory at a commit, by directory then path relative to it, each
 	// with its git object id (gitea.gitea_commit_trees with files): the listing a package's digest is computed from.
diff --git a/modules/mesh-delivery-indexer/internal/index/catalog.go b/modules/mesh-delivery-indexer/internal/index/catalog.go
index 0d5c30ce..33807d48 100644
--- a/modules/mesh-delivery-indexer/internal/index/catalog.go
+++ b/modules/mesh-delivery-indexer/internal/index/catalog.go
@@ -9,13 +9,15 @@ import (
 
 	"git.novox.be/novox/mesh-sdk/go/catalogue"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	"git.novox.be/novox/mesh-delivery/sdk/graph"
 )
 
 // The seat mesh-catalog's verbs, answered from the indexer's own states (novox/hq ADR 0604 §1, §2): modules, module,
 // provides and dependents read the modules state, the manifests state and the module graph, and write nothing. The
 // indexer serves no request subject (ADR 0437 §4): its tools bundle serves them as <seat>.<verb>. Each answer keeps the
 // field names of the old catalog module's tool it replaces (catalog_modules, catalog_module, catalog_provides,
-// catalog_dependents), so a caller that moves to the seat reads the same fields.
+// catalog_dependents): the answers are the seat's contract (catalogue.CatalogModules and the rest), built here.
 
 // CatalogRead reads the states the seat's verbs answer from.
 type CatalogRead struct {
@@ -24,99 +26,75 @@ type CatalogRead struct {
 	// Manifest is the manifest kept under a digest in the manifests state, as its JSON.
 	Manifest func(digest string) (string, error)
 	// Graph is the module graph, by module.
-	Graph func() (delivery.Graph, error)
+	Graph func() (graph.Graph, error)
 }
 
-// CatalogEntry is one module of the catalog: its repository, its directory there (delivery.RootPath for the root), the
-// merge commit it was last changed at, and its fingerprint or why it has none.
-type CatalogEntry struct {
-	Module     string `json:"module"`
-	Repository string `json:"repository"`
-	Path       string `json:"path"`
-	Commit     string `json:"commit"`
-	FP         string `json:"fp,omitempty"`
-	None       string `json:"none,omitempty"`
-}
-
-// CatalogModule is one module whole: its entry and its manifest as the trunk holds it.
-type CatalogModule struct {
-	CatalogEntry
-	Manifest json.RawMessage `json:"manifest"`
-}
-
-// CatalogEnd is a module that provides, requires or depends on something, with its commit; Scope is a provider's scope.
-type CatalogEnd struct {
-	Module string `json:"module"`
-	Commit string `json:"commit"`
-	Scope  string `json:"scope,omitempty"`
-}
-
-func entryOf(name string, m delivery.Module) CatalogEntry {
-	return CatalogEntry{Module: name, Repository: m.Repository, Path: m.Path, Commit: m.Commit, FP: m.FP2, None: m.None2}
+func entryOf(name string, m delivery.Module) catalogue.CatalogEntry {
+	return catalogue.CatalogEntry{Module: name, Repository: m.Repository, Path: m.Path, Commit: m.Commit, FP: m.FP2, None: m.None2}
 }
 
 // CatalogModulesAnswer is the verb modules: every module the modules state holds, by name.
-func (c CatalogRead) CatalogModulesAnswer() (map[string]any, error) {
+func (c CatalogRead) CatalogModulesAnswer() (catalogue.CatalogModules, error) {
 	mods, err := c.Modules()
 	if err != nil {
-		return nil, fmt.Errorf("the indexer's modules cannot be read: %w", err)
+		return catalogue.CatalogModules{}, fmt.Errorf("the indexer's modules cannot be read: %w", err)
 	}
-	out := []CatalogEntry{}
+	out := []catalogue.CatalogEntry{}
 	for _, name := range slices.Sorted(maps.Keys(mods)) {
 		out = append(out, entryOf(name, mods[name]))
 	}
-	return map[string]any{"modules": out}, nil
+	return catalogue.CatalogModules{Modules: out}, nil
 }
 
 // CatalogModuleAnswer is the verb module: one module whole, its manifest included.
-func (c CatalogRead) CatalogModuleAnswer(name string) (map[string]any, error) {
+func (c CatalogRead) CatalogModuleAnswer(name string) (catalogue.CatalogOne, error) {
 	name = strings.TrimSpace(name)
 	if name == "" {
-		return nil, fmt.Errorf("name the module")
+		return catalogue.CatalogOne{}, fmt.Errorf("name the module")
 	}
 	mods, err := c.Modules()
 	if err != nil {
-		return nil, fmt.Errorf("the indexer's modules cannot be read: %w", err)
+		return catalogue.CatalogOne{}, fmt.Errorf("the indexer's modules cannot be read: %w", err)
 	}
 	m, ok := mods[name]
 	if !ok {
-		return nil, fmt.Errorf("the trunk holds no module %s", name)
+		return catalogue.CatalogOne{}, fmt.Errorf("the trunk holds no module %s", name)
 	}
-	one := CatalogModule{CatalogEntry: entryOf(name, m)}
+	one := catalogue.CatalogModule{CatalogEntry: entryOf(name, m)}
 	if m.Manifest == "" {
-		return nil, fmt.Errorf("the indexer keeps no manifest of %s", name)
+		return catalogue.CatalogOne{}, fmt.Errorf("the indexer keeps no manifest of %s", name)
 	}
 	raw, err := c.Manifest(m.Manifest)
 	if err != nil {
-		return nil, fmt.Errorf("the manifest %s of %s cannot be read: %w", m.Manifest, name, err)
+		return catalogue.CatalogOne{}, fmt.Errorf("the manifest %s of %s cannot be read: %w", m.Manifest, name, err)
 	}
 	one.Manifest = json.RawMessage(raw)
-	return map[string]any{"module": one}, nil
+	return catalogue.CatalogOne{Module: one}, nil
 }
 
 // CatalogProvidesAnswer is the verb provides: the modules that provide a provision, each with its scope (a module provides
 // its own name, at node scope), and the modules that require it, from the module graph's provision edges.
-func (c CatalogRead) CatalogProvidesAnswer(provision string) (map[string]any, error) {
+func (c CatalogRead) CatalogProvidesAnswer(provision string) (catalogue.CatalogProvides, error) {
 	provision = strings.TrimSpace(provision)
 	if provision == "" {
-		return nil, fmt.Errorf("name the provision")
+		return catalogue.CatalogProvides{}, fmt.Errorf("name the provision")
 	}
 	g, mods, err := c.graphAndModules()
 	if err != nil {
-		return nil, err
+		return catalogue.CatalogProvides{}, err
 	}
-	provides, requires := []CatalogEnd{}, []CatalogEnd{}
+	provides, requires := []catalogue.CatalogEnd{}, []catalogue.CatalogEnd{}
 	for _, name := range g.Providers(provision) {
-		end := CatalogEnd{Module: name, Commit: mods[name].Commit, Scope: catalogue.ScopeNode}
+		end := catalogue.CatalogEnd{Module: name, Commit: mods[name].Commit, Scope: catalogue.ScopeNode}
 		if name != provision {
 			end.Scope = c.scopeOf(mods[name], provision)
 		}
 		provides = append(provides, end)
 	}
 	for _, name := range g.Requirers(provision) {
-		requires = append(requires, CatalogEnd{Module: name, Commit: mods[name].Commit})
+		requires = append(requires, catalogue.CatalogEnd{Module: name, Commit: mods[name].Commit})
 	}
-	return map[string]any{"provision": provision, "provides": provides, "requires": requires}, nil
+	return catalogue.CatalogProvides{Provision: provision, Provides: provides, Requires: requires}, nil
 }
 
 // scopeOf is the scope the module's manifest offers provision at, "" when its manifest cannot be read.
@@ -142,23 +120,23 @@ func (c CatalogRead) scopeOf(m delivery.Module, provision string) string {
 
 // CatalogDependentsAnswer is the verb dependents: the modules whose build edges reach the module, directly or through
 // others, from the module graph.
-func (c CatalogRead) CatalogDependentsAnswer(module string) (map[string]any, error) {
+func (c CatalogRead) CatalogDependentsAnswer(module string) (catalogue.CatalogDependents, error) {
 	module = strings.TrimSpace(module)
 	if module == "" {
-		return nil, fmt.Errorf("name the module")
+		return catalogue.CatalogDependents{}, fmt.Errorf("name the module")
 	}
 	g, mods, err := c.graphAndModules()
 	if err != nil {
-		return nil, err
+		return catalogue.CatalogDependents{}, err
 	}
-	out := []CatalogEnd{}
+	out := []catalogue.CatalogEnd{}
 	for _, name := range g.Dependents(module) {
-		out = append(out, CatalogEnd{Module: name, Commit: mods[name].Commit})
+		out = append(out, catalogue.CatalogEnd{Module: name, Commit: mods[name].Commit})
 	}
-	return map[string]any{"module": module, "dependents": out}, nil
+	return catalogue.CatalogDependents{Module: module, Dependents: out}, nil
 }
 
-func (c CatalogRead) graphAndModules() (delivery.Graph, map[string]delivery.Module, error) {
+func (c CatalogRead) graphAndModules() (graph.Graph, map[string]delivery.Module, error) {
 	g, err := c.Graph()
 	if err != nil {
 		return nil, nil, fmt.Errorf("the module graph cannot be read: %w", err)
diff --git a/modules/mesh-delivery-indexer/internal/index/catalog_test.go b/modules/mesh-delivery-indexer/internal/index/catalog_test.go
index 6cec8c2a..03c0b68c 100644
--- a/modules/mesh-delivery-indexer/internal/index/catalog_test.go
+++ b/modules/mesh-delivery-indexer/internal/index/catalog_test.go
@@ -11,6 +11,8 @@ import (
 	"testing"
 
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	"git.novox.be/novox/mesh-delivery/sdk/graph"
 )
 
 // capturedKeys are the field names of the first object at path (a list's first element when the value is a list) in the
@@ -67,15 +69,15 @@ func catalogVerbsAnswerFromTheStates(t *testing.T) {
 			raw, _, err := ix.manifestRaw(context.Background(), digest)
 			return raw, err
 		},
-		Graph: func() (delivery.Graph, error) {
-			g := delivery.Graph{}
+		Graph: func() (graph.Graph, error) {
+			g := graph.Graph{}
 			for k := range ix.Graph.(*memStore).vals {
 				g[k] = graphOf(t, ix, k)
 			}
 			return g, nil
 		},
 	}
-	answer := func(v map[string]any, err error) []byte {
+	answer := func(v any, err error) []byte {
 		t.Helper()
 		if err != nil {
 			t.Fatal(err)
diff --git a/modules/mesh-delivery-indexer/internal/index/graph.go b/modules/mesh-delivery-indexer/internal/index/graph.go
index deaac724..f9195d3b 100644
--- a/modules/mesh-delivery-indexer/internal/index/graph.go
+++ b/modules/mesh-delivery-indexer/internal/index/graph.go
@@ -8,10 +8,12 @@ import (
 
 	"git.novox.be/novox/mesh-sdk/go/catalogue"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	"git.novox.be/novox/mesh-delivery/sdk/graph"
 )
 
 // The module graph (novox/hq ADR 0603 §2): at every recompute the indexer writes, in its state graph
-// (delivery.GraphBucket), one key per module it holds the inputs of, its build and provision edges as that recompute
+// (graph.Bucket), one key per module it holds the inputs of, its build and provision edges as that recompute
 // computed them, and deletes the key of a module the modules state no longer holds. A key is written only when its value
 // changes, so its history of 5 is five changes of the module's edges. The delivery view, the checker and the seat
 // mesh-catalog's verbs read it; nothing stores an order (ADR 0603 §1).
@@ -33,11 +35,11 @@ type graphEdges struct {
 
 // graphNode is the graph node of e: its edges, the awaited provisions judged against providers (catalogue.Awaited, as
 // the assigner judges them).
-func graphNode(e graphEdges, providers func(string) []catalogue.Manifest) delivery.GraphNode {
+func graphNode(e graphEdges, providers func(string) []catalogue.Manifest) graph.Node {
 	if e.fp == "" && e.none == "" {
 		e.none = "its fingerprint was not computed"
 	}
-	n := delivery.GraphEdgesOf(e.manifest, providers)
+	n := graph.EdgesOf(e.manifest, providers)
 	n.FP, n.None, n.Repository, n.Path = e.fp, e.none, e.cur.Repository, e.cur.Path
 	n.Packages = slices.Sorted(maps.Keys(e.pkgs))
 	tcs := e.tcs
@@ -50,9 +52,9 @@ func graphNode(e graphEdges, providers func(string) []catalogue.Manifest) delive
 			continue
 		}
 		if n.Toolchains == nil {
-			n.Toolchains = map[string]delivery.GraphToolchain{}
+			n.Toolchains = map[string]graph.Toolchain{}
 		}
-		n.Toolchains[language] = delivery.GraphToolchain{Module: builder, Version: t.Version, Recipe: t.Recipe}
+		n.Toolchains[language] = graph.Toolchain{Module: builder, Version: t.Version, Recipe: t.Recipe}
 	}
 	return n
 }
@@ -79,7 +81,7 @@ func (ix *Indexer) writeGraph(ctx context.Context, edges map[string]graphEdges)
 		return out
 	}
 	for _, name := range names {
-		key, err := delivery.GraphKey(name)
+		key, err := graph.Key(name)
 		if err != nil {
 			ix.logf("graph.%s is not written: %v", name, err)
 			continue
@@ -87,11 +89,11 @@ func (ix *Indexer) writeGraph(ctx context.Context, edges map[string]graphEdges)
 		next := graphNode(edges[name], providers)
 		err = write(ctx, ix.Graph, key, func(value []byte, found bool) ([]byte, bool, error) {
 			if found {
-				if cur, err := delivery.DecodeGraphNode(value); err == nil && delivery.SameGraphNode(cur, next) {
+				if cur, err := graph.Decode(value); err == nil && graph.Same(cur, next) {
 					return nil, false, nil
 				}
 			}
-			data, err := delivery.EncodeGraphNode(next)
+			data, err := graph.Encode(next)
 			if err != nil {
 				return nil, false, fmt.Errorf("graph.%s: %w", key, err)
 			}
diff --git a/modules/mesh-delivery-indexer/internal/index/toolchains_test.go b/modules/mesh-delivery-indexer/internal/index/toolchains_test.go
index b9bd4efc..0fbe30d6 100644
--- a/modules/mesh-delivery-indexer/internal/index/toolchains_test.go
+++ b/modules/mesh-delivery-indexer/internal/index/toolchains_test.go
@@ -9,6 +9,8 @@ import (
 
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 
+	"git.novox.be/novox/mesh-delivery/sdk/graph"
+
 	"mesh-delivery-indexer/internal/fingerprint"
 )
 
@@ -61,13 +63,13 @@ type mod struct {
 // merged applies one merge of the catalogue carrying these modules (every one a Go bundle's go.sum, a TypeScript bundle's
 // package-lock.json) and returns the indexer.
 // graphOf is the graph node the indexer holds of module.
-func graphOf(t *testing.T, ix *Indexer, module string) delivery.GraphNode {
+func graphOf(t *testing.T, ix *Indexer, module string) graph.Node {
 	t.Helper()
 	v, ok := ix.Graph.(*memStore).vals[module]
 	if !ok {
 		t.Fatalf("graph.%s is not held", module)
 	}
-	g, err := delivery.DecodeGraphNode(v)
+	g, err := graph.Decode(v)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -232,7 +234,7 @@ func TestBasesAreComputedFirstAndNoFingerprintTakesTheBuilder(t *testing.T) { //
 		t.Errorf("other: fp2 = %q none2 = %q, want none2 naming the base ts-base", m.FP2, m.None2)
 	}
 	// L3 (ADR 0603 §2): the module graph holds each module's edges as this recompute computed them.
-	goTool := map[string]delivery.GraphToolchain{"go": {Module: "mesh-build-go", Version: "go1.27.1", Recipe: "1"}}
+	goTool := map[string]graph.Toolchain{"go": {Module: "mesh-build-go", Version: "go1.27.1", Recipe: "1"}}
 	if g := graphOf(t, ix, "avahi"); g.FP != want["avahi"] || !reflect.DeepEqual(g.Bases, []string{"mesh-tools"}) ||
 		!reflect.DeepEqual(g.Toolchains, goTool) || g.Repository != catalogueRepo || g.Path != "modules/avahi" {
 		t.Errorf("graph.avahi = %+v", g)
diff --git a/modules/mesh-delivery-indexer/manifest_test.go b/modules/mesh-delivery-indexer/manifest_test.go
index c77c7b80..7569b44c 100644
--- a/modules/mesh-delivery-indexer/manifest_test.go
+++ b/modules/mesh-delivery-indexer/manifest_test.go
@@ -13,6 +13,8 @@ import (
 	"testing"
 
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	"git.novox.be/novox/mesh-delivery/sdk/graph"
 )
 
 // The controller's manifest reader is mesh-controller internal/catalogue (Manifest, manifest.go: Consumes :521,
@@ -91,7 +93,7 @@ func TestManifestDeclarations(t *testing.T) { // 1238/AC1, 1444 (reads the build
 	}
 	// 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: "oldsections", History: 1}, {Name: delivery.PackagesState, History: delivery.PackagesHistory},
-		{Name: delivery.GraphState, History: delivery.GraphHistory}}; !reflect.DeepEqual(m.State, want) {
+		{Name: graph.State, History: graph.History}}; !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) {
diff --git a/modules/mesh-delivery-view/cmd/mesh-delivery-view-tools/main.go b/modules/mesh-delivery-view/cmd/mesh-delivery-view-tools/main.go
index 69e67c73..d147a802 100644
--- a/modules/mesh-delivery-view/cmd/mesh-delivery-view-tools/main.go
+++ b/modules/mesh-delivery-view/cmd/mesh-delivery-view-tools/main.go
@@ -13,6 +13,8 @@ import (
 	"mesh-delivery-view/internal/view"
 
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	"git.novox.be/novox/mesh-delivery/sdk/graph"
 	"git.novox.be/novox/mesh-sdk/go/provisions"
 
 	stdio "git.novox.be/novox/mesh-sdk/go"
@@ -318,7 +320,7 @@ func main() {
 		PredefinedState:       read(stdio.State(delivery.IndexerModule + "." + delivery.IndexerPredefinedState)),
 		ConfigCandidatesState: read(stdio.State(delivery.IndexerModule + "." + delivery.IndexerConfigCandidatesState)),
 		PackagesState:         read(stdio.State(delivery.IndexerModule + "." + delivery.PackagesState)),
-		GraphState:            read(stdio.State(delivery.GraphRead)), SourceState: read(stdio.State(delivery.GateModule + ".source")),
+		GraphState:            read(stdio.State(graph.Read)), SourceState: read(stdio.State(delivery.GateModule + ".source")),
 		ProvisionsState: read(stdio.State(provisions.ProvisionsRead)),
 		BuildLog:        stdio.Log(delivery.BuildLogRead).Since}
 	u := view.UsageReader{Haves: r.HavesState, Resolved: read(stdio.State("mesh-config.resolved")), Tries: read(stdio.State("mesh-delivery-checker.tries")),
diff --git a/modules/mesh-delivery-view/cmd/mesh-delivery-view-tools/tiers_rows_test.go b/modules/mesh-delivery-view/cmd/mesh-delivery-view-tools/tiers_rows_test.go
index 815e1407..6236315b 100644
--- a/modules/mesh-delivery-view/cmd/mesh-delivery-view-tools/tiers_rows_test.go
+++ b/modules/mesh-delivery-view/cmd/mesh-delivery-view-tools/tiers_rows_test.go
@@ -10,6 +10,8 @@ import (
 	"time"
 
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	"git.novox.be/novox/mesh-delivery/sdk/graph"
 	"git.novox.be/novox/mesh-sdk/go/provisions"
 
 	"mesh-delivery-view/internal/view"
@@ -34,8 +36,8 @@ func tiersToolSaysEachModulesWait(t *testing.T) {
 		b, err := delivery.EncodeModule(delivery.Module{FP2: f, Manifest: manifest, Src: src, FPSrc: src, Repository: "novox/mesh-catalog", Commit: "c"})
 		return encoded(t, b, err)
 	}
-	node := func(g delivery.GraphNode) string {
-		b, err := delivery.EncodeGraphNode(g)
+	node := func(g graph.Node) string {
+		b, err := graph.Encode(g)
 		return encoded(t, b, err)
 	}
 	build := func(b delivery.BuilderBuild) string {
@@ -59,9 +61,9 @@ func tiersToolSaysEachModulesWait(t *testing.T) {
 	since := time.Date(2026, 11, 3, 16, 40, 0, 0, time.UTC)
 	r := fake{"db": mod(fp("a"), 9), "web": mod(fp("b"), 9), "lib": mod(fp("c"), 9), "old": mod(fp("e"), 5)}.reader()
 	r.GraphState = fake{
-		"db":  node(delivery.GraphNode{FP: fp("a"), Repository: "novox/mesh-catalog", Provides: []string{"database"}}),
-		"web": node(delivery.GraphNode{FP: fp("b"), Repository: "novox/mesh-catalog", Requires: []string{"database"}, Awaits: []string{"database"}}),
-		"lib": node(delivery.GraphNode{FP: fp("c"), Repository: "novox/mesh-catalog"}),
+		"db":  node(graph.Node{FP: fp("a"), Repository: "novox/mesh-catalog", Provides: []string{"database"}}),
+		"web": node(graph.Node{FP: fp("b"), Repository: "novox/mesh-catalog", Requires: []string{"database"}, Awaits: []string{"database"}}),
+		"lib": node(graph.Node{FP: fp("c"), Repository: "novox/mesh-catalog"}),
 	}.reader().State
 	r.Builds = fake{
 		key(delivery.BuilderBuildKey("db", fp("a"))):  build(delivery.BuilderBuild{State: delivery.BuildDone, Manifest: manifest}),
diff --git a/modules/mesh-delivery-view/internal/view/read.go b/modules/mesh-delivery-view/internal/view/read.go
index 89d80210..5da2b0bb 100644
--- a/modules/mesh-delivery-view/internal/view/read.go
+++ b/modules/mesh-delivery-view/internal/view/read.go
@@ -55,7 +55,7 @@ type Reader struct {
 	PredefinedState, ConfigCandidatesState StateRead
 	// PackagesState is the indexer's published packages (delivery.PackagesBucket, ADR 0593 §2); unset reads none.
 	PackagesState StateRead
-	// GraphState is the indexer's module graph (delivery.GraphBucket, ADR 0603 §2), SourceState the gate's source and
+	// GraphState is the indexer's module graph (graph.Bucket, ADR 0603 §2), SourceState the gate's source and
 	// ProvisionsState the provisioner's keys: what view_tiers reads (tiers.go). Unset reads none, said in the answer.
 	GraphState, SourceState, ProvisionsState StateRead
 	// BuildLog reads the builder's log from a time (stdio.Log(delivery.BuildLogRead).Since); unset reads none.
diff --git a/modules/mesh-delivery-view/internal/view/tiers.go b/modules/mesh-delivery-view/internal/view/tiers.go
index 6289d96f..8055ad38 100644
--- a/modules/mesh-delivery-view/internal/view/tiers.go
+++ b/modules/mesh-delivery-view/internal/view/tiers.go
@@ -10,6 +10,8 @@ import (
 	"time"
 
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	"git.novox.be/novox/mesh-delivery/sdk/graph"
 	"git.novox.be/novox/mesh-sdk/go/provisions"
 )
 
@@ -93,13 +95,13 @@ func (r Reader) Tiers(revision uint64) (Tiers, error) {
 			len(names), TiersMost, names[TiersMost], len(names)-TiersMost-1)
 		names = names[:TiersMost]
 	}
-	graph := delivery.Graph{}
+	gr := graph.Graph{}
 	if raws, err := values(r.GraphState); err != nil {
 		out.Graph = "the module graph cannot be read, so no module is ordered after another: " + err.Error()
 	} else {
 		for key, raw := range raws {
-			if n, err := delivery.DecodeGraphNode(raw); err == nil {
-				graph[key] = n
+			if n, err := graph.Decode(raw); err == nil {
+				gr[key] = n
 			}
 		}
 	}
@@ -115,15 +117,15 @@ func (r Reader) Tiers(revision uint64) (Tiers, error) {
 	}
 	after := map[string][]string{}
 	for _, n := range names {
-		for _, b := range graph.Before(n) {
+		for _, b := range gr.Before(n) {
 			if in[b] {
 				after[n] = append(after[n], b)
 			}
 		}
 	}
-	sub := delivery.Graph{}
+	sub := graph.Graph{}
 	for _, n := range names {
-		if g, ok := graph[n]; ok {
+		if g, ok := gr[n]; ok {
 			sub[n] = g
 		}
 	}
@@ -168,7 +170,7 @@ func (r Reader) Tiers(revision uint64) (Tiers, error) {
 		}
 		m := moved[n]
 		tm := TierModule{Module: n, FP: m.FP2, None: m.None2, After: after[n]}
-		tm.Waits = r.waitsOf(n, m, graph[n], wants, provided, perr, away)
+		tm.Waits = r.waitsOf(n, m, gr[n], wants, provided, perr, away)
 		out.Tiers[t] = append(out.Tiers[t], tm)
 	}
 	compact := out.Tiers[:0]
@@ -202,7 +204,7 @@ func (r Reader) away() map[string]bool {
 
 // waitsOf is what module m waits on now: its build at its fingerprint, then on each node present that wants it, its want,
 // its have, and each provision its graph node awaits.
-func (r Reader) waitsOf(module string, m delivery.Module, g delivery.GraphNode, wants, provided map[string]json.RawMessage,
+func (r Reader) waitsOf(module string, m delivery.Module, g graph.Node, wants, provided map[string]json.RawMessage,
 	perr error, away map[string]bool) []TierWait {
 	var out []TierWait
 	if m.FP2 == "" {
diff --git a/sdk/go.mod b/sdk/go.mod
new file mode 100644
index 00000000..31746712
--- /dev/null
+++ b/sdk/go.mod
@@ -0,0 +1,5 @@
+module git.novox.be/novox/mesh-delivery/sdk
+
+go 1.26.0
+
+require git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103155154-cf5812101b0b
diff --git a/sdk/go.sum b/sdk/go.sum
new file mode 100644
index 00000000..cea3187b
--- /dev/null
+++ b/sdk/go.sum
@@ -0,0 +1,14 @@
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103155154-cf5812101b0b h1:UPkJqQj+1y6WraOxDidkrokNjA25jxmCk+zIRkujjMc=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103155154-cf5812101b0b/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+github.com/klauspost/compress v1.20.0 h1:a3C1ke2ohxFymNlb2HWAHjDeKCI90scRskErZkR0ezA=
+github.com/klauspost/compress v1.20.0/go.mod h1:LUdAzn7YLVvxLpc7y3V1m40wESHTgc1422pwwBSKYuI=
+github.com/nats-io/nats.go v1.54.0 h1:vsXoOxjHp/GmPUN+EcI7uOf/uB+iAP+kEsAFNQN0yzA=
+github.com/nats-io/nats.go v1.54.0/go.mod h1:y+DZoD1oBOYfZTU681eTUiUjI0vbqYGixNVFHcjHJ0k=
+github.com/nats-io/nkeys v0.4.16 h1:rd5oAuLOb8mnAycB0xleuEBNS1pVVnN0fv/FF34Eypg=
+github.com/nats-io/nkeys v0.4.16/go.mod h1:llLgWoI0o4z/Q57q2R1kHfmocyhGV6VG/U18Glg1Afs=
+github.com/nats-io/nuid v1.0.1 h1:5iA8DT8V7q8WK2EScv2padNa/rTESc1KdnPw4TC2paw=
+github.com/nats-io/nuid v1.0.1/go.mod h1:19wcPz3Ph3q0Jbyiqsd0kePYG7A95tJPxeL+1OSON2c=
+golang.org/x/crypto v0.57.0 h1:3ZVCjf8Ggz7zneR/EHRVx68Ctf+2pmIMP2UFhh9cC6M=
+golang.org/x/crypto v0.57.0/go.mod h1:Fdz0i5U6CoizGwLda9DttjSk6qlZo25zYNtR+ycvuZA=
+golang.org/x/sys v0.48.0 h1:bbX/i/6MgT9BVLM9RT1thmxL04yeTAhbEz4SyadbXoo=
+golang.org/x/sys v0.48.0/go.mod h1:hNLxWAXmnKAxqDtdwIYC4bM9oQPEecfsnNMuSxOs3og=
diff --git a/sdk/graph/graph.go b/sdk/graph/graph.go
new file mode 100644
index 00000000..6648ced8
--- /dev/null
+++ b/sdk/graph/graph.go
@@ -0,0 +1,398 @@
+package graph
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"maps"
+	"reflect"
+	"slices"
+	"strings"
+
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// Version is the version of a node's value this package writes and the only one it reads.
+const Version = 1
+
+// ErrUnknownVersion is what Decode returns for a value whose version is missing or not Version.
+var ErrUnknownVersion = errors.New("graph: unknown value version")
+
+func decode(data []byte, into *Node) error {
+	var probe struct {
+		V *int `json:"v"`
+	}
+	if err := json.Unmarshal(data, &probe); err != nil {
+		return fmt.Errorf("graph: value does not fit its shape: %w", err)
+	}
+	if probe.V == nil || *probe.V != Version {
+		return fmt.Errorf("%w: this reader reads %d", ErrUnknownVersion, Version)
+	}
+	if err := json.Unmarshal(data, into); err != nil {
+		return fmt.Errorf("graph: value does not fit its shape: %w", err)
+	}
+	return nil
+}
+
+// checkName refuses a module name a key cannot hold (delivery.ModulesKey's rule).
+func checkName(kind, name string) error {
+	if _, err := delivery.ModulesKey(name); err != nil {
+		return fmt.Errorf("graph: the %s name %q: %w", kind, name, err)
+	}
+	return nil
+}
+
+// checkRepository refuses a repository that is not <owner>/<name>.
+func checkRepository(repository string) error {
+	owner, name, ok := strings.Cut(repository, "/")
+	if !ok || owner == "" || name == "" || strings.Contains(name, "/") {
+		return fmt.Errorf("graph: the repository %q is not <owner>/<name>", repository)
+	}
+	return nil
+}
+
+// The module graph (novox/hq ADR 0603 §2, ADR 0604 §1): the indexer keeps, as its state `graph`, one key per module it
+// holds the inputs of, written at every recompute and deleted with the module. A key holds the module's build edges
+// (its bases, the mesh packages its fingerprint takes, and per language the build module, toolchain version and recipe
+// version its fingerprint names, ADR 0530 §1) and its provision edges (what its manifest provides, requires, and of what
+// it requires what a want of it waits for). Nothing stores an order: a reader works it out from the edges (ADR 0603
+// §1, §6). The indexer writes it and works the edges out (EdgesOf), the delivery view, the checker and the indexer's
+// answers of the seat mesh-catalog read it; all three are in this repository, which uses this package by path (the
+// operator, 2026-11-03: no graph-related code in mesh-sdk, only contracts). It names no module.
+
+const (
+	// State is the name of the indexer's state of the module graph, as its manifest declares it, and Bucket its
+	// bucket: one key per module (Key).
+	State  = "graph"
+	Bucket = delivery.IndexerModule + "_" + State
+	// Read is the line a reader's manifest names in `reads` to read the graph.
+	Read = delivery.IndexerModule + "." + State
+	// History is the revisions the graph state keeps per key (ADR 0603 §2).
+	History = 5
+)
+
+// Key is the key, in Bucket, of a module: `<module>`, as ModulesKey.
+func Key(module string) (string, error) { return delivery.ModulesKey(module) }
+
+// ParseKey is the inverse of Key.
+func ParseKey(key string) (string, error) {
+	module, err := Key(key)
+	if err != nil {
+		return "", fmt.Errorf("graph: %q is not a graph key: %w", key, err)
+	}
+	return module, nil
+}
+
+// Node is the value of a graph key: one module's edges as its last recompute computed them. FP is its new-form
+// fingerprint then, or None why it has none (exactly one is set); Repository and Path say where it is (as Module), so a
+// package edge is resolved to the module that publishes it (GraphPublisher). Bases are the modules it is built on;
+// Packages the mesh packages (Go module paths) its fingerprint took (Module.Packages); Toolchains, by language, the
+// build module and the toolchain it was computed with. Provides are the provisions its manifest offers (its own name is
+// provided too and is not listed), Requires what it requires and does not require optionally, and Awaits those of
+// Requires a want of it waits for (catalogue.Awaited, ADR 0570 §4): the provision edges that order a source revision.
+// Every list is sorted and each entry once; an encode sorts them.
+type Node struct {
+	V          int                  `json:"v"`
+	FP         string               `json:"fp,omitempty"`
+	None       string               `json:"none,omitempty"`
+	Repository string               `json:"repository"`
+	Path       string               `json:"path,omitempty"`
+	Bases      []string             `json:"bases,omitempty"`
+	Packages   []string             `json:"packages,omitempty"`
+	Toolchains map[string]Toolchain `json:"toolchains,omitempty"`
+	Provides   []string             `json:"provides,omitempty"`
+	Requires   []string             `json:"requires,omitempty"`
+	Awaits     []string             `json:"awaits,omitempty"`
+}
+
+// Toolchain is a build edge of one language: the build module that builds it (Module) and the toolchain version
+// and recipe version its fingerprint names.
+type Toolchain struct {
+	Module  string `json:"module"`
+	Version string `json:"version"`
+	Recipe  string `json:"recipe"`
+}
+
+func (g Node) check() error {
+	switch {
+	case (g.FP == "") == (g.None == ""):
+		return fmt.Errorf("graph: a graph node has either a fingerprint or a reason for none, not both or neither")
+	case g.FP != "" && !strings.HasPrefix(g.FP, delivery.SourcePrefix2):
+		return fmt.Errorf("graph: the graph node's fingerprint %q does not start with %s", g.FP, delivery.SourcePrefix2)
+	}
+	if err := checkRepository(g.Repository); err != nil {
+		return err
+	}
+	for _, b := range g.Bases {
+		if err := checkName("base", b); err != nil {
+			return err
+		}
+	}
+	for _, p := range g.Packages {
+		if _, _, ok := delivery.PackageRepository(p); !ok {
+			return fmt.Errorf("graph: the graph node's package %q is no mesh package's path", p)
+		}
+	}
+	for language, t := range g.Toolchains {
+		if err := checkName("build module", t.Module); err != nil {
+			return fmt.Errorf("graph: the graph node's toolchain of %q: %w", language, err)
+		}
+		if language == "" || t.Version == "" || t.Recipe == "" {
+			return fmt.Errorf("graph: the graph node's toolchain of %q needs its language, version and recipe version", language)
+		}
+	}
+	for _, list := range [][]string{g.Provides, g.Requires, g.Awaits} {
+		if slices.Contains(list, "") {
+			return fmt.Errorf("graph: a graph node names an empty provision")
+		}
+	}
+	for _, a := range g.Awaits {
+		if !slices.Contains(g.Requires, a) {
+			return fmt.Errorf("graph: the graph node awaits %q, which it does not require", a)
+		}
+	}
+	return nil
+}
+
+func sortedOnce(in []string) []string {
+	if len(in) == 0 {
+		return nil
+	}
+	out := slices.Clone(in)
+	slices.Sort(out)
+	return slices.Compact(out)
+}
+
+func (g Node) normal() Node {
+	g.Bases, g.Packages = sortedOnce(g.Bases), sortedOnce(g.Packages)
+	g.Provides, g.Requires, g.Awaits = sortedOnce(g.Provides), sortedOnce(g.Requires), sortedOnce(g.Awaits)
+	if len(g.Toolchains) == 0 {
+		g.Toolchains = nil
+	}
+	return g
+}
+
+// Encode is g as JSON at Version, its lists sorted; it refuses what Node's contract does not hold.
+func Encode(g Node) ([]byte, error) {
+	g = g.normal()
+	if err := g.check(); err != nil {
+		return nil, err
+	}
+	g.V = Version
+	return json.Marshal(g)
+}
+
+// Decode reads a graph node; it refuses an unknown version (ErrUnknownVersion) and what Encode refuses.
+func Decode(data []byte) (Node, error) {
+	var g Node
+	if err := decode(data, &g); err != nil {
+		return Node{}, err
+	}
+	if err := g.check(); err != nil {
+		return Node{}, err
+	}
+	return g.normal(), nil
+}
+
+// Same says whether two graph nodes are the same value once sorted, so a writer writes only when they differ.
+func Same(a, b Node) bool {
+	a, b = a.normal(), b.normal()
+	a.V, b.V = 0, 0
+	return reflect.DeepEqual(a, b)
+}
+
+// Graph is the module graph as a reader holds it: every graph node, by module.
+type Graph map[string]Node
+
+// Providers are the modules that provide provision: each whose Provides names it, and the module of that name (a module
+// provides its own name), sorted.
+func (g Graph) Providers(provision string) []string {
+	var out []string
+	for name, n := range g {
+		if name == provision || slices.Contains(n.Provides, provision) {
+			out = append(out, name)
+		}
+	}
+	slices.Sort(out)
+	return out
+}
+
+// Requirers are the modules that require provision, not optionally, sorted.
+func (g Graph) Requirers(provision string) []string {
+	var out []string
+	for name, n := range g {
+		if slices.Contains(n.Requires, provision) {
+			out = append(out, name)
+		}
+	}
+	slices.Sort(out)
+	return out
+}
+
+// Publisher is the module of the graph whose repository and directory publish the mesh package pkg (PackageRepository),
+// or "" when the graph holds none.
+func (g Graph) Publisher(pkg string) string {
+	repository, dir, ok := delivery.PackageRepository(pkg)
+	if !ok {
+		return ""
+	}
+	if dir == "" {
+		dir = delivery.RootPath
+	}
+	for _, name := range slices.Sorted(maps.Keys(g)) {
+		if n := g[name]; n.Repository == repository && n.Path == dir {
+			return name
+		}
+	}
+	return ""
+}
+
+// buildEdges are the modules n's build edges reach: its bases, the publisher of each of its packages, and the build
+// module of each language.
+func (g Graph) buildEdges(n Node) []string {
+	out := slices.Clone(n.Bases)
+	for _, p := range n.Packages {
+		if m := g.Publisher(p); m != "" {
+			out = append(out, m)
+		}
+	}
+	for _, t := range n.Toolchains {
+		out = append(out, t.Module)
+	}
+	return sortedOnce(out)
+}
+
+// Dependents are the modules whose build edges reach module, directly or through other modules' (a base of a base, a
+// module built by a build module that stands on module), sorted and without module itself (ADR 0604 §1): what a
+// change of module builds again.
+func (g Graph) Dependents(module string) []string {
+	reverse := map[string][]string{}
+	for _, name := range slices.Sorted(maps.Keys(g)) {
+		for _, to := range g.buildEdges(g[name]) {
+			reverse[to] = append(reverse[to], name)
+		}
+	}
+	seen := map[string]bool{module: true}
+	queue := []string{module}
+	var out []string
+	for len(queue) > 0 {
+		at := queue[0]
+		queue = queue[1:]
+		for _, from := range reverse[at] {
+			if !seen[from] {
+				seen[from] = true
+				out = append(out, from)
+				queue = append(queue, from)
+			}
+		}
+	}
+	slices.Sort(out)
+	return out
+}
+
+// Before are the modules name waits for, by the graph's ordering edges, sorted: its bases and, for each provision it
+// awaits, every other module that provides it (ADR 0603 §1). A toolchain or package edge orders nothing (§3).
+func (g Graph) Before(name string) []string {
+	n := g[name]
+	out := slices.Clone(n.Bases)
+	for _, a := range n.Awaits {
+		for _, p := range g.Providers(a) {
+			if p != name {
+				out = append(out, p)
+			}
+		}
+	}
+	return sortedOnce(out)
+}
+
+// Cycle is the first cycle of the graph's ordering edges, as the modules it passes through with the first named again
+// at its end (a -> b -> a), or nil for none (ADR 0603 §2: the check refuses it and names it). The ordering edges are a
+// module's bases and, for each provision it awaits, every other module that provides it: modules ordered on each other
+// would each wait for the other for good. A toolchain edge is no ordering edge (ADR 0603 §3: nothing waits on a build
+// module), and neither is a package edge. The modules are visited in sorted order, so the same graph names the same
+// cycle.
+func (g Graph) Cycle() []string {
+	edges := g.Before
+	const (
+		unseen = iota
+		onPath
+		done
+	)
+	state := map[string]int{}
+	var path []string
+	var visit func(string) []string
+	visit = func(name string) []string {
+		state[name] = onPath
+		path = append(path, name)
+		for _, to := range edges(name) {
+			if _, ours := g[to]; !ours {
+				continue
+			}
+			switch state[to] {
+			case onPath:
+				i := slices.Index(path, to)
+				return append(slices.Clone(path[i:]), to)
+			case unseen:
+				if c := visit(to); c != nil {
+					return c
+				}
+			}
+		}
+		path = path[:len(path)-1]
+		state[name] = done
+		return nil
+	}
+	for _, name := range slices.Sorted(maps.Keys(g)) {
+		if state[name] == unseen {
+			if c := visit(name); c != nil {
+				return c
+			}
+		}
+	}
+	return nil
+}
+
+// EdgesOf is the graph node of manifest's own edges: its bases (each module its build stands on), what it provides,
+// what it requires and does not require optionally, and of those what a want of it waits for (catalogue.Awaited, as the
+// assigner judges it), providers answering the manifests that provide a provision. The fingerprint, place, packages and
+// toolchains are the indexer's to add; this is the part a reader of manifests alone (the checker) works out the same way.
+func EdgesOf(manifest catalogue.Manifest, providers func(provision string) []catalogue.Manifest) Node {
+	var n Node
+	if manifest.Build != nil {
+		for _, on := range manifest.Build.On {
+			if on.Module != "" {
+				n.Bases = append(n.Bases, on.Module)
+			}
+		}
+	}
+	for _, o := range manifest.Provides {
+		n.Provides = append(n.Provides, o.Name)
+	}
+	for _, r := range manifest.Requires {
+		if !manifest.OptionalRequires[r] {
+			n.Requires = append(n.Requires, r)
+		}
+	}
+	n.Awaits = catalogue.Awaited(manifest, providers)
+	return n.normal()
+}
+
+// OfManifests is the graph of these manifests' own edges (EdgesOf), by module, each provision's providers being
+// the manifests among them that offer it: what the check works out for a change to find a cycle (ADR 0603 §2).
+func OfManifests(manifests map[string]catalogue.Manifest) Graph {
+	providers := func(provision string) []catalogue.Manifest {
+		var out []catalogue.Manifest
+		for _, name := range slices.Sorted(maps.Keys(manifests)) {
+			if slices.Contains(manifests[name].Offers(), provision) {
+				out = append(out, manifests[name])
+			}
+		}
+		return out
+	}
+	g := Graph{}
+	for name, m := range manifests {
+		g[name] = EdgesOf(m, providers)
+	}
+	return g
+}
diff --git a/sdk/graph/graph_test.go b/sdk/graph/graph_test.go
new file mode 100644
index 00000000..9c34b9db
--- /dev/null
+++ b/sdk/graph/graph_test.go
@@ -0,0 +1,174 @@
+package graph
+
+import (
+	"errors"
+	"reflect"
+	"slices"
+	"strings"
+	"testing"
+
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// TestGraphEdges: the module graph's cycle, dependents and providers, each from the edges alone (ADR 0603 §2, ADR 0604 §1).
+func TestGraphEdges(t *testing.T) {
+	t.Run("a node's value", nodeValues)
+	fp := "src2:" + strings.Repeat("b", 64)
+	node := func(repository, path string, edit func(*Node)) Node {
+		n := Node{FP: fp, Repository: repository, Path: path}
+		if edit != nil {
+			edit(&n)
+		}
+		return n
+	}
+	gotool := map[string]Toolchain{"go": {Module: "build-go", Version: "go1", Recipe: "1"}}
+	// A base chain, a package and a build module: app stands on base, imports lib's package, is built by build-go.
+	g := Graph{
+		"build-go": node("novox/mesh-catalog", "modules/build-go", func(n *Node) { n.Toolchains = gotool }),
+		"lib":      node("novox/lib", delivery.RootPath, nil),
+		"base":     node("novox/mesh-catalog", "modules/base", nil),
+		"app": node("novox/mesh-catalog", "modules/app", func(n *Node) {
+			n.Bases, n.Packages, n.Toolchains = []string{"base"}, []string{"git.novox.be/novox/lib"}, gotool
+		}),
+		"top": node("novox/mesh-catalog", "modules/top", func(n *Node) { n.Bases = []string{"app"} }),
+		"db":  node("novox/mesh-catalog", "modules/db", func(n *Node) { n.Provides = []string{"database"} }),
+		"web": node("novox/mesh-catalog", "modules/web", func(n *Node) {
+			n.Requires, n.Awaits = []string{"database", "db"}, []string{"database"}
+		}),
+	}
+	for module, want := range map[string][]string{
+		"base":     {"app", "top"},
+		"lib":      {"app", "top"},
+		"build-go": {"app", "top"}, // build-go's own toolchain edge reaches itself, which is left out
+		"top":      nil,
+		"db":       nil, // a provision edge is no build edge
+	} {
+		if got := g.Dependents(module); !reflect.DeepEqual(got, want) {
+			t.Errorf("dependents of %s = %v, want %v", module, got, want)
+		}
+	}
+	if got := g.Providers("database"); !reflect.DeepEqual(got, []string{"db"}) {
+		t.Errorf("providers of database = %v", got)
+	}
+	if got := g.Providers("db"); !reflect.DeepEqual(got, []string{"db"}) { // a module provides its own name
+		t.Errorf("providers of db = %v", got)
+	}
+	if got := g.Before("web"); !reflect.DeepEqual(got, []string{"db"}) { // web awaits database, which db provides
+		t.Errorf("web waits for %v", got)
+	}
+	if got := g.Before("top"); !reflect.DeepEqual(got, []string{"app"}) {
+		t.Errorf("top waits for %v", got)
+	}
+	if got := g.Requirers("db"); !reflect.DeepEqual(got, []string{"web"}) {
+		t.Errorf("requirers of db = %v", got)
+	}
+	if g.Publisher("git.novox.be/novox/lib") != "lib" || g.Publisher("git.novox.be/novox/mesh-sdk/go") != "" {
+		t.Error("a package's publisher is not the module at its repository and directory")
+	}
+	// From manifests alone (the check's graph): a requirement answered by a helper at mesh scope is awaited, an optional
+	// one is not, and two modules awaiting each other's provision are a cycle.
+	offer := func(name string) []catalogue.Offer {
+		return []catalogue.Offer{{Name: name, Scope: catalogue.ScopeMesh, AnsweredBy: catalogue.AnsweredByHelper}}
+	}
+	ms := map[string]catalogue.Manifest{
+		"db":  {Module: "db", Provides: offer("database"), Requires: []string{"site", "logs"}, OptionalRequires: map[string]bool{"logs": true}},
+		"web": {Module: "web", Provides: offer("site"), Requires: []string{"database"}, Build: &catalogue.Build{On: []catalogue.BuildsOn{{Module: "base"}}}},
+	}
+	mg := OfManifests(ms)
+	if db := mg["db"]; !reflect.DeepEqual(db.Requires, []string{"site"}) || !reflect.DeepEqual(db.Awaits, []string{"site"}) ||
+		!reflect.DeepEqual(mg["web"].Bases, []string{"base"}) || !reflect.DeepEqual(db.Provides, []string{"database"}) {
+		t.Errorf("the graph of manifests = %+v", mg)
+	}
+	if got := mg.Cycle(); !reflect.DeepEqual(got, []string{"db", "web", "db"}) {
+		t.Errorf("the cycle of manifests = %v", got)
+	}
+	for name, c := range map[string]struct {
+		edit func(Graph)
+		want []string
+	}{
+		"none: a toolchain on itself and a requirement not awaited order nothing": {func(Graph) {}, nil},
+		"bases": {func(g Graph) {
+			b := g["base"]
+			b.Bases = []string{"top"}
+			g["base"] = b
+		}, []string{"app", "base", "top", "app"}},
+		"provisions a -> b -> a": {func(g Graph) {
+			d := g["db"]
+			d.Requires, d.Awaits = []string{"site"}, []string{"site"}
+			g["db"] = d
+			w := g["web"]
+			w.Provides = []string{"site"}
+			g["web"] = w
+		}, []string{"db", "web", "db"}},
+		"a requirement not awaited is no edge": {func(g Graph) {
+			d := g["db"]
+			d.Requires = []string{"site"}
+			g["db"] = d
+			w := g["web"]
+			w.Provides = []string{"site"}
+			g["web"] = w
+		}, nil},
+	} {
+		h := Graph{}
+		for k, v := range g {
+			h[k] = v
+		}
+		c.edit(h)
+		if got := h.Cycle(); !reflect.DeepEqual(got, c.want) {
+			t.Errorf("%s: cycle = %v, want %v", name, got, c.want)
+		}
+	}
+}
+
+// sampleNode is a graph node with every kind of edge, its lists unsorted.
+func sampleNode() Node {
+	return Node{FP: "src2:" + strings.Repeat("a", 64), Repository: "novox/mesh-catalog", Path: "modules/gitea",
+		Bases: []string{"z-base", "a-base"}, Packages: []string{"git.novox.be/novox/mesh-sdk/go"},
+		Toolchains: map[string]Toolchain{"go": {Module: "build-go", Version: "go1.27.1", Recipe: "3"}},
+		Provides:   []string{"forge"}, Requires: []string{"postgres-database", "dns"}, Awaits: []string{"postgres-database"}}
+}
+
+// nodeValues: a node round-trips with its lists sorted, an unknown version is refused, a node that does not hold is
+// refused naming why, and the state is the indexer's graph (ADR 0603 §2).
+func nodeValues(t *testing.T) {
+	if Bucket != "mesh-delivery-indexer_graph" || Read != "mesh-delivery-indexer.graph" || History != 5 || State != "graph" {
+		t.Error("the graph's state differs from the decided layout")
+	}
+	g := sampleNode()
+	data, err := Encode(g)
+	if err != nil || !strings.Contains(string(data), `"v":1`) {
+		t.Fatalf("encode: %s %v", data, err)
+	}
+	if got, err := Decode(data); err != nil || !Same(got, g) || !slices.IsSorted(got.Bases) {
+		t.Errorf("round trip: %+v %v", got, err)
+	}
+	if Same(g, Node{None: "x", Repository: "a/b"}) {
+		t.Error("different graph nodes are the same")
+	}
+	for _, in := range []string{`{"none":"x","repository":"a/b"}`, `{"v":2,"none":"x","repository":"a/b"}`} {
+		if _, err := Decode([]byte(in)); !errors.Is(err, ErrUnknownVersion) {
+			t.Errorf("decode of %s = %v, want ErrUnknownVersion", in, err)
+		}
+	}
+	for name, c := range map[string]struct {
+		change func(*Node)
+		word   string
+	}{
+		"both":                              {func(g *Node) { g.None = "why" }, "both"},
+		"neither":                           {func(g *Node) { g.FP = "" }, "neither"},
+		"an old form":                       {func(g *Node) { g.FP = "src1:x" }, "src2:"},
+		"a dotted base":                     {func(g *Node) { g.Bases = []string{"a.b"} }, "a.b"},
+		"a foreign package":                 {func(g *Node) { g.Packages = []string{"example.com/x"} }, "example.com/x"},
+		"a toolchain of no module":          {func(g *Node) { g.Toolchains = map[string]Toolchain{"go": {Version: "go1", Recipe: "1"}} }, "build module"},
+		"a toolchain of no recipe":          {func(g *Node) { g.Toolchains = map[string]Toolchain{"go": {Module: "b", Version: "go1"}} }, "recipe"},
+		"awaiting what it does not require": {func(g *Node) { g.Awaits = []string{"other"} }, "other"},
+		"no repository":                     {func(g *Node) { g.Repository = "" }, "repositor"},
+	} {
+		g := sampleNode()
+		c.change(&g)
+		if _, err := Encode(g); err == nil || !strings.Contains(err.Error(), c.word) {
+			t.Errorf("a node with %s: %v, want it refused naming %q", name, err, c.word)
+		}
+	}
+}