Merge pull request 'A held module offers what it runs, and its hold no longer spreads to the modules that read from it (issue 1960)' (#131) from fix/1960-no-hold-spread into main

go/compose/frombus/answer.go

@@ -3,6 +3,7 @@ package frombus
 import (
 	"context"
 	"fmt"
+	"maps"
 	"regexp"
 	"slices"
 	"sort"
@@ -70,7 +71,7 @@ func Answer(ctx context.Context, r Reader, mesh Mesh, s Scope, fps map[string]st
 			return refuse(fmt.Errorf("frombus: the credentials of %s: %w", s.Node, err))
 		}
 	}
-	composed, skipped, stood, err := composeEach(in, s.Node, fps, false, s.Running, failed)
+	composed, skipped, stood, err := composeEach(in, s.Node, fps, false, s.Running, failed, ranOf(ctx, r, mesh, s.Running, fps))
 	if err != nil {
 		// Not one module's: the node's own (a value served elsewhere, the mesh's network), said once as the node's.
 		if len(failed) == 0 {
@@ -207,59 +208,24 @@ func Answer(ctx context.Context, r Reader, mesh Mesh, s Scope, fps map[string]st
 	return a
 }
 
-// heldBehind is why a module is held with a held one it reads (composeEach's dependents).
-func heldBehind(m string) string {
-	return "it reads what " + m + " contributes or listens on, and " + m + " is held"
-}
-
-// behind is the held module a refusal's words say it is held behind, or "".
-func behind(why string) string {
-	rest, ok := strings.CutPrefix(why, "it reads what ")
-	if !ok {
-		return ""
-	}
-	m, _, ok := strings.Cut(rest, " contributes or listens on, and ")
-	if !ok || why != heldBehind(m) {
-		return ""
-	}
-	return m
-}
-
 // heldAsToday moves into Held each refusal of a module the node keeps today as it runs (Scope.HeldToday, with how:
-// held, failed, running a build of the old form), and of each module held only behind one of those: the candidate keeps
+// held, failed, running a build of the old form): the candidate keeps it as the node does, which is no change (issue
-// them as the node does, which is no change (issue 1126: a seed reproduces today, and today keeps them so). Each says
+// 1126: a seed reproduces today, and today keeps them so). Each says how it stands today (ModuleRefused.Today). No
-// how it stands today (ModuleRefused.Today).
+// module is held behind another (issue 1960): a module that reads from a held one composes with what it last offered.
 func heldAsToday(a *delivery.CandidateAnswer, today map[string]string) {
 	if len(today) == 0 {
 		return
 	}
-	how := map[string]string{}
+	kept := a.Refusals[:0]
-	for m, w := range today {
+	for _, r := range a.Refusals {
-		how[m] = w
+		if w, keep := today[r.Module]; keep {
-	}
+			r.Today = w
-	for moved := true; moved; {
+			a.Held = append(a.Held, r)
-		moved = false
+		} else {
-		kept := a.Refusals[:0]
+			kept = append(kept, r)
-		for _, r := range a.Refusals {
-			w, keep := how[r.Module]
-			if !keep {
-				if m := behind(r.Why); m != "" {
-					if _, behindKept := how[m]; behindKept {
-						w, keep = "held behind "+m, true
-					}
-				}
-			}
-			if keep {
-				r.Today = w
-				how[r.Module] = w
-				a.Held = append(a.Held, r)
-				moved = true
-			} else {
-				kept = append(kept, r)
-			}
 		}
-		a.Refusals = kept
 	}
+	a.Refusals = kept
 	if len(a.Refusals) == 0 {
 		a.Refusals = nil
 	}
@@ -310,15 +276,18 @@ func standsInFor(x, node string) (string, string) {
 // **A held module is what runs of it** (review of the apply, round 1): composed from what running holds of it
 // (compose.Carried of its own composition there; the node's own carries it wherever it runs there), so what the others
 // read of it (the machine ports its containers publish, the routes reaching it) is what runs, and none of its own
-// composition is in out: the node keeps what it last applied. **A held module is no dependence of its neighbours**
+// composition is in out: the node keeps what it last applied.
-// (issue 1126, the spreading hold): a consumer of what it provides, or a collector of its items, composes against what
+//
-// runs of it like any other module, and is never held for how the held one would compose as its stub (that comparison
+// **A hold never spreads** (issue 1126, issue 1960: de-spiegel's hold for an unset value held mailu, which held
-// held every postgres consumer behind de-spiegel's hold on novox, three rounds in a row). What it composes is compared
+// route-proxy, nftables and postgres on novox). No module is held because a module it reads from is held: a consumer,
-// with what runs as any module's is: a real difference is still named, and a refusal of its own still refuses it. Only
+// a collector, the provider of what the held one contributes to and the filter where it listens each compose with what
-// what a held module's new manifest says to others, which may not be the build's that runs, is held with it
+// the held module last offered. That offer (what it contributes, contributes many, listens on) is its manifest at the
-// (dependents): the providers of what it contributes to in their own files (the proxy its routes), and, when it
+// build it runs where one is known (ran: a composition of its own running at another build than it is composed at),
-// listens, the filter; its items reach their collectors through its own plan, which it keeps as it runs.
+// else the manifest it is composed from. Only the part of the offer that cannot compose is left out, by provision
-func composeEach(in compose.Input, node string, fps map[string]string, applied bool, running []delivery.Composed, failed map[string]string) (out map[string]delivery.Composed, skipped, stood []string, err error) {
+// (culprit): de-spiegel's routes, its names unset, leave route-proxy without them while mailu keeps its smtp account,
+// and the hold says so.
+func composeEach(in compose.Input, node string, fps map[string]string, applied bool, running []delivery.Composed, failed map[string]string,
+	ran func(module string) (catalogue.Manifest, bool)) (out map[string]delivery.Composed, skipped, stood []string, err error) {
 	mode := compose.Foreseeing
 	if applied {
 		mode = compose.Reading
@@ -329,43 +298,46 @@ func composeEach(in compose.Input, node string, fps map[string]string, applied b
 			runs[m] = &running[i]
 		}
 	}
-	src := map[string]catalogue.Manifest{} // each held module's manifest before it was held
+	src := map[string]catalogue.Manifest{} // each held module's manifest before it was held, offering what it last offered
-	bareOf := map[string]bool{}
+	left := map[string]map[string]bool{}   // by held module, what of its offer is left out (leaveOut)
-	var hold func(m, why string, bare bool)
+	hold := func(m, why, leave string) {
-	hold = func(m, why string, bare bool) {
 		if _, done := failed[m]; !done {
-			failed[m] = why // a held module tried bare keeps the words it was first held for
+			failed[m] = why // a held module tried again keeps the words it was first held for
 		}
-		first := false
 		if _, ok := src[m]; !ok {
 			man, ok := manifestOn(in, node, m)
 			if !ok {
 				return
 			}
-			src[m], first = man, true
+			if ran != nil {
+				if was, ok := ran(m); ok {
+					man.Contributes, man.ContributesMany, man.Listens = was.Contributes, was.ContributesMany, was.Listens
+				}
+			}
+			src[m] = man
 		}
-		bareOf[m] = bareOf[m] || bare
+		if leave != "" {
-		in = heldAs(in, node, m, src[m], bareOf[m], runs[m])
+			if left[m] == nil {
-		if !first {
+				left[m] = map[string]bool{}
-			return
+			}
-		}
+			left[m][leave] = true
-		// What the others read of its manifest (what it contributes, what it listens on) is its new manifest's, not
+			if leave != leaveAll {
-		// necessarily the build's that runs: what reads it is held with it (review of the apply, round 2).
+				failed[m] += "; composed without what it contributes to " + leave + ", which does not compose"
-		for _, r := range dependents(in, node, src[m], failed) {
+			}
-			hold(r, heldBehind(m), false)
 		}
+		in = heldAs(in, node, m, src[m], left[m], runs[m])
 	}
 	for _, m := range sortedKeys(failed) {
-		hold(m, failed[m], false)
+		hold(m, failed[m], "")
 	}
 	for {
 		out, skipped, stood, err = compose.CompositionsIn(in, node, fps, mode)
 		if err != nil {
-			module, bare := culprit(in, node, fps, mode, failed, err)
+			module, leave := culprit(in, node, fps, mode, failed, err)
 			if module == "" {
 				return nil, nil, nil, err
 			}
-			hold(module, err.Error(), bare)
+			hold(module, err.Error(), leave)
 			continue
 		}
 		again := false
@@ -385,7 +357,7 @@ func composeEach(in compose.Input, node string, fps map[string]string, applied b
 			}
 			for _, m := range sortedKeys(of) {
 				if _, done := failed[m]; !done {
-					hold(m, "stands in for "+strings.Join(of[m], ", "), false)
+					hold(m, "stands in for "+strings.Join(of[m], ", "), "")
 					again = true
 				}
 			}
@@ -401,43 +373,9 @@ func composeEach(in compose.Input, node string, fps map[string]string, applied b
 	return out, skipped, stood, nil
 }
 
-// dependents is, of the modules placed on node and not held, those that read what man says to them: each that provides
+// leaveAll leaves out the whole of a held module's offer and its own secrets (a bare stub); any other word leaves out
-// what man contributes to (the proxy its routes), and, when man listens on a port, each that holds the filter (the
+// what it contributes to that provision alone.
-// openings).
+const leaveAll = "*"
-func dependents(in compose.Input, node string, man catalogue.Manifest, failed map[string]string) []string {
-	to := map[string]bool{}
-	for p := range man.Contributes {
-		to[p] = true
-	}
-	for p := range man.ContributesMany {
-		to[p] = true
-	}
-	listens := len(man.Listens) > 0
-	if len(to) == 0 && !listens {
-		return nil
-	}
-	var out []string
-	for _, m := range assignedOn(in, node) {
-		if _, held := failed[m]; held || m == man.Module {
-			continue
-		}
-		pm, ok := manifestOn(in, node, m)
-		if !ok {
-			continue
-		}
-		if listens && pm.Filtering != nil {
-			out = append(out, m)
-			continue
-		}
-		for _, o := range pm.Provides {
-			if to[o.Name] {
-				out = append(out, m)
-				break
-			}
-		}
-	}
-	return out
-}
 
 // assignedOn is the modules placed on node, in placement order.
 func assignedOn(in compose.Input, node string) []string {
@@ -462,18 +400,14 @@ func manifestOn(in compose.Input, node, module string) (catalogue.Manifest, bool
 	return man, ok
 }
 
-// culprit is the module placed on node whose composition the error is of: the first, in placement order, whose stub
+// culprit is the module placed on node whose composition the error is of, and what of its offer to leave out: the
-// (compose.Stub) makes the composition in mode succeed or fail otherwise; empty when none does (the error is not one
+// first, in placement order, whose stub (compose.Stub) makes the composition in mode succeed or fail otherwise (leave
-// module's). Modules already refused are passed over. A module whose stub still fails the same is tried bare (its stub
+// ""); else the first whose stub without what it contributes to one provision does (leave that provision: de-spiegel's
-// contributing nothing, bare true): a refusal of what it contributes is its own, which the stub keeps (issue 1126,
+// routes, its names unset, and not its smtp account, issue 1960); else the first whose bare stub does (leaveAll: its
-// seed-8: de-spiegel's route names on novox, an unset required value, refused the whole node).
+// stub contributing nothing, its own secret never issued, issue 1126 seed-8). Empty when none does (the error is not
-func culprit(in compose.Input, node string, fps map[string]string, mode compose.Mode, failed map[string]string, err error) (string, bool) {
+// one module's). Modules already refused are passed over for their stub.
-	var assigned []string
+func culprit(in compose.Input, node string, fps map[string]string, mode compose.Mode, failed map[string]string, err error) (string, string) {
-	for _, n := range in.Nodes {
+	assigned := assignedOn(in, node)
-		if n.Name == node {
-			assigned = n.Assigned
-		}
-	}
 	// Only the modules the error names: the words of a module's refusal name it. Each try is a whole composition, so a
 	// refusal naming none is no module's, answered at once rather than after a composition per module (issue 1126: ace's
 	// answer took 7m46s).
@@ -483,65 +417,97 @@ func culprit(in compose.Input, node string, fps map[string]string, mode compose.
 			order = append(order, m)
 		}
 	}
-	changes := func(m string, bare bool) bool {
+	changes := func(m, leave string) bool {
-		_, _, _, again := compose.CompositionsIn(stubbed(in, node, m, bare), node, fps, mode)
+		_, _, _, again := compose.CompositionsIn(stubbed(in, node, m, leave), node, fps, mode)
 		return again == nil || again.Error() != err.Error()
 	}
 	for _, m := range order {
 		if _, done := failed[m]; done {
 			continue
 		}
-		if changes(m, false) {
+		if changes(m, "") {
-			return m, false
+			return m, ""
-		}
-	}
-	var kept map[string]catalogue.Manifest
-	for _, n := range in.Nodes {
-		if n.Name == node {
-			kept = n.Kept
 		}
 	}
 	for _, m := range order {
-		// One already held is tried bare too, once: held for its build, its stub may still refuse (its own secret
+		man, ok := manifestOn(in, node, m)
-		// never issued, issue 1126).
+		if !ok {
-		if _, done := failed[m]; done && isBare(kept[m]) {
 			continue
 		}
-		if changes(m, true) {
+		// One already held is tried again too: held for its build, its stub may still refuse (its own secret never
-			return m, true
+		// issued, issue 1126). A provision named in the error is tried first, each at one more composition.
+		var to []string
+		for p := range man.Contributes {
+			to = append(to, p)
+		}
+		for p := range man.ContributesMany {
+			if _, both := man.Contributes[p]; !both {
+				to = append(to, p)
+			}
+		}
+		sort.SliceStable(to, func(i, j int) bool {
+			return strings.Contains(err.Error(), " "+to[i]) && !strings.Contains(err.Error(), " "+to[j])
+		})
+		for _, p := range to {
+			if changes(m, p) {
+				return m, p
+			}
+		}
+		if isBare(man) {
+			continue
+		}
+		if changes(m, leaveAll) {
+			return m, leaveAll
 		}
 	}
-	return "", false
+	return "", ""
 }
 
-// isBare says a stub contributes nothing and declares no own secret (stubbed, bare).
+// isBare says a stub contributes nothing and declares no own secret (stubbed, leaveAll).
 func isBare(m catalogue.Manifest) bool {
 	return len(m.Contributes) == 0 && len(m.ContributesMany) == 0 && len(m.OwnSecrets) == 0
 }
 
 // stubbed is in with module held on node as its stub alone (heldAs, nothing of it running), from the manifest node
-// composes it from: a culprit's try.
+// composes it from, leave left out of its offer: a culprit's try.
-func stubbed(in compose.Input, node, module string, bare bool) compose.Input {
+func stubbed(in compose.Input, node, module, leave string) compose.Input {
 	man, ok := manifestOn(in, node, module)
 	if !ok {
 		return in
 	}
-	return heldAs(in, node, module, man, bare, nil)
+	var left map[string]bool
+	if leave != "" {
+		left = map[string]bool{leave: true}
+	}
+	return heldAs(in, node, module, man, left, nil)
 }
 
 // heldAs is in with module held on node (compose.Node.Held): composed from man as what runs of it (compose.Carried of
-// runs; its stub, compose.Stub, when runs is nil or holds nothing of it), as node's Kept; bare, contributing nothing to
+// runs; its stub, compose.Stub, when runs is nil or holds nothing of it), as node's Kept; with what left names out of
-// what it requires and declaring no own secret: none of a held module's own composition is applied, so what it has not
+// its offer: a provision's contributions, or with leaveAll everything it contributes and its own secrets, none of a
-// been issued (restic's repository on a node it never ran on) is no refusal of the rest.
+// held module's own composition being applied, so what it has not been issued (restic's repository on a node it never
-func heldAs(in compose.Input, node, module string, man catalogue.Manifest, bare bool, runs *delivery.Composed) compose.Input {
+// ran on) is no refusal of the rest.
+func heldAs(in compose.Input, node, module string, man catalogue.Manifest, left map[string]bool, runs *delivery.Composed) compose.Input {
 	out := in
 	out.Nodes = append([]compose.Node(nil), in.Nodes...)
 	for i := range out.Nodes {
 		if out.Nodes[i].Name != node {
 			continue
 		}
-		if bare {
+		if left[leaveAll] {
 			man.Contributes, man.ContributesMany, man.OwnSecrets = nil, nil, nil
+		} else if len(left) > 0 {
+			contributes := map[string]map[string]any{}
+			for p, v := range man.Contributes {
+				if !left[p] {
+					contributes[p] = v
+				}
+			}
+			many := maps.Clone(man.ContributesMany)
+			for p := range left {
+				delete(many, p)
+			}
+			man.Contributes, man.ContributesMany = contributes, many
 		}
 		kept := make(map[string]catalogue.Manifest, len(out.Nodes[i].Kept)+1)
 		for k, v := range out.Nodes[i].Kept {

go/compose/frombus/answer_rows_test.go

@@ -104,12 +104,12 @@ func answerNamesEveryRefusalAndLeavesAnOldBuildToTheNode(t *testing.T) {
 	if part.Verdict != delivery.CandidateRefused || len(part.Refusals) != 2 || len(part.Held) != 1 || part.Held[0].Module != "api" {
 		t.Errorf("held as today in part: %+v", part)
 	}
-	// A module held only behind one kept today is kept as today too, saying behind which (novox's mailu behind de-spiegel).
+	// No module is held behind one kept today (issue 1960): mailu's own refusal stays a refusal beside de-spiegel's hold.
 	if a := (delivery.CandidateAnswer{Refusals: []delivery.ModuleRefused{{Module: "de-spiegel", Why: "a value is unset"},
-		{Module: "mailu", Why: heldBehind("de-spiegel")}, {Module: "proxy", Why: heldBehind("mailu")}, {Module: "web", Why: "no build"}}}); true {
+		{Module: "mailu", Why: "no build"}}}); true {
 		heldAsToday(&a, map[string]string{"de-spiegel": "runs a build of the old form"})
-		if len(a.Refusals) != 1 || a.Refusals[0].Module != "web" || len(a.Held) != 3 || a.Held[2].Today != "held behind mailu" {
+		if len(a.Refusals) != 1 || a.Refusals[0].Module != "mailu" || len(a.Held) != 1 {
-			t.Errorf("held behind a module kept today: %+v", a)
+			t.Errorf("held as today spreads: %+v", a)
 		}
 	}
 
@@ -330,23 +330,26 @@ func answerNamesEveryRefusalAndLeavesAnOldBuildToTheNode(t *testing.T) {
 	// de-spiegel folded, and its manifest at the indexer's commit (e25e1beb, captured) asks four required config values
 	// for its route names that nothing sets. novox answered the whole candidate refused ("de-spiegel contributing
 	// praktijk to route says ${setting:praktijk-name} ...": its stub still contributed the route). Only de-spiegel is
-	// refused, in the config form's words, and proxy, which receives its routes (what it would compose lacks them: review
+	// refused, in the config form's words; the rest is judged. Issue 1960, novox's chain on 2026-10-29: the hold spread
-	// of the apply, round 1); the rest is judged.
+	// to mailu (its smtp provider) and proxy (its route provider), and from them on. Neither is held now: proxy composes
+	// without de-spiegel's routes, which do not compose, and mailu with its smtp account, which does.
 	spiegel, err := os.ReadFile("testdata/de-spiegel-e25e1beb.module.json")
 	if err != nil {
 		t.Fatal(err)
 	}
-	proxy := []byte(`{"module":"proxy","version":"1","capabilities":["systemd"],"provides":[{"name":"route","scope":"mesh"},{"name":"smtp","scope":"mesh"}],` +
+	proxy := []byte(`{"module":"proxy","version":"1","capabilities":["systemd"],"provides":[{"name":"route","scope":"mesh"}],` +
 		`"resources":[{"id":"service","type":"service","unit":"proxy.service","state":"running","boot":"enabled"}]}`)
-	b = mk("lemurs", overlay.Name, "proxy", "de-spiegel")
+	mailu := []byte(`{"module":"mailu","version":"1","capabilities":["systemd"],"provides":[{"name":"smtp","scope":"mesh"}],` +
-	for m, raw := range map[string][]byte{"de-spiegel": spiegel, "proxy": proxy} {
+		`"resources":[{"id":"service","type":"service","unit":"mailu.service","state":"running","boot":"enabled"}]}`)
+	b = mk("lemurs", overlay.Name, "mailu", "proxy", "de-spiegel")
+	for m, raw := range map[string][]byte{"de-spiegel": spiegel, "proxy": proxy, "mailu": mailu} {
 		b.manifests[delivery.ManifestDigest(raw)] = raw
 		b.modules[m] = delivery.Module{Manifest: delivery.ManifestDigest(raw)}
 	}
 	p = b.placements["n1"]
 	p.Decided.Endpoint = "n1.example:51820"
 	b.placements["n1"] = p
-	fps = map[string]string{"lemurs": fp("e"), "proxy": fp("f")}
+	fps = map[string]string{"lemurs": fp("e"), "proxy": fp("f"), "mailu": fp("d")}
 	a = Answer(ctx, b, Mesh{}, Scope{Node: "n1", Placements: given(b), InOwn: []string{"de-spiegel"}}, fps, nil, "p-h1", 3)
 	refused = nil
 	for _, r := range a.Refusals {
@@ -355,11 +358,13 @@ func answerNamesEveryRefusalAndLeavesAnOldBuildToTheNode(t *testing.T) {
 			t.Errorf("de-spiegel is refused in other words than its config form's: %s", r.Why)
 		}
 	}
-	if a.Refused != "" || !reflect.DeepEqual(refused, []string{"de-spiegel", "proxy"}) {
+	if a.Refused != "" || !reflect.DeepEqual(refused, []string{"de-spiegel"}) {
-		t.Errorf("a module's own refusal: %+v, want de-spiegel refused with proxy, which receives its routes, the node not", a)
+		t.Errorf("a module's own refusal: %+v, want de-spiegel refused alone, the node, mailu and proxy not", a)
 	}
-	if !slices.ContainsFunc(a.Added, func(m delivery.ModuleAdded) bool { return m.Module == "lemurs" }) {
+	for _, m := range []string{"lemurs", "mailu", "proxy"} {
-		t.Errorf("lemurs, which composes, is not judged beside de-spiegel's refusal: %+v", a)
+		if !slices.ContainsFunc(a.Added, func(x delivery.ModuleAdded) bool { return x.Module == m }) {
+			t.Errorf("%s, which composes, is not judged beside de-spiegel's refusal: %+v", m, a)
+		}
 	}
 
 	// (E) Issue 1126, the applying path (review of the seed): the composition novox applies follows the same rule. It
@@ -393,16 +398,13 @@ func answerNamesEveryRefusalAndLeavesAnOldBuildToTheNode(t *testing.T) {
 	if err != nil {
 		t.Fatalf("de-spiegel's own refusal refuses the node's whole composition: %v", err)
 	}
-	if len(held) != 2 || !strings.Contains(held["de-spiegel"], "${config:praktijk-name}") || !strings.Contains(held["proxy"], "de-spiegel") {
+	if len(held) != 1 || !strings.Contains(held["de-spiegel"], "${config:praktijk-name}") || !strings.Contains(held["de-spiegel"], "without what it contributes to route") {
-		t.Errorf("held %v, want de-spiegel in its config form's words, and proxy for its routes", held)
+		t.Errorf("held %v, want de-spiegel alone, in its config form's words, composed without its routes", held)
 	}
-	lemursKey, _ := delivery.ComposedKey("n1", "lemurs", fps["lemurs"])
+	for _, m := range []string{"lemurs", "mailu", "proxy"} {
-	proxyKey, _ := delivery.ComposedKey("n1", "proxy", fps["proxy"])
+		if key, _ := delivery.ComposedKey("n1", m, fps[m]); got[key].Module != m {
-	if _, ok := got[lemursKey]; !ok {
+			t.Errorf("%s is not composed beside de-spiegel's hold: %v", m, sortedKeys(got))
-		t.Errorf("lemurs, which composes, is not composed beside de-spiegel's refusal: %v", sortedKeys(got))
+		}
-	}
-	if _, ok := got[proxyKey]; ok {
-		t.Errorf("proxy is composed without the routes of held de-spiegel: %v", sortedKeys(got))
 	}
 	carries := func(c delivery.Composed, what string) {
 		t.Helper()
@@ -434,7 +436,7 @@ func answerNamesEveryRefusalAndLeavesAnOldBuildToTheNode(t *testing.T) {
 	// (G) A held module that runs a composition of its own (review of the apply, round 1, finding 2): what the others
 	// compose of it is what runs, never its stub's. site listens on 8080, placed at the machine's 20005, and its own
 	// secret was never issued here: held, the filter must not open 8080 and drop the 20005 that runs. The filter, which
-	// reads what site's manifest listens on, is held with it (dependents).
+	// reads what site listens on, composes with it (issue 1960: a hold never spreads).
 	site := []byte(`{"module":"site","version":"1","capabilities":["container-runtime"],` +
 		`"listens":[{"port":8080,"from":"mesh","why":"the site"}],"own-secrets":{"key":"${dir:state}/key"},` +
 		`"resources":[{"id":"state","type":"directory","path":"/var/lib/site","mode":"0700"},` +
@@ -460,8 +462,12 @@ func answerNamesEveryRefusalAndLeavesAnOldBuildToTheNode(t *testing.T) {
 		json.RawMessage(`{"id":"site.state","module":"site","type":"directory","path":"/var/lib/site","mode":"0700"}`),
 		json.RawMessage(`{"id":"site.server","module":"site","type":"container","name":"site","image":"registry.example/site@sha256:` + strings.Repeat("c", 64) + `","ports":["10.77.0.1:20005:8080"]}`)}}
 	got, _, held, err = Compose(ctx, b, Mesh{}, Scope{Node: "n1", Running: []delivery.Composed{siteRuns}}, fps)
-	if err != nil || held["site"] == "" || held["nft"] == "" {
+	nftKey, _ := delivery.ComposedKey("n1", "nft", fps["nft"])
-		t.Fatalf("site, its own secret never issued: %v, held %v; want site held, and the filter, which depends on it", err, held)
+	if err != nil || held["site"] == "" || held["nft"] != "" || got[nftKey].Module != "nft" {
+		t.Fatalf("site, its own secret never issued: %v, held %v; want site held alone, and the filter composed", err, held)
+	}
+	if rules, _ := json.Marshal(got[nftKey].Resources); !strings.Contains(string(rules), "dport 20005") {
+		t.Errorf("the filter drops held site's opening where it runs (20005): %s", rules)
 	}
 	for key, c := range got {
 		for _, raw := range c.Resources {
@@ -501,26 +507,25 @@ func answerNamesEveryRefusalAndLeavesAnOldBuildToTheNode(t *testing.T) {
 		t.Errorf("app's binding does not reach held site where it runs (20005): %s", bound)
 	}
 	delete(fps, "app")
-	// A held feeder of a collector holds no collector: its items reach their collection through its own plan, which it
+	// A held module's offer is left out by provision, never whole when one part composes (issue 1960): de-spiegel's
-	// keeps as it runs. Only a provider it contributes to in that provider's own files is held behind it (the proxy its
+	// routes, its names unset, leave the proxy without them, and its smtp account stays with mailu.
-	// routes), as is the filter where it listens.
+	withProxy := compose.Input{Catalogue: map[string]catalogue.Manifest{},
-	withCollector := compose.Input{Catalogue: map[string]catalogue.Manifest{
+		Nodes: []compose.Node{{Name: "n1", Assigned: []string{"feeder"}}}}
-		"feeder": {Module: "feeder", Items: []catalogue.Item{{Collection: "routes", Content: "x"}}},
+	feeder := catalogue.Manifest{Module: "feeder", Contributes: map[string]map[string]any{"route": {"name": "x"}, "smtp": {"account": "feeder"}},
-		"col":    {Module: "col", Collections: []catalogue.Collection{{Name: "routes"}}},
+		OwnSecrets: catalogue.OwnSecrets{"key": {Path: "/k"}}}
-		"proxy":  {Module: "proxy", Provides: []catalogue.Offer{{Name: "route"}}}},
+	for _, row := range []struct {
-		Nodes: []compose.Node{{Name: "n1", Assigned: []string{"feeder", "col", "proxy"}}}}
+		left             map[string]bool
-	feeder := withCollector.Catalogue["feeder"]
+		route, smtp, own bool
-	if d := dependents(withCollector, "n1", feeder, map[string]string{"feeder": "held"}); len(d) != 0 {
+	}{{nil, true, true, true}, {map[string]bool{"route": true}, false, true, true}, {map[string]bool{leaveAll: true}, false, false, false}} {
-		t.Errorf("a held feeder of a collector holds %v, want none", d)
+		k := heldAs(withProxy, "n1", "feeder", feeder, row.left, nil).Nodes[0].Kept["feeder"]
-	}
+		if _, r := k.Contributes["route"]; r != row.route || (k.Contributes["smtp"] != nil) != row.smtp || (len(k.OwnSecrets) > 0) != row.own {
-	feeder.Contributes = map[string]map[string]any{"route": {"name": "x"}}
+			t.Errorf("held leaving out %v offers %+v, own secrets %v", row.left, k.Contributes, k.OwnSecrets)
-	if d := dependents(withCollector, "n1", feeder, map[string]string{"feeder": "held"}); !reflect.DeepEqual(d, []string{"proxy"}) {
+		}
-		t.Errorf("a held module contributing routes holds %v, want the proxy", d)
 	}
 	// (H) Review of the apply, round 2: a held module is composed from its new manifest, so what the others read of its
 	// manifest (its listens, what it contributes) may not be what runs. site's new manifest moves it to 9090 while the
-	// build that runs listens on 8080: the filter, the holder of what site listens on, is held with it, and nothing
+	// build that runs (7) listens on 8080. The filter composes with what site last offered, its manifest at the build
-	// applied opens 9090.
+	// that runs (issue 1960: a hold never spreads), so it opens 8080 and nothing applied opens 9090.
 	moved := []byte(strings.Replace(string(site), `"port":8080`, `"port":9090`, 1))
 	b.manifests[delivery.ManifestDigest(moved)] = moved
 	b.modules["site"] = delivery.Module{Manifest: delivery.ManifestDigest(moved)}
@@ -529,9 +534,15 @@ func answerNamesEveryRefusalAndLeavesAnOldBuildToTheNode(t *testing.T) {
 	}
 	b.placements["n1"] = p
 	siteRuns.Resources[1] = json.RawMessage(`{"id":"site.server","module":"site","type":"container","name":"site","image":"registry.example/site@sha256:` + strings.Repeat("c", 64) + `","ports":["8080"]}`)
+	siteRuns.FP = fp("7")
+	b.manifests[delivery.ManifestDigest(site)] = site
+	b.builds["site "+fp("7")] = &delivery.BuilderBuild{State: delivery.BuildDone, Manifest: delivery.ManifestDigest(site)}
 	got, _, held, err = Compose(ctx, b, Mesh{}, Scope{Node: "n1", Running: []delivery.Composed{siteRuns}}, fps)
-	if err != nil || held["site"] == "" || held["nft"] == "" {
+	if err != nil || held["site"] == "" || held["nft"] != "" {
-		t.Errorf("site moved to 9090 in its new manifest: %v, held %v; want site held, and the filter with it", err, held)
+		t.Errorf("site moved to 9090 in its new manifest: %v, held %v; want site held alone", err, held)
+	}
+	if rules, _ := json.Marshal(got[nftKey].Resources); !strings.Contains(string(rules), "dport 8080") {
+		t.Errorf("the filter drops what held site last offered (8080): %s", rules)
 	}
 	for key, c := range got {
 		for _, raw := range c.Resources {

go/compose/frombus/frombus.go

@@ -240,12 +240,7 @@ func input(ctx context.Context, r Reader, mesh Mesh, s Scope, refuse func(module
 			in.Authority = delivery.AuthorityBundle(in.Authority, vault)
 		}
 	}
-	parse := func(raw []byte) (catalogue.Manifest, error) {
+	parse := parser(mesh)
-		if mesh.Predefined != nil {
-			return catalogue.ParseManifestWith(raw, mesh.Predefined)
-		}
-		return catalogue.ParseManifestForInputs(raw)
-	}
 	read := func(module, digest string) (catalogue.Manifest, error) {
 		raw, err := r.Manifest(ctx, digest)
 		if err != nil {
@@ -425,10 +420,47 @@ func Compose(ctx context.Context, r Reader, mesh Mesh, s Scope, fps map[string]s
 			return nil, nil, held, fmt.Errorf("frombus: the credentials of %s: %w", s.Node, err)
 		}
 	}
-	out, skipped, _, err = composeEach(in, s.Node, fps, true, s.Running, held)
+	out, skipped, _, err = composeEach(in, s.Node, fps, true, s.Running, held, ranOf(ctx, r, mesh, s.Running, fps))
 	return out, skipped, held, err
 }
 
+// parser reads a manifest as the indexer does, against the mesh's predefined keys when given.
+func parser(mesh Mesh) func([]byte) (catalogue.Manifest, error) {
+	return func(raw []byte) (catalogue.Manifest, error) {
+		if mesh.Predefined != nil {
+			return catalogue.ParseManifestWith(raw, mesh.Predefined)
+		}
+		return catalogue.ParseManifestForInputs(raw)
+	}
+}
+
+// ranOf is what a module last offered the others, read when it is held (composeEach, issue 1960): its manifest at the
+// build its own composition runs at (running), where that is another build than the one it is composed at (fps) and
+// the builder holds it done. False where nothing is known of it (it runs no composition of its own, it runs the build
+// it is composed at, or its build is unread): the manifest it is composed from is its offer then. Only what it says to
+// others is taken of it, which needs no take-in of its artifacts.
+func ranOf(ctx context.Context, r Reader, mesh Mesh, running []delivery.Composed, fps map[string]string) func(string) (catalogue.Manifest, bool) {
+	parse := parser(mesh)
+	return func(module string) (catalogue.Manifest, bool) {
+		for _, c := range running {
+			if c.Module != module || c.FP == "" || c.FP == fps[module] {
+				continue
+			}
+			b, err := r.Build(ctx, module, c.FP)
+			if err != nil || b == nil || b.State != delivery.BuildDone || b.Manifest == "" {
+				return catalogue.Manifest{}, false
+			}
+			raw, err := r.Manifest(ctx, b.Manifest)
+			if err != nil {
+				return catalogue.Manifest{}, false
+			}
+			man, err := parse(raw)
+			return man, err == nil
+		}
+		return catalogue.Manifest{}, false
+	}
+}
+
 // fromBuilds puts in the built manifest of each module placed on the composing node, at the trunk's FP2, and of each
 // module it keeps at another build (Scope.KeptAt, into its node's Kept), read from the builder's done key and resolved
 // by the one take-in rule (takein.Manifest), a templates archive read in the artifact store as the node reaches it