diff --git a/modules/mesh-grants/grants_test.go b/modules/mesh-grants/grants_test.go
index 01c04158..117f1ee0 100644
--- a/modules/mesh-grants/grants_test.go
+++ b/modules/mesh-grants/grants_test.go
@@ -4064,6 +4064,17 @@ func TestPassComposesMembershipFromTheHaveBuild(t *testing.T) {
 			t.Errorf("b.mod-y's membership lacks the running build's read: %s", got)
 		}
 	})
+	t.Run("a pass that cannot read the build a have names keeps the membership last published", func(t *testing.T) {
+		b := fixture()
+		runs(b)
+		part := partOn(b)
+		part.Pass()
+		b.refused[grants.ReadBuilds] = true
+		part.Pass()
+		if got := string(b.own[grants.StateMemberships]["b.mod-y"]); !strings.Contains(got, "mod-x.old") {
+			t.Errorf("b.mod-y's membership lost the running build's read when its build could not be read: %s", got)
+		}
+	})
 	t.Run("a build that cannot be read is a failed read", func(t *testing.T) {
 		b := fixture()
 		runs(b)
@@ -4072,22 +4083,4 @@ func TestPassComposesMembershipFromTheHaveBuild(t *testing.T) {
 			t.Errorf("a build read refused is not a failed read: %v", f)
 		}
 	})
-	t.Run("the seats held are the have build's claims, then the want's, then the trunk's", func(t *testing.T) {
-		claims := catalogue.Manifest{Module: "m", Version: "1", Claims: []catalogue.Claim{{Name: "mesh-catalog", Scope: catalogue.ScopeMesh}}}
-		bare := catalogue.Manifest{Module: "m", Version: "1"}
-		for name, row := range map[string]struct {
-			had, running map[string]catalogue.Manifest
-			held         bool
-		}{
-			"trunk alone":  {nil, nil, false},
-			"have claims":  {map[string]catalogue.Manifest{"a.m": claims}, map[string]catalogue.Manifest{"a.m": bare}, true},
-			"want claims":  {nil, map[string]catalogue.Manifest{"a.m": claims}, true},
-			"have is bare": {map[string]catalogue.Manifest{"a.m": bare}, map[string]catalogue.Manifest{"a.m": claims}, false},
-		} {
-			in := grants.Inputs{Nodes: []string{"a"}, Assigned: map[string][]string{"a": {"m"}}, Manifests: map[string]catalogue.Manifest{"m": bare}, Had: row.had, Running: row.running}
-			if got := len(grants.HoldingsOf(in).Claimed) > 0; got != row.held {
-				t.Errorf("%s: claimed %v, want %v", name, got, row.held)
-			}
-		}
-	})
 }
diff --git a/modules/mesh-grants/internal/grants/inputs.go b/modules/mesh-grants/internal/grants/inputs.go
index ae603936..4b63aa60 100644
--- a/modules/mesh-grants/internal/grants/inputs.go
+++ b/modules/mesh-grants/internal/grants/inputs.go
@@ -154,6 +154,9 @@ type Inputs struct {
 	// Had is the manifest of the build each machine runs now (its have's fingerprint, the builder's build of it), by
 	// `<node>.<module>`; the want's Running may already be a newer build. A membership is composed from both and the trunk's.
 	Had map[string]catalogue.Manifest
+	// HadFailed is why the build a machine runs could not be read this pass (a have or a build read that failed), by
+	// `<node>.<module>`: its membership is then composed without that build's reads, and the part keeps the last published.
+	HadFailed map[string]string
 	// Values is each resolved config value, by `<node>/<module>/<key>`.
 	Values map[string]any
 	// BusNode is the machine running the bus's module, and Loaded what its node agent says it loaded.
@@ -325,7 +328,7 @@ func ReadInputs(r Reader, cache *Manifests) Inputs {
 	gate := cache.gate
 	cache.mu.Unlock()
 	in := Inputs{Assigned: map[string][]string{}, Manifests: map[string]catalogue.Manifest{}, Digests: map[string]string{}, Fingerprints: map[string]string{},
-		NoFingerprint: map[string]string{}, Running: map[string]catalogue.Manifest{}, Had: map[string]catalogue.Manifest{},
+		NoFingerprint: map[string]string{}, Running: map[string]catalogue.Manifest{}, Had: map[string]catalogue.Manifest{}, HadFailed: map[string]string{},
 		Values: map[string]any{}, Gaps: append([]Gap(nil), standingGaps...)}
 	in.SeatListUnread = gate != nil && !gate.MayAct()
 	nodes := map[string]bool{}
@@ -756,6 +759,8 @@ func runningByHaves(r Reader, in *Inputs, cache *Manifests, into map[string]cata
 			raw, found, err := r.Get(ReadHave, node+"."+module)
 			if err != nil {
 				in.Gaps = append(in.Gaps, Gap{Input: ReadHave + " " + node + "." + module, Why: "cannot be read, so the build it runs is unknown: " + err.Error(), Failed: true})
+				in.HadFailed[node+"."+module] = ReadHave + " cannot be read"
+
 			}
 			if err != nil || !found {
 				fromTrunk = append(fromTrunk, node+"."+module)
@@ -773,6 +778,7 @@ func runningByHaves(r Reader, in *Inputs, cache *Manifests, into map[string]cata
 			}
 			braw, found, err := r.Get(ReadBuilds, bk)
 			if err != nil {
+				in.HadFailed[node+"."+module] = ReadBuilds + " cannot be read"
 				in.Gaps = append(in.Gaps, Gap{Input: ReadBuilds + " " + bk, Why: "cannot be read, so the manifest of the build " + node + "." + module + " runs is unknown: " + err.Error(), Failed: true})
 			}
 			if err != nil || !found {
diff --git a/modules/mesh-grants/internal/grants/memberships.go b/modules/mesh-grants/internal/grants/memberships.go
index 165c12b6..55946fc1 100644
--- a/modules/mesh-grants/internal/grants/memberships.go
+++ b/modules/mesh-grants/internal/grants/memberships.go
@@ -206,10 +206,7 @@ func HoldingsOf(in Inputs) Holdings {
 	}
 	for node, modules := range in.Assigned {
 		for _, module := range modules {
-			m, ok := in.Had[node+"."+module]
-			if !ok {
-				m, ok = in.Running[node+"."+module]
-			}
+			m, ok := in.Running[node+"."+module]
 			if !ok {
 				m, ok = in.Manifests[module]
 			}
diff --git a/modules/mesh-grants/internal/grants/part.go b/modules/mesh-grants/internal/grants/part.go
index 82c59b34..6590b9ec 100644
--- a/modules/mesh-grants/internal/grants/part.go
+++ b/modules/mesh-grants/internal/grants/part.go
@@ -436,7 +436,11 @@ func (p *Part) Compose() Result {
 		// A pass that composes part of the mesh only grows a published membership: it publishes the union of the one last
 		// published and the one composed (keeploaded.go, issue 1966), so a tool runner or a seat holder goes on serving what it
 		// serves and still receives what the pass that ends the hold needs.
-		if why := in.keepsLoaded(); found && why != "" {
+		why := in.keepsLoaded()
+		if why == "" && in.HadFailed[key] != "" {
+			why = "the build it runs is unread (" + in.HadFailed[key] + ")"
+		}
+		if found && why != "" {
 			if bare, err := membership.BareGrantsMembership(was); err == nil {
 				if body, err := json.Marshal(ms[key].Membership); err == nil {
 					if grown, kept, err := UnionMembership(bare, body); err == nil && len(kept) > 0 {
diff --git a/modules/mesh-grants/internal/grants/records.go b/modules/mesh-grants/internal/grants/records.go
index 06e674f9..b82f4dd1 100644
--- a/modules/mesh-grants/internal/grants/records.go
+++ b/modules/mesh-grants/internal/grants/records.go
@@ -448,10 +448,7 @@ func holdersAfterPass(in Inputs) ([]catalogue.Held, []Gap) {
 	var assignments []catalogue.Assignment
 	for _, node := range slices.Sorted(maps.Keys(in.Assigned)) {
 		for _, module := range in.Assigned[node] {
-			m, ok := in.Had[node+"."+module]
-			if !ok {
-				m, ok = in.Running[node+"."+module]
-			}
+			m, ok := in.Running[node+"."+module]
 			if !ok {
 				m, ok = in.Manifests[module]
 			}