diff --git a/modules/mesh-build-go/cmd/mesh-build-go/level.go b/modules/mesh-build-go/cmd/mesh-build-go/level.go
index 9043b1db..0b867566 100644
--- a/modules/mesh-build-go/cmd/mesh-build-go/level.go
+++ b/modules/mesh-build-go/cmd/mesh-build-go/level.go
@@ -142,10 +142,15 @@ func (m *Module) nodeToolchains() []string {
 	return []string{dir}
 }
 
-// Has says whether this node has a need a check ask or a package's tests name (issue 890; mesh-sdk delivery.AskNeeds),
-// read from the node itself at every ask: node-build-node when the Node build module's toolchains directory holds an
-// installed toolchain this account may read, given to the integration level as nodeToolchains gives it, and node and npm
-// are installed, as mesh-build-node's integration tests look for them before they run. Any other need it lacks.
+// nodeToolchainMark is the file the Node build module writes in a toolchain directory once it is installed whole
+// (mesh-build-node toolchain.go installedMark).
+const nodeToolchainMark = ".installed"
+
+// Has says whether this node has a need a check ask or a package's tests name (issue 890, ADR 0552; mesh-sdk
+// delivery.AskNeeds), read from the node itself at every ask: node-build-node when the Node build module's toolchains
+// directory, given to the integration level as nodeToolchains gives it, holds a toolchain installed whole (its mark and
+// its package-lock.json readable by this account), and node, npm and bwrap are installed: what mesh-build-node's
+// integration tests (realMachine) look for before they run. Any other need it lacks.
 func (m *Module) Has(need string) bool {
 	if m.HasNeed != nil {
 		return m.HasNeed(need)
@@ -156,15 +161,26 @@ func (m *Module) Has(need string) bool {
 		if len(dirs) == 0 {
 			return false
 		}
-		if entries, err := os.ReadDir(dirs[0]); err != nil || len(entries) == 0 {
-			return false
-		}
-		for _, p := range []string{"node", "npm"} {
+		for _, p := range []string{"node", "npm", "bwrap"} {
 			if _, err := exec.LookPath(p); err != nil {
 				return false
 			}
 		}
-		return true
+		entries, err := os.ReadDir(dirs[0])
+		if err != nil {
+			return false
+		}
+		for _, e := range entries {
+			dir := filepath.Join(dirs[0], e.Name())
+			if _, err := os.Stat(filepath.Join(dir, nodeToolchainMark)); err != nil {
+				continue
+			}
+			if f, err := os.Open(filepath.Join(dir, "package-lock.json")); err == nil {
+				f.Close()
+				return true
+			}
+		}
+		return false
 	}
 	return false
 }
diff --git a/modules/mesh-build-go/cmd/mesh-build-go/node_toolchains_test.go b/modules/mesh-build-go/cmd/mesh-build-go/node_toolchains_test.go
index bd032546..b1ecbe7c 100644
--- a/modules/mesh-build-go/cmd/mesh-build-go/node_toolchains_test.go
+++ b/modules/mesh-build-go/cmd/mesh-build-go/node_toolchains_test.go
@@ -75,7 +75,7 @@ func TestANodeWithoutNodeToolchainsRunsTheLevelWithNothingMoreBound(t *testing.T
 	// Issue 890/AC4: such a node lacks node-build-node; one with an installed toolchain and node and npm has it; nothing
 	// else is had.
 	bin := t.TempDir()
-	for _, p := range []string{"node", "npm"} {
+	for _, p := range []string{"node", "npm", "bwrap"} {
 		if err := os.WriteFile(filepath.Join(bin, p), []byte("#!/bin/sh\n"), 0o755); err != nil {
 			t.Fatal(err)
 		}
@@ -90,15 +90,27 @@ func TestANodeWithoutNodeToolchainsRunsTheLevelWithNothingMoreBound(t *testing.T
 	if m.Has(delivery.NeedNodeBuildNode) {
 		t.Error("a node with an empty toolchains directory has node-build-node")
 	}
-	if err := os.Mkdir(filepath.Join(installed, "0.1.0"), 0o755); err != nil {
+	half := filepath.Join(installed, "0.1.0")
+	if err := os.Mkdir(half, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(half, "package-lock.json"), []byte("{}"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if m.Has(delivery.NeedNodeBuildNode) {
+		t.Error("a toolchain without its installed mark counts")
+	}
+	if err := os.WriteFile(filepath.Join(half, nodeToolchainMark), nil, 0o644); err != nil {
 		t.Fatal(err)
 	}
 	if !m.Has(delivery.NeedNodeBuildNode) || m.Has("gpu") {
 		t.Errorf("with a toolchain installed: node-build-node %v, gpu %v; want true, false", m.Has(delivery.NeedNodeBuildNode), m.Has("gpu"))
 	}
-	t.Setenv("PATH", t.TempDir())
+	if err := os.Remove(filepath.Join(bin, "bwrap")); err != nil {
+		t.Fatal(err)
+	}
 	if m.Has(delivery.NeedNodeBuildNode) {
-		t.Error("a node with no node installed has node-build-node")
+		t.Error("a node with no bubblewrap installed has node-build-node")
 	}
 }
 
diff --git a/modules/mesh-build-go/go.mod b/modules/mesh-build-go/go.mod
index d44cc621..b2f31200 100644
--- a/modules/mesh-build-go/go.mod
+++ b/modules/mesh-build-go/go.mod
@@ -3,7 +3,7 @@ module meshbuildgo
 go 1.26.0
 
 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026123512-bb713103371a
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026130105-45564e69a648
 	github.com/distribution/distribution/v3 v3.1.2
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0
diff --git a/modules/mesh-build-go/go.sum b/modules/mesh-build-go/go.sum
index 5c5c5ca0..88077cab 100644
--- a/modules/mesh-build-go/go.sum
+++ b/modules/mesh-build-go/go.sum
@@ -2,6 +2,8 @@ git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026095702-79649c3fa9f4 h1:05sVel/U
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026095702-79649c3fa9f4/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026123512-bb713103371a h1:ZxKOtc8LusZEEpbbu41lYxJiaITN8lZCIcasA5kdgGQ=
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026123512-bb713103371a/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026130105-45564e69a648 h1:UUhWHYnaTJwgkgoYhQtJrm+r5S5UNAQ4DRMlt4x21Hg=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026130105-45564e69a648/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/alicebob/miniredis/v2 v2.35.0 h1:QwLphYqCEAo1eu1TqPRN2jgVMPBweeQcR21jeqDCONI=
 github.com/alicebob/miniredis/v2 v2.35.0/go.mod h1:TcL7YfarKPGDAthEtl5NBeHZfeUQj6OXMm/+iu5cLMM=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=