diff --git a/.github/workflows/qualify-secure-runtime-release.yml b/.github/workflows/qualify-secure-runtime-release.yml
index d0fcc1a2dd..348c337f31 100644
--- a/.github/workflows/qualify-secure-runtime-release.yml
+++ b/.github/workflows/qualify-secure-runtime-release.yml
@@ -224,7 +224,7 @@ jobs:
           COPY --from=dind /usr/local/bin/ /usr/local/bin/
           COPY pulse-qualification-docker.service /etc/systemd/system/pulse-qualification-docker.service
           RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
-                ca-certificates curl dbus systemd systemd-sysv util-linux && \
+                ca-certificates curl dbus systemd systemd-sysv util-linux iproute2 && \
               apt-get clean && \
               systemctl mask dev-hugepages.mount sys-fs-fuse-connections.mount systemd-remount-fs.service docker.service docker.socket && \
               systemctl enable pulse-qualification-docker.service
@@ -269,7 +269,19 @@ jobs:
             sleep 2
           done
           docker exec "${container}" sh -c \
-            'for command in curl docker dockerd id nsenter runuser systemctl; do command -v "$command" >/dev/null || exit 1; done'
+            'for command in curl docker dockerd id ip nsenter runuser systemctl; do command -v "$command" >/dev/null || exit 1; done'
+          # The immutable RC test needs a reachable non-loopback host-interface
+          # canary to prove that the helper's private network cannot reach it.
+          # Both veth ends stay inside this --network none namespace; neither
+          # endpoint is attached to the runner or an egress bridge.
+          docker exec "${container}" sh -ceu '
+            ip link add pulse-can0 type veth peer name pulse-can1
+            ip address add 192.0.2.1/32 dev pulse-can0
+            ip link set pulse-can1 up
+            ip link set pulse-can0 up
+            test -z "$(ip -4 route show default)"
+            ip -4 address show dev pulse-can0 | grep -F "192.0.2.1/32"
+          '
           docker exec "${container}" systemctl start pulse-qualification-docker.service
           for attempt in $(seq 1 60); do
             if docker exec "${container}" docker info >/dev/null 2>&1; then
diff --git a/docs/release-control/v6/internal/subsystems/deployment-installability.md b/docs/release-control/v6/internal/subsystems/deployment-installability.md
index 2dc44f5b9f..59716371ea 100644
--- a/docs/release-control/v6/internal/subsystems/deployment-installability.md
+++ b/docs/release-control/v6/internal/subsystems/deployment-installability.md
@@ -1239,6 +1239,14 @@ artifact-selection behaviour.
    privileged systemd container must mount that exact snapshot read-only and
    must never execute directly from the download directory. The post-run
    attester must consume the same snapshot paths.
+   The outer systemd qualification container must retain `--network none`:
+   it may create a non-loopback host-interface canary only as a veth pair
+   wholly inside that container's network namespace, with no runner bridge,
+   egress attachment, or default IPv4 route. The immutable RC lab uses this
+   reachable local canary to distinguish host-network access from the typed
+   helper's private network isolation. Canary setup and the no-default-route
+   check must fail qualification before that lab if the boundary is absent;
+   they must not skip the lab or change the release packet under test.
    PVE jobs must consume their runner users' persistent local Go and npm caches
    directly; disposable-runner Actions cache restore/save phases must remain
    disabled because archiving those same caches adds network work after the
diff --git a/scripts/installtests/build_release_assets_test.go b/scripts/installtests/build_release_assets_test.go
index 05b87acc70..03ecfb81e0 100644
--- a/scripts/installtests/build_release_assets_test.go
+++ b/scripts/installtests/build_release_assets_test.go
@@ -2847,12 +2847,15 @@ func TestSecureRuntimeQualificationPacketIsHostedAndReleaseBound(t *testing.T) {
 		`git remote set-url origin https://github.com/rcourtman/Pulse.git`,
 		"ca-certificates curl dbus systemd systemd-sysv util-linux",
 		`docker:27.5.1-dind@sha256:f649ef046008ca7f926a2571c32b0ac22e5c59eb61b959617f9acc2a4c638cf5`,
-		`for command in curl docker dockerd id nsenter runuser systemctl`,
+		`for command in curl docker dockerd id ip nsenter runuser systemctl`,
 		`--host=unix:///var/run/docker.sock`,
 		`--storage-driver=vfs`,
 		`--bridge=none`,
 		`--iptables=false`,
 		`--network none`,
+		`ip link add pulse-can0 type veth peer name pulse-can1`,
+		`ip address add 192.0.2.1/32 dev pulse-can0`,
+		`test -z "$(ip -4 route show default)"`,
 		`pulse-secure-runtime-fixture:v7`,
 		"--verify-release-packet-only",
 		"--verified-packet-dir",
@@ -2870,6 +2873,16 @@ func TestSecureRuntimeQualificationPacketIsHostedAndReleaseBound(t *testing.T) {
 			t.Fatalf("post-publication secure-runtime qualification missing %q", required)
 		}
 	}
+	canaryIndex := strings.Index(qualificationWorkflow, `ip link add pulse-can0 type veth peer name pulse-can1`)
+	labIndex := strings.Index(qualificationWorkflow, `--env PULSE_SECURE_RUNTIME_SYSTEMD_LAB=1`)
+	if canaryIndex <= privilegedExecutionIndex || labIndex <= canaryIndex {
+		t.Fatal("the isolated host-interface canary must be configured before running the immutable RC lab")
+	}
+	if !strings.Contains(qualificationWorkflow, `--privileged \
+            --network none \
+            --cgroupns=host`) {
+		t.Fatal("the outer systemd lab must retain its no-network namespace")
+	}
 	for _, forbidden := range []string{
 		`/var/run/docker.sock:/var/run/docker.sock`,
 		`--host=tcp://`,