diff --git a/tests/smoke-rootfs.sh b/tests/smoke-rootfs.sh
new file mode 100755
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--- /dev/null
+++ b/tests/smoke-rootfs.sh
@@ -0,0 +1,99 @@
+#!/usr/bin/env bash
+# Per-flavor rootfs smoke test (NAROS.md §10.3).
+#
+#   smoke-rootfs.sh <flavor> <image> <arch>
+#
+# <flavor> is the build-rootfs.sh tier: base | vm | vm-desktop.
+# <image>  is an ALREADY-IMPORTED docker image (the caller runs `docker import` on the
+#          tarball, because it usually wants the named image for later steps too).
+# <arch>   amd64 | arm64 — passed to --platform.
+#
+# Assertions run inside the image under nash. They live here rather than inline in
+# naros.yml because the vm and vm-desktop jobs are one matrix over a single set of steps:
+# the flavors differ ONLY in what is asserted, and inlining that difference is what forced
+# the two near-identical jobs the matrix replaced.
+#
+# Exit: 0 all assertions hold, non-zero on the first failure (the container shell is `set -e`).
+set -euo pipefail
+
+FLAVOR="${1:?usage: smoke-rootfs.sh <flavor> <image> <arch>}"
+IMAGE="${2:?missing image}"
+ARCH="${3:?missing arch}"
+
+run() { docker run --rm --platform "linux/$ARCH" "$IMAGE" /usr/bin/nash -lc "$1"; }
+
+# Sourced by every flavor: narOS identity plus the forced-nash /bin/sh with the real bash kept
+# aside. Leaves os-release variables ($VARIANT_ID, $VERSION_ID) in scope for the flavor blocks.
+COMMON='
+  set -e
+  . /etc/os-release; test "$ID" = naros
+  readlink /bin/sh | grep -q nash
+  test -x /usr/bin/bash.real
+'
+
+# A runtime-clean sources.list (no build-time copy:// pool left in), scoped away from
+# sources.list.d so the not-yet-live hosted-repo entry (naros-keyring) cannot fail this
+# before the apt domain is provisioned.
+APT_CLEAN='
+  apt-get update -q -o Dir::Etc::SourceParts=-
+'
+
+case "$FLAVOR" in
+  base)
+    echo "smoke: base rootfs ($ARCH)"
+    run "$COMMON"'
+      naros version
+      naros info --json > /dev/null
+      # Kernel identity shim (NAROS.md §2.3). Every command in this smoke test already runs
+      # under the global preload, so a broken .so fails the job long before here; these assert
+      # the tag is actually applied and correctly scoped.
+      grep -qxF /usr/lib/naros/libnaros-uname.so /etc/ld.so.preload
+      # VERSION_ID comes from the os-release sourced above.
+      uname -r | grep -q -- "-naros$VERSION_ID"
+      # sysname must stay "Linux" — build tooling switches on it.
+      test "$(uname -s)" = Linux
+      # The escape hatch /lib/modules consumers depend on must really bypass. Compare against
+      # procfs, which the shim cannot touch (a file read, not a syscall).
+      test "$(NAROS_UNAME_PASSTHROUGH=1 uname -r)" = "$(cat /proc/sys/kernel/osrelease)"
+    '"$APT_CLEAN"
+    ;;
+
+  vm)
+    echo "smoke: vm rootfs — identity + forced shell + systemd present ($ARCH)"
+    # nash directly (systemd is PID 1 only under a real boot); assert the bootable base is sane.
+    run "$COMMON"'
+      test "$VARIANT_ID" = vm
+      test -x /usr/lib/systemd/systemd || test -x /lib/systemd/systemd
+      command -v systemctl > /dev/null
+      naros version
+      # The control-plane agent IS baked (from the local pool): it is the only way the host can
+      # reach the guest, and the phase-1 bootstrap no longer overlays a GHCR copy on top. The
+      # rest of the tier still arrives at firstboot via `apt install naros-tier-vm`.
+      test -x /usr/local/bin/nucleic-linux-agent
+      test -L /etc/systemd/system/multi-user.target.wants/nucleic-linux-agent.service
+    '"$APT_CLEAN"
+    ;;
+
+  vm-desktop)
+    echo "smoke: vm-desktop rootfs — GNOME 50 + agent user + semantic surface ($ARCH)"
+    run "$COMMON"'
+      test "$VARIANT_ID" = vm
+      naros info --json | jq -e ".variant == \"vm\" and .flavor == \"desktop\"" > /dev/null
+      test "$(id -u agent)" = 501
+      test -x /usr/lib/systemd/systemd || test -x /lib/systemd/systemd
+      command -v gnome-shell > /dev/null
+      gnome-shell --version | grep -qE "GNOME Shell 5[0-9]"
+      command -v gdm3 > /dev/null || test -x /usr/sbin/gdm3
+      test -x /usr/local/bin/nucleic-a11y-agent
+      test -x /usr/local/bin/nucleic-linux-agent
+      test -f /usr/share/gnome-shell/extensions/nucleic-geometry@nucleic.xyz/metadata.json
+      grep -q "AutomaticLogin=agent" /etc/gdm3/daemon.conf'
+    ;;
+
+  *)
+    echo "unknown flavor: $FLAVOR (expected base, vm, or vm-desktop)" >&2
+    exit 2
+    ;;
+esac
+
+echo "smoke OK ($FLAVOR/$ARCH)"