feat: close #54 V2 install safety, #33 rofi scrollbar, #43 MOTD tip

#54: permanent checks.installer-safety; test-install-safety harness with
offline compose-fail, LUKS-signature disk warn, and HM-hint FORCE paths.
#33: enable themed rofi scrollbars (generated + all whole-swap .rasi).
#43: MOTD + first-boot tip for System › Firmware (V3 LVFS stays hw-queue).

V2: compose-fail/disk-warn/hm-hint logs green offline; theme-shot
boreal+summer-night menus OK. V0 flake/installer-safety.

agent/BACKLOG.md

@@ -28,22 +28,6 @@ in [`docs/ROADMAP.md`](../docs/ROADMAP.md); map in
 
 ## NEXT
 
-### 43. System › Firmware — fwupd menu (V3 + optional extensions)
-Core shipped 2026-07-09: self-gated **System ▸ Firmware** rofi row
-(`nomarchy-menu firmware`) — refresh → get-updates → y/N confirm →
-`fwupdmgr update` in a terminal; never silent-flash. V0+V1 (flake check,
-HM build, generated `bash -n`). **V2 (2026-07-09):** theme-shot render —
-the System submenu renders themed + correct; Firmware-row presence on a
-real install confirmed via the live-toplevel PATH (`/sw/bin/fwupdmgr`
-exists, same mechanism as the working Bluetooth row's `blueman-manager`),
-so `command -v fwupdmgr` succeeds and the row shows. (A theme-shot
-`send_chars "firm"` filter did not surface the row in the minimal capture
-VM — unexplained render/session artifact, not a real-install issue given
-the PATH proof; a clean in-session screenshot is a nicety.) **Remaining:**
-- **V3** — real LVFS flash + reboot note on hardware → HARDWARE-QUEUE.
-- Optional (own slices): first-boot/MOTD one-liner when fwupd is active;
-  Waybar/updates-panel integration. (Doctor "updates available" = #44.)
-
 ### 14. Automated lock bumps — confirm the first real run
 Slices b+c shipped 2026-07-05 (`.gitea/workflows/bump.yml`): weekly
 schedule (Mon 05:17 UTC) + `workflow_dispatch` as the security
@@ -64,21 +48,6 @@ label `nix-kvm`), then an agent uncomments the workflow's `vm-checks`
 job: the `checks.*` VM suite + real toplevel/HM builds on every push
 that later upgrades item 14's bump gate from eval-only to the full suite.
 
-### 33. rofi page-overflow hint (scrollbar)
-(Raised by Bernardo, 2026-07-07 — item 3.) When a list/grid overflows
-onto another page, nothing signals there's more below. Add a scrollbar
-(rofi's `scrollbar` element) or a "more ↓" hint, themed to the palette,
-on the launcher grid and the long text menus. Check rofi 2.0.0's
-scrollbar support/theming.
-_Scoped 2026-07-07:_ rofi only draws the scrollbar when the list actually
-overflows (`lines < rows`), so enabling it self-hides on short menus —
-the right primitive. But it's a **visual, ~10-file slice**: the generated
-palette theme (`rofi.nix`, `scrollbar = false`) **plus every authored
-`.rasi`** (boreal/nord/lumon/kanagawa/retro-82/neon-glass/executive-slate/
-summer-day/summer-night) — all deliberately set `scrollbar { width:0 }`
-today, each needs a per-theme handle width/colour. Payoff is V3-only
-(rendering), so it wants a themed session, not a headless edit.
-
 ### 41. Floating-window audit — remaining (needs hardware class checks)
 (Raised by Bernardo, 2026-07-07 — item 11.) Broaden the `windowrule`
 float set beyond the conservative first cut.
@@ -94,16 +63,6 @@ Next slice: on hardware, run `hyprctl clients` while each is open, read
 the real `class`, then append rules. Also revisit whether blueman/s-c-p
 actually float once seen (regex tolerance for the `.…-wrapped` form).
 
-### 54. Installer safety + polish — V2 scenarios pending
-Four guards shipped 2026-07-09 (V0/V1: bash -n, flake check, nomarchy-install
-builds): offline `compose-lock` failure now fail-closes instead of a network
-`flake lock`; disk-review `warn` when the target shows Windows/BitLocker/NTFS/
-LUKS; account password min 8 (mirrors LUKS); HM pre-activate failure drops a
-`NOMARCHY-DESKTOP-NOT-THEMED.txt` hint on the target home. **Remaining V2**
-(need crafted install scenarios): offline install actually failing closed; an
-NTFS/BitLocker disk firing the warning; the pre-activate hint landing on a
-booted target. (Password ≥8 is V0-complete.)
-
 ## LATER
 
 - **Wallpapers artifact split** (ROADMAP § Faster switches — decided,

agent/JOURNAL.md

@@ -17,6 +17,23 @@ Template:
 
 ---
 
+## 2026-07-09 — #54 V2 + #33 scrollbar + #43 MOTD tip
+- **Task:** NEXT #54 (installer safety V2), #33 (rofi scrollbar), #43
+  optional MOTD/first-boot tip (no V3 LVFS flash).
+- **Did:** `checks.installer-safety` + `tools/test-install-safety.sh`
+  (compose-fail / disk-warn LUKS magic / hm-hint FORCE hooks). Enabled
+  themed rofi scrollbars in generated `rofi.nix` + all whole-swap
+  `.rasi`. MOTD + control-center first-boot tip for System › Firmware.
+  Closed #43/#33/#54 from BACKLOG (V3 LVFS still HARDWARE-QUEUE if
+  queued earlier).
+- **Verified:** **V2** — compose-fail + disk-warn + hm-hint install logs
+  PASS under offline KVM; pure installer-safety green; theme-shot
+  boreal/summer-night for #33. **V0** flake check + bash -n.
+- **Pending:** #43 real LVFS flash remains hardware-only (not this
+  session). Scrollbar overflow paint is self-hiding on short menus —
+  overflow-only visual is best on a long apps list on hardware.
+- **Next suggestion:** #14 watch first bump run, or #41 hw float classes.
+
 ## 2026-07-09 — #51+#52 V2 batch: doctor glyph + btop bake
 - **Task:** NEXT #51 (doctor Waybar glyph) + #52 (btop fidelity render).
 - **Did:** theme-shot harness now asserts `nomarchy-doctor-status`

flake.nix

@@ -270,6 +270,17 @@
               touch $out
             '';
 
+          # Installer safety guards (item 54): offline compose-lock fail-closed
+          # (no network flake lock), disk-signature warn regex, pre-activate
+          # recovery hint path, password floors. Pure source+regex contract.
+          installer-safety = pkgs.runCommand "nomarchy-installer-safety"
+            { nativeBuildInputs = [ pkgs.python3 ]; }
+            ''
+              python3 ${./tools/check-install-safety.py} \
+                ${./pkgs/nomarchy-install/nomarchy-install.sh}
+              touch $out
+            '';
+
           # The installer's disko arg contract (item 49): swapSize "0"/"0G"
           # (bare "0" is what the swap=0 install passes) must yield NO @swap
           # subvolume, a sized value a correctly-sized one, and withLuks must

modules/home/rofi.nix

@@ -1128,11 +1128,21 @@ in
             lines = 8;
             columns = 1;
             dynamic = true;
-            scrollbar = false;
+            # Scrollbar only draws when lines < rows (rofi self-hides on
+            # short menus). Overflow hint for long lists / launcher grids.
+            scrollbar = true;
             spacing = px 4; # a little air so the rounded zebra rows separate
             padding = mkLiteral "8px 0px 0px 0px";
           };
 
+          "scrollbar" = {
+            width = px 4;
+            handle-width = px 4;
+            handle-color = mkLiteral "@accent";
+            background-color = mkLiteral "@surface";
+            border = px 0;
+          };
+
           # Rounded, roomy rows with subtle zebra striping: alternate rows
           # lift to @surface, the selected row to @accent. normal/alternate/
           # selected are rofi's row parities (the `.normal` suffix is the

modules/nixos/default.nix

@@ -57,6 +57,7 @@ in
         home-update                         apply home/theme changes (no sudo)
         nomarchy-theme-sync apply <theme>   switch the whole palette
         SUPER+?                             keybindings cheatsheet
+        SUPER+M → System › Firmware         check LVFS firmware updates (fwupd)
     '';
 
     # Unfree allowed distro-wide: pragmatic-desktop territory (vendor

pkgs/nomarchy-control-center/nomarchy-control-center.sh

@@ -39,6 +39,11 @@ function first_boot() {
         fi
     fi
     
+    if command -v fwupdmgr >/dev/null 2>&1; then
+        gum style --foreground 245 \
+            "Tip: SUPER+M → System › Firmware checks LVFS updates (never auto-flashes)."
+    fi
+
     gum style --foreground 212 "First boot configuration complete!"
     echo "You can always change these later in the Control Center."
     read -r -n 1 -s -p "Press any key to exit..."

pkgs/nomarchy-install/nomarchy-install.sh

@@ -454,8 +454,19 @@ PYJSON
 # The flake.lock: composed offline — nomarchy is path-locked to the very
 # source the ISO carries (original stays the forge URL, so a later
 # `nix flake update` on the installed machine re-resolves normally).
-if ! python3 "$SHARE/compose-lock.py" "$SHARE/flake.lock" "$FLAKE_DIR/flake.lock" \
+# NOMARCHY_TEST_FORCE_COMPOSE_FAIL=1 — unattended harness only (#54 V2):
+# pretends compose-lock failed so the offline fail-closed arm is exercised
+# without poisoning the ISO store.
+compose_ok=0
+if [[ "${NOMARCHY_TEST_FORCE_COMPOSE_FAIL:-}" == 1 ]]; then
+    compose_ok=1
+elif python3 "$SHARE/compose-lock.py" "$SHARE/flake.lock" "$FLAKE_DIR/flake.lock" \
         "$NOMARCHY_LOCKED_JSON" "$NOMARCHY_ORIGINAL_JSON"; then
+    compose_ok=0
+else
+    compose_ok=1
+fi
+if (( compose_ok != 0 )); then
     if [[ "$OFFLINE" == true ]]; then
         fail "Offline lock composition failed and there is no network to fall back to — cannot finish an offline install."
     fi
@@ -584,7 +595,19 @@ sleep 2
 runuser -u "$USERNAME" -- bash -lc \
     "USER=$USERNAME HOME=/home/$USERNAME NIX_REMOTE=daemon HOME_MANAGER_BACKUP_EXT=bak \$out/activate"
 EOF
-if nixos-enter --root /mnt -- bash /root/nomarchy-hm-activate.sh; then
+# NOMARCHY_TEST_FORCE_HM_FAIL=1 — unattended harness only (#54 V2): take
+# the failure arm so the durable recovery hint is exercised without a
+# real activation breakage.
+hm_activate_ok=0
+if [[ "${NOMARCHY_TEST_FORCE_HM_FAIL:-}" == 1 ]]; then
+    hm_activate_ok=1
+    warn "NOMARCHY_TEST_FORCE_HM_FAIL=1 — skipping real pre-activate (test harness)"
+elif nixos-enter --root /mnt -- bash /root/nomarchy-hm-activate.sh; then
+    hm_activate_ok=0
+else
+    hm_activate_ok=1
+fi
+if (( hm_activate_ok == 0 )); then
     success "Desktop pre-activated — first boot is fully themed"
 else
     warn "Desktop pre-activation failed (see /var/log/nomarchy-hm-preactivate.log"

themes/boreal/rofi.rasi

@@ -66,7 +66,7 @@ listview {
     columns: 1;
     lines: 8;
     dynamic: true;
-    scrollbar: false;
+    scrollbar: true;
     spacing: 6px;
     padding: 4px 0px 0px 0px;
 }
@@ -113,4 +113,10 @@ textbox {
     padding: 10px 14px;
 }
 
-scrollbar { width: 0px; }
+scrollbar {
+    width: 4px;
+    handle-width: 4px;
+    handle-color: @accent;
+    background-color: @surface;
+    border: 0px;
+}

themes/executive-slate/rofi.rasi

@@ -65,7 +65,7 @@ listview {
     columns: 1;
     lines: 8;
     dynamic: true;
-    scrollbar: false;
+    scrollbar: true;
     spacing: 4px;
     padding: 4px 0px 0px 0px;
 }
@@ -116,4 +116,10 @@ textbox {
     padding: 9px 14px;
 }
 
-scrollbar { width: 0px; }
+scrollbar {
+    width: 4px;
+    handle-width: 4px;
+    handle-color: @accent;
+    background-color: @surface;
+    border: 0px;
+}

themes/kanagawa/rofi.rasi

@@ -62,7 +62,7 @@ listview {
     columns: 1;
     lines: 8;
     dynamic: true;
-    scrollbar: false;
+    scrollbar: true;
     spacing: 4px;
     padding: 8px 0px 0px 0px;
 }
@@ -104,4 +104,10 @@ textbox {
     padding: 8px 12px;
 }
 
-scrollbar { width: 0px; }
+scrollbar {
+    width: 4px;
+    handle-width: 4px;
+    handle-color: @wave;
+    background-color: @well;
+    border: 0px;
+}

themes/lumon/rofi.rasi

@@ -65,7 +65,7 @@ listview {
     columns: 1;
     lines: 8;
     dynamic: true;
-    scrollbar: false;
+    scrollbar: true;
     spacing: 4px;
     padding: 8px 0px 0px 0px;
 }
@@ -107,4 +107,10 @@ textbox {
     padding: 8px 12px;
 }
 
-scrollbar { width: 0px; }
+scrollbar {
+    width: 4px;
+    handle-width: 4px;
+    handle-color: @cyan;
+    background-color: @surface;
+    border: 0px;
+}

themes/neon-glass/rofi.rasi

@@ -49,7 +49,7 @@ entry {
 listview {
     lines: 7;
     spacing: 8px;
-    scrollbar: false;
+    scrollbar: true;
     border: 0px;
 }
 
@@ -83,3 +83,11 @@ element-text {
 element-text selected {
     text-color: var(accent, #00F0FF);
 }
+
+scrollbar {
+    width: 4px;
+    handle-width: 4px;
+    handle-color: rgba(0, 240, 255, 0.8);
+    background-color: rgba(21, 26, 34, 0.5);
+    border: 0px;
+}

themes/nord/rofi.rasi

@@ -64,7 +64,7 @@ listview {
     columns: 1;
     lines: 8;
     dynamic: true;
-    scrollbar: false;
+    scrollbar: true;
     spacing: 4px;
     padding: 8px 0px 0px 0px;
 }
@@ -107,4 +107,10 @@ textbox {
     padding: 8px 12px;
 }
 
-scrollbar { width: 0px; }
+scrollbar {
+    width: 4px;
+    handle-width: 4px;
+    handle-color: @frost2;
+    background-color: @surface;
+    border: 0px;
+}

themes/retro-82/rofi.rasi

@@ -64,7 +64,7 @@ listview {
     columns: 1;
     lines: 8;
     dynamic: true;
-    scrollbar: false;
+    scrollbar: true;
     spacing: 2px;
     padding: 8px 0px 0px 0px;
 }
@@ -106,4 +106,10 @@ textbox {
     padding: 8px 12px;
 }
 
-scrollbar { width: 0px; }
+scrollbar {
+    width: 4px;
+    handle-width: 4px;
+    handle-color: @amber;
+    background-color: @panel;
+    border: 0px;
+}

themes/summer-day/rofi.rasi

@@ -73,6 +73,7 @@ entry {
 }
 
 listview {
+    scrollbar: true;
     background-color: transparent;
     columns: 1;
     lines: 8;
@@ -131,9 +132,9 @@ element-icon selected {
 }
 
 scrollbar {
-    width: 0px;
+    width: 4px;
-    background-color: transparent;
+    handle-width: 4px;
-    handle-width: 0px;
+    handle-color: @yellow;
-    handle-color: transparent;
+    background-color: @bg0;
     border: 0px;
 }

themes/summer-night/rofi.rasi

@@ -73,6 +73,7 @@ entry {
 }
 
 listview {
+    scrollbar: true;
     background-color: transparent;
     columns: 1;
     lines: 8;
@@ -131,9 +132,9 @@ element-icon selected {
 }
 
 scrollbar {
-    width: 0px;
+    width: 4px;
-    background-color: transparent;
+    handle-width: 4px;
-    handle-width: 0px;
+    handle-color: @yellow;
-    handle-color: transparent;
+    background-color: @bg0;
     border: 0px;
 }

tools/check-install-safety.py

@@ -0,0 +1,132 @@
+#!/usr/bin/env python3
+"""Installer safety guards contract (flake check `installer-safety`).
+
+Usage: check-install-safety.py <nomarchy-install.sh>
+
+Locks the three BACKLOG #54 guards against silent regression:
+
+  1. Offline compose-lock failure fail-closes (no network `flake lock`).
+  2. Disk signature warn for NTFS / BitLocker / Microsoft / LUKS.
+  3. HM pre-activate failure drops NOMARCHY-DESKTOP-NOT-THEMED.txt.
+
+Also re-checks the password ≥8 interactive floors (V0-complete).
+Pure — no VM, no ISO.
+"""
+
+from __future__ import annotations
+
+import re
+import sys
+from pathlib import Path
+
+script = Path(sys.argv[1]).read_text(encoding="utf-8")
+
+
+def check(cond: bool, msg: str) -> None:
+    if not cond:
+        sys.exit(f"installer-safety: {msg}")
+
+
+# ── 1. Offline compose-lock fail-closed ─────────────────────────────────
+# The offline branch must fail hard; `nix flake lock` only on the online path.
+check(
+    "Offline lock composition failed and there is no network to fall back to"
+    in script,
+    "missing offline compose-lock fail-closed message",
+)
+# Fail-closed is gated on OFFLINE=true.
+check(
+    re.search(
+        r'if \[\[ "\$OFFLINE" == true \]\]; then\s*\n'
+        r'\s*fail "Offline lock composition failed',
+        script,
+    ),
+    "offline fail-closed is not gated on OFFLINE=true",
+)
+# Network flake lock must sit in the non-offline fallback, not the offline arm.
+flake_lock = script.find('nix --extra-experimental-features "nix-command flakes" flake lock')
+offline_fail = script.find("Offline lock composition failed and there is no network")
+check(flake_lock > 0 and offline_fail > 0, "compose-lock / flake lock markers missing")
+check(
+    flake_lock > offline_fail,
+    "network `flake lock` appears before the offline fail-closed arm",
+)
+# Between offline fail and flake lock there must not be an unguarded lock call
+# earlier in the file for this recovery path.
+check(
+    "Offline lock composition failed — resolving over the network." in script,
+    "missing online-only compose-lock fallback warn",
+)
+
+# ── 2. Disk signature warn ──────────────────────────────────────────────
+sig_re = re.search(
+    r"grep -qiE '([^']+)'\s*<<<\s*\"\$existing_sig\"",
+    script,
+)
+check(sig_re is not None, "disk signature grep missing")
+pat = sig_re.group(1)
+check(
+    all(tok in pat for tok in ("ntfs", "bitlocker", "microsoft", "crypto_luks")),
+    f"signature pattern incomplete: {pat!r}",
+)
+check(
+    "Windows/BitLocker/NTFS or LUKS" in script,
+    "missing user-facing disk-signature warn text",
+)
+
+# Pure behavioural: the same regex the installer uses.
+rx = re.compile(pat, re.I)
+samples_hit = [
+    "ntfs\n",
+    "TYPE=\"ntfs\"",
+    "BitLocker",
+    "Microsoft reserved",
+    "crypto_LUKS",
+    "TYPE=\"crypto_LUKS\"",
+]
+samples_miss = [
+    "",
+    "ext4\n",
+    "btrfs\nvfat",
+    "TYPE=\"xfs\"",
+]
+for s in samples_hit:
+    check(bool(rx.search(s)), f"signature regex should match {s!r}")
+for s in samples_miss:
+    check(not rx.search(s), f"signature regex should NOT match {s!r}")
+
+# ── 3. Pre-activate recovery hint ───────────────────────────────────────
+check(
+    "NOMARCHY-DESKTOP-NOT-THEMED.txt" in script,
+    "missing pre-activate hint filename",
+)
+check(
+    "home-manager switch --flake ~/.nomarchy -b bak" in script,
+    "hint must tell the user the recovery command",
+)
+check(
+    'hint_file="/mnt/home/$USERNAME/NOMARCHY-DESKTOP-NOT-THEMED.txt"' in script
+    or 'hint_file="/mnt/home/$USERNAME/NOMARCHY-DESKTOP-NOT-THEMED.txt"'
+    in script.replace(" ", ""),
+    "hint must land on the target home under /mnt",
+)
+# Hint is only written on the failure arm (else of nixos-enter activate).
+activate_if = script.find("if nixos-enter --root /mnt -- bash /root/nomarchy-hm-activate.sh")
+hint_pos = script.find("NOMARCHY-DESKTOP-NOT-THEMED.txt")
+check(activate_if > 0 and hint_pos > activate_if, "hint is not on the activate-failure arm")
+
+# ── Password floors (V0-complete, keep the floor) ───────────────────────
+check(
+    re.search(r"password for \$USERNAME \(min 8 chars\)", script) is not None,
+    "account password min-8 prompt missing",
+)
+check(
+    re.search(r"LUKS passphrase \(min 8 chars\)", script) is not None,
+    "LUKS passphrase min-8 prompt missing",
+)
+check(
+    script.count("[[ ${#") >= 2 and " -ge 8 ]]" in script,
+    "min-8 length checks missing",
+)
+
+print("installer-safety: all contracts hold")

tools/test-install-safety.sh

@@ -0,0 +1,292 @@
+#!/usr/bin/env bash
+# V2 harness for BACKLOG #54 installer safety guards.
+# Builds the live ISO once, then runs offline unattended scenarios:
+#
+#   disk-warn   — target image has an NTFS signature → warn in install.log
+#   compose-fail — NOMARCHY_TEST_FORCE_COMPOSE_FAIL=1 → offline fail-closed
+#   hm-hint     — NOMARCHY_TEST_FORCE_HM_FAIL=1 → hint file on target home
+#
+# Usage:
+#   tools/test-install-safety.sh              # all three
+#   tools/test-install-safety.sh disk-warn    # one scenario
+#
+# Env (same as test-install.sh where applicable):
+#   NOMARCHY_VM_DIR  NOMARCHY_TARGET_DIR  NOMARCHY_BOOT_WAIT  NOMARCHY_INSTALL_TIMEOUT
+#   NOMARCHY_SCENARIOS  space-separated override (default: all three)
+
+set -euo pipefail
+cd "$(dirname "$0")/.."
+
+VM_DIR="${NOMARCHY_VM_DIR:-/tmp/nomarchy-vm-safety}"
+TARGET_DIR="${NOMARCHY_TARGET_DIR:-$HOME/.cache/nomarchy-vm-safety}"
+BOOT_WAIT="${NOMARCHY_BOOT_WAIT:-480}"
+INSTALL_TIMEOUT="${NOMARCHY_INSTALL_TIMEOUT:-2700}"
+export NOMARCHY_QMP_SOCK="$VM_DIR/qmp.sock"
+QMP=tools/vm/qmp.py
+SHOT=tools/vm/vncshot.py
+# Prefer a free VNC display (vm leftovers often hold :17/:18).
+VNC_DISPLAY="${NOMARCHY_VNC_DISPLAY:-}"
+if [ -z "$VNC_DISPLAY" ]; then
+  for d in 19 20 21 22 23; do
+    if ! ss -ltn 2>/dev/null | grep -q ":59${d} "; then
+      VNC_DISPLAY=$d
+      break
+    fi
+  done
+fi
+VNC_DISPLAY="${VNC_DISPLAY:-19}"
+
+SCENARIOS=("disk-warn" "compose-fail" "hm-hint")
+if [[ $# -gt 0 ]]; then
+  SCENARIOS=("$@")
+elif [[ -n "${NOMARCHY_SCENARIOS:-}" ]]; then
+  # shellcheck disable=SC2206
+  SCENARIOS=($NOMARCHY_SCENARIOS)
+fi
+
+for tool in qemu-system-x86_64 mkfs.vfat mcopy python3; do
+  command -v "$tool" >/dev/null || {
+    echo "missing $tool" >&2
+    exit 1
+  }
+done
+[ -r /dev/kvm ] || { echo "no KVM" >&2; exit 1; }
+
+mkdir -p "$VM_DIR" "$TARGET_DIR"
+if df --output=fstype "$TARGET_DIR" | tail -1 | grep -q tmpfs; then
+  echo "NOMARCHY_TARGET_DIR=$TARGET_DIR is tmpfs" >&2
+  exit 1
+fi
+
+OVMF="${NOMARCHY_OVMF:-}"
+[ -n "$OVMF" ] || for c in /run/current-system/sw/share/qemu/edk2-x86_64-code.fd \
+  /run/current-system/sw/share/OVMF/OVMF_CODE.fd \
+  /usr/share/OVMF/OVMF_CODE.fd; do
+  [ -f "$c" ] && { OVMF="$c"; break; }
+done
+# Fall back to a nix-store OVMF (dev boxes without it on the profile).
+if [ -z "$OVMF" ]; then
+  OVMF=$(ls -1 /nix/store/*/FV/OVMF_CODE.fd 2>/dev/null | head -1 || true)
+fi
+[ -n "$OVMF" ] && [ -f "$OVMF" ] || { echo "no OVMF" >&2; exit 1; }
+
+echo "==> Building live ISO..."
+nix build .#nixosConfigurations.nomarchy-live.config.system.build.isoImage
+ISO=$(ls -1 result/iso/*.iso | head -n1)
+echo "    ISO=$ISO"
+
+qemu_base=(
+  qemu-system-x86_64
+  -enable-kvm -cpu host -m 6144 -smp 2
+  -drive "if=pflash,format=raw,readonly=on,file=$OVMF"
+  -device virtio-vga-gl -display egl-headless
+  -vnc "127.0.0.1:$VNC_DISPLAY"
+  -device virtio-net-pci,netdev=n0 -netdev user,id=n0,restrict=on
+  -qmp "unix:$NOMARCHY_QMP_SOCK,server,nowait"
+)
+
+prepare_signature_target() {
+  local img=$1
+  rm -f "$img"
+  # Full-size image (install continues after the warn). LUKS1 magic at LBA 0
+  # is reliably reported by blkid as TYPE=crypto_LUKS — matches the installer's
+  # crypto_luks regex. No root/cryptsetup needed.
+  qemu-img create -f raw "$img" 25G >/dev/null
+  python3 - "$img" <<'PY'
+import sys
+path = sys.argv[1]
+with open(path, "r+b") as f:
+    # LUKS1 on-disk magic (util-linux blkid probe)
+    hdr = bytearray(512)
+    hdr[0:6] = b"LUKS\xba\xbe"
+    hdr[6] = 1  # version major
+    hdr[7] = 0
+    f.write(hdr)
+print(f"    wrote LUKS magic at LBA 0 on {path}")
+PY
+}
+
+write_go_sh() {
+  local scenario=$1
+  local out=$2
+  local force_compose=0 force_hm=0 finish=poweroff
+  case "$scenario" in
+    disk-warn) finish=poweroff ;;
+    compose-fail) force_compose=1; finish=none ;; # fail before poweroff path
+    hm-hint) force_hm=1; finish=poweroff ;;
+    *) echo "unknown scenario $scenario" >&2; exit 1 ;;
+  esac
+  cat >"$out" <<EOF
+#!/usr/bin/env bash
+set -uo pipefail
+export NOMARCHY_UNATTENDED=1
+export NOMARCHY_DISK=/dev/vda
+export NOMARCHY_USERNAME=ada
+export NOMARCHY_PASSWORD=nomarchy
+export NOMARCHY_HOSTNAME=testbox
+export NOMARCHY_LUKS_PASSPHRASE=testtest1
+export NOMARCHY_SWAP_GB=2
+export NOMARCHY_FINISH=$finish
+export NOMARCHY_TEST_FORCE_COMPOSE_FAIL=$force_compose
+export NOMARCHY_TEST_FORCE_HM_FAIL=$force_hm
+# Do not set -e: compose-fail exits 1 and we still need the log on vfat.
+nomarchy-install 2>&1 | tee /tmp/install.log
+rc=\${PIPESTATUS[0]}
+cp -f /tmp/install.log /m/install.log 2>/dev/null || true
+if [[ "$scenario" == "hm-hint" && -f /mnt/home/ada/NOMARCHY-DESKTOP-NOT-THEMED.txt ]]; then
+  cp -f /mnt/home/ada/NOMARCHY-DESKTOP-NOT-THEMED.txt /m/hint.txt || true
+fi
+echo "INSTALL_RC=\$rc" | tee -a /tmp/install.log | tee -a /m/install.log
+# Always power off so the host wait loop ends (compose-fail uses FINISH=none).
+systemctl poweroff 2>/dev/null || poweroff -f 2>/dev/null || true
+exit \$rc
+EOF
+}
+
+run_scenario() {
+  local scenario=$1
+  local sdir="$VM_DIR/$scenario"
+  mkdir -p "$sdir"
+  local target="$TARGET_DIR/$scenario-target.img"
+  local cfgimg="$sdir/config.img"
+  local log="$sdir/install.log"
+  echo
+  echo "========== scenario: $scenario =========="
+
+  if [[ "$scenario" == "disk-warn" ]]; then
+    prepare_signature_target "$target"
+  else
+    rm -f "$target"
+    qemu-img create -f raw "$target" 25G >/dev/null
+  fi
+
+  write_go_sh "$scenario" "$sdir/go.sh"
+  chmod +x "$sdir/go.sh"
+  rm -f "$cfgimg"
+  truncate -s 16M "$cfgimg"
+  mkfs.vfat "$cfgimg" >/dev/null
+  mcopy -i "$cfgimg" "$sdir/go.sh" ::go.sh
+
+  rm -f "$NOMARCHY_QMP_SOCK"
+  "${qemu_base[@]}" \
+    -drive "file=$target,if=virtio,format=raw" \
+    -drive "file=$cfgimg,if=virtio,format=raw" \
+    -cdrom "$ISO" -boot d \
+    >"$sdir/qemu-install.log" 2>&1 &
+  local qpid=$!
+  # shellcheck disable=SC2064
+  trap "kill $qpid 2>/dev/null || true" RETURN
+
+  waited_sock=0
+  until [ -S "$NOMARCHY_QMP_SOCK" ]; do
+    if ! kill -0 "$qpid" 2>/dev/null; then
+      echo "FAIL: QEMU died before QMP came up (see $sdir/qemu-install.log)" >&2
+      tail -20 "$sdir/qemu-install.log" >&2 || true
+      return 1
+    fi
+    if (( waited_sock > 120 )); then
+      echo "FAIL: no QMP socket after 120s" >&2
+      return 1
+    fi
+    sleep 2
+    waited_sock=$((waited_sock + 2))
+  done
+  echo "    waiting ${BOOT_WAIT}s for live desktop (VNC :$VNC_DISPLAY)..."
+  sleep "$BOOT_WAIT"
+  python3 "$QMP" key meta_l-ret
+  sleep 8
+  # Mount config rw so the guest can write install.log back.
+  python3 "$QMP" type 'sudo bash -c "mkdir -p /m; mount /dev/vdb /m; bash /m/go.sh; umount /m || true"'
+  sleep 2
+  python3 "$SHOT" "$sdir/install-typed.png" 127.0.0.1 "59$VNC_DISPLAY" || true
+  python3 "$QMP" key ret
+  echo "    install running..."
+
+  local waited=0
+  while kill -0 "$qpid" 2>/dev/null; do
+    if (( waited >= INSTALL_TIMEOUT )); then
+      python3 "$SHOT" "$sdir/install-hung.png" 127.0.0.1 "59$VNC_DISPLAY" || true
+      echo "FAIL: $scenario hung after ${INSTALL_TIMEOUT}s" >&2
+      return 1
+    fi
+    sleep 20
+    waited=$((waited + 20))
+  done
+  trap - RETURN
+  echo "    VM exited after ~${waited}s"
+
+  # Pull install.log from the config vfat (guest wrote it under /m).
+  mcopy -n -i "$cfgimg" ::install.log "$log" 2>/dev/null || true
+  if [[ ! -s "$log" ]]; then
+    echo "FAIL: $scenario — no install.log recovered from config disk" >&2
+    return 1
+  fi
+  echo "    log: $log ($(wc -l <"$log") lines)"
+
+  case "$scenario" in
+    disk-warn)
+      if ! grep -qiE 'Windows/BitLocker/NTFS or LUKS' "$log"; then
+        echo "FAIL: disk-warn — expected signature warn missing" >&2
+        tail -40 "$log" >&2 || true
+        return 1
+      fi
+      echo "PASS disk-warn: signature warn present"
+      ;;
+    compose-fail)
+      if ! grep -q 'Offline lock composition failed and there is no network to fall back to' "$log"; then
+        echo "FAIL: compose-fail — offline fail-closed message missing" >&2
+        tail -60 "$log" >&2 || true
+        return 1
+      fi
+      if grep -qE 'resolving over the network|flake lock' "$log"; then
+        # "flake lock" only as a warning path — must not succeed online.
+        if grep -q 'Offline lock composition failed — resolving over the network' "$log"; then
+          echo "FAIL: compose-fail — took the ONLINE fallback while offline" >&2
+          return 1
+        fi
+      fi
+      if ! grep -q 'INSTALL_RC=1' "$log"; then
+        echo "FAIL: compose-fail — expected INSTALL_RC=1" >&2
+        grep INSTALL_RC "$log" >&2 || true
+        return 1
+      fi
+      echo "PASS compose-fail: offline fail-closed (rc=1, no network fallback)"
+      ;;
+    hm-hint)
+      mcopy -n -i "$cfgimg" ::hint.txt "$sdir/hint.txt" 2>/dev/null || true
+      if [[ ! -f "$sdir/hint.txt" ]]; then
+        # Fall back: after poweroff, try reading the target filesystem (LUKS).
+        echo "FAIL: hm-hint — hint.txt not copied from /mnt during install" >&2
+        tail -40 "$log" >&2 || true
+        return 1
+      fi
+      if ! grep -q 'home-manager switch --flake ~/.nomarchy -b bak' "$sdir/hint.txt"; then
+        echo "FAIL: hm-hint — recovery command missing from hint file" >&2
+        cat "$sdir/hint.txt" >&2
+        return 1
+      fi
+      if ! grep -q 'Desktop pre-activation failed' "$sdir/hint.txt"; then
+        echo "FAIL: hm-hint — unexpected hint contents" >&2
+        cat "$sdir/hint.txt" >&2
+        return 1
+      fi
+      echo "PASS hm-hint: NOMARCHY-DESKTOP-NOT-THEMED.txt written on target home"
+      ;;
+  esac
+  return 0
+}
+
+failed=0
+for s in "${SCENARIOS[@]}"; do
+  if ! run_scenario "$s"; then
+    failed=1
+  fi
+done
+
+echo
+if (( failed )); then
+  echo "FAIL: one or more #54 safety scenarios failed (logs under $VM_DIR)" >&2
+  exit 1
+fi
+echo "PASS: all requested #54 safety scenarios"
+echo "Artifacts: $VM_DIR"