diff --git a/full-ai-cluster/usb-nixos-installer/nixos/installer/configuration.nix b/full-ai-cluster/usb-nixos-installer/nixos/installer/configuration.nix
index 7748cf644a..4b0b5bd39b 100644
--- a/full-ai-cluster/usb-nixos-installer/nixos/installer/configuration.nix
+++ b/full-ai-cluster/usb-nixos-installer/nixos/installer/configuration.nix
@@ -16,6 +16,19 @@
   time.timeZone = "America/New_York";
   i18n.defaultLocale = "en_US.UTF-8";
 
+  # B-0754 iter-3 hardware-firmware cleanup: enable redistributable
+  # firmware on the installer (Intel SoF / linux-firmware). Without
+  # this, modern Intel chipsets (Meteor Lake / Lunar Lake / Arrow
+  # Lake) print scary `ASoC: failed to instantiate card -2` /
+  # `snd_soc_register_card failed -2` errors during boot because
+  # their HD Audio Controller probes a SoundWire codec topology that
+  # needs SoF firmware blobs. Cosmetic — audio is not load-bearing
+  # for cluster substrate — but per B-0759 first-time-CLI-user
+  # persona, scary 'ERROR' lines in dmesg are UX noise we don't
+  # need. Redistributable-only (no allowUnfree needed); ~80MB
+  # added to ISO; covers WiFi/BT/NIC firmware too as a side benefit.
+  hardware.enableRedistributableFirmware = true;
+
   nix.settings = {
     experimental-features = [ "nix-command" "flakes" ];
     auto-optimise-store = true;
diff --git a/full-ai-cluster/usb-nixos-installer/zeta-install.sh b/full-ai-cluster/usb-nixos-installer/zeta-install.sh
index 7681a762f2..752a440a89 100755
--- a/full-ai-cluster/usb-nixos-installer/zeta-install.sh
+++ b/full-ai-cluster/usb-nixos-installer/zeta-install.sh
@@ -162,7 +162,23 @@ for d in "${DATA_DISKS[@]}"; do
   i=$((i + 1))
 done
 
-sudo partprobe
+# Per-device partprobe: bare `partprobe` (no args) probes EVERY
+# block device the kernel knows about, including the USB stick we
+# booted from (kernel typically exposes USB mass-storage as
+# /dev/sdX — commonly /dev/sda on boards with no SATA disks; the
+# specific letter isn't guaranteed across hardware/boot order, but
+# the failure mode is the same regardless of letter). The booted
+# ISO has mounted partitions on that sdX device; partprobe rightfully
+# refuses to refresh those + returns non-zero; `set -euo pipefail`
+# then bails the whole install. Fix per B-0754 iter-3 empirical
+# anchor: pass only the disks WE just partitioned, with an explicit
+# per-disk failure handler so the abort message names the offending
+# disk + suggests next steps (vs silent set -euo pipefail bail).
+echo "Refreshing kernel partition table for installed disks ..."
+sudo partprobe "$BOOT_DISK" || bail "partprobe failed for BOOT disk $BOOT_DISK — check 'dmesg | tail' for kernel detail; manual recovery: 'sudo partprobe $BOOT_DISK' then 'lsblk' to verify partition table"
+for d in "${DATA_DISKS[@]}"; do
+  sudo partprobe "$d" || bail "partprobe failed for DATA disk $d — check 'dmesg | tail'; manual recovery: 'sudo partprobe $d' then 'lsblk' to verify partition table"
+done
 sleep 2
 
 # ── Step 5: format + mount ────────────────────────────────────────