diff --git a/fedac/native/scripts/flash-mac.sh b/fedac/native/scripts/flash-mac.sh
index 737fc8a088..2d31ece438 100755
--- a/fedac/native/scripts/flash-mac.sh
+++ b/fedac/native/scripts/flash-mac.sh
@@ -453,6 +453,16 @@ mount_fat() {  # $1=partition device  $2=mount point
     mount_msdos "$1" "$2"
 }
 log "Mounting partitions…"
+# macOS 26+ no longer loads the msdosfs kext (mount_msdos fails with "msdos
+# filesystem is not available"); FAT is mounted by a userland driver that
+# diskutil knows how to reach. diskutil mount also works on older releases.
+mount_fat() {
+    local part="$1" mnt="$2"
+    diskutil unmount "${part}" >/dev/null 2>&1 || true
+    diskutil mount -mountPoint "${mnt}" "${part}" >/dev/null \
+        || mount_msdos "${part}" "${mnt}" \
+        || die "Could not mount ${part} at ${mnt}"
+}
 mount_fat "${P1}" "${M1}"
 mount_fat "${P2}" "${M2}"
 
@@ -463,11 +473,12 @@ cp "${KERNEL}"   "${M1}/EFI/BOOT/BOOTX64.EFI"
 cp "${INITRAMFS}" "${M1}/initramfs.cpio.gz"
 # Boot piece: aesel by default (the Claude session that writes pieces this
 # machine runs). Override per-flash with AC_BOOT_PIECE (e.g.
-# AC_BOOT_PIECE=notepat flash-mac.sh ...). The kernel resolves the name to
-# /pieces/<piece>.mjs at boot — see the "Boot piece from config" block in
-# ac-native.c. Devices already flashed keep whatever piece their
-# /mnt/config.json names.
-BOOT_PIECE="${AC_BOOT_PIECE:-aesel}"
+# AC_BOOT_PIECE=notepat flash-mac.sh ...) or with usbConfig.piece in the
+# inscription. The kernel resolves the name to /pieces/<piece>.mjs at boot —
+# see the "Boot piece from config" block in ac-native.c. Devices already
+# flashed keep whatever piece their /mnt/config.json names.
+INSCRIBED_PIECE=$(node -e 'try { const c=JSON.parse(require("fs").readFileSync(process.argv[1],"utf8")).usbConfig||{}; if (typeof c.piece === "string" && /^[a-z0-9-]+$/.test(c.piece)) process.stdout.write(c.piece); } catch {}' "${INSCRIPTION_FILE}")
+BOOT_PIECE="${AC_BOOT_PIECE:-${INSCRIBED_PIECE:-aesel}}"
 
 # Write a device config.json. Base identity fields come from the shell vars
 # (set from the inscription OR the legacy API path); the boot-personalization
@@ -485,7 +496,8 @@ write_device_config() {  # $1=dest  $2=udp(1=include udpMidiBroadcast)
             if (c.city) cfg.city = c.city;
             if (Array.isArray(c.colors) && c.colors.length) cfg.colors = c.colors;
             if (c.mood) cfg.mood = c.mood;
-            if (c.mono) cfg.mono = true;
+            if (typeof c.mono === "boolean") cfg.mono = c.mono;
+            if (["left", "right", "both"].includes(c.monoOutput)) cfg.monoOutput = c.monoOutput;
         } catch (e) { /* no inscription (anon/legacy) — base fields only */ }
         fs.writeFileSync(dest, JSON.stringify(cfg) + "\n");
     ' "$1" "${USER_HANDLE}" "${BOOT_PIECE}" "${USER_SUB}" "${USER_EMAIL}" "$2" "${INSCRIPTION_FILE}"
diff --git a/fedac/native/scripts/flash-usbs.sh b/fedac/native/scripts/flash-usbs.sh
new file mode 100755
index 0000000000..9d2f8616ac
--- /dev/null
+++ b/fedac/native/scripts/flash-usbs.sh
@@ -0,0 +1,40 @@
+#!/bin/bash
+# flash-usbs.sh — flash every attached external physical disk with the cached
+# AC OS release in /tmp/ac-os-pull. Dry run by default: lists the disks it
+# would WIPE. Pass --go to flash them all, one after another.
+# Disks over 256 GB are skipped unless --big is also passed (backup-drive guard).
+set -uo pipefail
+SRC=/tmp/ac-os-pull
+FLASH=/Users/jas/aesthetic-computer/fedac/native/scripts/flash-mac.sh
+LOG="${LOG:-$HOME/.ac-os/flash-six.log}"
+mkdir -p "$(dirname "$LOG")"
+GO=0; BIG=0
+for a in "$@"; do [ "$a" = "--go" ] && GO=1; [ "$a" = "--big" ] && BIG=1; done
+[ -f "$SRC/vmlinuz" ] && [ -f "$SRC/initramfs.cpio.gz" ] || { echo "cache missing in $SRC — run: ac-os pull"; exit 1; }
+DISKS=$(diskutil list external physical 2>/dev/null | awk '/^\/dev\/disk/{print $1}')
+[ -z "$DISKS" ] && { echo "no external disks attached"; exit 1; }
+TARGETS=()
+for d in $DISKS; do
+  info=$(diskutil info "$d")
+  name=$(echo "$info" | awk -F': *' '/Device \/ Media Name/{print $2}')
+  bytes=$(echo "$info" | awk -F'[()]' '/Disk Size/{print $2}' | awk '{print $1}')
+  gb=$(( ${bytes:-0} / 1000000000 ))
+  removable=$(echo "$info" | awk -F': *' '/Removable Media/{print $2}')
+  vols=$(diskutil list "$d" | awk 'NR>2 && $NF ~ /disk/ {print $(NF-3)}' | tr '\n' ',' | sed 's/,$//')
+  flag=""
+  if [ "$gb" -gt 256 ] && [ "$BIG" -ne 1 ]; then flag="  SKIP (>256 GB, pass --big)"; else TARGETS+=("$d"); fi
+  printf '%-12s %-28s %5s GB  removable=%-3s vols=%s%s\n' "$d" "$name" "$gb" "$removable" "$vols" "$flag"
+done
+[ "$GO" -eq 1 ] || { echo; echo "dry run — pass --go to ERASE and flash the ${#TARGETS[@]} disk(s) above"; exit 0; }
+ok=0; bad=0
+for d in "${TARGETS[@]}"; do
+  echo; echo "=== $(date '+%H:%M:%S') flashing $d"
+  if sudo "$FLASH" "$d" "$SRC" >>"$LOG" 2>&1; then
+    echo "$(date '+%H:%M:%S') DONE $d"; ok=$((ok+1))
+    echo "$(date -u +%FT%TZ) DONE $d" >> "$LOG"
+  else
+    echo "$(date '+%H:%M:%S') FAILED $d — see $LOG"; bad=$((bad+1)); tail -8 "$LOG"
+  fi
+done
+echo; echo "flashed $ok, failed $bad, log: $LOG"
+[ "$bad" -eq 0 ]