say 'WARNING: THE NEXT STAGE DESTROYS ALL DATA ON THE INTERNAL APPLE SSD.'

say "TARGET CONFIRMED: $TARGET $MODEL $BYTES bytes"

say 'Recovery stdin/TTY is restricted, so this explicitly authorized diagnostic uses a guarded countdown instead of read(1).'

say 'Safety gates remain active: target must be internal + physical + APPLE SSD + 0.8-1.3TB + not Recovery root.'

say 'Press Ctrl-C NOW to cancel. Destructive I/O begins automatically after 15 seconds.'

# Identity and root-device checks repeated immediately before destructive I/O.

ORIG_TARGET=$TARGET; ORIG_BYTES=$BYTES; ORIG_MODEL=$MODEL

find_target

[ "$TARGET" = "$ORIG_TARGET" ] || fail 'target changed before destructive stage'

[ "$BYTES" = "$ORIG_BYTES" ] || fail 'target size changed before destructive stage'

[ "$MODEL" = "$ORIG_MODEL" ] || fail 'target model changed before destructive stage'

DISK=$(basename "$TARGET")

RAW="/dev/r$DISK"; [ -e "$RAW" ] || RAW="$TARGET"

ROOTDEV=$(df / 2>/dev/null | awk 'NR==2{print $1}')

case "$ROOTDEV" in *"$DISK"*) fail "refusing: Recovery root appears on target ($ROOTDEV)";; esac

N=15

while [ "$N" -gt 0 ]; do

printf '\rDESTRUCTIVE_START_IN=%02d_seconds Ctrl-C=cancel ' "$N"

sleep 1

N=$((N-1))

done

printf '\n'

# One final identity check after countdown, immediately before unmount/write.

find_target

[ "$TARGET" = "$ORIG_TARGET" ] || fail 'target changed after countdown'

[ "$BYTES" = "$ORIG_BYTES" ] || fail 'target size changed after countdown'

[ "$MODEL" = "$ORIG_MODEL" ] || fail 'target model changed after countdown'

DISK=$(basename "$TARGET")

RAW="/dev/r$DISK"; [ -e "$RAW" ] || RAW="$TARGET"

ROOTDEV=$(df / 2>/dev/null | awk 'NR==2{print $1}')

case "$ROOTDEV" in *"$DISK"*) fail "refusing: Recovery root appears on target ($ROOTDEV)";; esac

say "DESTRUCTIVE_GATE=PASS target=$TARGET model=$MODEL bytes=$BYTES raw=$RAW"

if command -v pmset >/dev/null 2>&1; then pmset -g batt 2>/dev/null | tee -a "$LOG" || true; fi

say 'Keep AC power connected. Do not interrupt unless the Mac hangs or persistent I/O errors appear.'

diskutil unmountDisk force "$TARGET" 2>&1 | tee -a "$LOG"; URC=${PIPESTATUS[0]:-1}

[ "$URC" -eq 0 ] || fail "cannot unmount internal disk rc=$URC"

raw_sequential_scan 'PREWRITE_RAW_SCAN'

PRE_SCAN_IOERR=$SCAN_IOERR

random_4k_scan 'PREWRITE_RANDOM_SCAN'

PRE_RND_IOERR=$RND_IOERR

if [ "$PRE_SCAN_IOERR" -ne 0 ] || [ "$PRE_RND_IOERR" -ne 0 ]; then

err "PREWRITE_ERRORS sequential=$PRE_SCAN_IOERR random=$PRE_RND_IOERR"

err 'Continuing because a destructive diagnostic was explicitly requested; errors remain evidence of storage-path instability.'

fi

write_pattern_pass A

A_WRITE_IOERR=$WRITE_IOERR

verify_pattern_pass A INPROGRESS_A "$BOOT_NOW"

if [ "$A_WRITE_IOERR" -ne 0 ] || [ "$VERIFY_IOERR" -ne 0 ] || [ "$VERIFY_HASHERR" -ne 0 ]; then

fail "PATTERN_A_FAILED write_io=$A_WRITE_IOERR verify_io=$VERIFY_IOERR hash=$VERIFY_HASHERR"

fi

commit_complete_marker A || fail 'cannot commit/verify COMPLETE_A marker'

say 'PATTERN_A_WRITE_VERIFY=PASS'

say 'STAGE=COMPLETE_A'

persist_log_if_possible COMPLETE_A

say 'REBOOT_REQUIRED: restart into Internet Recovery, then run the SAME st.sh command again.'

exit 0