diff --git a/.claude/skills/calibration-charge/SKILL.md b/.claude/skills/calibration-charge/SKILL.md
index 2ec26f5..71c9027 100644
--- a/.claude/skills/calibration-charge/SKILL.md
+++ b/.claude/skills/calibration-charge/SKILL.md
@@ -53,18 +53,26 @@ Record and check:
   curve to bulk 56.4 V and holds absorption on its own — exactly the clean termination
   the BMS needs to re-anchor. No flash, no risk. Just monitor §4 and verify §5; skip §3.
   This is the method to default to.
-- **Grid-assist — ADVANCED / UNVALIDATED:** the field flash.py calls
-  `stop_charge_voltage` is really `battery_re_discharge_voltage`; the firmware **NAKs
-  `0`/"Full"** (confirmed 2026-06-24 — both units rejected `BUCD480,000`). The corrected
-  lever raises it 54.0 → 56.0 so grid charges higher, but it may band-oscillate near
-  56 V instead of holding a clean absorption, so it is **not proven** to re-anchor.
-  Only use as a supervised experiment when solar can't reach full and you accept it
-  may not fully work. Needs §3.
+- **Grid-assist — for cloudy days (CORRECT lever, validated 2026-06-25):** force a full
+  grid charge by switching **output priority to SUB**, NOT by touching voltage
+  thresholds. In the everyday SBU mode the inverter won't grid-charge unless the bank is
+  critically low; SUB makes it run loads on grid AND charge the battery to full. Both
+  setters go through lvx-control (all-mode-safe, atomic, no flash). Needs §3.
+  (Do NOT use `re_discharge`/flash.py — firmware NAKs it; see memory
+  `project_lvx6048_grid_charge_lever`.)
 
-## 3. Grid-assist (ADVANCED): apply the calibration profile (USER-CONFIRMED setter change)
-Run `flash.py diff` FIRST and confirm the ONLY change is `stop_charge_voltage 54.0 ->
-56.0` before applying. If any apply NAKs, the cluster is unchanged (flash.py aborts on
-first failure) — fall back to solar-only.
+## 3. Grid-assist: enable grid charging via output priority (USER-CONFIRMED)
+Publish via lvx-control (atomic to both units, no powermon stop):
+```bash
+B=...   # broker creds from ~/.config/powermon/powermon.yaml
+mosquitto_pub ... -t solar/control/lvx6048/charger_priority -m solar_and_utility
+mosquitto_pub ... -t solar/control/lvx6048/output_priority  -m solar_utility_battery   # SUB
+```
+Confirm within ~1 min: `device_mode` -> Hybrid/Line, `line_power_direction` -> input,
+pack current jumps. Verify BOTH units match (output_source_priority) — parallel sync.
+Then run `lib/grid-cal-monitor` (detached) to drive/verify/auto-revert; it reverts
+`output_priority->solar_battery_utility` + `charger_priority->solar_first` on completion
+(trap-guaranteed). Skip §3 entirely for the solar-only method.
 Mirror to BOTH inverters (parallel cluster — mismatched settings throw fault 86).
 `flash.py apply` stops powermon for exclusive USB, so MQTT telemetry pauses briefly.
 ```bash
diff --git a/.claude/skills/lib/grid-cal-monitor b/.claude/skills/lib/grid-cal-monitor
new file mode 100755
index 0000000..2e8046f
--- /dev/null
+++ b/.claude/skills/lib/grid-cal-monitor
@@ -0,0 +1,91 @@
+#!/usr/bin/env bash
+# grid-cal-monitor — supervise a grid-assisted calibration charge to full, then
+# auto-revert the inverter back to normal (battery-priority, solar-only charging).
+#
+# Assumes the operator already set, via lvx-control:
+#   output_priority  = solar_utility_battery  (SUB: grid powers loads + charges batt)
+#   charger_priority = solar_and_utility
+# This script ONLY monitors and then REVERTS those two (POP->solar_battery_utility,
+# PCP->solar_first). It changes nothing else. Reverting is trap-guaranteed on exit.
+#
+# Done = all 6 packs report SoC>=99 (BMS re-anchored), or pack_V>=56.2 with combined
+# current tapered <20A for 2 polls. Safety: abort+revert if any cell>3.60V or temp>45C.
+# Max runtime guard then revert regardless.
+set -uo pipefail
+
+HA="http://10.0.0.41:8123"; TOKEN_FILE="$HOME/.config/ha/token"
+POWERMON_CONF="$HOME/.config/powermon/powermon.yaml"
+CELL_ABORT=3.60; TEMP_ABORT=45; SOC_DONE=99
+VFULL=56.2; ITAPER=20; MAX_HOURS=8; POLL_S=300
+RUNDIR="$HOME/solar-runs"; mkdir -p "$RUNDIR"
+LOG="$RUNDIR/gridcal-$(date +%Y%m%d).log"
+REVERTED=0
+log(){ printf '%s %s\n' "$(date '+%F %T')" "$*" | tee -a "$LOG"; }
+
+read -r BHOST BPORT BUSER BPASS < <(awk '/^[^[:space:]]/{i=0}/^mqttbroker:/{i=1;next} i&&/^[[:space:]]+name:/{h=$2} i&&/^[[:space:]]+port:/{p=$2} i&&/^[[:space:]]+username:/{u=$2} i&&/^[[:space:]]+password:/{w=$2} END{print h,(p?p:1883),u,w}' "$POWERMON_CONF")
+TOKEN="$(cat "$TOKEN_FILE")"
+ha(){ curl -s -H "Authorization: Bearer $TOKEN" "$HA/api/states/$1"; }
+st(){ ha "$1" | python3 -c 'import sys,json
+try:print(json.load(sys.stdin).get("state",""))
+except:print("")'; }
+tc(){ ha "$1" | python3 -c 'import sys,json
+try:
+ d=json.load(sys.stdin);s=float(d["state"]);u=d["attributes"].get("unit_of_measurement","")
+ print(round((s-32)*5/9,1) if "F" in u else round(s,1))
+except:print("")'; }
+P(){ echo "sensor.eg4_lifepower4_lifepower4_${1}_lifepower4_${1}_${2}"; }
+pub(){ mosquitto_pub -h "$BHOST" -p "$BPORT" -u "$BUSER" -P "$BPASS" -t "solar/control/lvx6048/$1" -m "$2"; }
+
+revert(){
+  [ "$REVERTED" = 1 ] && return 0
+  log "REVERT: output_priority->solar_battery_utility, charger_priority->solar_first"
+  pub output_priority solar_battery_utility; sleep 3
+  pub charger_priority solar_first; sleep 8
+  log "REVERT done. live POP=$(st sensor.lvx6048_lvx6048_1_output_source_priority)/$(st sensor.lvx6048_lvx6048_2_output_source_priority) PCP=$(st sensor.lvx6048_lvx6048_1_charger_source_priority)/$(st sensor.lvx6048_lvx6048_2_charger_source_priority)"
+  REVERTED=1
+}
+trap 'revert; log "exit"' EXIT INT TERM
+
+# read packs -> "minSoC maxSoC maxcell maxtemp minV maxV totI ndone"
+read_packs(){
+  local socs=() cells=() temps=() vs=() is=() i s t tmax
+  for i in 1 2 3 4 5 6; do
+    socs+=("$(st "$(P $i soc)")"); cells+=("$(st "$(P $i cell_voltage_max)")")
+    vs+=("$(st "$(P $i pack_voltage)")"); is+=("$(st "$(P $i pack_current)")")
+    tmax=0
+    for s in temperature_pcb temperature_01 temperature_02 temperature_03; do
+      t="$(tc "$(P $i $s)")"; t=${t%.*}; [[ "$t" =~ ^-?[0-9]+$ ]] && [ "$t" -gt "$tmax" ] && tmax=$t
+    done
+    temps+=("$tmax")
+  done
+  python3 - "${socs[*]}" "${cells[*]}" "${temps[*]}" "${vs[*]}" "${is[*]}" <<'PY'
+import sys
+f=lambda a:[float(x) for x in a.split() if x]
+soc,cell,tmp,v,i=map(f,sys.argv[1:6])
+print(f"{min(soc):.0f} {max(soc):.0f} {max(cell):.3f} {max(tmp):.0f} {min(v):.2f} {max(v):.2f} {sum(i):.0f} {len([s for s in soc if s>=99])}")
+PY
+}
+
+log "=== grid-cal-monitor start (auto-revert on full/abort/exit) ==="
+START=$(date +%s); taper_hits=0
+while :; do
+  read MNS MXS MXCELL MXT MNV MXV TOTI NDONE <<<"$(read_packs)"
+  el=$(( ($(date +%s)-START)/60 ))
+  log "[+${el}m] SoC ${MNS}-${MXS}% packs@100=${NDONE}/6 | packV ${MNV}-${MXV} | totI ${TOTI}A | maxcell ${MXCELL}V maxtemp ${MXT}C"
+  # SAFETY
+  if (( $(python3 -c "print(1 if $MXCELL>$CELL_ABORT or $MXT>$TEMP_ABORT else 0)") )); then
+    log "!!! SAFETY ABORT: maxcell ${MXCELL}V / maxtemp ${MXT}C — reverting now"; exit 2; fi
+  # DONE: all re-anchored
+  if [ "$NDONE" = 6 ]; then log "COMPLETE: all 6 packs >=${SOC_DONE}% — re-anchored"; break; fi
+  # DONE backstop: at bulk + tapered for 2 consecutive polls
+  if (( $(python3 -c "print(1 if $MXV>=$VFULL and $TOTI<$ITAPER else 0)") )); then
+    taper_hits=$((taper_hits+1)); log "  (at bulk + tapered, ${taper_hits}/2)"
+    [ "$taper_hits" -ge 2 ] && { log "COMPLETE: bulk reached + current tapered"; break; }
+  else taper_hits=0; fi
+  # TIMEOUT
+  if [ "$el" -ge $((MAX_HOURS*60)) ]; then log "TIMEOUT ${MAX_HOURS}h — reverting at packV ${MXV}"; break; fi
+  sleep "$POLL_S"
+done
+read MNS MXS _ _ _ MXV _ NDONE <<<"$(read_packs)"
+log "RESULT: SoC ${MNS}-${MXS}%, packs@100=${NDONE}/6, packV up to ${MXV}"
+# revert runs via trap
diff --git a/LVX6048/lvx-flash/profiles/eg4-lp4-v2-calibration.yaml b/LVX6048/lvx-flash/profiles/eg4-lp4-v2-calibration.yaml
index f93c5c0..8257869 100644
--- a/LVX6048/lvx-flash/profiles/eg4-lp4-v2-calibration.yaml
+++ b/LVX6048/lvx-flash/profiles/eg4-lp4-v2-calibration.yaml
@@ -7,6 +7,12 @@
 # / high-load stretches the bank may go weeks without a full charge and the coulomb
 # counters drift (e.g. pack 6 read 76% while physically at ~53% on 2026-06-24).
 #
+# !!! DEPRECATED 2026-06-25 — DO NOT USE. The re_discharge lever does not work for
+# grid calibration: firmware NAKs stop_charge_voltage above float (56 > 54), and it's
+# the wrong mechanism anyway. The CORRECT grid-charge lever is output priority -> SUB
+# (solar_utility_battery) via lvx-control — see the calibration-charge skill §3 and
+# memory project_lvx6048_grid_charge_lever. Kept only as a record of the dead end.
+#
 # !!! 2026-06-24 FINDING — grid-assist lever corrected, still UNVALIDATED !!!
 # The original idea (stop_charge_voltage: 0 = "Full") was REJECTED by the firmware:
 # `flash.py apply` got an inverter NAK on `BUCD480,000` on BOTH units (no change made).