fix(sunsynk): hold-charge keeps Predbat's charge rate

Reverts the power half of c0bc164, which was an over-correction.

Hold-charge - a charge window whose target is at or below the current SoC -
must not trigger a charge, so grid charge stays off. But the slot should
still carry Predbat's chosen charge rate for that window: only the
behaviour differs, not the power.

c0bc164 made it report zero power so it would classify as a self-use slot
and be written with the inverter's full rating. That discarded the rate
Predbat asked for. Zero is also the freeze encoding, so overloading it as a
classification signal made two opposite meanings share one value at the
same call site.

The grid-charge-off part of that commit was correct and is unchanged; only
the power reverts.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: springfall2008

apps/predbat/sunsynk.py

@@ -648,13 +648,12 @@ def derive_control_state(self, schedule, current_soc):
                 # Zero power IS the freeze: the slot is enabled for grid charge but given no
                 # power, so the battery neither charges nor discharges and simply holds.
                 return {"behaviour": "freeze_charge", "work_mode": SUNSYNK_WORKMODE["zero_export_ct"], "grid_charge": True, "solar_sell": False, "slot_soc": reserve, "power": 0}
-            # The battery is already at or above the requested target, so there is nothing
-            # to charge: this behaves exactly like self-use. Reporting zero power here is
-            # what makes build_tou_slots classify it as a self-use slot, which then writes
-            # the inverter's full power - it does NOT emit a zero-power (frozen) slot. A
-            # non-zero power would classify it as an action slot and needlessly constrain
-            # the battery while it is only being asked not to charge.
-            return {"behaviour": "hold_charge", "work_mode": SUNSYNK_WORKMODE["zero_export_ct"], "grid_charge": False, "solar_sell": False, "slot_soc": reserve, "power": 0}
+            # The battery is already at or above the requested target, so grid charge stays
+            # OFF - the charge is simply not triggered. The slot still carries Predbat's
+            # charge rate, because that is the rate it has chosen for this window; only the
+            # behaviour differs, not the power. Zero here would mean freeze, which is a
+            # different state, and the inverter's full rating would discard Predbat's rate.
+            return {"behaviour": "hold_charge", "work_mode": SUNSYNK_WORKMODE["zero_export_ct"], "grid_charge": False, "solar_sell": False, "slot_soc": reserve, "power": int(charge.get("power", 0))}
 
         return {"behaviour": "idle", "work_mode": SUNSYNK_WORKMODE["zero_export_ct"], "grid_charge": False, "solar_sell": False, "slot_soc": reserve, "power": 0}
 

apps/predbat/tests/test_sunsynk_control.py

@@ -919,13 +919,12 @@ def test_freeze_states_are_expressed_as_zero_power():
     assert not failed, "test_freeze_states_are_expressed_as_zero_power"
 
 
-def test_hold_charge_behaves_as_self_use():
-    """A charge target at or below current SoC must not constrain or freeze the battery.
+def test_hold_charge_keeps_predbat_rate_without_charging():
+    """A charge target at or below current SoC must not trigger a charge, but keeps the rate.
 
-    There is nothing to charge, so the slot should be an ordinary self-use one: no grid
-    charge, and the inverter's full power so the battery keeps serving the house. A
-    zero-power slot would freeze it; an action slot carrying the requested charge power
-    would needlessly cap it.
+    Grid charge stays off - there is nothing to charge - while the slot still carries
+    Predbat's chosen charge rate for that window. Zero would mean freeze, a different
+    state; the inverter's full rating would discard the rate Predbat asked for.
     """
     failed = False
     s = MockSunsynk()
@@ -936,19 +935,27 @@ def test_hold_charge_behaves_as_self_use():
     if state["behaviour"] != "hold_charge":
         print(f"ERROR: expected hold_charge, got {state['behaviour']}")
         failed = True
-    if state["grid_charge"] or state["power"] != 0:
-        print(f"ERROR: hold_charge should not charge and should classify as self-use, got {state}")
+    if state["grid_charge"]:
+        print("ERROR: hold_charge must not enable grid charge - there is nothing to charge")
+        failed = True
+    if state["power"] != 3000:
+        print(f"ERROR: hold_charge should keep Predbat's 3000W rate, got {state['power']}")
         failed = True
     sched = _schedule(reserve=20, charge={"enable": True, "soc": 40, "power": 3000, "start": "03:00:00", "end": "04:00:00"})
     payload = s.build_settings_payload("INV1", sched, current_soc=60, now_minutes=3 * 60 + 30)
-    for n in range(1, TOU_SLOT_COUNT + 1):
+    hold = [n for n in range(1, TOU_SLOT_COUNT + 1) if payload[TOU_FIELD["time"].format(n=n)] == "03:00"]
+    if not hold:
+        print("ERROR: no slot at the window start")
+        failed = True
+    else:
+        n = hold[0]
         if payload[TOU_FIELD["grid_charge"].format(n=n)]:
-            print(f"ERROR: hold_charge produced a grid-charge slot at {payload[TOU_FIELD['time'].format(n=n)]}")
+            print("ERROR: the hold-charge slot enabled grid charge")
             failed = True
-        if int(payload[TOU_FIELD["power"].format(n=n)]) != 8000:
-            print(f"ERROR: slot {n} power {payload[TOU_FIELD['power'].format(n=n)]}, expected the full 8000W rating")
+        if int(payload[TOU_FIELD["power"].format(n=n)]) != 3000:
+            print(f"ERROR: hold-charge slot power {payload[TOU_FIELD['power'].format(n=n)]}, expected Predbat's 3000W")
             failed = True
-    assert not failed, "test_hold_charge_behaves_as_self_use"
+    assert not failed, "test_hold_charge_keeps_predbat_rate_without_charging"
 
 
 def run_sunsynk_control_tests(my_predbat):
@@ -960,7 +967,7 @@ def run_sunsynk_control_tests(my_predbat):
         ("tou_slots_shape", test_build_tou_slots_shape),
         ("self_use_never_zero", test_self_use_slots_are_never_zero_power),
         ("freeze_zero_power", test_freeze_states_are_expressed_as_zero_power),
-        ("hold_charge_self_use", test_hold_charge_behaves_as_self_use),
+        ("hold_charge_rate", test_hold_charge_keeps_predbat_rate_without_charging),
         ("tou_slots_seconds", test_build_tou_slots_seconds_are_dropped),
         ("tou_slots_idle", test_build_tou_slots_idle_is_still_six_distinct),
         ("tou_slots_zero_length_window", test_build_tou_slots_zero_length_window_has_no_effect),