feat(car): raise the maximum supported cars from 4 to 8

Some users have more than 4 EVs/chargers registered (e.g. multiple Octopus
Intelligent devices), which the previous 4-car ceiling (CONFIG_ITEMS entities,
KERNEL_MAX_CARS) rejected outright by clamping num_cars down. Doubling the
limit to 8 needs three things kept in lockstep: the shared PREDBAT_MAX_CARS
constant, the C++ kernel's PK_MAX_CARS array size (with PK_PARITY_REVISION/
KERNEL_PARITY_REVISION bumped 5 -> 6, on top of the ABI 4 already on main,
so a stale 4-car binary is safely rejected rather than corrupting the ctypes
struct layout), and the matching ctypes.Structure array sizes on the Python
side (previously hardcoded to 4 independently of KERNEL_MAX_CARS - this
mismatch caused a segfault before the fix).

- const.py: PREDBAT_MAX_CARS 4 -> 8
- prediction_kernel.cpp / .py: PK_MAX_CARS/KERNEL_MAX_CARS -> 8, parity
  revision bumped 5 -> 6, ctypes array fields now reference KERNEL_MAX_CARS
  instead of a hardcoded 4 (car_charging_limit, car_charging_soc, car_soc_next)
- config.py: added car_charging_rate_4..7 and car_charging_manual_soc(_kwh)_4..7
  CONFIG_ITEMS entries so cars 4-7 have HA entities to configure
- Regression tests for the new ceiling: kernel parity, 8-car config
  resolution via the real config_index, MockConfigProvider car rate defaults,
  and reset_inverter's car_charging_limit/soc arrays sized from
  PREDBAT_MAX_CARS instead of a hardcoded 4 (Copilot review catch)

Kernel binaries are intentionally not included - CI's kernel-binaries job
cross-builds and auto-commits all 6 platform binaries once this merges.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: springfall2008

apps/predbat/config.py

@@ -322,6 +322,58 @@
         "enable": "num_cars",
         "enable_condition": "num_cars > 3",
     },
+    {
+        "name": "car_charging_rate_4",
+        "friendly_name": "Car charging rate (Car 4)",
+        "type": "input_number",
+        "min": 1,
+        "max": 24,
+        "step": 0.10,
+        "unit": "kW",
+        "icon": "mdi:ev-station",
+        "default": 7.4,
+        "enable": "num_cars",
+        "enable_condition": "num_cars > 4",
+    },
+    {
+        "name": "car_charging_rate_5",
+        "friendly_name": "Car charging rate (Car 5)",
+        "type": "input_number",
+        "min": 1,
+        "max": 24,
+        "step": 0.10,
+        "unit": "kW",
+        "icon": "mdi:ev-station",
+        "default": 7.4,
+        "enable": "num_cars",
+        "enable_condition": "num_cars > 5",
+    },
+    {
+        "name": "car_charging_rate_6",
+        "friendly_name": "Car charging rate (Car 6)",
+        "type": "input_number",
+        "min": 1,
+        "max": 24,
+        "step": 0.10,
+        "unit": "kW",
+        "icon": "mdi:ev-station",
+        "default": 7.4,
+        "enable": "num_cars",
+        "enable_condition": "num_cars > 6",
+    },
+    {
+        "name": "car_charging_rate_7",
+        "friendly_name": "Car charging rate (Car 7)",
+        "type": "input_number",
+        "min": 1,
+        "max": 24,
+        "step": 0.10,
+        "unit": "kW",
+        "icon": "mdi:ev-station",
+        "default": 7.4,
+        "enable": "num_cars",
+        "enable_condition": "num_cars > 7",
+    },
     {
         "name": "car_charging_loss",
         "friendly_name": "Car charging loss",
@@ -741,6 +793,90 @@
         "default": 0.0,
         "restore": False,
     },
+    {
+        "name": "car_charging_manual_soc_4",
+        "friendly_name": "Car charging manual SOC (Car 4)",
+        "type": "switch",
+        "default": False,
+        "enable": "num_cars",
+        "enable_condition": "num_cars > 4",
+    },
+    {
+        "name": "car_charging_manual_soc_kwh_4",
+        "friendly_name": "Car manual SOC kWh (Car 4)",
+        "type": "input_number",
+        "min": 0,
+        "max": 100,
+        "step": 0.01,
+        "unit": "kWh",
+        "icon": "mdi:ev-station",
+        "enable": "car_charging_manual_soc_4",
+        "default": 0.0,
+        "restore": False,
+    },
+    {
+        "name": "car_charging_manual_soc_5",
+        "friendly_name": "Car charging manual SOC (Car 5)",
+        "type": "switch",
+        "default": False,
+        "enable": "num_cars",
+        "enable_condition": "num_cars > 5",
+    },
+    {
+        "name": "car_charging_manual_soc_kwh_5",
+        "friendly_name": "Car manual SOC kWh (Car 5)",
+        "type": "input_number",
+        "min": 0,
+        "max": 100,
+        "step": 0.01,
+        "unit": "kWh",
+        "icon": "mdi:ev-station",
+        "enable": "car_charging_manual_soc_5",
+        "default": 0.0,
+        "restore": False,
+    },
+    {
+        "name": "car_charging_manual_soc_6",
+        "friendly_name": "Car charging manual SOC (Car 6)",
+        "type": "switch",
+        "default": False,
+        "enable": "num_cars",
+        "enable_condition": "num_cars > 6",
+    },
+    {
+        "name": "car_charging_manual_soc_kwh_6",
+        "friendly_name": "Car manual SOC kWh (Car 6)",
+        "type": "input_number",
+        "min": 0,
+        "max": 100,
+        "step": 0.01,
+        "unit": "kWh",
+        "icon": "mdi:ev-station",
+        "enable": "car_charging_manual_soc_6",
+        "default": 0.0,
+        "restore": False,
+    },
+    {
+        "name": "car_charging_manual_soc_7",
+        "friendly_name": "Car charging manual SOC (Car 7)",
+        "type": "switch",
+        "default": False,
+        "enable": "num_cars",
+        "enable_condition": "num_cars > 7",
+    },
+    {
+        "name": "car_charging_manual_soc_kwh_7",
+        "friendly_name": "Car manual SOC kWh (Car 7)",
+        "type": "input_number",
+        "min": 0,
+        "max": 100,
+        "step": 0.01,
+        "unit": "kWh",
+        "icon": "mdi:ev-station",
+        "enable": "car_charging_manual_soc_7",
+        "default": 0.0,
+        "restore": False,
+    },
     {
         "name": "octopus_intelligent_charging",
         "friendly_name": "Octopus Intelligent Charging",

apps/predbat/const.py

@@ -40,7 +40,7 @@
 INVERTER_MAX_RETRY_REST = 5  # Maximum number of retries for inverter REST commands
 INVERTER_REST_TIMEOUT = 10  # Seconds to wait for a REST response before giving up (local network call, should be fast)
 INVERTER_QUICK_UPDATE_SECONDS = 120  # Minimum seconds between quick inverter data updates
-PREDBAT_MAX_CARS = 4  # Matches PK_MAX_CARS in prediction_kernel.cpp and the car_charging_rate_0..3 config items - the hard ceiling on num_cars
+PREDBAT_MAX_CARS = 8  # Matches PK_MAX_CARS in prediction_kernel.cpp and the car_charging_rate/_1../_7 config items - the hard ceiling on num_cars
 
 # 240v x 100 amps x 3 phases / 1000 to kW / 60 minutes in an hour is the maximum kWh in a 1 minute period
 MAX_INCREMENT = 240 * 100 * 3 / 1000 / 60

apps/predbat/prediction_kernel.cpp

@@ -43,8 +43,8 @@
 // falling back. Bumping makes the loader reject it and use the Python engine, which is the whole
 // point of the check.
 #define PK_ABI_VERSION 4
-#define PK_PARITY_REVISION 5
-#define PK_MAX_CARS 4
+#define PK_PARITY_REVISION 6
+#define PK_MAX_CARS 8
 #define PK_RUN_EVERY 5 // const.py RUN_EVERY
 
 namespace {

apps/predbat/prediction_kernel.py

@@ -32,7 +32,7 @@
 
 # Expected ABI/parity revisions of the shared library (see prediction_kernel.cpp)
 KERNEL_ABI_VERSION = 4
-KERNEL_PARITY_REVISION = 5
+KERNEL_PARITY_REVISION = 6
 
 # Maximum number of cars supported by the kernel (PK_MAX_CARS in prediction_kernel.cpp)
 KERNEL_MAX_CARS = PREDBAT_MAX_CARS
@@ -97,8 +97,8 @@ class PkContext(ctypes.Structure):
         ("export_today_now", ctypes.c_double),
         ("iboost_today", ctypes.c_double),
         ("car_charging_loss", ctypes.c_double),
-        ("car_charging_limit", ctypes.c_double * 4),
-        ("car_charging_soc", ctypes.c_double * 4),
+        ("car_charging_limit", ctypes.c_double * KERNEL_MAX_CARS),
+        ("car_charging_soc", ctypes.c_double * KERNEL_MAX_CARS),
         ("iboost_max_energy", ctypes.c_double),
         ("iboost_max_power", ctypes.c_double),
         ("iboost_min_power", ctypes.c_double),
@@ -169,7 +169,7 @@ class PkResult(ctypes.Structure):
         ("metric_keep", ctypes.c_double),
         ("final_iboost", ctypes.c_double),
         ("final_carbon_g", ctypes.c_double),
-        ("car_soc_next", ctypes.c_double * 4),
+        ("car_soc_next", ctypes.c_double * KERNEL_MAX_CARS),
         ("iboost_next", ctypes.c_double),
         ("soc_min_minute", ctypes.c_int32),
         ("car_soc_next_valid", ctypes.c_int32),

apps/predbat/tests/test_fetch_config_options.py

@@ -363,11 +363,11 @@ def mock_expose_config(key, value):
     # misconfiguration) must not be allowed through - car indices beyond the supported maximum
     # have no HA config entity, which previously crashed get_car_charging_planned() with
     # TypeError: float() argument must be a string or a real number, not 'NoneType'.
-    mock_config.config["num_cars"] = 6
+    mock_config.config["num_cars"] = 12
 
     my_predbat.fetch_config_options()
 
-    assert my_predbat.num_cars == 4, "num_cars should be clamped to 4 (the supported maximum), got {}".format(my_predbat.num_cars)
+    assert my_predbat.num_cars == 8, "num_cars should be clamped to 8 (the supported maximum), got {}".format(my_predbat.num_cars)
 
     print("✓ num_cars clamp test passed")
 
@@ -384,5 +384,25 @@ def mock_expose_config(key, value):
     my_predbat.expose_config = original_expose_config
     my_predbat.args = original_args
 
+    # Test 15: get_car_charging_planned resolves all 8 supported cars against the real
+    # CONFIG_ITEMS/config_index (not the MockConfigProvider above) - this is the exact code path
+    # that crashed with TypeError: float() argument must be a string or a real number, not
+    # 'NoneType' when num_cars exceeded the number of car_charging_rate_N entities defined.
+    print("\n*** Test 15: get_car_charging_planned resolves all 8 cars via real config_index ***")
+
+    original_num_cars = my_predbat.num_cars
+    my_predbat.num_cars = 8
+    my_predbat.get_car_charging_planned()
+
+    assert len(my_predbat.car_charging_rate) == 8, "car_charging_rate should have 8 entries, got {}".format(len(my_predbat.car_charging_rate))
+    for car_n, rate in enumerate(my_predbat.car_charging_rate):
+        assert rate == 7.4, "car {} charging rate should default to 7.4, got {}".format(car_n, rate)
+
+    # Restore real config state for any tests that run after this one
+    my_predbat.num_cars = original_num_cars
+    my_predbat.fetch_config_options()
+
+    print("✓ 8-car config resolution test passed")
+
     print("\n**** All fetch_config_options tests passed! ****")
     return False

apps/predbat/tests/test_infra.py

@@ -9,6 +9,7 @@
 # pylint: disable=attribute-defined-outside-init
 
 from datetime import datetime, timedelta
+from const import PREDBAT_MAX_CARS
 from prediction import Prediction
 from matplotlib import pyplot as plt
 import asyncio
@@ -408,6 +409,10 @@ def get_default_config(self):
             "car_charging_rate_1": 7.4,
             "car_charging_rate_2": 7.4,
             "car_charging_rate_3": 7.4,
+            "car_charging_rate_4": 7.4,
+            "car_charging_rate_5": 7.4,
+            "car_charging_rate_6": 7.4,
+            "car_charging_rate_7": 7.4,
             "car_charging_battery_size_0": 100.0,
             "car_charging_battery_size_1": 100.0,
             "car_charging_limit_0": 100.0,
@@ -509,8 +514,8 @@ def reset_inverter(my_predbat):
     my_predbat.num_cars = 0
     my_predbat.car_charging_slots[0] = []
     my_predbat.car_charging_from_battery = True
-    my_predbat.car_charging_limit = [100.0, 100.0, 100.0, 100.0]
-    my_predbat.car_charging_soc = [0, 0, 0, 0]
+    my_predbat.car_charging_limit = [100.0] * PREDBAT_MAX_CARS
+    my_predbat.car_charging_soc = [0] * PREDBAT_MAX_CARS
     my_predbat.iboost_enable = False
     my_predbat.iboost_solar = False
     my_predbat.iboost_gas = False
@@ -523,7 +528,7 @@ def reset_inverter(my_predbat):
     my_predbat.best_soc_keep = 0.0
     my_predbat.carbon_enable = 0
     my_predbat.inverter_soc_reset = True
-    my_predbat.car_charging_soc_next = [None for car_n in range(4)]
+    my_predbat.car_charging_soc_next = [None for car_n in range(PREDBAT_MAX_CARS)]
     my_predbat.charge_limit_best = []
     my_predbat.charge_window_best = []
     my_predbat.export_limits_best = []

apps/predbat/tests/test_octopus_misc.py

@@ -1872,10 +1872,11 @@ def test_octopus_automatic_config_num_cars(my_predbat):
     original_args = dict(my_predbat.args)
 
     # Test 1: 5 registered devices, 2 suspended - only the 3 active devices should count towards
-    # num_cars and appear in the entity lists. Without this filter num_cars would be bumped to 5,
-    # which exceeds the 4 cars Predbat/the kernel support and previously crashed
-    # get_car_charging_planned() with TypeError: float() argument must be a string or a real number,
-    # not 'NoneType' (car_charging_rate_4 has no config entity).
+    # num_cars and appear in the entity lists. A stale/decommissioned device left in an Octopus
+    # account should not be treated as a car needing a charging slot (and, before
+    # fetch_config_options' num_cars clamp existed, an inflated count could push num_cars past
+    # what Predbat supports and crash get_car_charging_planned() with TypeError: float() argument
+    # must be a string or a real number, not 'NoneType').
     print("\n*** Test 1: Suspended devices are excluded from num_cars and entity lists ***")
     api = OctopusAPI(my_predbat, key="test-api-key", account_id="test-account", automatic=False)
     api.intelligent_devices = {