feat(car): raise the maximum supported cars from 4 to 8 (#4545)

* 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>

* chore: update prediction kernel binaries for all platforms

---------

Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: 3 people

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),