Fix soc_max_calculated 7-day history being wiped on every Home Assistant restart

[Copilot]

sensor.predbat_soc_max_calculated stores a 7-day rolling history whose trimmed mean feeds battery_scaling_auto/soc_max. That history lived only in the live entity's history attribute, which is ephemeral and not restored after a Home Assistant restart. Both read sites used the live-state-only accessor, so after any HA restart the history was silently reset to a single day, defeating the smoothing and causing soc_max/degradation readings to jump on noise alone.

Core fix

• Inverter.battery_size_tracking() and Inverter.update_soc_max_calculated_sensor() (inverter.py) now read the history attribute via load_previous_value_from_ha() instead of get_state_wrapper(), so the recorder is used as a fallback when the live entity is missing:

existing_history = self.base.load_previous_value_from_ha(soc_max_sensor_name, attribute="history") or {}
...
history = self.base.load_previous_value_from_ha(sensor_name, attribute="history") or {}

This mirrors the pattern already used for savings_total_predbat and inverter_register_writes.

Test infrastructure

• TestHAInterface.get_state hardcoded "" for missing entities when an attribute was requested, ignoring the default argument. This diverged from the real HAInterface.get_state (which correctly returns default) and made the "entity gone after restart, recorder still has it" scenario impossible to simulate, masking this exact bug class. Corrected to honor default.
• Added test_battery_scaling_auto_history_survives_ha_restart in test_find_battery_size.py, which removes the live entity, mocks recorder history via get_history, and asserts the trimmed mean/soc_max are computed as if the history had survived the restart.

[Copilot]

Pull request overview

This PR addresses a Home Assistant restart edge case where sensor.*_soc_max_calculated’s 7‑day rolling history attribute was effectively treated as empty after restart, causing the trimmed-mean smoothing (and thus battery_scaling_auto / soc_max) to jump based on a single day.

Changes:

• Switch Inverter.battery_size_tracking() and Inverter.update_soc_max_calculated_sensor() to read the history attribute via load_previous_value_from_ha() so recorder history is used when the live entity is missing.
• Fix TestHAInterface.get_state() to honor default for missing entities even when an attribute is requested.
• Add a regression test simulating “entity missing after restart but recorder history present” to ensure trimmed-mean behavior is preserved.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
apps/predbat/inverter.py	Uses recorder-backed reads for soc_max_calculated history to preserve the rolling window across HA restarts.
apps/predbat/tests/test_infra.py	Aligns test HA interface behavior with real HAInterface for missing-entity + attribute reads.
apps/predbat/tests/test_find_battery_size.py	Adds regression coverage for history recovery after simulated HA restart.