Fix: float slot end crash in yesterday_reconstruct_car_slots (issue #3911)

[springfall2008]

Problem

Fixes #3911 — crash introduced in v8.39.2: TypeError: 'float' object cannot be interpreted as an integer in yesterday_reconstruct_car_slots.

Root Cause

In plan.py, both plan_car_charging and plan_iboost_smart contain a length-clamping block that fires when the battery is nearly full and the charging window supplies more energy than needed:

percent = kwh_left / kwh_add
length = min(round(((length * percent) / 5) + 0.5, 0) * 5, end - start)
end = start + length

round(x, 0) in Python 3 returns a float (e.g. 4.0, not 4), so length and therefore end = start + length become floats (e.g. 1570.0). These float values are stored in the slot dict and later passed to range(start, end, PREDICT_STEP) in yesterday_reconstruct_car_slots, which raises TypeError because range requires integers.

Users with fractional car_charging_battery_size (e.g. 11.9) or iBoost iboost_max_energy values are most likely to hit the clamping path and trigger this crash.

Fix

Wrap the min(...) result with int() at both sites:

length = int(min(round(((length * percent) / 5) + 0.5, 0) * 5, end - start))

This is a minimal, targeted change — only the two clamping expressions are touched.

Tests

Added run_car_charging_slot_integer_test to test_car_charging_smart.py. Three new test cases (smart_int1/2/3_issue3911) confirm that:

• battery_size=11.9, soc=9.9 (exact reporter config) — slot end is int
• battery_size=11.9, soc=0.0 — all slots have int ends
• battery_size=77.0, soc=74.3, loss=0.9 — different battery/loss combination

All existing tests continue to pass (./run_all --quick).

[Copilot]

Pull request overview

This PR fixes a crash in yesterday_reconstruct_car_slots caused by plan_car_charging (and similarly plan_iboost_smart) sometimes producing float start/end minute values after length-clamping, which later breaks range(start, end, step).

Changes:

• Ensure clamped length values are converted to int in both plan_car_charging and plan_iboost_smart so resulting slot boundaries remain integer minutes.
• Add regression tests in test_car_charging_smart.py to confirm plan_car_charging slot start/end are always int for configurations that previously triggered the float-end bug.

Reviewed changes

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

File	Description
apps/predbat/plan.py	Casts clamped slot lengths to int in car-charging and iBoost smart planning to prevent float minute boundaries.
apps/predbat/tests/test_car_charging_smart.py	Adds regression coverage to ensure car charging slots always have integer start/end values.