_resolve_time_with_day_offset() was calling dt_util.now() internally
instead of using the injected now parameter. This caused incorrect date
calculations in tests and any caller that passes a specific reference time.
Also add missing price_rank_* sensor keys to TIME_SENSITIVE_ENTITY_KEYS
in coordinator/constants.py so quarter-hour refresh is registered for all
11 price rank sensors (current/next/previous interval and hour variants).
Rename dt as dt_utils → dt as dt_util (ICN001) across 11 files to follow
the project-wide import alias convention. Apply ruff auto-fixes for import
ordering and collapsing single-item imports throughout the codebase.
Released-Bug: no
Introduced TibberPricesMidnightHandler to prevent duplicate midnight
turnover when multiple timers fire simultaneously.
Problem: Timer #1 (API poll) and Timer #2 (quarter-hour refresh) both
wake at midnight, each detecting day change and triggering cache clear.
Race condition caused duplicate turnover operations.
Solution:
- Atomic flag coordination: First timer sets flag, subsequent timers skip
- Persistent state survives HA restart (cache stores last_turnover_time)
- Day-boundary detection: Compares current.date() vs last_check.date()
- 13 comprehensive tests covering race conditions and HA restart scenarios
Architecture:
- coordinator/midnight_handler.py: 165 lines, atomic coordination logic
- coordinator/core.py: Integrated handler in coordinator initialization
- coordinator/listeners.py: Delegate midnight check to handler
Impact: Eliminates duplicate cache clears at midnight. Single atomic
turnover operation regardless of how many timers fire simultaneously.
