Add calculate_coefficient_of_variation() as central utility function:
- CV = (std_dev / mean) * 100 as standardized volatility measure
- calculate_volatility_with_cv() returns both level and numeric CV
- Volatility sensors now expose CV in attributes for transparency
Used as foundation for quality gates, adaptive smoothing, and period statistics.
Impact: Volatility sensors show numeric CV percentage alongside categorical level,
enabling users to see exact price variation.
Implemented configurable display format (mean/median/both) while always
calculating and exposing both price_mean and price_median attributes.
Core changes:
- utils/average.py: Refactored calculate_mean_median() to always return both
values, added comprehensive None handling (117 lines changed)
- sensor/attributes/helpers.py: Always include both attributes regardless of
user display preference (41 lines)
- sensor/core.py: Dynamic _unrecorded_attributes based on display setting
(55 lines), extracted helper methods to reduce complexity
- Updated all calculators (rolling_hour, trend, volatility, window_24h) to
use new always-both approach
Impact: Users can switch display format in UI without losing historical data.
Automation authors always have access to both statistical measures.
Introduce TimeService as single source of truth for all datetime operations,
replacing direct dt_util calls throughout the codebase. This establishes
consistent time context across update cycles and enables future time-travel
testing capability.
Core changes:
- NEW: coordinator/time_service.py with timezone-aware datetime API
- Coordinator now creates TimeService per update cycle, passes to calculators
- Timer callbacks (#2, #3) inject TimeService into entity update flow
- All sensor calculators receive TimeService via coordinator reference
- Attribute builders accept time parameter for timestamp calculations
Key patterns replaced:
- dt_util.now() → time.now() (single reference time per cycle)
- dt_util.parse_datetime() + as_local() → time.get_interval_time()
- Manual interval arithmetic → time.get_interval_offset_time()
- Manual day boundaries → time.get_day_boundaries()
- round_to_nearest_quarter_hour() → time.round_to_nearest_quarter()
Import cleanup:
- Removed dt_util imports from ~30 files (calculators, attributes, utils)
- Restricted dt_util to 3 modules: time_service.py (operations), api/client.py
(rate limiting), entity_utils/icons.py (cosmetic updates)
- datetime/timedelta only for TYPE_CHECKING (type hints) or duration arithmetic
Interval resolution abstraction:
- Removed hardcoded MINUTES_PER_INTERVAL constant from 10+ files
- New methods: time.minutes_to_intervals(), time.get_interval_duration()
- Supports future 60-minute resolution (legacy data) via TimeService config
Timezone correctness:
- API timestamps (startsAt) already localized by data transformation
- TimeService operations preserve HA user timezone throughout
- DST transitions handled via get_expected_intervals_for_day() (future use)
Timestamp ordering preserved:
- Attribute builders generate default timestamp (rounded quarter)
- Sensors override when needed (next interval, daily midnight, etc.)
- Platform ensures timestamp stays FIRST in attribute dict
Timer integration:
- Timer #2 (quarter-hour): Creates TimeService, calls _handle_time_sensitive_update(time)
- Timer #3 (30-second): Creates TimeService, calls _handle_minute_update(time)
- Consistent time reference for all entities in same update batch
Time-travel readiness:
- TimeService.with_reference_time() enables time injection (not yet used)
- All calculations use time.now() → easy to simulate past/future states
- Foundation for debugging period calculations with historical data
Impact: Eliminates timestamp drift within update cycles (previously 60+ independent
dt_util.now() calls could differ by milliseconds). Establishes architecture for
time-based testing and debugging features.
