When the data starts inside an interval (no start bound) and its first value is
Uncertain, the frozen 1.5.378.182 AverageAggregateCalculator integrated the
uncovered span as a ramp from 0 and divided TimeAverage by the whole interval:
GetRegionsInValueSet (ignoreBadData, sloped) overwrites the BadNoData start
region's status with UncertainDataSubNormal in its one branch without a not-Bad
guard. Live AggregateFilter therefore disagreed with HistoryRead and Part 13
§5.4.3.6/§5.4.3.8 ("No Start Bound: Calculate Partial Interval"); QP: Total
188.96 vs 163.96, TimeAverage 9.448 vs 10.931. SDK 2.0.1 stock does the same.
Owner-approved 2026-11-11.
- New app-owned CoveredTimeAverageAggregateCalculator subclasses the baseline
and recomputes only TimeAverage/Total, restoring the Bad status of a region
that starts at a Bad point (only the start bound can). Only such an interval's
value changes; status, timestamps, type and bits are the baseline's. Stepped
and TreatUncertainAsBad=true never reached the defect. CompatibilityAggregate-
Factory routes exactly those two IDs; copied SDK files untouched.
- Golden test: 0 fixture vectors change (every data set has a usable value at
-10 s), asserted. New sweep over late-start variants of every data set (cut
+5 s / +25 s, first non-Bad sample Uncertain, all directions/stepping/configs/
incremental): 150 / 142 of 384 change, each pinned to a baseline-derived
oracle (untouched baseline's value with that sample Good, its status/bits on
the variant itself) - never our calculator. Plus a hand-computed case.
- Live-vs-HistoryRead parity (TimeWeightedAggregator) forward + reverse, no
masks, with discrimination against the pre-#821 baseline; QualityMix now
compares QP's TimeAverage/Total with the live oracle on both SQL backends;
booted-runtime facts test expects 163.96 / 10.93.
- README recorded decision, ServerAggregateConfiguration remarks, oracle
remarks, docs/Historian.md and .claude/rules/historian.md updated.
Claude-Session: https://claude.ai/code/session_01GT67AD99zQQqpLCVm3p7xk
Joseph Doherty
8a0032bfdf