Add a third Akka periodic timer (kpi-rollup) to KpiHistoryRecorderActor that
folds the trailing RollupLookbackHours of raw KpiSample rows into the hourly
KpiRollupHourly table via the idempotent FoldHourlyRollupsAsync upsert, with the
in-progress hour excluded (toHourUtc = current hour start, exclusive). A
_rollupInFlight guard coalesces overlapping ticks (mirrors _sampleInFlight), the
fold is best-effort (no exception escapes a tick), and a missed/failover tick
self-heals via the lookback re-fold. The daily purge now runs BOTH the raw
PurgeOlderThanAsync (RetentionDays) and PurgeRollupsOlderThanAsync
(RollupRetentionDays), isolated so one failure never skips the other.
New KpiHistoryOptions: RollupInterval (1h), RollupLookbackHours (3),
RollupRetentionDays (365), RollupThresholdHours (168, consumed by Task 5).
Validator adds bounds incl. the coherence rule RollupRetentionDays >=
RetentionDays so long-range trends have no data hole.
Claude-Session: https://claude.ai/code/session_01MtdgwpEeCUn6cUA5f1LMPj
Joseph Doherty